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2 things come to mind. First, is that while Simon is undoubtedly correct that greater degrees of accuracy can be obtained through using sophisticated tools and instruments, there probably comes point where the quest for ever greater accuracy is the enemy of "good enough." Particularly for most riders. Second, it is quite amazing the degree of accuracy that talented people can achieve with simple hand tools. I am talking about beating metal for close, almost water tight, fits with nothing more sophisticated than a hammer and a tape measure. My Velo goes down the road nice and straight. It had been thrown down the road before I got it and the wheels were going in different directions. I straightened it with a plumb bob, a tape measure, a 4' level, a string line, an 18" adjustable wrench and a cheater pipe. It works fine. Might of been more accurate if done on an engineers table, but I didn't have access to one, didn't have the money to pay someone else, and if I had to wait until I either had the money or access, the bike would never have gotten back on the road.

Ed from NJ

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Ed,

The most sophisticated tool I use is a vernier height gauge bought of eBay and the surface table cost approx. the same as what some people spend on getting the bike painted. For me it's a question of priorities: get the bike steering and handling at it's best comes before making it look pretty.


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Simon,.I know exactly what you're saying... but... I bet you couldn't find any measurable power difference between what I did and what you do........ The dynamics of a primary chain drive on dual engines at 7500 rpm makes chain alignment more accurate that mine not necessary. Chain harmonics, crankshaft flex, the slight differences in chain pitch as it wears in is calling the shots.. ..A gear drive is what should be used but chain is commonly used because it's something inexpensive and what a guy can do in a home shop....
You noticed the jackshaft primary drive shown in the photos ? Most all dual engine bikes use a single chain linking the two engines....The second dual land speed racing bike naked frame over 200 was at Bonneville in 1970 with two nitro fueled Triumph engines using a similar primary drive...Built by a Brit and ridden by an American..So I figured why not use his idea? The chain is #428 double strand as used on Harley Davidson primary drives... The first jackshaft bearings were destroyed in 15 minutes The shaft was supported by three 8000 rpm rated ball bearings assemblies ....Then I modified a 2005 Saburu rear wheel bearing hub. Large cast iron hub with two 2-7/8" OD ball bearings, using gear oil rather than grease.....This has done the job despite being run beyond the recommended RPM.. Engine phasing is the front left cylinder fires 5 degrees before rear left....
The prototype drive I made from Triumph triplex T-140 running on the three bearings....I had several discussions with John Healy about the three stand chain being intolerant of chain misalignment...After the bearings failed I made the duplex chain drive....I had no designs of any sort for any of this other than looking at internet photos...

[Linked Image]


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Now it seems to me with a Norton Commando frame/engine mount, where you can bend it nearly at will, that when you find some real HP that it will bend like a archery bow when you put that power to the ground with a good sticky road race tire. Now I had an ex Norton dealer work for me who seemed to be able to find some of those elusive horses and when he used a belt he had to stiffen the engine mounting plates or the belt would be laying on the track. Horsepower dose strange things. Stiffen up those plates and he was good to go!

Simon you would be interested in looking at Computrack Boston
http://www.computrackboston.com/category-s/4401.htm

Their system uses a theodolite, and special frame jigs and bench, to make corrections you would be hard to get on a table using a vertical vernier. Yes, they do Norton frames. Besides checking they are also pretty clever at putting things right.

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Sometimes it hard to know exactly how far the high tech approach needs to be taken on grass roots racers like land speed racing. My double engine bike has yet to prove it itself...but the success of my single engine modified production LSR Triumph says a low tech approach can do the job in some situations..John Healy is aware of the very short primary chain life on the unit 650 due to crank flex or harmonics or misalignment under load ............... Since alignment and flex is being discussed....Kevin Cameron speaks about "designed in " flex on Moto GP bikes...Kevin Cameron


79 T140D, 89 Honda 650NT ,61 A10 .On a bike you can out run the demons
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But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
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Originally Posted by edunham
2 things come to mind. First, is that while Simon is undoubtedly correct that greater degrees of accuracy can be obtained through using sophisticated tools and instruments, there probably comes point where the quest for ever greater accuracy is the enemy of "good enough." Particularly for most riders. Second, it is quite amazing the degree of accuracy that talented people can achieve with simple hand tools. I am talking about beating metal for close, almost water tight, fits with nothing more sophisticated than a hammer and a tape measure. My Velo goes down the road nice and straight. It had been thrown down the road before I got it and the wheels were going in different directions. I straightened it with a plumb bob, a tape measure, a 4' level, a string line, an 18" adjustable wrench and a cheater pipe. It works fine. Might of been more accurate if done on an engineers table, but I didn't have access to one, didn't have the money to pay someone else, and if I had to wait until I either had the money or access, the bike would never have gotten back on the road.

