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With the gearbox apart and degreased, it was time to look at the bearing that resulted in a trail of several gallons of corn head grease from one side of the U.S. to the other.

[Linked Image]

As can be seen, there's only a tiny gap between the case and the inner race, which any reasonable person would have thought makes it nearly impossible for much grease to escape via that route. Further, the bearing is near the top of the gearbox case, whereas any reasonable person would have assumed most of the "semi-liquid" grease would pool at the bottom. But, if a tiny amount of grease did manage to sneak by between the case and inner race, it would find clear sailing from after that.

[Linked Image]

Because of that, three years ago I machined a teflon spacer that was a close fit between the gear at that end of the mainshaft and the case, which any reasonable person would have thought was belt-and-braces overkill for blocking that escape route.

[Linked Image]

But, as the first photograph in an earlier post shows, "semi-fluid" grease can deceive you into thinking it's semi-solid when stopped, but it obviously turns super-fluid when the engine is running.

Chaterlea25 and one other person who I don't remember (but thanks to both) told me of a bearing with shields on both sides (used in something like a Lambretta?) that had the correct dimensions, but they waited to tell me about that bearing until after I had rebuilt the gearbox three years ago and it was too late to do anything about it (damn you Chaterlea25 and one other person). So, I hope this bearing slows the outflow of the superfluid grease.

[Linked Image]

Yes, I agree that any reasonable person would say it will stop the grease, but once burned, twice shy. I'll be happy if it slows it.

The other issue is whether or not the gearbox needs new bushes. Here I'll say any motorcycle rebuild that is done without needing a lathe is not a real rebuild. The two bushes on the layshaft are seriously worn.

[Linked Image]

"Seriously worn," as in at least 0.020". There's enough wear that the layshaft is quite loose in them, and they're loose in the bearings (they should be press fits) as well, so precise measurements would be pointless. But, other than that, everything else inside the gearbox looks to be fine. I have three types of bearing bronze in appropriate sizes on the shelf, so after deciding which to use it shouldn't take too much time to lathe, drill, ream, press and hone to have the layshaft good as new again.

Assuming it was an unnoticed drop in grease level early in the Cannonball that was responsible for the wear, rather than an intrinsic design flaw or a lubrication issue of the Morris K400EP plus 50cc of 90W, the new shielded bearing, plus paying close attention to the level and watching for the possible appearance of gold flecks, should take care of the problem.

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Looking back through the many pages in the thread, it appears that it was me who suggested the sealed bearing, which was actually intended as a Vespa main bearing, see This Post number #745963 on the 18 Aug 2018.

The link in the original post to the eBay supplier doesn't work any more, but you can still get these bearings on eBay UK, search for part no 98305-2RSC3 Vespa VN1-2-3-150S-160-GS Crankshaft Bearing 25x62x12mm, or see This Link, Henderson bearings are the supplier

Pity it didn't get to you in time for the Cannonball but there's always next time .....

Just wondering about the cause of the bronze bushing wear, was it lack of grease or some other factor?

Last edited by gunner; 05/09/21 10:18 pm. Reason: updated spelling and clarified links

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Hi MM and All,
It would seem easy to blame others in hindsight!!!
After the low level of lubricant was initially found, my "maintenance" for the rest of the event was to stuff and spoon as much corn head grease into the gearbox as was physically possible every evening
The other bike in our group the HD which Tom rode early in the event also ran low on gear oil on day one/two, they have really porus casings which is something I later found out.. The HD box had a lip seal fitted to the drive side and I fitted a sealed bearing to the kickstart side
The HD boxes only hold a half pint of oil from memory

If I remember correctly, once the sealed bearing had been located I offered to order it from Germany and bring it withe me to Portland Maine
in the hope it would arrive here in Ireland before we left for USA less than two weeks after Gunners post on Aug 18
However You declined the offer !!
Subsequently after the event I did order two bearings, one for MM and the other for Paddy G and pressed one into your cold ungrateful hand the next time we met


LOL
John

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Originally Posted by gunner
looks like it was me who suggested the sealed bearing,
Thank you again for alerting me to that bearing and, again, damn you for not telling me in time to install it before the Cannonball.

