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And now, a thread documenting the total restoration of a 1950 Series C Vincent Black Shadow that I bought thirty years ago, in October 1991, and that has been waiting patiently ever since then for me to get to it.

[Linked Image]

Prologue

A little over a year ago Buzz Kanter stopped publication of 'American Iron' magazine and at the same time the associated web site disappeared, which apparently had a huge amount of relevant Harley technical information. This year the Vincent Owners Club bought a new package to combine the functions of separate software they had been using for membership, inventory, accounting etc., and they are now about to kill their excellent forum and start a new one using software that's part of the package. In doing so they will effectively lose a huge amount of relevant technical information to the dismay of a number of users of the current forum. Unfortunately, the new forum is not structured in a way that would allow me to continue with my Vincent Black Shadow rebuild thread there, so a month ago I stopped uploading new posts.

Both of the above examples show how fragile information is on the web. One day it seems like it will be there forever, but the next day it can be gone. Or, archived in such a way that it might as well be gone. Of course, in this regard Britbike is no different since there is nothing stopping Morgan from walking away if he tires of running this site.

Still, despite the information being non-permanent, a significant advantage that the web offers a "content creator" over the permanence of paper is the possibility of receiving real-time feedback. For example, the draft text of the novel that later became the movie 'The Martian' was posted online in installments, and reader comments allowed the author to make revisions that corrected scientific inaccuracies..

My original reason for posting the rebuild thread on the Vincent forum rather than here is, obviously, there is much more Vincent expertise there than here. However, at least for the three months my thread was active, that didn't turn out to be as big of an advantage as I had hoped. Anyway, for me at least, the limitations of the Vincent club's replacement forum make posting there impossible. However, here, like there, my reasons for taking the time to post this thread are selfish -- I want helpful feedback as I proceed.

As a final note, the initial posts in what follows will be repurposed from the Vincent forum so, although I will edit them, some references to that other forum may slip by. And, as a final, final note in this Prologue, posting my Ariel rebuild in the Ariel forum didn't seem to hurt the number of views, so I'm posting this Vincent rebuild in the Vincent forum rather than in the Projects forum.

Oh, one last final note. Dumping the 144 pages of old posts from my Word document all at once to bring things up to date would give everyone 144 pages I'm sure no one would have the attention span to read. On the other hand, there's a backlog of ~100 posts that would take three months at the rate of one per day to post here, by which time I would have completed the total restoration (yeh, sure...). So, I haven't yet decided the rate at which to meter out the "old" posts to catch things up to the present as quickly as possible, but in bites that are still small enough to be digestible and, I hope, generate useful comments.

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briefly allow me to christen your thread by going off topic one time.

that film, the martian. didnt they have anybody with a calculator on standby? twice they messed up gas pressure in ways i could not ignore. atmospheric pressure on mars is 0.095 psi, compared to earths pressure of 14.7. so when the astronaut hung a plastic tarp over his damaged garden to hold in the air, each square inch of that tarp had to hold back a pressure of 14.6 pounds.

a plastic tarp ten feet square was holding back 210,240 pounds? no.

then he covered tbe top of his rocket capsule with another tarp to hold back the full force of the atmospheric resistance as his capsule went into orbit?

where can i get tarps like these?

okay ill quit. id rather hear about the vincent. the VOC is behind a paywall, so i cant learn anything there.


i'm old enough to remember when patriotism meant not trying to overthrow the government.
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Originally Posted by kevin
twice they messed up gas pressure in ways i could not ignore.
Two anecdotes come to mind. Someone reading this post, whom I won't name, once said that someone should never let the facts get in the way of telling a good story.

Related to this, another friend, Philip Steadman, who wrote 'Vermeer's Camera' had a gig as an advisor on the film 'Girl With a Pearl Earring'. When they were shooting the scene where a wooden box is used as a camera obscura Philip pointed out to the Director that he had showed in his book what Vermeer's setup would have been like, and it didn't involve anything like a box. The Director replied to him, "yes, but the box looks better, doesn't it?"

I was an advisor on another film where I pointed out to the Director that the projected image starting at 9'10" was at the wrong scale given the size of the room. In that case making it the correct size didn't affect the story, so they redid it at what I calculated to be the correct size. However, had it detracted from the story I'm quite sure I would have been ignored.

There's scientific accuracy, and there's movie making. They only overlap where the science tells a visually-compelling story that the Director likes, otherwise not.

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I am the one, mea culpa, who explained to MMan, no doubt over a glass of very good wine, that, indeed, facts should never get in the way of a good story. I was talking about fiction, of course. As a filmmaker, my job is to tell stories, and I generally try to get the facts right.

Regarding the tarp on the nose of the Martian's rocket ship, it failed. And somehow, everyone who watched that film thought it couldn't possibly succeed. We were right. Still, the movie is great, and two lines stand out: One is, when he realizes he is in deep do-do, he says, "I am going to have to science the sh*t out of this!". And the end, when he is talking to wannabe astronauts, he says,. "When you get a problem, you do the math, solve the problem and move on to the next problem.. questions?"

Now can we get on to this Vincent restoration?

Last edited by NYBSAGUY; 11/23/21 12:19 am.
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Originally Posted by kevin
briefly allow me to christen your thread by immediately going off topic one time.......
Sorry, Kevin, I just couldn't help it, the edits.......I'm still chuckling...........best laugh in quite a while.........
But seriously, this thread will be sure to brighten all our days for a long time.
Let the saga begin!

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Since I want to catch everyone up on work done previously before I start posting ongoing work, this means I'll be aiming at a moving target for a while. There was the work from when I got the bike until around July of this year when I (again) got serious about the restoration, the work from July until "the present" (i.e. today, November 23), and the work I'll be doing from now until "the new present" sometime in December when I finish the "old" posts. But, this only adds a bit of difficulty to writing a few of the section headings.

Background

--------------------------------------------------------
Sidebar: Original vs. Modified vs. Concours

I strongly encourage people to point out errors I'm about to make (or have just made, and need to correct), and welcome advice and constructive criticism on what I'm doing as this thread evolves. However, to be clear from the start, my intention is to restore this Black Shadow as close as possible to original 1950 condition, not to incorporate "reasonable modifications" that some Vincent owners feel are important. I realize this decision isn't universally popular. Despite that, I hope everyone will respect that mine is an informed decision that was not made out of ignorance of the alternatives. Certainly, anyone who feels it is unreasonable not to make "reasonable" modifications should feel free to discuss their personal preferences, but I strongly hope it will be in threads other than this one so as not to detract from what I would like to accomplish. This thread is about returning a Vincent to what it was then, not about what anyone thinks it should be now. Finally, "original" and "concours" are not the same. Original would be to use the same hydraulic dampers as Vincent used. Concours would be to paint and polish the dampers to look even better than when they were new. I'm aiming for original. Note that a "concours" restoration doesn't necessarily mean a "better" motorcycle, because it only applies to the exterior. All too often the skin-deep beauty hides a mechanical disaster on the inside.

While on the subject of original vs. modified, it's worth pointing out that three years ago I crossed the U.S. on what I had rebuilt as an essentially factory-stock 1928 Ariel. The year before that a friend and I took my essentially factory-stock 1954 BB and 1962 DBD Catalina Gold Stars on a 1300-mile ride across Texas. Catalinas came from the factory with straight pipes and without lights, so I had to add those to make it street legal. On our Texas ride the welds on the aftermarket silencer broke after ~800 miles, and the brackets I had fabricated to mount a tail light and license holder broke ~100 miles after that. Both problems likely were influenced by the fact I had rebuilt the Catalina with stock, low gearing whereas it covered those ~800 miles at highway speeds. But, other than those minor issues, and routine evening maintenance on each (lube chains, check oil levels, etc.), those essentially factory-stock bikes, of not too dissimilar age to my 1950 Black Shadow, had no problems. If, as some people seem to believe today, a factory-stock Black Shadow is only suitable as a museum display, not to be ridden, it would mean they were intrinsically unsuitable for riding when they left the showroom. Reading reports and reviews of Vincents written at the time, that doesn't seem to have been the case.

