Proactive approach to preventing FD failures

[Keith S]

I experienced a FD failure on my 2004 R1150RT at 35000 km. I was traveling just outside of Billings Montana and noticed a sound coming from the bike at low speed that I thought was road/tire noise. I continued the trip and was averaging 140 KPH to the next stop. When I slowed down I again heard the same noise, pulled in the clutch and the noise was still there this time on a side road not the pavement of the interstate. Once I got to the campsite I drained the FD oil and it was black. There is a whole story of flying back to Calgary and coming back with a trailer to retrieve the RT. Upon disassembly of the FD it turned out the only failure was the main crown bearing, yes the one you have heard a lot about. This scared the crap out of me, my estimate is that the bearing would have completely failed in about 2 more hours of ride time at 140 KPH (87 MPH) and the thought of the FD failing at that speed …..well I’m just thankful that it didn’t

I had changed the FD oil before the trip and the drain plug magnet was clean so this means that the bearing went from no indication of failure to failure in less the 2000 km (1220 miles). Other people have experienced the same thing….no warning or indication. Having said all that I am thinking of changing the crown bearing on a proactive basis every 30,000 km. Here is a post "changes my bearings" that covers the debate of changing the crown bearing without reshimming. If my new crown bearing also measures within spec of the old bearing then I will just install it without reshimming……comments/thoughts??

 

Keith

[Stan Walker]

I would measure, or have a shop replace it. The fact that your first one failed at such low mileage may mean it was shimmed incorrectly at the factory. Dropping in a new one without checking the preload will likely result in another low mileage failure if that is the case.

 

I've got 93,000+ miles on my crown bearing. No play yet. Replacing one every 30,000 Kilometers (18,641 miles) seems like overkill to me.

 

Stan

[Keith S]

Stan

I replaced the FD. There was no way to inspect the gear backlash with the FD disassembled. I guess it comes down to my comfort level. This summer I had the bike up into the Yukon during an Alaska trip. To have a FD failure up there was not acceptable. This is what started me thinking about a proactive approach.

Keith

[BigAL]

Could you tell us what your VIN # is ? I'm just wondering how close my bike is to yours in the assembly line. I haven't had any problems (yet) on my 2004 RT, but I'll be listening. What does is the sound like?

 

AL

[T__]

I experienced a FD failure on my 2004 R1150RT at 35000 km. I was traveling just outside of Billings Montana and noticed a sound coming from the bike at low speed that I thought was road/tire noise. I continued the trip and was averaging 140 KPH to the next stop. When I slowed down I again heard the same noise, pulled in the clutch and the noise was still there this time on a side road not the pavement of the interstate. Once I got to the campsite I drained the FD oil and it was black. There is a whole story of flying back to Calgary and coming back with a trailer to retrieve the RT. Upon disassembly of the FD it turned out the only failure was the main crown bearing, yes the one you have heard a lot about. This scared the crap out of me, my estimate is that the bearing would have completely failed in about 2 more hours of ride time at 140 KPH (87 MPH) and the thought of the FD failing at that speed …..well I’m just thankful that it didn’t

I had changed the FD oil before the trip and the drain plug magnet was clean so this means that the bearing went from no indication of failure to failure in less the 2000 km (1220 miles). Other people have experienced the same thing….no warning or indication. Having said all that I am thinking of changing the crown bearing on a proactive basis every 30,000 km. Here is a post "changes my bearings" that covers the debate of changing the crown bearing without reshimming. If my new crown bearing also measures within spec of the old bearing then I will just install it without reshimming……comments/thoughts??

 

Keith

 

Keith, if your original bearing went 35,000km & you are going to replace the bearing at 30,000km intervals even if the original shimming was off a little you should catch that at the 30,000km replacement..

 

While absolutely correct shimming would be the desired route you would have to miss the installed preload by quite a lot to cause an early bearing failure.. If after you put about 500km on the replaced bearing you still get a final drive heating problem you probably have a tight bearing preload,, if you notice any rear wheel play in the final drive you probably set it up too loose..