Originally Posted by chaterlea25
pressed one into your cold ungrateful hand the next time we met
If ungrateful, which I deny, it only would be because the idea of rebuilding the gearbox in a motel parking lot would be as absurd as... well, as absurd as deciding to install a new valve guide in a motel parking lot. Which, obviously, no one in their right mind would even consider doing.

The latest sign of my country's crumbling infrastructure was waking up today to find the neighborhood had lost power at 1:30am, with the utility's estimated time to restore it not until 6pm. Then, a few hours later, they updated that to 8am tomorrow. However, although the map still shows the power is out very close to us, ours was back on after "only" eleven hours in the dark.

After we lost power for 24 hours last summer, on what turned out to be the hottest day of the year, I bought a portable generator that I put to good use this morning powering the coffee maker -- first things first -- and then for topping up the refrigerators twice after that. Anyway, as a result of not having power for even the lights in the garage, let alone the lathe, there has been no progress to report on the Ariel as yet today. I have the A/C on in the garage now but it may not drag the temperature down before I lose interest in working on the bike (along with the heat, several Mother's Day mimosas add to my lethargy).

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Since both Chaterlea and myself appear to be Dammed and your local power supply infrastructure is fickle, together with the gearbox issues, I can imagine your frustration, the following video from a band last seen when I was about 19 immediately sprang to mind, Smash it Up by the Dammed.

I would have a couple more mothers day mimosas, sit back, relax and start afresh in the morning smile

[video:youtube]
[/video]

Last edited by gunner; 05/09/21 11:24 pm.

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Originally Posted by gunner
have a couple more mothers day mimosas, sit back, relax and start afresh in the morning
I took your excellent advice to heart. Also, it gives me the opportunity to weight my bronze options.

As a reminder, the gears on the mainshaft turn with the shaft so those gears don't have bushes but, unlike "modern" BSA and Triumph gearboxes, the gears on the layshaft turn on the shaft, which itself doesn't turn. The rear wheel has a diameter of ~27" so it makes 747 turns/mile. At 50 mph the wheel turns at 622 rpm so the mainshaft as well as the layshaft gears turn at 47T/23T × 622 = 1272 rpm.

I have a spec sheet for every material I used in rebuilding the Ariel in my workshop Manual so it's easy to look up what I used for various applications, and compare the specs with how the material performed. It's important to note that although the bushes in the gearbox wore out, those were the ones that came in the bike so I don't know what material they were made from. As I think will be apparent when the photograph is on your computer screen, the bush has a slightly more redish color than the SAE660 bronze next to it.

[Linked Image]

PB1 Phosphor Bronze. "Traditionally used in heavy load applications run at high speeds." This is the bronze Chaterlea25 recommended (and sent me a slug of) for use in the small end of the rod.

C544 Phosphor Bronze. "an excellent material for bearings because of its high machinability and resistance to wear." I used this for the timing-side crankshaft bush, and it survived unscathed after a steady diet of heavy loading at ~2500 rpm for most of 3500 miles. Most sources list C544 and PB1 as having the same composition.

SAE660 (C932) Leaded Tin Bronze. "The standard bearing material for light duty applications... hard, strong and resistant to wear... Less dependent on lubrication than other alloys." I used this for the camshaft bushes.

In addition, I have four more choices on the shelf that I didn't use in the rebuild, three of which are commonly used as valve guides

SAE863. Oil impregnated sintered bronze that is higher strength than SAE 841 (Oilite), but still of moderate strength for low speeds.

C630 Nickel Aluminum Bronze.

Ampco 18 Aluminum Bronze

Manganese Bronze. This is in the form of two valve guide blanks I bought from Kibblewhite very early on.

So, seven bronzes to pick from for this moderate speed, relatively low load application. I like overkill, so I'm tempted to go for the C544/PB1, but the lubrication comment for SAE660 makes me wonder if it would be a better choice for this application. The timing-side C544 bush received steady oil lubrication that dropped onto the rotating shaft, whereas centripetal force of the spinning layshaft gears will tend to keep the heavier grease lubrication from reaching the stationary shaft.

What I'll probably do is use the C544 and then cut spirals on the ID in the hope they help suck the grease in. The C544 bronze is strong enough, and the load light enough, that the loss of surface area won't affect the ability of the gears to handle the load.

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Is one of the three Oilite? I still think it has a higher survival rate in situations where lubrication might get iffy at times. Although.... the iffy lubrication may have more to do with lack of clearance because of improper installation. Who knows.

