[LTFan]

i have read many threads on final drive failure and the reasoning. but i could not understamd the consequences of a fd failure

will it leave me stranded on the road?
will it alwats leak oil on the road?
will the rear wheel lock up and skid?

i am mainly concerned with the safety aspect of the failure.

 

[CharlieVT]

i have read many threads on final drive failure and the reasoning. but i could not understamd the consequences of a fd failure

will it leave me stranded on the road?
will it alwats leak oil on the road?
will the rear wheel lock up and skid?

i am mainly concerned with the safety aspect of the failure.

Yes, it can leave you stranded.
It will not always leak oil on the road. If your are paying attention to the bike's ride, you may catch a failing FD before the seal is torn. This is assuming that we are talking about the most common failure, that of the crownwheel bearing.

I am not aware of any case of wheel lockup or skid secondary to FD failure. The have been no documented cases of injury secondary to FD failure. This is probably why BMW has managed to avoid mandatory recall related to FDs.

 

[Voyager]

i have read many threads on final drive failure and the reasoning. but i could not understamd the consequences of a fd failure

will it leave me stranded on the road?
will it alwats leak oil on the road?
will the rear wheel lock up and skid?

i am mainly concerned with the safety aspect of the failure.

A failure may well leave you stranded if you don't catch it soon enough. Often there are warning signs, but not always it seems.

It may or may not leak. Leaks appear to occur only once the bearing is in really bad shape.

Unlikely to lock up, at least I have read almost no reports about that. I think I heard someone claim that one FD had done that, but I never saw any real confirmation on that.

 

[David13]

Yes.
The posts in advrider indicated that as we post, there is a rider in Poland, on vacation, stranded.
The rear crown bearing, the large one, started to disintegrate and destroyed the seal, causing a leak. He then pulled the wheel, and the seal, and the basket outside the balls had shredded, cutting open the seal to leak.
He's 1200 km from home.
I believe he may be on a GS, so the final drive probably is not 100% identical, but just the same design and manufacture.
dc

 

[kimokk]

So has anyone done a comparative analysis between shave drives versus chain and sprockets? We all know the convenience of shaft drives but what is overall maintenance cost and wear and tear between the two?

If the FD fails between say 15,000 - 25000 miles and costs anywyhere between $250 and $1500 for FD repair isn't this a reasonable cost over doing constant chain maintenance and replacements over that same mileage? Or is everyone expecting the FD to last forever with just FD oil changes? I don't think so.

 

[David13]

Toss a coin. Honda has shaft drives. With very very few problems. And it isn't a single side arm issue, either. Every front wheel drive car, in essence is a single side arm wheel. And no problem.
dc

 

[CharlieVT]

The irony is that in the early 70s and prior, only BMW and a few others had production bikes with a driveshaft. And the final drives on those BMWs were pretty much bullet proof. Before I moved to a BMW, I was long distance touring on chain drive bikes. Every morning I'd adjust and lube the chain, what a messy pain. I understand modern chains and belt drives are good "low tech" options.

There were some problems with those 70s BMW bikes, spun wheel bearing races comes to mind, but that was basically an assembly issue. Properly assembled those old wheel bearings were pretty bullet proof. And the final drives rarely needed anything but an occasional gear lube change and the drive splines lubed.

I suspect that the modern FD on our KLT is engineered well. Properly machined components and properly assembled, I suspect the K1200LT final drive is pretty much bullet proof as well. It is a shame that bad machining and bad assembly has given BMW the FD black eye, but they deserve it.