Boxerworks.com

I was doing my duty and changing my oil this morning when I got to the bevel drive noticed a bunch more metal shavings than normal. Then I noticed that there wasn't much oil coming out, so I poked a small allen wrench up there and whoosh.
Out came all the oil but out came some big hunks of bevel drive with it.

I haven't pulled the drive off yet....sort of afraid to see the damage.

So here is the question:
I don't hear any bad noise in the rear end when riding.

Would you suggest that I park the bike until I get the drive replaced?
Would you keep riding...it's broke, it could get worse but nothing that is dangerous?
Throw the !@#$%$# bike away because I am tired of some major repair issue every season?
Buy a Harley, if I going to have to repair the bike every year, may as well do it to a bike that has plenty of cheap replacement parts?

opinions, oh and anyone have repair or replacement options?
oh, bike is a '77 R100/7

Just get if fixed, there is no other option. There are enough reputable people out there: Anton Lagiarder, Bruno's and others.

I am in the process of rebuilding mine now, but I have a spare.

Take it off and open it up.

Inspect it for the exact problem.

Check for play in the pinion gear that runs off the shaft. It shouldn't move. On mine, the whole bit could move 2-3 mm. Bad.

Check for wear on the crown gear. Usual spot. I rode my bike without symptoms until I too did an oil change. This is what I found when I eventually opened it up.



You'll find lots of metal sludge around the drain hole. There was a moderate amount on the magnet, but despite three rapid cycles of oil changes, I was still surprised to see the amount of metal slough I found.



My advice. fwiw...
1. Inspect and confirm the damage.
2. Look for a replacement. Cheapest, and as one might say ...a crapshoot. The crown and pinion gears are matched, and cannot be replaced singularly. You'll also need to be aware of a replacement unit's spline condition. Splines can be replaced/rebuilt (Hansen's) but more money. It will still need to be rebuilt. Cheapest? maybe not. You might get lucky.
3. Repair. Take note of the shim position when you remove the cover. Don't damage the shims. If the damage you find is similar to my pictures, this isn't a good option.
3. Buy a new unit. Be seated when they tell you the cost, if you can find one.
4. Buy a parts bike. You might get one for the price of the new final drive.

I'm afraid the news won't be good. You will have costly decisions to make.

http://www.bmwra.org/otl/finaldrive/

Remove your drive, inspect the damage and then search the internet and buy a used replacement.

I've had more than a half dozen used drives pass through my hands during the last three years and I've never had a bad one. It's probably the most reliable part of your bike except for the handlebars.

OTOH, I would never ride a known bad drive. Can you imagine that thing locking up on the highway during rush hour? No friggin way. Not me!

You can inspect the damage without removing the final drive.

This won't help you at all, but here it is again. The photo shown with the ruined teeth is preventable. I rail against ignoring simple tests. A FD should have the cover removed within the first 15-25 k miles to inspect for gear tooth wear pattern. That gear would have most likely failed badly.

BoxerTwin wrote: Buy a Harley, if I going to have to repair the bike every year, may as well do it to a bike that has plenty of cheap replacement parts?

I'd bet that having a reliable bike of any brand will cost at least as much as your BMW does. If you want a new bike, buy a new one. Most of us here end up fixing ours. From the sound of things, none of us are rich. We just buy what we need and do what work we can do ourselves.

Every mile covered after seeing chunks come out of my FD would be spent thinking of the chunk(s) that didn't come out and wondering when one would lodge in the gears. A sudden unexpected skid while on the freeway in traffic sounds too challenging. I'd consider replacing it.

Chuey

Chuey wrote: Every mile covered after seeing chunks come out of my FD would be spent thinking of the chunk(s) that didn't come out and wondering when one would lodge in the gears. A sudden unexpected skid while on the freeway in traffic sounds too challenging. I'd consider replacing it.

Chuey

I drove it around the block and was thinking the same thing the whole way. I don't think I could actually ride it and enjoy myself.

Probably won't repair it, way too much money from what I can tell....will replace it with a used one though. I've found a couple that supposedly in good shape. I'll check them out and see.

Duane Ausherman wrote:You can inspect the damage without removing the final drive.

This won't help you at all, but here it is again. The photo shown with the ruined teeth is preventable. I rail against ignoring simple tests. A FD should have the cover removed within the first 15-25 k miles to inspect for gear tooth wear pattern. That gear would have most likely failed badly.

yep, I was looking at your page...I always go there first (thanks for the great info).
This bike had a PO who rebuilt it himself. He was a good guitar player and a crappy mechanic. So far I've had to redo most of his poor electrical, had to have the valves and seats done because he put the intake in the exhaust and the exhaust in the intake, undid his botched fiberglass work on the s fairing, etc

BoxerTwin wrote: had to have the valves and seats done because he put the intake in the exhaust and the exhaust in the intake,

What an IDIOT!