What's missing

I know there's something missing but not sure what. Any ideas anyone? [You must be registered and logged in to see this image.]

Yes, the pinion nut has dumped its preload, come loose and chewed up the lock washer that secures it.

You may well find the crown wheel and pinion have been destroyed but if you are really lucky you can simply replace the lock washer and re-torque the nut.

I recently talked another bloke through this and he managed to save his, but he was lucky. Look for posts by a member called Havli, (I think?) I’m typing on my phone in a pub in Bendigo at the moment. When I get back to our motel I’ll try and post a link to it.

Havli’s thread.

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Thanks for the reply and link. The pinion nut has had all of its thread worn away, rendering it useless. There appears no damage to the input shaft and crown wheel, nor is there any more loose metal floating around. Is the nut and lock washer available or do I have to make one or, worse still, buy another drive unit?

As long as the teeth of the pinion and crownwheel are undamaged you can just give everything a really good wash, (It looks very black. Has someone put a moly additive in there at some point?) and don’t take anything apart further. Doing so just makes a rod for your own back.

There are a few parts you will need that aren’t listed in the parts lists because us mere mortals aren’t supposed to be smart enough to work on bevel drives any more, and the sad thing is in a lot of cases they are right! Under the collar that the pinion seal runs on, between it and the front pinion bearing, there is an O-ring that acts as a crush seal to prevent oil from seeping up the pinion shaft. The old one is still there most likely so just match it up at the bearing factor. You will need to replace the pinion seal inside the seal holder, it’s a Viton seal and its dimensions are in the parts list 45x58x7. The factory supplied seal is directional but we replace them with a standard *Ambi-directional* seal with no leaks or other ill effects.

The easiest solution to the nut and lockwasher problem is just to get on to Mario at Thunderbikes or one of the other suppliers of parts for ‘Older’ Guzzis and ask them to send you the locknut and lockwasher as used on T3/LeMans/SP1000 or whatever from the ‘70’s-‘80’s that was used to secure the crank timing sprocket onto the front of the crank. Alternatively you can go to your local SKF dealer and simply match it up. If you read Havli’s thread I think I stuck in a link to the SKF nut and lockwasher lists but as I say, the easiest is simply to order the old motor crank nut and washer as they are always in stock.

I think I explained fairly thoroughly in Havli’s thread about the why’s and wherefore’s of re-torquing the pinion nut and why you don’t just crank it down like a demon like you used to with the older final drives. Havli ended up using a slightly higher torque than I probably would of but as far as we know his FD is still working fine so using his spec is probably as good as any since the factory wouldn’t tell us! Anyway, when you torque the nut to its preload secure it not only with the tab washer but also some red or green Loctite to make sure the bastard doesn’t come loose again!

One other thing to check while it’s apart. On the early CARC boxes there was a problem with the ‘Big’ (Edit.) 85x120x18 bearing that supports the crownwheel on the wheel side of the reactive bridge. There was actually a recall for this as the bearing’s cage would break up and bits of it would get poked through the seal so the rear wheel and brake got covered with oil with, errrr, predictable results! There was also the risk of the bearing, and therefore the wheel, collapsing! As I said there was a recall and I’d be very surprised if after all these years one might still of slipped through the net and still be working BUT…. It’s easy to check. Just count the balls in the bearing. The early, failure prone, bearings only had seventeen balls and a flimsy cage. The ‘Good’ bearings used in all subsequent boxes have nineteen balls and a much more robust cage. If, for any reason, your box still has the 17 ball bearing? Replace it before you reassemble the box as it will almost certainly fail, possibly with catastrophic results. If you need to replace it the bearing ID is 61917 with a C3 clearance. I always purchase the FAG brand ones.

If you have any further questions? Fire away and I’ll try to answer them.

Thanks Pete, this is all very good, and timely as I was half way through making a nut but not good at cutting internal threads on the lathe, especially in harder metals. Mario has both pieces and will post them across. I'll check that bearing before reassembly. I have a new seal left over from the Breva which is why we got this far in the first place. Cheers

You’re welcome. If you need the bearing I think I left one with Michael for stock when I retired. The are usually special order so if you do need one contact him. If the FB page doesn’t work I can PM you his number.

Morning Pete. The bearing is the old 17 ball type and now it's out is very notchy. I don't do FB so can you pass on Michael's details, please. Cheers.

Check your PM’s.

If you cut the 17 ball race open I’ll bet you anything both the races and the balls will be heavily brinneled. Typical penny pinching. It shits me.

Hi Pete,
I was checking your thread with Havli. Great thread....

It left me a bit ansious though....
This preload nut/locking washer thing it's something that will allways hapen with time/milleage, or just for the most unfortunate?
Is there any symptoms besides the overrun noise you already mentioned?

My bike has 56 000 km, and I removed the bevelbox for the swingarm bearings replacement a couple of weeks ago. I turned it by hand and it seemed to have a smooth movement without play...
I changed the oil this week. It looked dark and nasty, but there were no chunks of metal (or to much metal powder) on the draing plug.

But I do have a rolling noise (that I have mentioned a couple of times before) that could come from this bevelbox...but not particularly when it overruns...

What could I look for to confirm everything is still OK?...
Any records of accidents caused by a jammed CARC [You must be registered and logged in to see this image.] ?..............

Is it inevitable? No. It seems like it only happens on some units and my guess is that the failure of the nut to retain its preload has to be to do with the installation of the pinion and bearing assembly into the throat of the reactive bridge. The lack of Loctite on the nut won’t help!

If your oil is very dark it is more likely that you have a problem with the ‘Big’ bearing on the wheel side of the reactive bridge. If your 1100 is an early model it may of missed the recall for this bearing and it may well be failing. It was the nasty colour of the inside of Will’s unit that made me suggest he check the ball count on that bearing and lo and behold his had somehow slipped through the net.

When you took the final drive off the swingarm was there any evidence of oil in the arm or in the inside of the pinion seal holder?

There was a bit....But the oil level was a bit high too (not on the bottom of the threaded hole but on top...)

That shouldn’t matter. If there was oil there the pinion seal may of blown or the nut may be loosening.

At this point I’d advise dropping the box off and checking the nut, (This can be done easily enough just by poking it with a thin screwdriver down the neck of the seal holder and seeing if it moves at all in relation to the pinion itself.) if it does, or if there is evidence of oil pooling side the seal holder you’ll need to remove the seal holder to replace the seal andIf you split the CARC case to do that you can do a ball count on the bearing at the same time.

Yeah.......I'm about to go on holidays for 3 weeks, but I will have to take a look at that afterwards....

Probably they won't tell much, but there are a couple of pictures on this thread that show how the seal holder looked like.

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Hi Pete. What's the proper torque for the bearing nut? I would normally tap it up till I thought enoughs right then lock it down. I watched my old man set diffs with feeler guages when I was a kid but didn't learn much.

Which nut? The pinion nut?

Yeah, sorry, the pinion nut.

Sorry for the late reply, I was out yesterday evening.

Torquing the pinion nut we covered pretty extensively in Havli’s thread. Read through that again and if you have further questions come back to me but it doesn’t need duplicating endlessly.