Arrrrgh! Broken!

[jacksonracingcomau]

All fixed. The CW&P actually looked fine but since I have several basically new ones I just pulled the bridge out of one of those and used it. I did take the precaution of taking the nut and lockwasher off and loctiting the bejasus out of it.

I agree that not using solid spacer is dumb but it is CHEAP and everybody always loves cheap. I'm considering cannibalising another one and solid spacing it. No reason you can't.

I've seen two cases of this in ten years. I saw at least as many other bevelbox failures over the years with other designs. I knew that people would shriek. Perhaps I should just not bother?

Pete

Back OT after watching Dakar on SBS-- Go Toby, unbelievable first Dakar, boy will go far
Definitely should have posted, shriek or not, this stuff is good info for long term owners
Solid spacer would add SFA to price of bike, it's not sold as bargain basement toy is it ?
But a few minutes are needed to get it right, for anyone interested, this is probably the saving

Ol dungers, even my 67, are shimmed as well as solid spacered, spacer a little short, add shims till perfect.
Dunger shims "might" fit but not hard to buy shims in any ID.
I "think" dunger locknut will fit too, they have the parts just not the time, world has changed. Once they paid tradesmen to build bikes, now it's a robot, they need another one to finish the carc but cheap tab washer won the vote.
Precision for exact sized spacer would be lovely, I wonder if BMW have done that ?

[Chuck in Indiana]

Definitely should have posted, shriek or not, this stuff is good info for long term owners

Absolutely. It still bothers me, though. It's just not good engineering practice.

[Dick]

By the view of the  stacking of the outer races, it doesn't appear there's any room between bearings to accept a spacer. It might be possible to squeeze a shim between the inner races, though??

http://www.labellehistoiremotoguzzi.info/dotclear/public/technique/carc/carc4.jpg

http://upload.wikimedia.org/wikipedia/commons/c/cc/Moto_Guzzi_-_CARC_system.jpg

[Phang]

I posted this section diagram in a Griso forum, looks like there is a little space between the inner races.

According to Pete, there is a torque collapsible wavy washer in between the inner races.

[Dick]

Ahh, so a shim should be doable. Now you would assume the factory has some specified torque/preload applied to those bearings,like tapered rollers used in some car wheels. I guess you'd want to add that into the equation when deciding on a shim.

[Antietam Classic Cycle]

That is a very pretty thing Martin. Have you run one of the earlier 'Pumpkin' boxes with a later, higher powered, motor than the original V7? I seem to remember that there were issues with them cracking in higher load situations. Not claiming it to be fact but Charlie might know.

And I'm now a slow old git, will watch for leaks of course, has viton seals O rings at pinion etc, only oil level remains to be decided, will try 250cc first (factory quoted 300 then 230)

No issue with cracking that I'm aware of. I'm sure someone somewhere has managed to bust one open, though.

The factory recommended oil volume for the "starburst" rear drive was always 180 cc (160 cc gear oil, 20 cc moly) and never changed. The volume went up to 360 cc for the "deep sump" rear drive that followed and dropped back to 250 cc for the rear drive common to Tontis from the Convert on.

[Phang]

Ahh, so a shim should be doable. Now you would assume the factory has some specified torque/preload applied to those bearings,like tapered rollers used in some car wheels. I guess you'd want to add that into the equation when deciding on a shim.

Here's the complete diagram of the one I posted above.

The peg nut of the pinion is torque to 170Nm

[mikeproctor]

<snip> I knew that people would shriek. Perhaps I should just not bother?

Pete

I don't even have a motorcycle right now and articles like this are the reason I stay on this site!

[Cheese]

That's the first I've seen the peg-nut torque value. I'm not saying it aint so, but where did you find it?

[Phang]

I found it in 1100 Breva/Griso workshop manual. the 8V CARC models workshop manual have this page omitted for unknown reason.

I'll take the torque specs with a pinch of salt, until someone verified it.