For anyone confused by the term "as-original," at a minimum it will have tires made in 2022 (or '23, or ...), and will have at least a few reproduction parts fabricated in the 21st century. Even replating an original factory part means that part would no longer be exactly as it came from the factory. The fact is, it would be essentially impossible to restore a Vincent to be exactly as it came from the factory 71 years ago even if all of them made that year had been truly identical in every way when they rolled out the door. However, that doesn't mean a bike can't be restored to its "as-original" 1950 configuration (as opposed to concours or modified), which is what I intend to do.
-------------------- end sidebar ----------------------

The rest of this post consists of introductory material to establish the context for people who might be new to the marque. Knowledgeable Vincent people won't miss anything they don't already know if they stop reading here and wait for the next post.

There are posts and videos on the web, and at least one DVD, showing various aspects of a Vincent rebuild, but to the best of my knowledge no one has undertaken to document in detail the complete rebuild of one, either in print or on the web. Since, as will be seen, this Black Shadow will require me to refurbish everything down to the last fastener, I'm taking this opportunity to fill that vacuum.

There are four sets of numbers on a Vincent that determine whether or not a particular motorcycle has the same major components as it had when it left the factory: engine, crankcase (showing the cases were machined together), Upper Frame Member (UFM), and Rear Frame Member (RFM).

[Linked Image]

As a general rule, although with exceptions, frame# = engine# +1900 for both the UFM and RFM.

[Linked Image]

Of course, a bike will perform the same if the four numbers don't match the factory records, and a Rapide easily can be made to be the functional equivalent of a Black Shadow. However, you could buy a nice Gold Star for the difference in price between Black Shadows with numbers that do and don't match, and two nice Gold Stars for the difference between a matching numbers Black Shadow and a "Shadowized" Rapide. As the above certificate and the following Works Order Form indicate, the Vincent I will be restoring is a matching numbers Black Shadow.

[Linked Image]

An important aside for anyone looking for a Vincent to buy is the above 'Certificate of Authenticity' was issued to me nearly 30 years ago. The Vincent Owners Club (VOC) now cautions against anyone buying a "matching numbers" machine based only on one of these old certificates, which they no longer issue. Apparently, the VOC wasn't as rigorous in the past as they are now in verifying the numbers provided to them.

The Completion Note for this bike is dated 20 July 1950, three days after the Road Test Report, showing the customer as I.S.C. Springfield. This was the U.S. distributor, the Indian Sales Corporation of Springfield, Massachusetts, so the bike would have left the factory configured with whatever was required for the U.S. market. For what it's worth, this was the 298th Series C Black Shadow so it was within the first 20% of this model produced. For other Vincent owners, or people contemplating spending a lot of money to become a Vincent owner, copies of these factory forms, and confirmation of the numbers on a given machine, are available through the VOC.

The 1950 Vincent catalog, with The World's Fastest Standard Motorcycle on the front cover, lists among its specifications a top speed of 125 mph and cruising speed of 100 mph to support the cover's claim. At 120 mph a Jaguar XK120 was the fastest automobile at that time, which means a 1950 Vincent Black Shadow wasn't just the fastest standard motorcycle, it was the fastest standard two, three, or four-wheeled vehicle.

[Linked Image]

Compressing an entire book's worth of information into a paragraph, the Black Shadow model first appeared in February 1948 in Series B form, with Brampton girder forks. The Series C, whose major difference was Vincent-designed Girdraulic forks, appeared in December. However, only 7 C-Shadows were produced from then until May 1949, at which time the supply of Girdraulics was sufficient to let them stop producing the Series B after only 74 had been made (although, an additional 4, for a final total of 78, were made over the next twelve months). According to the Vincent Owners Club, 1568 C-Series Vincent Black Shadows were produced, accounting for ~23% of the total number of twins of all four Series (A, B, C, and D), and ~14% of the total Vincent production of singles as well as twins.

To keep these production numbers in perspective, as a very rough estimate, ten times as many BSA Gold Stars were made as Vincent Black Shadows, and nearly as many Honda Super Cubs are made every day as the total 27-year output of the Vincent company (as many Super Cubs are made in 90 minutes as the entire 5-year production of C-Shadows).

I have a fairly complete set of books written about Vincent, with the following photograph showing a number of them.

[Linked Image]

Many of these books deal with the history of the marque and are quite interesting, although not all contain information that is useful for a rebuild.

--------------------------------------------------------
Sidebar: Bibliography

Books I recommend that anyone should have if they will be rebuilding a Series B or C Vincent twin are:

Anon./New England Section of VOC, 'Indian/Vincent Overhaul manual' (Vincent Owners Club, 1976)
Anon., 'Alternative Spares List', The (Vincent Owners Club, 2014)
Bowen, Jeff, Editor, 'Forty Years On' (Jeff Bowen, 1991)
Bowen, Jeff, Editor, 'Another Ten Years: A Continuation of Forty Years On' (Jeff Bowen, c1998)
Ebbs, Stephen, Jeff Bowen, Lyn Bowen and Graham Smith, 'Into the Millennium' (Vincent HRD Owners Club, 2018)
Factory manual, 'Illustrated Rider's Handbook for Vincent Motorcycles' (Vincent, c1950)
Factory manual, 'Vincent Service manual for "B," "C" and "D" Singles and Twins' (Vincent, c1955)
Factory manual , 'Vincent Spare Parts List for the Series "B" and "C"' (Vincent, c1950)
Richardson, Paul, 'Vincent: Motor Cycle Maintenance and Repair Series', 3rd Edition (Vincent Owners Club, 1996)
Stevens, E.M.G., 'Know Thy Beast', 3rd Edition (Vincent Owners Club, 1989)

There are useful books and manuals in addition to the ones on this list, and some of the above factory manuals exist in different editions and as reprints, but I consider this list to be a minimum for anyone planning a rebuild. The last two books in this list are often referred to as 'Richardson' and 'KTB'.
-------------------- end sidebar ----------------------------

Before getting any further into this thread, it's worthwhile pointing out that a Vincent differs in several significant respects from the more common post-WWII Ariels, BSAs, Nortons, Royal Enfields, Triumphs, etc. Obviously, one difference is it is a V-twin. Another is it doesn't have a conventional frame and instead uses the engine as a stressed member. And, speaking as someone who owns and enjoys various models of Ariel, BSA, Matchless and Triumph, Vincents actually are made to a higher standard than any of those more common British marques.

In the 1990s the Vincent Owners Club established a committee to carefully reverse engineer the parts on a Vincent to create engineering drawings so they could be accurately reproduced. The Club also set up a Spares Company that, among other things, arranges production and sales of those high-quality reproductions (available in the U.S. from Coventry Spares). As a proof of concept, approximately 15 years ago a Vincent was completely assembled using just the reproduction parts sold by the Spares Company. This gives a restorer like me a third choice beyond the usual two of either searching for a factory part (NOS or used), or hoping an Indian-made, but deceptively marked as 'made in England', reproduction can be made to fit.

As a final note before I start on the Vincent, when I documented my rebuild of my 1928 Ariel the thread eventually ran to over 3200 posts, of which at least three-quarters were mine. A Word document of just my posts is 427k words and 720 single-spaced pages. The actual rebuild of that bike took me 16 months from its arrival at my house, and might have taken longer had I not faced the hard deadline of the start of the 2018 cross-U.S. Cannonball Rally. Facing no such deadline, my post-Cannonball re-rebuild of the engine and gearbox took twice that long, 33 months. I note this here because I'm not facing a hard deadline for restoring the Vincent (although having it ready in time for the September 2023 Vincent International Rally in California might be nice, that's only a soft deadline), and I'll probably get distracted by other projects along the way, so I make no promise how long this will take, nor how much time might elapse between one post and the next, nor how many total posts there will be before I'm done.

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Summary of My Restoration Work: October 1991–July 2021

The following several posts will catch everyone up to where things stood as of when I restarted the restoration a few months ago. The next photograph shows the bike at the time I bought it in 1991.

[Linked Image]

It doesn't take close inspection to notice some "issues" that will need to be dealt with.