More importantly congrats on the latest addition.

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Originally Posted by Cyborg
Is one of the three Oilite? I still think it has a higher survival rate in situations where lubrication might get iffy at times. Although.... the iffy lubrication may have more to do with lack of clearance because of improper installation.
One of my selection of bronzes is a heavier-duty version of normal Oilite, but I need Greaselite.

I have 16 ball, roller, and needle bearing catalogs, but none for plain bearings. However, I can infer enough from the technical sections of some of those catalogs that clearance is critical, and the "normal" rule of thumb of 0.001" for each inch of diameter used for oil-lubricated bushes doesn’t apply. However, it's going to take a bit more research to find what clearance does apply.

Three years ago, before I discovered the gears in my gearbox didn't correspond to the code stamped on the case, I bought a set of the ones I wanted that someone in the Ariel Club had arranged to be made and advertised in the club newsletter. Because I found I didn't need it, and they had quickly sold out, that set then went to a friend in Ireland, where it turned out not to fit his gearbox (things were changing quickly around '28-'29 and his gearbox has a speedometer outlet that mine doesn't). It's now at my Cannonball partner's house in Dublin waiting for me to bring it here once covid is under control.

Anyway, the point I'm finally getting to is I remember the "feel" of that gearset, and it had very little clearance. In light of experience with my own gearbox, and what I've learned so far, I wouldn't be surprised if the clearance the machinist used in making that new gearset was based on the 0.001" rule, rather than whatever it will turn out that semi-fluid grease needs.

update: The most authoritative paper I've found so far, taking into account rotation speed, viscosity, hydrodynamic force, temperature, etc., recommends a clearance of

0.0015"/inch (=0.00094" for a 5/8" shaft), or alternatively 0.001"/inch plus 0.001" (=0.0016") with a maximum of 0.002"

Originally Posted by Cyborg
More importantly congrats on the latest addition.
Thanks for that. We couldn't be happier.

Last edited by Magnetoman; 05/13/21 9:53 pm. Reason: was missing a 0 in the update
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Originally Posted by Magnetoman
What I'll probably do is use the C544 and then cut spirals on the ID in the hope they help suck the grease in...
How about getting all the various leak paths under control so a lighter oil would stay in. I'm sure there are more of them than that one the double sealed bearing is intended for. Those bronze bushes would appreciate it.

Just thinkin'.

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Originally Posted by Stuart Kirk
Originally Posted by Magnetoman
What I'll probably do is use the C544 and then cut spirals on the ID in the hope they help suck the grease in...
How about getting all the various leak paths under control so a lighter oil would stay in. I'm sure there are more of them than that one the double sealed bearing is intended for. Those bronze bushes would appreciate it.

Just thinkin'.

That would mean you could drain it and get an indication of the horrors occurring inside. Perhaps grease is better...

MM... I assuming you mean oilite and grease filled gearboxes don’t mix?

Ps.... when I asked about oilite, I hadn’t seen the previous post... posted at the same time? Although my reading comprehension is suspect at times.

Last edited by Cyborg; 05/10/21 3:35 pm.
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Originally Posted by Cyborg
I assuming you mean oilite and grease filled gearboxes don’t mix?
As discussed below, I think the underlying problem was the thickness of the grease (well, the problem underlying the thickness of the grease was the leaking of the gearbox). The measures I plan to take should address that and, if not, it will be the next owner's problem to make new bushes and figure out different measures.

Originally Posted by Stuart Kirk
How about getting all the various leak paths under control so a lighter oil would stay in.
Interestingly, grease didn't exit through the main drive bearing, or any of the other potential paths. I don't seem to have any photographs of the side of the case after removing the sprocket, but note that there is no sign that any grease came out between the bush and mainshaft, nor any sign at the bottom of the case that grease had oozed to there, either.

[Linked Image]

Unlike on "modern" BSA and Triumph gearboxes, there is no oil seal on the drive side. However, as the next photograph shows, there is a sealed bearing. Although the splines and the bush provide two potential leakage paths, it doesn't appear the grease took advantage of either.

[Linked Image]

All the action was at the other end of the mainshaft, where grease just didn't ooze out, the gearbox did an excellent job of pumping it out.