Ed from NJ


String, plumb bobs and straight edges can achieve more accurate wheel alignment on cars / automobiles than using lasers.

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Dibnah, really? My '73 911 rear suspension specification is 36.5 - 37 deg. inclination, toe-in 0 +/- 20' deg, camber -1 +/-10' deg. You can measure to that accuracy with string, plumb bobs and straight edges? Theodolite can measure down to 2 seconds (that is 0.0000727" on the edge of a 15" rim).

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Originally Posted by DMadigan
Dibnah, really? My '73 911 rear suspension specification is 36.5 - 37 deg. inclination, toe-in 0 +/- 20' deg, camber -1 +/-10' deg. You can measure to that accuracy with string, plumb bobs and straight edges? Theodolite can measure down to 2 seconds (that is 0.0000727" on the edge of a 15" rim).

I make use a dedicated alignment equipment for cars/trucks....Do you really think an accuracy of two seconds makes a difference on a suspension with rubber bushing mounted trailing arms and the deflection in the various parts as the suspension reacts to road conditions and G forces? I would be surprised if it can hold a degree of accuracy on the road...
i ride a bike with my hands off the bars...If it tracks straight without me applying body English, I figure it's good to go.......... cool


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Think I'll drive to find a place, to be surly"
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maddoman,

in regards to your questions, i have successfully run a newby belt drive and clutch on my pre-unit triton with a triumph box, while retaining an alternator, all within the primary cover.

the newby system uses a pulley with guides on the crank with a non-guided pulley on the clutch, presumably to absorb minor misalignment while running. i set mine up carefully using precision ground straightedges and have not had a problem at all. in my shop i have a blanchard ground (not precision ground) steel table that is large enough to accommodate the entire frame (my profession is a maker of custom bicycles and use the table, and associated measuring tools, to measure my frames to hold tolerances to single digit thousandths over the entirety of the weldment, far tighter than what is accurately measurable using a 4' long, 4" thick blanchard ground steel table as a baseline). i used the table to check the '53 frame and found the front end was slightly out of alignment (no surprise there), while the bolt-on subframe had definitely seen better days and was replaced. since then there's been nothing that i've been able to feel while riding and with seemingly no ill effects or premature wear of the power train or running gear. i'm sure with the tools at my disposal i could get things down to much more accurate as it sits on the bench, but as someone who builds things out of steel tubes in an application where stiffness is a priority, i can tell you that i'd be able to create enough torque with my hands and feet to make a measurable deflection between the crank and main shafts when all is assembled. compared to the torque applied to the frame/3/16" frame tabs/engine plates/shafts when thwacking through the gears on the gas, my hands and feet are not much. should you pay attention when you bolt it all up? yes. definitely. should you worry about it if things seem to work ok? no. once the belt is fitted and running, it will tell you if there is a misalignment by wandering on the clutch pulley or being chewed up by the guides on the crank pulley. if after several rides all is good, you're probably set. if you're defending your championship racing title, please disregard my comments and break out the lasers.

as far as the alternator in the primary cover goes, i spaced the inner cover from the crank case 3/16" using the paper gasket as a template for the spacer (that also meant making a new cover-to-engine-plate footrest spacer). i also had to make a spacer for between the belt pulley and the rotor. now here's the tricky part, not all outer covers are the same depth. in looking for covers in reasonably good shape, i ended up with several pairs (good inners sold as a pair with bad outers, and vice versa), and found that part number 57-1237 (thunderbird marking) is deeper than 57-1601 (no marking). don't know why. i'm sure someone else with more historical knowledge than i can expound. all i know is that with the 1237 part, everything fits, and with 1601, the cover is about 3/16" to 1/8" from closing, with the interference coming from the alternator end. i'm using a 57-1600 inner cover.