It turns out I'm effectively the second owner from new, and at the time I bought it 30 years ago I was able to speak to the original owner (there was an intermediate owner who purchased it hoping to quickly flip it for a profit). The original owner had committed some unspoken transgression in 1960, resulting in his then-wife pouring gasoline on his hot rod and setting it on fire. The Vincent was parked nearby and was collateral damage in their marital disagreement.

Fire Damage

As the next two photographs show in greater detail, the bike had been in a fire.

[Linked Image]

[Linked Image]

The most obvious question to ask at this point is, what about structural damage from the fire, e.g. annealing or loss of heat treatment?

The original owner told me that he was present at the time and managed to quickly put the fire out. But, is there any way to confirm this? The answer is, yes. Contained within the machine itself is the evidence that lets me infer both the temperature reached as well as how long various components were at an elevated temperature.

Making a long story short, the first important piece of evidence is the fuel tank is intact and shows no sign of fire damage. This means that if there had been even a few mL of fuel in the tank, which would have heated up quickly, it did not reach the auto-ignition temperature of 380 ℃. Had there been a few liters of fuel, which would have heated more slowly, it was not exposed to heat long enough to have its temperature raised to 380 ℃. Further, if the tank held only a tiny amount of vapor, it did not see an open flame and explode, which at a minimum would have distorted the tank.

As can be seen from one of the above photographs, the thin H51 aluminum water excluders on the front brake are intact, which means they never reached the ~625 ℃ melting point for even a relatively brief time. It's important to remember that the thermal time constant of a thin piece of material is much shorter than a thick piece, i.e. the water excluders would heat up much more quickly than a fork leg or engine cover. More precisely, thermal time constant ≈ (heat capacity × thickness2) / (4×thermal conductivity).

The fork blades FF40R and FF40L are made of L40 alloy (I hope this mix of similar-appearing part numbers and materials identification number isn't confusing), whose specifications are in a 12-page publication of the British Standards Institute.

[Linked Image]

My research found that the procedure to straighten a piece of L40 alloy is to heat it to ~510 ℃ for 2 hours to soften it, remove the bend, then follow with a heat treatment to return it to its original 72 Rockwell B hardness. While the un-melted H51 water excluders set an upper limit of less than ~625 ℃ on the temperature that was reached, the thermal time constant of the thick fork leg was sufficient to keep it from annealing during the duration of the fire as evidenced by the 72 Rockwell B hardness that I measured for both fork legs. However, even had the fork leg annealed, I could have returned it to its original specification by simply applying the appropriate heat treatment.

In the middle of the bike it can be seen the carburetor on the right side is intact, but the float bowl is partially melted (the bowl on the left side is undamaged). However, the hoses adjacent to the carburetor on the right are not burned so it's likely the float bowl was empty and that the nearby fire was hot enough for the thinnest portion of the walls of the Mazak alloy to reach the melting point of 380 ℃, although the thicker portions remained below that temperature. Although that's also the ignition point of gasoline, the lack of surrounding fire damage to the hoses makes it unlikely there was fuel in the float bowl. Also, even if it was burning fuel in the float bowl that that caused the damage, it had to have been extinguished fast enough that there wasn't time for it to melt the entire bowl.

Moving to the rear, the top of the Al fender is melted so it reached at least 625 ℃, but the rear tire is intact. However, the shape of the melted area is consistent with something hot that fell on it rather than proximity to the fire. In any case, the melting point of the rubber is ~170 ℃ and the ignition temperature is ~260 ℃ so, although a portion of the thin Al fender melted, the fire wasn't hot enough for long enough to raise the temperature of the thicker, lower thermal conductivity rubber enough to melt or set fire to it.

Anyway, while I suspect its appearance scared off other potential buyers before me, and lowered its asking price, based on calculations such as those briefly outlined above that I made before purchasing the bike, I determined that it was structurally sound. A variety of subsequent measurements confirmed my assessment.

If nothing else, the photographs in this post explain why, by the time this thread ends in the months (years, decades...) to come, I will have described every aspect of a total rebuild of a 1950 Black Shadow, down to the last nut and bolt.

My background in materials physics is directly relevant for evaluating my determination of the fundamental condition of this Black Shadow in light of its horrible apparent condition. Without that background to draw on I, like other potential buyers, might well have steered clear of it.

After the kerfuffle with his then-wife, the owner hauled the Vincent with him for the next 30 years intending to rebuild it, but finally gave up and sold the bike. During this period he collected a few parts for his intended rebuild, such as a set of AMAL's Shadow-only brass 1⅛" carburetors that were included with my purchase. A glass half full aspect of this is the bike was effectively frozen in time only ten years after it was made so there is a reasonable chance that during my restoration I will find that many parts are unaltered.

I've never tried to keep track of how many hours it has taken to rebuild anything I've worked on, but I've noted what other people have written. Flat rate manuals are useless for this (e.g. BSA allowed 15.0 hours to 'completely disassemble, inspect, and reassemble' a Rocket 3 engine 'with new parts where necessary'). I wonder how many readers managed to rebuild their Rocket 3 or Trident engines in just two full days. Without crediting (or blaming) the sources, I extracted the following from my notes:

-- Average Vincent restoration needs ~1000 hours of shop time
-- Vincent restoration needs ~750 hours
-- Strip, refurbish, reassemble and test a Vincent twin is 235 hours
-- Vincent engine rebuild 100 hours
-- Complete restoration of '68 Dunstall Norton takes 260+ hours
-- Complete rebuild of a Scott takes 250 hours.

So, based on the above, I should expect it to take me anywhere from 235 to 1000 hours to completely restore my Black Shadow...

For what (little) it's worth, in 1992 I estimated it would take me a minimum of 500 hours plus $6500 ($12,000 in 2021 dollars) to restore it. I have a folder of invoices from the 1990s that add up to about one-third of that, although there's an uncertain number of additional items I know that I have that aren't represented by those invoices. None of the invoices in that folder are from the now-retired Ron Kemp so it's quite possible additional invoices are in a folder that was in my office on campus that I should probably try to locate now that this restoration is underway again.

Looking through the Vincent images on my computer to try to arrive at an estimate of hours already worked, but mostly just pulling a number out of the air, I'll say I've possibly spent as many as 100 hours so far. Which might sound like a lot, except it averages to just 3 hours per year since I bought the bike...

No matter what the actual dollars and hours expended thus far are, and although I've already "invested" some of the total required, mostly during the 1990s, a lot more remains to be done. Scientifically speaking, time and dollar estimates "always" are off by a factor of π, so I won't be surprised if it turns out to be 1500 hours and $36,000 by the time I'm done. Not that it matters how long it will take, and not that I'll try to keep track of the hours as I work...

As an aside, I "interviewed" a number of well-known Vincent restorers during the 1990s, and kept notes of their advice on various restoration topics. In reviewing those notes, and in light of what I now know, I'd say that at least one-quarter of what they told me about "properly" restoring a Vincent has not stood the test of time. In retrospect, it's probably good I didn't restore the bike at the time because I know a lot more about motorcycle restoration now than I knew then, as well as am much better equipped to do the job properly.

Documenting the Missing and Damaged Parts

My first task at the time I bought the bike was to document as thoroughly as possible what was missing (e.g. the iconic 150 mph speedometer) or too damaged to repair (e.g. rear mudguard). After doing that I began searching for those items through the VOC Spares Co., Ron Kemp, autojumbles, and personal connections, checking them off my must-find list as I located them. For example, the next photograph shows the speedometer I bought at that time, and that I paid an additional $130 in 1993 dollars to have rebuilt.

[Linked Image]

--------------------------------------------------------
Sidebar: Terminology:

Vincent owners tend to refer to parts only by their part numbers, e.g. FT163 or ET29, rather than by their names (magneto cowling and cam follower, respectively), although two major components are referred to by acronyms: UFM (upper frame member) and RFM (rear frame member). Since my hope is to make this thread as useful as possible for as many people as possible, I'll try to mention numbers as well as names wherever it seems relevant to mention both.
---------------- end sidebar -------------------------

Rebuilding the Magneto

As I've written elsewhere, everything I know about magnetos I owe to the late Ken Bell, who also restored Vincents. Not because he knew very much about magnetos, which I learned to my dismay that he certainly did not, but because after falling for his bluster and paying him to restore my first Gold Star's magneto, which failed after 50 miles, I realized I needed to learn to do this work myself.