Ariel's instructions call for adding a "egg cup" of oil to Vaccum Mobilubricant Extra Soft grease, which I converted to modern Imperial units as 50 cc of 90W, and which Morris Lubricants converted to being equivalent to their K400 EP Semi-Fluid grease. However, that 50 cc would have been pumped out of the gearbox early in the ride so the gears spent most of their miles lubricated by "pure" corn head grease. At NLGI consistency 0 it is one grade thicker than the K400's consistency 00, which I now suspect further contributed to lubrication problems. The issue with using thicker grease in a gearbox is the spinning gears can cut a cavity in it that keeps the lubrication away from where it needs to be.

A lubricated bush wouldn't have shown any sign of wear in only 3500 miles so, assuming the original bushes were made of an appropriate bronze (i.e. not made of brass), evidence strongly points to it having been a lubrication issue, and circumstantial evidence points to it having been caused by a too-thick grease. After rebuilding the gearbox I'll refill it with K400 and hope Morris is right about 00 being the appropriate consistency for this purpose, to which I'll add two egg cups of 90W. Maybe even three. Having experienced the consequences, I'll keep close track of the exit points to make sure the 90W stays in. And, if it doesn't, I'll keep it replenished.

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There's an interesting website which discusses the various grease consistencies, their NLGI and ASTM worked penetration together with a foodstuff analogy ranging from Ketchup to Soft Cheese, see This Link.

They mention that NLGI grades 000 to 0 are useful for enclosed and centralized applications such as gear boxes, where grease migration is not an issue. However, as we have seen migration is an issue in your case. Their analogy is that the 00 has the consistency of yoghurt whereas 0 is like mustard.

It would be interesting to know what the consistency of the original Vacuum Mobil Lubricant Extra Soft grease actually was and why they thought it necessary to add EP gear oil. Perhaps the grease was something much thicker like NLGI 2 (Peanut Butter) which would have leaked out much slower and the EP oil was to help keep the gears lubricated?


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MM, this is a bit of a stretch, but could it be that the gearbox became pressurized due to the extended periods of your ride?
Norton gearboxes had insufficient breathing, and their final two years saw the addition of a small breather nipple to the outer shell to relieve pressure build up.
.. Gregg


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Originally Posted by gunner
Their analogy is that the 00 has the consistency of yoghurt whereas 0 is like mustard.
That's a culturally-biased website. Depending on location in the world, yogurt varies widely in consistency, as does mustard (in the U.S., ranging from nearly liquid mustard in a squeeze bottle, to quite solid coarse mustard in a jar).

Originally Posted by gunner
It would be interesting to know what the consistency of the original Vacuum Mobil Lubricant Extra Soft grease
Correction -- it would be very interesting to know. Although I don't remember the details, I do remember that three years ago I researched this as extensively as possible so I must have had what I thought was a good reason for selecting Morris K400 as a reasonable equivalent. I do remember that the U.S. distributor of Morris products doesn't import it, but they added a can to their next order from England and it showed up on my doorstep some weeks later.

Originally Posted by gREgg-K
could it be that the gearbox became pressurized due to the extended periods of your ride?
Although I could instrument the gearbox (or just add a breather), I have no way of knowing. It certainly doesn't seem out of the question.

As can be seen in the first photograph, a pin in the layshaft that keeps it from rotating had broken off.

[Linked Image]

The pin was hanging by a thread when I removed the shaft from the outer case so the shaft had not been able to rotate, but I needed to reattach it. I used the case itself as the jig to ensure proper alignment of the pieces and attached the pin with Al bronze to minimize the input of heat.

[Linked Image]

A few minutes in the lathe had the shaft (nearly) as good as new again.

[Linked Image]

I tapped the two bushes out of the layshaft gears and found their ODs are different, which seems a bit surprising. Since the bushes are worn, more relevant are precision measurements I made of the IDs of the gears at either end. At one end the ID is 0.8125 (13/16"), and at the other end it's 0.875" (⅞"). Although the designer at Burman might have had a good reason not to use the same bore all the way through, his reasoning escapes me. The bushes are shown next to the gear cluster in the next photograph.

[Linked Image]

To make the oil holes in two of the gears easier to see in the photograph I put small cap screws in them (the gear at the bottom in the photograph does not have a hole). The bush at the top has a hole at the same location as the one in the gear, while the bush at the bottom doesn't have a hole but does have a straight groove running its length. However, I don't know if these have the lengths of the ones that originally would have been in the gearbox. The Burman parts Manual doesn't illustrate them separate from their gears and lists them only as "bush".