the belt drive does run hot! i tried to run it with no vents in the cover early on as i'm loathe to "ruin" original parts, but it was very hot and i got nervy about melting the stator or doing damage to the clutch. i found some covers that had been poorly re-welded and "repaired beyond repair", so i didn't feel bad venting the covers. the airflow helped to dissipate the heat considerably. the outer cover is still hot-ish, but i think it's due to the proximity of the swept back pipe.

as for the oil passage, i used a later model metal crank seal on an aluminum ring jb welded to the case (as well documented by others on this site). i also did not use the rotating breather disc on the cam breather, but used the small reed valve from MAP instead, as well as their larger breather machined into the blanking plate for my unused dynamo opening. all breathers are routed into the frame itself.

i'm certainly no expert in all this, but that's my experience. yours may vary.


Last edited by t ingermanson; 12/08/17 7:12 pm. Reason: forgot to mention power train!
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I have never been a fan of belts on these old clunkers. Admittedly I am more than a bit thrifty. When I was first lucky enough to finds some real HP, and breaking crankshafts, I asked Nourish if he saw an improvement in crankshaft life with people who used belts. He explained that he saw more breakage with belts than with people who used chains.

We also raced against a very clever Triumph builder who made the change to belts (Hayward). I cannot tell you how many times we saw his rider sitting on the side of the track after suffering a belt failure. He eventually got it down and became very competitive. The one thing I have learned about belts, is if you are really getting some HP to the ground there can be a learning curve. And yes, they are expensive with little to gain as far as getting down the track any faster.

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yes, i'm sure the belts can cause more problems than they solve (or maybe just different problems) on these old bikes. i purchased mine due to the fact that my bike had no primary or clutch components when i got it, finding a non-leaking primary case these days is getting more and more difficult, and the newby clutch is fantastic.

i'm not racing my bike, just plodding along the country roads and having a good time. i'm sure there's a difference in application, durability, and wear.

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Originally Posted by DMadigan
Dibnah, really? My '73 911 rear suspension specification is 36.5 - 37 deg. inclination, toe-in 0 +/- 20' deg, camber -1 +/-10' deg. You can measure to that accuracy with string, plumb bobs and straight edges? Theodolite can measure down to 2 seconds (that is 0.0000727" on the edge of a 15" rim).


I check horizontal alignment relative to the thrust line (which includes toe) and also camber, I use linear measurements (easier with tape measure), but back of the envelope suggests plus/minus 2 minutes for horizontal alignment and plus/minus 4 minutes for camber. The trick is to extend the measuring point ahead / behind / above / below the vehicle.

I've never seen anyone using a theodolite to measure wheel alignment! Will it detect deviation over 15" or so? How many theodolites needed for a four wheel alignment?

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Originally Posted by Dibnah
How many theodolites needed for a four wheel alignment?


Buy a pair and let them breed.


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Originally Posted by John Healy
Now it seems to me with a Norton Commando frame/engine mount, where you can bend it nearly at will, that when you find some real HP that it will bend like a archery bow when you put that power to the ground with a good sticky road race tire. Now I had an ex Norton dealer work for me who seemed to be able to find some of those elusive horses and when he used a belt he had to stiffen the engine mounting plates or the belt would be laying on the track. Horsepower dose strange things. Stiffen up those plates and he was good to go.


The biggest force going through any frame is when cornering. The rear wheel wants to stay upright due to centrifugal force and this applies a torque (twisting force) through the frame via the swing-arm frame mounts.

On a Commando the swing-arm pivots on the rear of the gearbox cradle. The cradle plates are made of ¼" steel plate and braced at seven points around the periphery, these being; welded rear iso tube 1¾" dia. welded swing-arm tube 1⅜" dia. top and bottom gearbox mounts and rear crankcase mounts x 3. With the gearbox and crankcase bolted in situ it is a very stiff assembly.

Lateral rear wheel play is due to Isolastic clearances (0.004" to 0.006") which are necessary to allow vertical movement of the drive train and isolate the rider and rest of the bike from vibration.