One result of spending the nearly three decades since then squandering way too much time, money, and intellectual energy on magnetos is that my garage houses what likely is the most comprehensive set of magneto rebuilding and testing instrumentation in existence. Just a few examples are a 400-MHz, 4-channel oscilloscope with high voltage probes that lets me observe the behavior of the primary and secondary circuits to within 2.5 nanoseconds of the onset of ignition, a "megohm" bridge that lets me measure the resistance of capacitors to 1000 TΩ (a thousand, million, million ohms), an impedance bridge that lets me measure the inductance of coils in the range 0.1 mH–100 H to four significant figures, a coil winder for winding my own armatures, etc. Despite this, I hasten to add that I only rebuild magnetos for myself and a few close friends who I can't refuse (and who I can't bring myself to charge for doing it).

Before, and because, my interaction with Ken Bell triggered my obsession with magnetos, I had him restore the Vincent's KVF magneto in the mid-'90s, at the same time as the Gold Star's KNC, so I knew he must have used the same inappropriate condenser in the KVF that failed in the KNC. Also, one of my questions in my initial discussion with him was whether he would magnetize the magnetos, to which he responded that he had an electromagnet. As I discovered on a visit to his home/shop after my rebuilt Gold Star magneto failed, he indeed had an electromagnet. Unfortunately, it was a small electromagnet with pole faces that couldn't be separated wide enough to insert a magneto even if they had the right shape, which they didn't, so I knew he hadn't re-magnetized it after he finished.

In his defense, Ken had answered my question by saying he had an electromagnet, not that it actually was good for anything. Sigh... Oh well, the KVF had to come apart to replace the condenser, which meant it also would have to be magnetized even if it had been properly magnetized before.

The 50° angle of the Vincent's V means one cylinder intrinsically gets a weaker spark from a magneto than the other, which means that returning a KVF to full magnetization after rebuilding it will make an owner's knee last much longer. So, a few years ago I re-rebuilt the KVF myself. Indeed, I found it had one of Ken's guaranteed-to-fail capacitors in it.

A decade or so years ago I conducted a series of tests on potential replacement capacitors and I installed one of the type my accelerated lifetime tests show will last a minimum of 177,000 miles and 51 years. After I installed one of these capacitors I reassembled the magneto and magnetized it using my 84,000 A-turn magnetizer. Lucas calls for using 65,000–70,000 A-turns and, while more than this won't necessarily further improve performance, it ensures the magnetization is at least at the value it had when it left the factory.

The next photograph shows the magneto for my 1928 Ariel in the electromagnet (The KVF uses a different set of pole pieces having a concave shape).

[Linked Image]

[Rebuilding the Magneto: to be continued]

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Sidebar: Electromagnet for Magnetizing Magnetos

I based the design of my electromagnet on requirements given in the 1953 Lucas Workshop Instructions booklet Remagnetisation of Magnetos, after also checking specifications in several texts for magnetizing the half-dozen types of Alnico. The Lucas booklet calls for an electromagnet with a core winding value of 65,000-70,000 A-turns in order to magnetize their post-WWII Alnico-based magnetos.

Incorporating construction principles detailed in the book 'Laboratory Magnets' by D.J. Kroon (Philips Technical Library, 1968), the electromagnet I designed weighs an estimate 225 lbs. and consists of ~4500 turns of 14 AWG wire of total resistance 12.9 Ohms wound on a yoke machined from Armco magnet iron. Since its inductance stores a serious amount of energy at full current, and a DC current is difficult to interrupt without arcing, I use a 20 Amp Variac to ramp the current up and back down over a few seconds. Also, having an electromagnet whose field I can vary continuously with the Variac, rather than only operate on/off, has advantages for my experiments on magnetos. In any case, applying the full 240 V of rectified AC from the wall results in 18.6 Amps and therefore 83,721 A-turns, which is comfortably above the values Lucas recommended for remagnetizing their Alnico-based magnetos. I have an ammeter in the circuit to verify the applied current, and also used this ammeter along with a digital gaussmeter to determine the field vs. current curve of the electromagnet.

At 18.6 Amps I22R = 4.5 kW, which is a fair amount of heat. However, the magnetizer only sees current for less than 10 sec., with less than 2 sec. of that at the full value. Also, the Cu coils are in close contact with the ~200 lbs. of iron so the heat capacity of a lot of metal keeps the temperature rise under control. Still, the 18.6 Amps does warm it up enough to increase the resistance of the Cu wire enough that if I apply a second dose of magnetism right away the current might only make it to 18.4 Amps.

I initially considered designing a water-cooled electromagnet, but as soon as I ran a few calculations I realized that wouldn't be necessary. If the Cu and Fe were in good thermal contact, which they are, and if both had high thermal conductivity (Fe is 4.8× lower than Cu), it would take 50 sec. at full power to raise the temperature by 10 ℃. The way I designed and constructed the magnet it could have a temperature rise of over 20 ℃ without problem. But, to keep the magnetizer from warming by more than ~10 ℃ the throughput would have to be limited to about a half-dozen magnetos per day. I think the highest rate it has had to deal might have been as much as two per year.

I machined interchangeable Armco iron pole pieces with faces shaped to closely conform to the shapes of a variety of Lucas and BTH rotating armature and rotating magnet magnetos to minimize flux leakage. Actually, the operating fundamentals of magnetos don't leave a lot of room for unique designs, so these pole pieces also work on Fairbanks-Morse (and A.R.D., Joe Hunt, and Morris), Splitdorf, Wico, etc. If ever needed, I also have blanks to machine into whatever shape is required.
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As I wrote above, I discovered on a visit to Ken Bell's home/shop after my rebuilt KNC magneto failed that he didn't even have an electromagnet to magnetize them, so the KVF and KNC he had returned to me were pretty on the outside, but useless on the inside. Much the same as is the case for many "concours" motorcycle restorations. Sigh...

[Linked Image]

Completing the story of the magneto:

After rebuilding the KVF I ran it for several hours on my long-term tester, shown here with a Magdyno on it.

[Linked Image]

I built this tester using a reversible ½-hp motor with modified pulleys to fit on the 1:10 taper to spin magnetos at the equivalent engine speeds of 2150, 2800 or 4000 rpm. I also have a thermocouple controller and heating jacket for it to allow long term testing at elevated temperatures, in case I'm ever tempted to ride an old British bike across the Sahara in summer. Although, the Arizona desert in summer is a pretty good approximation of those conditions, which is why I have this testing capability.

Another instrument I use on every magneto I rebuild is a distributor tester that I modified to carry the spark(s) from a magneto to its large-diameter protractor, with the direction of rotation reversible and a tachometer to determine the rotation rate. It can spin magnetos as slow as equivalent engine speed 300 rpm, or as fast as 7000 rpm.

[Linked Image]

I didn't take any photographs when I ran the KVF so the ones I took a decade ago when I rebuilt a friend's Bosch ZEV for his early Harley-Davidson will have to do. With the tester set so cylinder #1 on his 45° V-twin sparked at 0°, the points for cylinder #2 should have opened at 157.5° (360°–45°=315° engine, ÷2=157.5° magneto), but the next photograph shows the spark was 1.3° early on the tester (2.6° engine), at 156.2°.

[Linked Image]

The above photograph shows how this tester determines if the relative timing of multiple cylinders is correct to within ~0.2°, as well as if the timing wanders. For this photograph the magneto was running at 1250 rpm (2500 rpm engine) and I used a ¼-sec. exposure to capture 6 sparks. The protractor is slightly blurred because of vibration of the tester during the long exposure. Although it might appear that the timing was wandering by a degree, the apparent variation is largely an illusion due to the spark finding a different route to earth each time. Note that all the sparks radiate from the same point (to within ~0.2°), which was the tip of the spark wire passing by much too quickly to be photographed with this long exposure. Also, some of the ~0.2° variation could be due to vibration of the tip of this wire in the temporary configuration I used on my tester at that time, since the last ~⅜" was unsupported. This test showed that the timing of the Bosch wandered by no more than ~0.2° from one cycle to the next and, although this photograph only captured 6 sparks, I watched it closely for several minutes without seeing any sign of problems.