The final photograph shows the mainshaft has a spiral groove running its length to lubricate the bush on the sleeve gear.

[Linked Image]

The mainshaft is a bit of a puzzle since its OD is 0.8407"–0.8411", which is ~0.003" from the nearest fraction. Not that 27/32" (= 0.84375) is a "reasonable" fraction. The clearance with the sleeve gear bush is 0.0045"–0.0050". Perhaps the shaft originally was a reasonable ⅞" but had deep damage so someone had 0.034" ground from it to remove that damage. If I ever rebuilt another Burman 'Q' gearbox, which I never will, I definitely would be interested in measuring the OD of its mainshaft.

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Hi All,
Observations and opinions if I may?

I seem to remember there was some discussion on the quantity of grease /oil to be filled into the Burman gearbox back in 2018
My thoughts at the time and now is fill the box with as much grease as you can LOL!!! It's not like greasing a bearing cavity where the quantity can be important..
I seem to remember that I read that (Draganfly??) sell semifluid grease in 800gm quantities as suitable to fill one gearbox (4 speed??)

There is no need to worry about pressurising the gearbox as there are no seals on the sleeve gear or gearchange spindle

MM , Please remember to fit the bolt on the gearchange spindle bolt from the inside when rebuilding the gearbox
I got the reassembly sequence wrong and could not get the bolt to fit from the inside once I had other parts back together, rather than strip and reassemble again in a hotel car park it was deemed OK to put it back together with the nut on the inside (with loctite)

I would not use oilite for the layshaft bushes !!
The C544/ PB1 would be my choice.
Clearance ? I would go for 0.002- 0.0025in. to give the grease a better chance of "flowing " into the gap. a grease groove would be a good idea, but if spiral it needs to be in the correct direction to "suck" the grease in using the gear rotation as an "Archimedes screw"
Are there any holes in the layshaft cluster to allow lube to be expelled if the spiral sucks the lube in at the ends
(This is how I believe BSA gearboxes circulate the gear oil through the layshafts)

MM, Do You remember when we were in Sturgis on the rest day, Tom found some lube bottles that were from 00 or 000 lube intended for steering boxes ? You kept one of the containers or photographed it for future reference as a possible source
I would prefer to have the lube liquid enough to flow rather than adhere to the upper insides of the gear casing now that sealed bearings will be at each end of the gearbox ??
Of course the intended future use of the Ariel and the climate of that location also need to be taken into account ???????
My experiences of Arizona weather would suggest that high temp grease would be liquid enough in Summer time LOL

John

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Originally Posted by chaterlea25
I seem to remember that I read that (Draganfly??) sell semifluid grease in 800gm quantities as suitable to fill one gearbox (4 speed??)
Are you sure about the units, i.e. grams instead of mL? Burman calls for it to be one-third full, and I estimated that to be ~750 mL when I originally filled it with K400. Correcting for the ~0.75-0.9 density of grease, your 800 gm would be ~890–1070 mL, which probably is still within the range of accuracy of my estimate.

Originally Posted by chaterlea25
Please remember to fit the bolt on the gearchange spindle bolt from the inside when rebuilding the gearbox
Will do. Thanks for this, and for your other comments.

Originally Posted by chaterlea25
The C544/ PB1 would be my choice.
Clearance ? I would go for 0.002- 0.0025in. to give the grease a better chance of "flowing " into the gap. a grease groove would be a good idea, but if spiral it needs to be in the correct direction to "suck" the grease in using the gear rotation as an "Archimedes screw"
Are there any holes in the layshaft cluster to allow lube to be expelled if the spiral sucks the lube in at the ends
Great minds... I'm definitely going with deep grooves on my replacements, with the only issue still to be resolved is how long to make each of them. There's isn't a lot of side thrust, as evidenced by the short bush used on ordinary, non-"T" or "T2" BSA gearboxes, so with the higher strength C544 they don't have to be any longer than the ones I took out, and I can afford to give up some surface area in favor of groove depth and width.

If you look at the third photograph in my previous post you can see a fairly large hole in the underlying steel shaft. The gears are in the position they would have in top (3rd) so if the grooves in the bushes are properly oriented and succeed in sucking grease into the cavity as I hope they will, it will be blown out that hole when cruising in top gear, so the flow of fresh lubricant will be constant.

