What does a final drive "feel like" when it's going out?

[DAQ421]

What does a final drive "feel like" when it's going out? I have a sort of low grinding vibration that I am trying to track down. No metal in the oil, no low oil, and no issues with axles.. So I'm looking for other areas.

Thoughts?

-Peter

[NoRRmad]

Mine started with a light tictictictic in the right footpeg, getting steadily worse. A good test is to put the bike on the centerstand and rotate the rear wheel by hand. I could definitely feel a grinding through my hand as I rotated the wheel.

[wncbmw]

I felt a funky, wobbly vibration while cornering in one direction (I believe it was left) and later did the centerstand test of wiggling the wheet from the 3 and 9 position and had some play.

When you said you checked the oil, did you mean the final drive oil? When I got home and drained the FD oil, there was no doubt. It was a metal soup. If you drain the FD oil and check it, that should give you a big clue. If it's clean or mostly clean, I would look elsewhere. The bearings grinding down should leave lots of evidence.

Finding the problem before it goes too far would save some money. It's cheaper to replace the bearing than the whole final drive by far.

Good luck.

[MIXR]

Mine was a very pronounced 'rumble' through the footpegs. Started instantly, got worse, and then stayed constant. Significant failure of the big bearing.

Feeling was like running over the 'ripple-strips' or 'rumble-strips' that we use to mark road edges here. Without the noise. Just the feel.

Rotating the wheel felt like stiring marbles in a corrugated jam tin. This is why:

[DAQ421]

Mine was a very pronounced 'rumble' through the footpegs. Started instantly, got worse, and then stayed constant. Significant failure of the big bearing.

Feeling was like running over the 'ripple-strips' or 'rumble-strips' that we use to mark road edges here. Without the noise. Just the feel.

Rotating the wheel felt like stiring marbles in a corrugated jam tin. This is why:

Yikes..

[BCBlueR]

I felt a funky, wobbly vibration while cornering in one direction (I believe it was left) and later did the centerstand test of wiggling the wheet from the 3 and 9 position and had some play.

When you said you checked the oil, did you mean the final drive oil? When I got home and drained the FD oil, there was no doubt. It was a metal soup. If you drain the FD oil and check it, that should give you a big clue. If it's clean or mostly clean, I would look elsewhere. The bearings grinding down should leave lots of evidence.

Finding the problem before it goes too far would save some money. It's cheaper to replace the bearing than the whole final drive by far.

Good luck.

I just replaced the FD gear lube in my 02 (15K) there was a blob of black stuff (gel-like) attached to the magnetic drain plug. Is this normal or should I start to worry.

Rob

[MIXR]

You will often get a 'paste' of gunk on the mag plug. Ride a few thousand miles and do another oil change. If it comes out clean, there is nothing to worry about.

Also note that changing oil types/brands can have a cleaning effect as the new oil strips off all the accumulated 'muck' from inside the case and spreads it through the oil and on to the mag plug. I recommend that if you start doing your own oil changes with a different oil to what a dealer (or you) may have been using, that you do a change after a couple of thousand miles. It may come out 'dirty' the first time, but subsequent changes should be clear.

My experience only. Cheers.

[BCBlueR]

Thanks MIXR, I'll take your advice and the gear lube in a few k. Much appreciated.

[MattPie]

What does a final drive "feel like" when it's going out? I have a sort of low grinding vibration that I am trying to track down. No metal in the oil, no low oil, and no issues with axles.. So I'm looking for other areas.

Thoughts?

-Peter

Make sure your tires aren't severely scalloped/cupped/feathered. Mine are right now and there's a noticable vibration when cornering.

[DAQ421]

What does a final drive "feel like" when it's going out? I have a sort of low grinding vibration that I am trying to track down. No metal in the oil, no low oil, and no issues with axles.. So I'm looking for other areas.

Thoughts?

-Peter

Make sure your tires aren't severely scalloped/cupped/feathered. Mine are right now and there's a noticable vibration when cornering.

Oh.. Now that is interesting. I do have a very pronounced, and odd, wear pattern. I went and looked last night and the tires is very unevenly worn.
Hmm...

-Peter

[DAQ421]

What does a final drive "feel like" when it's going out? I have a sort of low grinding vibration that I am trying to track down. No metal in the oil, no low oil, and no issues with axles.. So I'm looking for other areas.

Thoughts?