Anyway, after rebuilding the Vincent's magneto I did the same test on it. However, since I don't photograph each step with every magneto I rebuild, I didn't photograph it. Also, I can't find in my notes how different in timing the two HT leads were (although, the difference was small enough from the correct values that I considered the magneto finished at the time) so I'll be running the KVF again sometime between now and when I'm ready to install it.

A very important parameter is the speed the magneto needs to spin before it generates sufficient voltage and energy to ignite an engine, since this determines how hard it will be to start the bike. Fully magnetizing a magneto makes a significant difference in this, and I use the variable speed capability of my lathe to determine the lowest speed at which my rebuilt/remagnetized magnetos reliably spark across a 5 mm / 0.200" gap, which approximates the voltage required for the 0.018" gap of a spark plug at the ~125–150 psi in the cylinder.

[Linked Image]

My notes show that both leads on the KVF sparked down to 140-145 rpm (280-290 rpm engine) with the cam at all positions between fully advanced and fully retarded. A Lucas manual says 300 rpm is at the low end of kick-starting speeds, with 500 rpm normal, so the Vincent's magneto passed this test.

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Other Restoration-Related Work

Immediately after buying the Vincent I started compiling a bespoke shop manual consisting of tabbed sections with every piece of technical information I could find in my collection of books and magazines.

[Linked Image]

The tabbed sections in the six binders of that manual are:

ENGINE—I
-- Engine Overhaul
-- Lubrication System; Oil Pump
-- Timing Chest
-- Crankcase and Main Bearings

ENGINE—II
-- Crankshaft, Flywheel, and Connecting Rods
-- Barrels and Pistons
-- Heads, Valves, and Rockers
-- Primary Drive and ESA
-- Clutch

ENGINE—III
-- Gearbox
-- Carburetors and Adapters
-- Exhaust System

CYCLE PARTS—I
-- Upper Frame Member
-- Fuel Tank
-- Girdraulic Forks
-- Dampers
-- Rear Frame, suspension, and Seat

CYCLE PARTS—II
-- Wheels and Brakes
-- Speedometer, Tray, Tools, and Special Tools
-- Propstand, Engine Plates, and Stand
-- Paint, Transfers, Finish, and Fasteners
-- Controls, Levers, Cables, & Miscellaneous

ELECTRICAL EQUIPMENT
-- Lighting System (General)
-- Wiring Harness
-- Head Lamp, Lighting Switch, and Ammeter
-- Dynamo
-- Voltage Regulator
-- battery
-- Horn
-- Tail Lamp and Stoplight Switch
-- Magneto
GENERAL
-- Initial Startup after Rebuild
-- Misc. Information and Techniques
-- General Data and Specifications
-- Fault Finding

I've also made specific variations of such manuals for other bikes I'm restoring because I find them very useful. I don't edit material before adding it so each tabbed section contains a mix of correct, incorrect, and redundant information, as well as alternative approaches to achieve the same end result. I review the contents and do the editing in real time as I work on whatever is covered by a particular section.

Whenever new information has appeared, I've added it, causing the manual to swell to its current size. For example, in the '90s I acquired a fairly complete set of the Vincent Owners Club magazine 'MPH' dating back to the first issue in 1949, many of which have relevant technical information that I added to the manual. Further, the three books listed in the mini-bibliography in an earlier post with Jeff Bowen as an editor are compilations from 'MPH', so they filled in gaps in my 'MPH' collection.

The six-volume manual is currently at ~2100 pages, so imagine the type of technical content that's in 'Know Thy Beast' except printed 8½"×11" and with 8× as many pages. Certainly, someone, somewhere may have assembled as much printed material in making a shop manual of their own, but it's fairly unlikely that very many people have assembled more.

As I write this there is still a huge amount of technical information on the Vincent Owners Club site that can be found by searching the forum. However, when the present forum is shut down that information will only exist on the new forum in pdf form that will be searchable only by title, not by content, so much of it will be effectively lost.

However, for me at least, even if all the information in those six binders were available on-line, it wouldn't be nearly as useful when restoring a bike as having it pre-sorted and on paper.

It's worth mentioning that prior to c2000 useful technical information appeared in each month's issue of 'MPH', but maybe by then everything that could be written, had been written, because the amount of technical information has fallen off to pretty close to zero. The October issue happens to be within reach and, of the 60 pages in it, only 2½ contain anything that I would count as somewhat technical. In any case, seldom does a new issue of 'MPH' contain any useful information for me to add to my shop manual.

The bike came to me with all the tools from a standard toolkit, plus I then purchased the additional tools the Vincent Spares company offers, and made all the special tools described in old issues of 'MPH'.

[Linked Image]

I started labeling special tools like these with a paint pen a few years ago when I realized I had a number of very nice ones for various marques whose function I no longer remembered.

While doing all of the above, not too long after buying the bike I started on the actual restoration. Since I very much wanted to work on the engine, I decided instead to begin with the Girdraulic forks and to save the engine for last, as a carrot to motivate me.

[Linked Image]

I disassembled the forks, had the appropriate pieces Cd plated, and installed and reamed new bushes. I now own a Sunnen hone, and definitely would use it instead of a reamer if I were to do this now. Also, to make it easier to work on the Upper Frame Member (UFM), which also serves as the oil tank, I bought an engine stand and attached a plate with spacers so I could hold it as well as rotate it to any angle.

[Linked Image]

[Linked Image]

Paint

After a lot of time, manual labor, and paint removers so toxic they're banned under the Geneva Convention, I had the fork blades, upper frame member (UFM) and fuel tank ready for paint. Unfortunately, at that point c1995 the restoration hit a psychological brick wall. I had turned the parts over to a shop that specializes in repairing British cars to have their painter take care of them. Unknown to the shop owner (a friend), the painter had just accepted a job at an aircraft maintenance firm and as a "favor" to the owner he had quickly painted my parts as well as others in the shop before moving to his new job. When I retrieved the parts I found runs and drips as well as newspaper stuck to them in various places. In the next photograph you can see that paint is missing from the bottom of the front engine mounting lug, because that's one place where newspaper had been stuck.

[Linked Image]

In the background of the above photograph you can see the fuel tank, which has been repaired and primered, and under the UFM is a box containing the parts for the forks.

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Originally Posted by magneto
This test showed that the timing of the Bosch wandered by no more than ~0.2° from one cycle to the next and, although this photograph only captured 6 sparks, I watched it closely for several minutes without seeing any sign of problems.

i have zilcho experience with any magneto excepting a fairbanks morse unit in an ARD application. i know youve messed with these since you built your magnetizer to accomodate them.

mine has significant spark scatter at speed. possibly as much as 5 degrees. the people at morris magneto explain that this is the nature of the beast.

what sort of spark scatter do typical british magnetos exhibit? what sort of improvrments can reduce spark scatter?

Last edited by kevin; 11/26/21 9:24 pm.

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Originally Posted by kevin
mine has significant spark scatter at speed. possibly as much as 5 degrees. the people at morris magneto explain that this is the nature of the beast.
They all do that, sir. Except, they don't. If your magneto has a 5° scatter of the spark, it's the fault of the points.

Originally Posted by kevin
what sort of spark scatter do typical british magnetos exhibit? what sort of improvrments can reduce spark scatter?
If you look at the photograph of the spark discharging to the protractor, you'll see a bright, sharp light at ~2° before '0' (because I had bumped the protractor without noticing it), with a long magenta tail as the energy of the spark dissipated until finally the spark went out. You'll also see two much-weaker, intermittent rogue sparks at 351° and 10°, which subsequent posts dealt with eliminating. But, the point is, the magneto was spinning at ~2100 rpm so the photograph is a composite of many sparks, all of which happened within no worse than ½° of each other.

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You can’t safely use a magneto that has timing randomly varying over 5 degrees. Is Morris Magneto staffed by people who would say such a thing?


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shades of 4CA, isnt it?

i didnt discuss actual figures with the people at morris. i asked if spark scatter was curable and barry there told me it was not. and im running it with a rubber belt.

i dont know what the actual scatter is, but when i strobe the machine with the ARD, i definitely have to average the image. ill measure. i use a dial back to zero light so ill see what it says.

i recall when the japanese 6CA points first came out there was significant bounce, and you had to decide which of two images to strobe to. didnt like that.