Originally Posted by chaterlea25
I would prefer to have the lube liquid enough to flow rather than adhere to the upper insides of the gear casing
I haven't touched the can of K00 since using it three years ago. Interestingly, note that although some oil has separated from the grease, even after three years the "semi-liquid" 00 grease still hasn't sought its own level as even a liquid as viscous as honey in a cold garage would have done long ago.

[Linked Image]

However, the reason for this is grease is a "non-Newtonian" fluid, whose viscosity decreases with stress (honey is Newtonian, with viscosity independent of stress), so near the churning gears its behavior would be more liquid-like than when living a stress-free life in a can on the shelf. But, the grease only will be more liquid-like in the gearbox if the gears don't create a cavity in it, removing it from the viscosity-reducing action of the gears. The fact that "soft" grease was successfully used in gearboxes for a number of years shows that the right grease (which, I hope, is K00) can do the job, but I'll add some 90W as well.

The gearbox doesn't have an oil seal on the output shaft, but the next photograph shows the sleeve gear.

[Linked Image]

The shiny ring next to the gear is what is pulled up hard against the inner race of the bearing when the gearbox is assembled. That blocks one potential escape route for the grease/oil at this bearing. If the seals on the sealed bearing continue to seal, that blocks the other potential escape route. Given the lack of a mess near this bearing, there's a good chance it will continue blocking egress of grease/oil. This means, keeping the contents in comes down to how well the new sealed bearing at the other end works.

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Maybe you've seen this already but there's a link on the VOC UK website with a pdf download of the early Burman gearboxes including model Q. See This link.

Page 16 mentions lubrication and some of the products include Castrolease medium, Mobil grease no 2. These greases sound a bit thicker than what you used maybe equivalent to NLGI 2 ?

It also mentions that the box is factory-filled and that any slight overfilling should settle, additionally if completely filled the grease will be thrown out as the gears exert a pumping action. They claim 1/3 full is best.

*** I've updated the link as it was previously wrong **

Last edited by gunner; 05/11/21 5:37 pm.

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Originally Posted by gunner
Maybe you've seen this already
I have, but thanks very much anyway for sending the information.

The heading of one section in a set of Burman instructions is "Taking the Gearbox Apart" followed by "We recommend only those with expert mechanical knowledge undertake this." Now they tell me...

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Part of the vast amount of useless motorcycle information I have garnered over the years is that on gearboxes of this vintage the grease is there to coat the inside of the external surfaces of the gearbox and by dint of being cooled by external air it remains pretty much solid and “seals” the box. —- allowing the oil to exist within the grease jacket and lubricate the gears without leaking out as it is constrained by the grease “jacket”.
Don’t ask me where I picked up that idea from but it seems somewhat logical— especially if you think about it only superficially!

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I've updated the link to the Burman Manual in by previous post as it was wrong, See This link for the Manual.


1968 A65 Firebird
1967 B44 Shooting Star
1972 Norton Commando
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Originally Posted by chaterlea25
Hi All,
Observations and opinions if I may?

I would not use oilite for the layshaft bushes !!
The C544/ PB1 would be my choice.

John

John... could you expand on that a little. The reason I ask is that the Spares Company for the lesser marque offers oilite for some gearbox bits. Also... the general consensus amongst lesser marque owners is that using anything other than oilite for cam bushes is like dancing with the devil. I more or less get why that would be your choice and in the case of the lesser marque with an oil filled gearbox, the use of oilite seems odd. I noticed in the Manual that gunner posted that they originally used graphite impregnated layshaft bushes in that Burman box.

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Originally Posted by Tridentman
it remains pretty much solid and “seals” the box. —- allowing the oil to exist within the grease jacket and lubricate the gears without leaking out as it is constrained by the grease “jacket”.
In the same vein, didn't your namesake motorcycle use basically the same concept to impregnate porous engine castings with epoxy to keep the oil from leaking out of them? Or did I read that (mis?)information in a poorly researched motorcycle magazine article?

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Originally Posted by Magnetoman
Originally Posted by Tridentman
it remains pretty much solid and “seals” the box. —- allowing the oil to exist within the grease jacket and lubricate the gears without leaking out as it is constrained by the grease “jacket”.
In the same vein, didn't your namesake motorcycle use basically the same concept to impregnate porous engine castings with epoxy to keep the oil from leaking out of them? Or did I read that (mis?)information in a poorly researched motorcycle magazine article?