 

I’m guessing here but would imagine the BMW bearing is a C-3 bearing therefore so should the replacement’s from BMW.. If you go aftermarket on the bearing you should try & find the same C spec on the bearing as that has the best chance of keeping apples to apples..

 

If you pull your existing bearing & it looks good at 30,000 km the shimming was probably close.. If you measure the bearing before it self destructs you can probably compare those measurement to the new bearing..

 

Twisty

[smiller]

I've got 93,000+ miles on my crown bearing. No play yet.

Same here (90,000 + miles.) The bearings fail for a reason. If it were a design issue you wouldn't have the majority of installations lasting a long time, so it must be either a materials or assembly issue. By that theory, if you use a high-quality bearing and shim it properly (perhaps correcting an error originally made at the factory) you should see a long life. I would try that route before proactive replacements... if those two items are properly attended to then the crown bearing should last 100,000 miles and beyond, as it does in many/most cases.

[DrPaul]

I had changed the FD oil before the trip and the drain plug magnet was clean so this means that the bearing went from no indication of failure to failure in less the 2000 km (1220 miles).

Keith,

What gear oil did you use? Was it different from oil used previously? Do you run the same oil in the transmission?

[Linz]

Do we gather from your comments about FD heating, that a sign that all is not well, is a hot FD after a run?

 

I've been reading about this for some time. I've read that some FD's are so hot after a run that it's difficult to hold your hand there for any length of time.

 

Mine has never left mildly warm even after a full day run on a freeway on an interstate blast on a warm day.

 

Wondering if this is significant. Is a hot FD after a run a precursor to failure?

 

Linz

[T__]

Do we gather from your comments about FD heating, that a sign that all is not well, is a hot FD after a run?

 

I've been reading about this for some time. I've read that some FD's are so hot after a run that it's difficult to hold your hand there for any length of time.

 

Mine has never left mildly warm even after a full day run on a freeway on an interstate blast on a warm day.

 

Wondering if this is significant. Is a hot FD after a run a precursor to failure?

 

Linz

 

Linz, not really.. A hot final drive that has always gotten hot is just a sign of high speed load & hot ambient temps.. A final drive that didn’t heat before a bearing change but does after the bearing change is usually a sign of something being too tight..

 

I made a 200 mile run a week or so ago at close to 30°f ambient & speeds that averaged low 90’s & the final drive was just warm to the touch.. The same run made last summer with the ambient temp at close to 90°f & travel speed average closer to the mid 80’s resulted in the final drive being too hot to hold my hand on for more that a few seconds..

 

Final drive heating is more of a general test indicator than a finite indicator of final drive condition..

 

Twisty

[philbytx]

so it must be either a materials or assembly issue.

Oh! No! Not the old "was it a Friday afternoon/Monday morning build" issue rearing it's ugly head again

I thought we got rid of that at the end of the last century

[smiller]

I thought we got rid of that at the end of the last century

Most manufacturers did.

[Boffin]

so it must be either a materials or assembly issue.

Oh! No! Not the old "was it a Friday afternoon/Monday morning build" issue rearing it's ugly head again

I thought we got rid of that at the end of the last century

 

Call me a cynic but....

 

Since the re-unification of the two Germany's a lot of the lower paid workers, such as assembly line workers, come from the former communist state where "quality control" meant a well-made knob. Whereas western Hans may be dilligent, Eastern Gerhart may not be. Just a thought....

 

Andy

[Keith S]

Could you tell us what your VIN # is ? I'm just wondering how close my bike is to yours in the assembly line. I haven't had any problems (yet) on my 2004 RT, but I'll be listening. What does is the sound like?