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Part of preparing the UFM for painting was to thoroughly flush the inside. I did this by allowing solvents (acetone and MEK, for sure, and probably trichlorethylene, but I don't remember whether I used anything else) to soak in it for days at a time, followed by replacing with fresh solvent, followed by a different solvent, and repeating the process until the "dirty" solvent looked clean. I then used a peristaltic pump with Tygon tubing to circulate a diesel/Gunk degreasing solution through the tank at a rate of 0.7 L/hr. for several weeks. In total, the tank was subjected to strong solvents of various types for well over a month.

[Linked Image]

The next photograph shows the mechanism of the pump that I used.

[Linked Image]

When both sides of the plexiglas housing are snapped closed they press the Tygon tubing against the three rollers of the drive mechanism, one of which is visible, so at any given moment a volume of liquid is trapped in the tubing between two of the rollers. My pump operates at 6 rpm so that volume of liquid is pushed through the tubing 18 times per minute. The actual volume depends on the ID of the tubing, and the particular "head" that's on my pump unit accepts tubing of a range of sizes that lets me select a flow anywhere between 0.06 mL/rev. and 3.8 mL/rev. With tubing that gives, say, 3 mL/rev., that's a flow rate of just over 1 L/hour.

The advantage of a pump like this is the liquid is only exposed to the inside of the tubing. This means that as long as I use tubing that isn't affected by the properties of the liquid, I can use the pump with liquids that could be highly flammable or very corrosive without problem. Not especially important for motorcycle uses, but if the tubing is inert to the liquid, the pump introduces no contamination whatever.

Inspection of the internal nooks and crannies with a borescope a few years ago shows my cleaning procedure was effective.

[Linked Image]

It takes a bit of experience to "read" borescope photographs, but the above one is at fairly high magnification and shows an area of smooth, clean steel. This inspection was aided by two drawings in an old issue of 'MPH' that provided a road map to the low spot where sludge was especially likely to accumulate.

[Linked Image]

What the drawings show as an oil feed hole is ½"-diameter, at least in my tank.

[Linked Image]

This provides a second access point for inspecting the tank using my borescope's smallest diameter probe, 4.5 mm (0.18").

[Linked Image]

The hole is much larger than 4.5 mm, but the reason for the small probe is it has only a short length of rigid tubing at the end (0.58" long), allowing it to be inserted, whereas the next larger 5.5 mm probe has a longer length of rigid tubing (1.3") so it can't make the required 90° turn.

In a discussion elsewhere with Cyborg he posted a photograph of a UFM that he has with the outlet fitting removed because of some other problem. With that fitting removed there is a ~1"-dia. hole which seems to me allows ample room to inspect and scrape away any accumulation in the sump. Rewelding the fitting would leave the UFM in identical condition as before the start. Why is this approach not used, rather than cutting a huge "manhole cover" that leaves a permanent scar in the UFM?

I realize that today a "manhole cover" is regarded as a "reasonable modification." I can't help but be reminded of the officer during the Vietnam War who was quoted as saying "It became necessary to destroy the town to save it." If I were to clean the UFM today I would do it the same way as I did in the '90s, and would not be the least bit tempted to cut a hole in it. But, that's just me.

After all the work I had done preparing the parts for painting, the thought of possibly doing it all over again after the painter's rushed efforts was more than I was prepared to deal with just then. Around that same time, especially interesting (and time-consuming) things were taking place in my lab at the university, and then in 1995 I bought a Competition Gold Star that needed a fair amount of time to get on the road. Since the effort to get the Gold Star running would be a lot less than needed by the Vincent, it pushed the Vincent to lower priority. One thing led to another and, before I knew it, here we are a quarter-century later.

On p. 114 of his 2nd edition (1960), Richardson he says "The bronze idler gear was superseded by the light-alloy component which weighs less, runs quieter and has stood up to racing conditions." KTB says "The alloy idler has the reputation of shedding its teeth too easily but it is, in fact reliable. Most failures are no doubt due to incorrect meshing, a loose idler shaft on the Series C, old age, or the wrong material in the case of some replacement idlers." Hmm.

Harper's "Instruction Sheet No. 6" dated Jan. 1972 says that the idler gear was switched from bronze to Al starting with engine number 4548, which is approximately 250 after mine. So, if this is correct, the fact mine is Al means it would have been replaced at some point in the machine's short life before flaming out. But, replaced with a "reliable" one, or one of "the wrong material"? Again, hmm.

No matter what, when I get to that point in the engine, my Al idler will be subjected to penetrating dye to look for cracks near the roots of the teeth, and spending time under the metallurgical microscope.

Even though, according to the Harper's sheet, my engine would have come with a bronze idler, and depending what additional information can be brought to light, I would have no problem keeping the present Al (if it turns out to be in good condition), or replacing it with steel, or with bronze. Or kryptonite, for that matter, should they become available again.

But in the interests of resolving inconsistencies, KTB's "shedding teeth too easily" seems to describe a different phenomenon that having some Al scrubbed from the teeth after possibly a large number of miles. Also, as for slithers in the sludge, given that it's now 70 years after the factory switched to Al, and absent detailed histories of the engines, it certainly seems possible that might have been caused by a replacement idler of "the wrong material" that had been used sometime in the intervening 70 years, prior to being re-replaced with something else when it proved faulty.

The best Al alloy to use for this gear isn't necessarily 6061, and yield strength isn't necessarily the best property to judge how long it would last with the sliding contact the gear teeth are subjected to, but the difference in properties with proper heat treatment is illustrative:

6061 Aluminum
temper ___ yield strength
_____________(KSI)
T0 ___________ 12
T4 ___________ 16
T6 ___________ 35

As can be seen, if 6061 were the proper alloy to use, a replacement that had been improperly heat treated would have a 3× lower yield strength. A replacement made with a different alloy of Al could be even worse.

Anyway, when it comes time to remove my idler to inspect it in detail, it would help to know if it came from Vincent or was an aftermarket replacement.

Post-1990s Paint Debacle Work

Well, my work on the Vincent didn't entirely cease after the paint debacle of the mid-'90s. In the late '90s we moved from a house where I had one space in a small two-space garage to work on my motorcycles, to another house where I had two larger spaces in a three-space garage (but, by then there were more motorcycles and machine tools sharing that larger space...). I modified the Vincent's rolling stand into a lift-height (29") version to make the bike easier to work on (assuming I ever would find the time to work on it...).

[Linked Image]

Turning it into a rolling work stand was based on the premise that it would let me pull the bike into a working area, work on it and, when I'm waiting for parts or want to work on something else, I could push it back out of the way. I have three such stands, plus two commercial lifts that aren't on wheels (one of which had been dedicated to my 1928 Ariel since I bought that bike almost four years ago), ensuring I never make too much progress on any one motorcycle. Yes, it's true, for some years I've pretended it's reasonable to rebuild/restore four bikes semi-simultaneously. Although, in my defense, I actually managed to finish five of them, with four "new" ones taking their place -- I re-rebuilt the engine and gearbox of the Ariel after the 2018 Cannonball so I'm counting it twice.

Although I had a lathe, mill, TIG welder, hydraulic press and other tooling at my university lab, during this period I added those items to my home shop. It's great to have full access to these tools even if 30 minutes away, but it is a qualitatively better situation to have them only 30 seconds away. However, although these pieces of tooling added capabilities, they came at the expense of taking up ever-decreasing amounts of working space in that garage.

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In the photo of the tools what is the small rectangular tool with two SHCS. I can not see what it says but think it is Vincent RFM straighter. Third tool down on the left.
Also the lower tool is for the clutch not the ESA.
Glad your back posting on the Vincent. I enjoy it.

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Originally Posted by RPM
In the photo of the tools what is the small rectangular tool with two SHCS. I can not see what it says but think it is Vincent RFM straighter.
Indeed, that's what I wrote on it at the time I made it. However, I don't remember what part of the UFM it would straighten. This points out that simply painting a few words on a special tool is way better than nothing, but not always sufficient. I wish I had attached microdots with full instructions to some of them when I knew what they actually were for.