Are you thinking of Shadow cases? Except they used some other strange concoction to fill the voids..... or so the story goes.

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Hi Cyborg
Like everything "oilite" I suppose comes in a lot of variants?
The usual uses I have seen are/were in small electric motors , Lucas starters and dynamo's and other applications that rely on the initial
application of lube to last forever
I have seen cases where when heavily loaded (cam bushes) the oilite either crumbles or squeezes out
I am by no means any kind of expert on anything ! just working from experiences of what has worked for me over the years

Hi MM,
I can see the oil holes in post #848596 .. In the photo of the layshaft gears the top gear teeth look black in the centre and have what look like wear marks either side of he "black" Is this a trick of the light ? or is there damage ?
The sleeve gear bush clearance of 4.5-5 thou sounds a bit large to me !

John

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Originally Posted by Cyborg
Are you thinking of Shadow cases?
No, I was thinking of the Trident but, now that you mention it, the Shadow is another example of the same type of British engineering, i.e. "If you can't fix it, fill it."

Originally Posted by chaterlea25
have what look like wear marks either side of he "black" Is this a trick of the light ? or is there damage ?
Your question sent me out to the garage for a close inspection. The appearance in that photograph is a combination of bright reflection from the shiny gear teeth, which means they look black when the angle is off that of reflection, combined with clumps of oil that refract the light and make some of the teeth look other than smooth. All the teeth are in fine shape.

Originally Posted by chaterlea25
The sleeve gear bush clearance of 4.5-5 thou sounds a bit large to me !
I've been concentrating on the layshaft, but the sleeve gear will be treated to a new bush as well. There's no point coming this far and not taking care of all the issues I find.

I only had time to make one of the two layshaft bushes today and, even then, there is still more work to do on it.

[Linked Image]

As can be seen, my 3-point hole micrometers are being put to good use and I'm very happy to now have them. They're so much quicker to use than the split-ball type, although both types definitely have their uses.

The shaft around which this bush will rotate has an OD 0.6087"–0.6090" so, as can be seen in the above photograph, on the final cut I left ~0.0015", plus whatever final clearance I decide on, to be honed after I press it into the gear. Also, rather than worrying about getting the oil hole in the right location, and then remembering to press the bush into the gear with the holes aligned, I'll drill the hole through the one in the gear once it's in place. Given the odd size of the shaft, if I didn't have a hone I'd have no choice but to do my best to hit the final diameter and then live with whatever roughness the cutting tool left.

The other operation that remains to be done is to cut a spiral grease groove. I conducted extensive research on what is the "correct" value to use for the pitch, determining from one Ariel shaft and two BSA shafts that the actual value seems to be unrelated to rpm, viscosity of the oil, or whatever. The only thing that matters is that the groove have at least one turn in the length of the bush to ensure the full length of the bush is lubricated. For example, the groove under the sleeve gear in the Ariel's mainshaft has a pitch of ~3½", and the sleeve gear is ~3½" long. The next photograph shows that the mainshaft in a BSA gearbox has two grooves, with helixes of opposite handedness, and with the shorter one having a pitch of one-tenth of that of the Ariel mainshaft, at ~0.35".

[Linked Image]

The handedness of the shorter helix is such that it pushes oil back into the gearbox rather than toward the oil seal.

Rather than trying to crudely cut these helixes by hand, if I install my lathe's accessory head it will allow me to cut a "thread" inside the bush with pitch 0.4", which will result in two and a half full turns in the shorter, 1" bush (in addition to providing greater swing, the accessory head reduces the rpm, and increases the pitch of any threads, by 4×). That should be fine. Anyway, I'll make both bushes first, reconfigure the lathe with the accessory head, cut the oil grooves, then hone both of them to size. I'll have to decide which direction(s) to cut the helixes in the bushes, since I could cut both of them to suck grease in and push it out through that hole in the middle of the shaft, or cut them to flow the grease straight through from left-to-right, or from right-to-left. So many decisions to make...

No such helix will be needed on the sleeve gear bush since the mainshaft shaft itself has the necessary channel.

The issue of determining which bronze is best for which application is an interesting and important one, and one that I expect to return to in due time.

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