The angular displacement of the rear wheel is therefore small as the pivot point is effectively the front Isolastic mount.

Quote from "Motorcycle Chassis Design: the theory and practice" by T. Foal and V. Willoughby.

"Despite the much larger trail of the rear wheel, it's slip angle for a given displacement is considerably smaller than that of the front wheel hence both the upsetting effect of the displacement and the restoring force are less significant.'

The three Isolastic mounts: cylinder head, front crankcase and upper rear gear box cradle describe a vertical plane. So the torque applied at the swing-arm tube is countered by the cylinder head iso at the end of the lever-arm which is on a point of line perpendicular to a line between the lower Isolastic mounts.

Where the rear Isolastic is mounted to the frame, those points are heavily triangulated to the 2½" dia spine tube which has very high strength and has very high resistance to torque.

The two biggest problems with the Commando or any frame is rear wheel to frame alignment and alignment of the swing-arm spindle axis. Horizontal and perpendicular misalignment (end and plan view respectively) means that as the swing-arm move's up and down the rear wheel will move left to right and back or vice versa depending on misalignment bias. It's what gives the Commando the so called 'hinge' or 'bendy' feel especialy when going through bumpy corners. The bike can wander even in a straight line.

A "cure" for poor handling bikes was to fit rear shocks with stiffer springs. This reduced swing-arm up and down movement and therefore reduced lateral side to side movement of the rear wheel hence feeling as if the handling/steering was improved and the problem solved.

Anyone interested in motorcycle chassis design should get hold of a copy of the book I quoted from. Available used only - try eBay possibly £30 but worth the money.

Last edited by Simon Ratcliff; 12/08/17 9:32 pm.

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The Norton crank is also very flexy so at any moment it can be inclined upwards/downwards/forwards/backwards. The clutch is also a long way out from the gearbox bearing allowing flex in the gearbox shaft


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Originally Posted by kevin roberts
tony, what was the story on the oil pressure?

I haven't seen the bike since before the July races in Maine, it's at my friend's place....The claim is low oil pressure on the front engine, about 35 PSI instead of 80.He checked the obvious stuff.......Could be a pump or trashed rod bearings...This is the engine that suffered a piston seizure during initial illegal road testing.....I never really found the cause but I modified the oiling system and repaired the engine.. Then was about two hours of flogging the bike on the dyno before for durability testing..Many full throttle runs to 7500 rpm and the engines and driveline were no problem. ....The rear engine had carb flooding issues at the track that comes and goes with no clues.... I think what pilots used to say is true " two engines doubles the risk of an engine failure and fire"..I'll get the tune up straightened out.....The APG 1350 record is about 170 mph and Bonneville and El Mirage...I believe the bike can do it and put a horse face on the Harley guys...


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Think I'll drive to find a place, to be surly"
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Originally Posted by t ingermanson

the belt drive does run hot! i tried to run it with no vents in the cover early on as i'm loathe to "ruin" original parts, but it was very hot and i got nervy about melting the stator or doing damage to the clutch. i found some covers that had been poorly re-welded and "repaired beyond repair", so i didn't feel bad venting the covers. the airflow helped to dissipate the heat considerably. the outer cover is still hot-ish, but i think it's due to the proximity of the swept back pipe.



i have a newby in a unit motor, with a big belt that interferes with the cover. i bought a handful of aluminum spacers and longer case screws, that let me space a stock cover out a half-inch around its circumference, leaving a big gap for cooling and also clearing the belt. my motor is UNF, though, so longer screws are easy to come by.

http://www.aluminumspacers.com/?gclid=EAIaIQobChMIya2Gzrv71wIVSY1-Ch32zQ1bEAAYASAAEgLeq_D_BwE


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Interesting discussion.