Prop Stand

Vincents have side stands, "prop stands," on both sides of the bike, on a bracket located at the front of the engine. As shown at the top of the next photograph, the bracket on the right was broken and the stand itself was missing.

[Linked Image]

On trip to England in the late '90s that coincided with the Beaulieu autojumble I was lucky enough to find a complete prop stand that I brought back to the U.S. (but, even pre-911, only after a guard at Heathrow took me aside when my bag came out of the x-ray machine and wanted to hear all about my trip, as well as personally inspect the souvenirs I had packed). Only some years later did I realize that stands for singles are different than for twins, and the one I had bought was a narrower one for a Comet. This also was the case for the magneto cowling I bought at the same time. Oh well (since then I bought the correct FT163 magneto cowling).

Seven or eight years ago the Vincent candle flickered on again and I decided a good way to restart the restoration would be by repairing the broken FT118 prop stand bracket. The next photograph shows the then-present state of the steel.

[Linked Image]

And the next photograph shows it after I had bead blasted it.

[Linked Image]

The next photograph shows it after I used a die grinder and burr on it to prepare for welding.

[Linked Image]

I built up the metal with plenty of weld.

[Linked Image]

Then milled it flat in preparation for attaching a half-round steel bar.

[Linked Image]

I then welded the bar, bored the hole, and milled the flat, resulting in the following.

[Linked Image]

Through the 1990s I had continued to search autojumbles on trips to England as well as buy items from Vincent Stores and now-retired Ron Kemp, slowly checking things off my list of must-find items. As a result, I managed to accumulate all the hard-to-find parts, and much of everything else, that I determined I would need for the restoration (of course, I'll discover new items that are needed during the course of the restoration).

[Linked Image]

In addition to the boxes in the above photograph, a shelving unit held additional parts, along with the forks, tank, and Upper Frame Member (UFM).

However, after repairing the prop stand, the Vincent restoration candle flickered out again and only very briefly flickered on a few times since then. At least, until now.

The Restoration Begins Again

Six years ago we moved again, this time to a house with a detached garage which gave me 1044 sq.ft. (97 sq.m) of workshop space that I had a contractor-friend configure to my specs with laboratory-grade lighting, an excessive number of 120 V and 240 V receptacles, air line with multiple quick-connect outlets, A/C, heat, etc. I have no way of knowing if it's actually true, but it's not obviously false that I have what is possibly the best equipped motorcycle restoration shop between Los Angeles and Dallas.

As mentioned before, recently I completely rebuilt a 1928 Ariel without farming out any of the work other than having new brake linings installed and arced to the dimensions of the drums by Vintage Brake. This rebuild required me to fabricate guides, install a new exhaust seat, weld Stellite on the rockers and regrind the profile, fabricate a new plunger and spring for the oil pump, etc., so it was anything but a paint and chrome-plate restoration.

"Unfortunately," two additional Gold Stars, both requiring work, entered my life after we moved to this new house, along with the 1928 Ariel that I completely rebuilt to use in the 2018 cross-U.S. Cannonball Rally, and then re-rebuilt the engine and gearbox after it. As a result, despite having my bespoke workshop, until earlier this year the only work I had done on the Vincent since moving to my present house was to loosen the ET56 head bolt nuts after having given Silikroil a week to work on them. I also had removed the exhaust system and loosened the rocker covers and many of the screws.

[Linked Image]

As I mentioned in an earlier post, I have the contents of my workshop in a multi-layer Photoshop document. Having finished the Ariel, I used that document to "re-optimize" the layout with the Vincent in place of the Ariel in the work area. The new layout wasn't just a swap of two bikes, so when I made the moves it took two hours, including time spent cleaning oil slicks that revealed themselves on the floor. As an aside, I was struck by the toy-like diameter of the exhaust pipes on my Trident as compared with the massive one on the Ariel. I also was reminded why I dislike the Trident. It's a nice bike when underway, but its 700-lb. weight (estimated) makes it a pig to move around, and a scary pig when doing that on a wet, slick floor. But, I digress...

A previous post has a photograph of the rolling workstand I built to work on the Vincent, taken shortly after I moved into our present house. I know it was taken then because, after the two hours spent reconfiguring the garage, I then had to spend quite a while finding new homes for all the unauthorized items that had accumulated on the top surface (packages of disposable gloves, shop rags, bungee cords, registration document for one of my bikes that had expired 21 years ago, etc.)

After I had the surface of the work stand clean, I then set about moving boxes of Vincent parts from a couple of locations in the garage to the "temporary" 4-shelf shelving unit that I had used during the Ariel rebuild. This rearrangement of boxes wasn't quite the same as rearranging deck chairs, but it wasn't quite not the same. But, it usefully reminded me of where things stood.

After the dust from rearranging the garage had settled, I spent time sitting on a stool staring at the Vincent trying to come to terms with this new reality, and thinking about how best to proceed. Starting from the engine and proceeding clockwise, a Vincent consists of four "modules": engine, rear, top, and front. I've already made good progress dealing with the top (UFM and fuel tank) and front (Girdraulics), so "only" painting and reassembly of those remains to be done. Hey, that's two of the four modules essentially finished, so my rebuild is already half-way done...

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Originally Posted by Magnetoman
I wish I had attached microdots with full instructions to some of them when I knew what they actually were for.
Actually, these days you could add a sticker with a QR code that took you to the relevant page in the manual.

(if you you could be bothered that is)

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Originally Posted by George Kaplan
Actually, these days you could add a sticker with a QR code that took you to the relevant page in the manual.
Excellent idea, although they would have to be micro-stickers to fit on most of the tools.

Although I'm saving the engine until later, curiosity made me remove the timing cover to see what it looks like inside. The photograph shows it, in case anyone can see anything obviously amiss (I'm getting way ahead of myself, but what's the deal with the non-protruding stud to the right of the idler gear?).

[Linked Image]

Also, I was pleased to see the timing cover has the same mating code as the two halves of the engine case.

[Linked Image]

This brings the situation up to approximately July of this year, so the next series of posts will be from that restart until "now", where "now" is November 29, after which they will be from today's now to a near-future now, which likely will be by mid-December if things go smoothly. After that the posts will be contemporary rather than retrospective.

Despite the 1990s having been a time when documentation involved 36 relatively-expensive Kodachrome images per cartridge (equivalent image size ~25 Mpixels), I still managed to capture the essentials of the work I did at the time (I have many more photographs than the ones shown in the posts so far). However, now that digital cameras exist with thousands of essentially-free images per flash drive (although, still with equivalent image size ~25 Mpixels...), I'll be documenting the remainder of this restoration more thoroughly. For example, the folder for the Ariel rebuild I mentioned earlier has 2573 jpegs in it, and I expect the folder for the Vincent won't be any smaller by the time the rebuild is completed some months, years, or decades from now.

Editing Comment: It turns out that simply copying the thread from the VOC forum to here isn't as straightforward as I would have hoped. I should remove all the wanderings in search of solutions that took place between July and now, and only post the solutions that I eventually arrived at. But, that would take a lot of time and effort, so that's not what I'm going to do. Also, I've tried to smoothly incorporate within what follows my responses to suggestions made by people when the posts originally appeared on the VOC forum, but there still will be places where the text doesn't flow as smoothly as it otherwise might. Again, in the interests of saving me time and effort, I haven't done as good a job with editing some of these places as I might have.

Restoration Work: July–November 2021

"Reasonable" Modifications

As I mentioned in my first post of this thread, and was highlighted by several posts that responded to what I wrote, some Vincent owners have collectively decided that "reasonable" modifications that "should"[*] be made to these machines include 12 Volt electrics, electronic ignition, an "elephant trunk" breather, "manhole cover" hole in the UFM, stainless Fasteners, etc. It worth repeating here that my present intention is to be as unreasonable as possible in my restoration, instead returning it to the way it was when it left the factory in 1950. For what it's worth, and whether or not everyone agrees with my intention, I believe I am aware of all the "reasonable" modifications that have been proposed, as well as understand the issues they are intended to deal with. So, although some may feel my decision to restore it to original 1950 factory condition was made out of stupidity, they can't argue it was made out of ignorance. Also, I wrote "my present intention" because I will deal with things as I come to them, and what I find at any given point certainly could influence how I will proceed. Paraphrasing Field Marshal von Moltke, 'no battle plan survives contact with the enemy'.