-Peter

Make sure your tires aren't severely scalloped/cupped/feathered. Mine are right now and there's a noticable vibration when cornering.

Oh.. Now that is interesting. I do have a very pronounced, and odd, wear pattern. I went and looked last night and the tires is very unevenly worn.
Hmm...

-Peter

So what would cause the right side of the front tire to wear twice as fast as the left?

-Peter

[mcmarcia]

right turns are sharper than left because we drive on the left side of the road and this could be a factor for the right side of the tire to wear more. However the road crown would tend to wear out the left side of the tire you would think. I change my final drive and tranny lube every 6K miles, lube is cheap and it is so easy to change.

[dc10bill]

Yesterday 16th rode to store about 5 miles away when I came out Their was a small pool of oil from rear housing on to tire and rim, cleaned up but could see the oil dripping from under wheel and housing, rode home slowly/carefully.

When I got home looked in Maint. manual and parts catalog so shaft seal went out "just like that" I thought to my self. so today 17th pulled rear wheel off boy getting them 8 allen bolts out were tought, heated outer housing as per maint. manual and tapped with small wood dowel on top caliper lugs and out fell the crown gear with cover !

A little more than bad seal the drive bearing cage had failed @ 107407 miles when it did so it took wire out of drive seal so the reason for the oil leak!

I guess a common problem nothing like failure with photo of green rag, above however. So looks like a $150. dollar job. I don't want to guess if this had happened out in the boon docks and perhaps rear wheel had locked up at speed, just shi* house luck for me being close to home and noticing leak.

Yes when I drained oil from rear housing their was just several tea spoons of oil left their was some fuzz on magnet drain plug, but not what one would expect from this type of failure of bearing cage

[MIXR]

Mine's the one with the green rag. It happened about 100 kms from home, and I rode it slowly for another 40 kms before giving up. What happens is that the big bearing falls completely apart and the rear wheel generates enough slop (play) to start the rear disk rotor grinding against the fixed rear brake caliper. It's a noise I won't forget in a hurry. The other risk is that some of the hard balls from the big bearing also chew up the drive gears and then eat the housing from the inside. Better to accept defeat and stop.

I trailered mine home after getting a rescue. Note that the likely cause for a failure is incorrect shimming from the factory. It could be too tight, or it could be too loose. Do not assume that a new set of bearings on the old shims will be a good job. It probably won't be. The reasoning behind the failures is still disputed by some. Anyway, you will need a new big bearing. You should replace the tapered roller bearing (some don't). You will need a new cover-plate seal. You must re-shim the new bearing!

It cost me AU$400 to have mine rebuilt after I pulled it out. About 3/4 of that was in parts, which is why I didn't bother doing that bit myself. It's now a spare. Interestingly, I fitted a 'temporary' second hand unit from an RT into my GSA and it's now done 10,000 kms (pushing a sidecar) while the original GSA unit only did 3,000 kms after the sidecar went on. The GSA unit had about 60,000 kms but was always 'sloppy'. The RT unit had 100,000 kms, and must have been properly shimmed as it's still going strong at the moment.

[DAQ421]

So there is oil seeping at the boot on the wheel side.. Enough that the wheel is black..Thoughts?

[MIXR]

So there is oil seeping at the boot on the wheel side.. Enough that the wheel is black..Thoughts?

Peter - No other replies, so I'll give it a go. If it's like this:


Then you have problems. It may just be a leaking seal around the diff cover plate. Very rare. Very unlikely. More likely is that the big bearing inside has gone west (see your first post) and the movement inside has torn out the wire retainer for the seal, and dislodged the seal itself. You can see that in my earlier photo with the green rag.

If the leak is from the flexible boot, then it may just be the front diff seal. Again, unlikely given your earlier post.

Don't risk a more catastrophic failure that could take out the tapered bearing and the crown wheel etc. Get it seen to, or do the job yourself. The removal of the drive isn't a big deal if you have the gear and some basic mechanical skills. There is some potential to really screw things up and do some expensive damage if you don't know what you are doing. See the ADVRiders Hall of Wisdom for more info on that. The rebuild? I took mine to a specialist BMW Tech as he didn't charge much for labour and had the gear for the internal rebuild. It was a small % of the total rebuild cost. I did the bike R & R myself and fitted a used unit while I waited for the rebuild. The rebuilt unit is now my spare.

Good luck, but it sounds a bit terminal. Cheers, Mick.