I am quite sure you will pull some threads if you torque that CARC filler plug to 35Nm and the breather to 30Nm as shown in the diagram  ;D

[Vasco DG]

Phang, 170Nm is definitely NOT the torque for the peg nut. Use that and all you'll have is a locked up pinion. While the diagram may indicate that the figure of 170Nm actually applies to the seal holding collar, (Hence the need for the long breaker bar and heat to get the bugger undone.) there is no specified toque for the nut because the unit is 'Non Serviceable' remember! Why would they give a torque figure for something that supposedly has 'Magic' properties? ::)

Chuck, as far as engineering practice goes this is now common practice in many car differentials. Nissan Navaras, (Dunno if you get the Navara? Think pick 'em up truck 4x4.) used a very similar system in their differentials for setting pinion nut preload. It was abandoned I believe after about 3 years as Australian dirt roads were causing the pinion nuts to loose preload and flog the diffs out. I'm not suggesting it's good but it is commonplace and it all comes down to assembly times.

It's also interesting to note that there is no facility for changing crownwheel depth. There are usually written notations on the bridge casting which one presumes have some relevance to setting pinion depth with the under bearing shim on the pinion but the crownwheel itself is a non adjustable item. The only assumption I can make is that machining accuracy has meant that combined with the huge tooth face makes it possible to jig up each gear set, match it to a bridge and then assemble it with an acceptable margin of accuracy.

Pete

[Phang]

there is no specified toque for the nut because the unit is 'Non Serviceable' remember! Why would they give a torque figure for something that supposedly has 'Magic' properties? ::)
Pete

A fresh mind in the morning is obviously sharper than the one at 2am  ;-T

[Vasco DG]

By the view of the  stacking of the outer races, it doesn't appear there's any room between bearings to accept a spacer. It might be possible to squeeze a shim between the inner races, though??

Certainly any spacer won't be large, only the depth of the crush washer. That in itself is an issue. One would assume that it could be replaced with a similar flat washer. The fact that it is only going to be three or four mm deep is something I had been thinking about because the pinion itself has a cross drilling, one presumes to allow oil to move around and escape from between the bearings. Puting a spacer in there would occlude this and I don't know how vital it is. My guess would be not very. I can't see it as being a gallery for delivery of oil as the fluid would have to come up the centre of the pinion and the tip of that sits in one of the *Driest* areas in the box in service. If it does have to be cross drilled though there is very little *Meat* there to allow it. It would have to be a jewlers drill size hole to not compromise the integrity of the spacer.

Pete

[Don G]

Why not use a crush sleeve like the automotive industry? Tighten until the proper preload is acheived, works splendid. It does take a bit to get the sleeve started to crush then gets easy. not rocket science by no means.  ;-T DonG

[acogoff]

     I would think a person could temporarily glue a couple of pieces of lead shot into the area of interest(between the cones) and thighten untill it feels about right and them disassemble and measure said shot to get you an idea of the shim thickness you are going for as a starting point.

[Vasco DG]

Why not use a crush sleeve like the automotive industry? Tighten until the proper preload is acheived, works splendid. It does take a bit to get the sleeve started to crush then gets easy. not rocket science by no means.  ;-T DonG

The wavy washer between the outer races performs the same task.

Pete

[Don G]

I see, no room. Shim until its correct then i guess.  DonG

[johnr]

A "non serviceable" part! Yea Gods!

[Vasco DG]

Yes, complete shit. But I got sent one, one that I may of rebuilt but I wasn't made privy to that information, by a supposed 'Guru' locally last week after he found a bit of frag on the drain plug. Simply pulling the seal and looking at the clamps showed it had been gone through and re-bearinged at some point but when I pointed this out I got a litany of woe about anything and everything 'Modern'.

That's fine. I just can't understand why I have as few problems as I do if they are such a shitbox?

If you want a story of a TRUE headache I'll post details when Mark and I fix it. This one is a screaming two-holer that has been giving us, me particularly, kittens for months! It's only am aching though. We'll get there, and it has become a sort of 'Pro Bono' job!

Pete

[beetle]

Be afraid, be very afraid..

The 1200 Sport From Hell



......film at eleven...