[*]Although I wrote "should," English lacks a proper word for this, which would be closer to required (in the German sense of the command Sie müßen) in the opinion of some owners.

The engine stand that I modified with a plate to hold the UFM was designed to hold a 2-ft. wide, 400-pound V8 engine so its footprint is larger than it needs to be for my purposes since the UFM only weighs 16½ lbs. As the photograph shows, after 30 years in its former form, I decided to modify it with a shorter front foot.

[Linked Image]

Even though Unistrut is a bit smaller than the opening in the base, out of laziness I used a piece I had that already was the right length (i.e. it sticks out 6" further than the center of mass of the UFM), rather than unearthing a long piece of 2" square steel tubing from the rack, cutting it, and drilling the necessary holes. A length of ¾" Al rod that I tapped ½"-16 at one end serves as a "foot" on the end of the Unistrut.

The next photograph shows the underside of the UFM as bolted to the engine stand, with pieces of rubberized material next to the painted surfaces and a ½" spacer to take care of the offset of the mounting lugs with respect to each other.

[Linked Image]

My first use of the engine stand was to hold the UFM while I removed the hardened masking tape that had been on it ever since it had protected the steering races when it was painted 25+ years ago. After I removed the tape that had protected it from paint, I then removed the paint that had sneaked past the tape. A brass wire wheel on a die grinder took care of that, as can be seen in the next photograph.

[Linked Image]

There's no sign of indentations in either race, and I'm resisting the temptation to make a special measuring tool to check that quantitatively. However, there's plenty of time in the future to give in to that temptation.

After contemplating my choices, I decided to rebuild the dampers and spring boxes next, although thanks to a suggestion by Keith Martin (RPM) I will send my rims to Buchanans to make them round, and then get them to a chrome shop. What is supposed to be the best local plater is fine with doing small batches, but has a 6–8-week turnaround on all their jobs because of high demand. Good, fast, and cheap; is that too much to ask?

Rebuilding the dampers requires painting them, which is another small-batch headache I'll have to deal with many times during this rebuild.

[Linked Image]

There are ~65 pages in the 'damper' section of my shop manual and, judging from the number of 'MPH' articles dating back decades describing how and with what to fill them (not to mention, how far to throw them...), one might infer that they leak. Surely, that can't be the case... Oh, wait, it's not a defect of the design, it's a feature. Instruction Sheet No. 10A from the factory, dated September 1953, blithely notes that "Some loss for fluid from new" is to be expected, basically admitting that leaking fluid is a "feature" of Vincent's design.

Richardson says the dampers should be removed from the bike and refilled every 2000 miles. While the development of a hydraulic damper was a suspension improvement, the friction damper in my 1928 Ariel's forks only needs to be inspected every 4000 miles so it was a step backward in suspension maintenance. In any case, this means I'm about to add to those ~65 pages of articles about the damper since I want the dampers to damp as-original, not leak as-original.

An operational goal of mine in a rebuild like this is to try to minimize the total number of loose parts at any one time. If I counted the numbers in the parts book correctly, the forks are currently in 68 pieces. Since the front damper is needed for assembling those 68 separate pieces into one set of forks, once I've rebuilt the damper and painted the fork parts, I can mount the Girdaulics on the UFM and, ahem, turn to the wheels without adding to the loose parts count. As I wrote earlier, I'm saving the engine for last.

Unfortunately, most of the ~65 pages in the damper section of my manual aren't helpful for the purposes of rebuilding leak-free dampers. The ones that do seem they might be useful ended up at just 7 pages

The first thing I noticed when reading those ~65 pages was that something as simple as substituting X-rings for the O-rings in the D11 piston seal isn't mentioned, which is surprising since X-rings are superior to O-rings for sealing reciprocal shafts. Have I missed an article in 'MPH' discussing the use of X-rings in the dampers? Or, will it be obvious when I look more closely at a disassembled damper why X-rings haven't been mentioned?

The next thing I discovered was the only exploded diagram of the damper that I have in my shop manual is misleading as drawn. There has to be a passage that carries the oil between the inner and outer Concentric cylinders, but the drawing "hides" that passage because the draftsman drew it vertically. To make that passage apparent, I used a darker color for the oil in this slot in D5 in the version I colorized below.

[Linked Image]

The next photograph shows the internal parts of my damper, that came apart exactly as described in Instruction Sheet 10A.

[Linked Image]

After disassembling the damper I attached string to the main body and several of the internal components and hung them overnight in my 5-gal. bucket of Gunk+diesel. The internal components would have cleaned up easily with acetone and a rag, but since I was hanging the body anyway in the hopes of the residue coming off, I hung the other pieces as well.

All the damping action takes place at the bottom of the damper, which is shown in the next colorized diagram.

[Linked Image]

The D6 "valve" is a floating steel disk with a small hole in it, with the OD of the disk ~⅔ the ID of the compartment in the valve housing D5 in which it sits, as shown in the next photograph.

[Linked Image]

On compression, some of the oil in the inner chamber is forced up through the end of the D4/1 piston and through the small passages back into the inner chamber, and the rest of the displaced oil is forced through the small hole in the D6 valve and into the outer chamber. However, on rebound the flow of oil from the outer chamber pushes the D6 valve up, against the screen, so the oil flows through the large area around D6 and thus little resistance is offered to its return to the inner chamber. Hence, the rebound damping is much less than the compression damping.

[Damper: to be continued]

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Originally Posted by Magnetoman
.... my decision to restore it to original 1950 factory condition
Fair enough.

But.

If the actual factory stated that:

Originally Posted by Magnetoman
Instruction Sheet No. 10A from the factory, dated September 1953, blithely notes that "Some loss for fluid from new" is to be expected
Then in that case "original" must mean that leaks should* be expected

* see MM's sidebar for definition of should. smile

Originally Posted by Magnetoman
I want the dampers to damp as-original, not leak as-original
Therefore this statement means that you are already breaking away from your intention to keep it to "original 1950 factory condition"

As it happens I have been rebuilding quite a few hydraulic cylinders recently and my advice is to use modern seals (which might mean making replacement parts to accept modern seals) and make them leak free. However you might choose to ignore this advice in the pursuit of originality. laughing

John

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Originally Posted by George Kaplan
my advice is to use modern seals
Remember what I wrote in the "Editing Comment" near the top of my most recent post. There will be much floundering and grasping at straws in the following posts before I found the perfect, although thus far unobtainable, modern sealing solution.

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Originally Posted by Magnetoman
Originally Posted by George Kaplan
my advice is to use modern seals
Remember what I wrote in the "Editing Comment" near the top of my most recent post. There will be much floundering and grasping at straws in the following posts before I found the perfect, although thus far unobtainable, modern sealing solution.
Of course, I should have realised that you had already got to the solution given that this movie is, at the moment, told in retrospect.

I am interested in why the said seals are "thus far unobtainable"

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Having already read MM's very detailed and interesting account of where the BS restoration got to on the VOC forum (which wasn't much further than it is on this site), I won't say anything about his decisions on the best seals to use on the shock absorbers etc.

The forum debate did lead to some interesting exchanges and as a result, some very useful info has come to light, which I'm sure MM will post in due course.

Last edited by gunner; 11/29/21 9:38 pm.

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Originally Posted by George Kaplan
I am interested in why the said seals are "thus far unobtainable"
Patience is a virtue, and all things come to those who wait. Or, so I'm told, although I have no patience myself, and I'm still waiting on a lot of things, so I can't vouch for either of those statements.

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When facing problems working on a Vincent one should be prepared to go from one problem to the next with great enthusiasm.

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Originally Posted by John Healy
When facing problems working on a Vincent one should be prepared to go from one problem to the next with great enthusiasm.
That's good advice for working on any motorcycle, although with the complexities of a Vincent there may be more problems and/or they may be more inscrutable so even greater enthusiasm is required.

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