I ran a race bike 4 or 5 years with chain primary drive; a box of spare chains for the front sprocket changes as it had a fixed rear sprocket. I might have broken a chain once.
I then built a 350 from bits & fitted a belt drive. Simple as that, just fitted the clutch & front pulley, adjusted the belt for correct "slack", tightened gearbox adjuster etc. & raced it fairly successfully.
In 10 years racing I broke the belt once after I'd had the gearbox out & back in a hurry. After that I fitted "fixed distance" spacers in the gearbox slots & had no more breakages. Ok this was only a 30bhp bike but it spent most of it's life at 7000 + rpm. The belts lasted years. They were of course very well ventilated. The belts were Optibelt /Optiflex AT10 polyurethane belts, steel reinforced. They have some oil resistance. There may be others with even more oil resistance if it is an issue.
In an ideal world I would have checked everything for perfect alignment but beyond some good squares & straight edges I didn't have the equipment or the money to pay someone else to do it. Come to think of it I didn't even know it could be done any better...;-)

To contrast, a mate had an A10 with a belt drive fitted (professionally I think). We went touring on our bikes & his belt broke on the 2nd or 3rd day. It had been very hot, there must have been a lot of expansion of engine /gearbox plates., the belt got too tight &... thwack. Maybe it was set up a little tight. He was a very big guy & the bike had a fair amount of torque.
In general, from my race track experience belts don't appear to break any more often than chains.

I understand something putting out more power like a T150, would be more likely to break belts & also chains, let alone a big bore / highly tuned motor. I can see that setting up with these motors might require a little more care.




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I believe chains break when some links seize ...Sportsters making north of 120 HP don't normally break a #30 three strand very similar to the Trident/T140 chain..


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Think I'll drive to find a place, to be surly"
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maddoman,

just checked another outer primary cover numbered 1232, and it has the same depth as the 1237. the 1232 has the "speed twin" marking on it.

best of luck on your project.

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Originally Posted by John Healy


Simon you would be interested in looking at Computrack Boston
http://www.computrackboston.com/category-s/4401.htm

Their system uses a theodolite, and special frame jigs and bench, to make corrections you would be hard to get on a table using a vertical vernier. Yes, they do Norton frames. Besides checking they are also pretty clever at putting things right.


Main advantage of the above system over a surface table is that the bike dosen't have to be stripped down for checking. But if the bike has not suffered from crash damage then it will have to be taken apart to correct misalignment - bending a frame that is'nt bent to correct misalignment will create further misalignment else where.

Advantage of a surface table and parallel blocks over the theodolite system is simplicity and repeatabilty. When working from solid, fixed horizontal and vertical planes you're working in 3D so the surface table is equally as capable as the theodolite - and you don't need frame jigs which can add to inaccuracies unless accurately made and then checked on something like......a surface table! They've been used in engineering for probably over a hundred year's.


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Originally Posted by Simon Ratcliff
The biggest force going through any frame is when cornering.


Or possibly when accelerating, or when braking, or when hitting bumps in the road, or the frame-breaking vibration forces from some engines.


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Accelerating hard over bumps and ripples is brutal on chains, belts and gearboxes


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Originally Posted by triton thrasher
Originally Posted by Simon Ratcliff
The biggest force going through any frame is when cornering.


Or possibly when accelerating, or when braking, or when hitting bumps in the road, or the frame-breaking vibration forces from some engines.


Acceleration forces will only have an effect between the gear box and rear wheel sprocket so limited to the swing-arm and swing-arm bushes I think. Braking and bump forces will be largely dissipated by the suspension. Engine vibration is a frequency and only a problem when the frequency is the same as the natural frequency of the frame (resonance) and can lead to fractures. It's a very small force applied many times in quick succession and will not effect wheel alignment in the short term. It certainly won't bend a frame which is what I was pertaining to.

Last edited by Simon Ratcliff; 12/09/17 5:34 pm.

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Originally Posted by Simon Ratcliff


Acceleration forces will only have an effect between the gear box and rear wheel sprocket so limited to the swing-arm and swing-arm bushes I think.


I'm sure the engine is involved.

Quote
Braking and bump forces will be largely dissipated by the suspension.

The front brake and the bumps put a fair old stress on the frame, through the steering head.


Quote
Engine vibration- blah blah blah blah blah blah -can lead to fractures.

That's what I said.

Quote
It's a very small force applied many times in quick succession and will not effect wheel alignment in the short term.

"Affect."

Quote
It certainly won't bend a frame which is what I was pertaining to.

You should have said so.


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