 

Al

VIN# WB 10419A83ZK51223 The sound was like road noise but it oscillates, best description would be louder then quieter. Imagine a tire with tread on only 50% of the tire…. tread noise…no tread noise. When I change the FD oil before the trip the oil was a normal colour and the magnet was clean, not even the black paste that most speak of.

 

Keith

 

AL

[Keith S]

Keith, if your original bearing went 35,000km & you are going to replace the bearing at 30,000km intervals even if the original shimming was off a little you should catch that at the 30,000km replacement..

 

While absolutely correct shimming would be the desired route you would have to miss the installed preload by quite a lot to cause an early bearing failure.. If after you put about 500km on the replaced bearing you still get a final drive heating problem you probably have a tight bearing preload,, if you notice any rear wheel play in the final drive you probably set it up too loose..

 

I’m guessing here but would imagine the BMW bearing is a C-3 bearing therefore so should the replacement’s from BMW.. If you go aftermarket on the bearing you should try & find the same C spec on the bearing as that has the best chance of keeping apples to apples..

 

If you pull your existing bearing & it looks good at 30,000 km the shimming was probably close.. If you measure the bearing before it self destructs you can probably compare those measurement to the new bearing..

 

Twisty

 

Twisty

This is a new FD. I asked the dealer to contact BMW and see if the new FD had the 17-ball crown gear bearing. From what I have read this is BMW’s solution to FD failures of this vintage. BMW never got back to them so I do not know which bearing is in this FD. When I disassembled the failed FD I was amazed with the amount of metal fillings in the oil and the other bearings (tapered roller etc.) were in great shape. It would make sense to check the shimming when I replace the bearing and after that assuming the tolerances of the replacement bearing are good then I can just replace the bearing. As far as the C3 tolerance bearing….a C3 bearing is what most suppliers have on the shelf. Tighter tolerance bearings i.e. C2, C1 and no marking are tighter tolerance bearings and from I know you use a looser tolerence bearing in applications where the shaft heats up before the housing that supports the outside race of the bearing so I am not sure what BMW would use in the FD. And yes I do plan on replacing the crown bearing on a regular basis.

 

Keith

[ShovelStrokeEd]

Most, if not all, bearing manufacturers have statistical data available on their bearings and provide charts to determine bearing life or mean time between failures.

 

Some of the factors involved are loading, lubrication and rotational speed and bearing fit. None of them can account for improper assembly technique, poor tolerance control or bad design.

 

In general, a bearing will work fine until it fails and when it does, it will fail over a very short period of use. As witness most of the failures reported on this site and others. Invariably, the bearing showed no symptoms, clean oil on a recent final drive oil change then a failure a short time after. An oil analysis might reveal impending failure if the oil is compared to fresh oil and then again, it might not.

 

I wouldn't go so far as to exchange bearings at some arbitrary interval until I found a history on a particular final drive. Once the bearing has failed, a prudent mechanic would have changed all the bearings anyway which brings back the issue of fit and proper assembly. Since the assembly requires a fixture to set the pre-load on the opposing tapered bearing, it is best left to someone who has the proper tools and experience/training to use them.

[Keith S]

I had changed the FD oil before the trip and the drain plug magnet was clean so this means that the bearing went from no indication of failure to failure in less the 2000 km (1220 miles).

Keith,

What gear oil did you use? Was it different from oil used previously? Do you run the same oil in the transmission?

 

Paul

Since I purchased the bike used then I do not know what was used in the FD before I got it. At that time I used 90-weight API GL-5 gear oil. I now use Amsoil 75/140 in the FD and transmission.

 

Keith

[Keith S]

Most, if not all, bearing manufacturers have statistical data available on their bearings and provide charts to determine bearing life or mean time between failures.

 

Some of the factors involved are loading, lubrication and rotational speed and bearing fit. None of them can account for improper assembly technique, poor tolerance control or bad design.

 

In general, a bearing will work fine until it fails and when it does, it will fail over a very short period of use. As witness most of the failures reported on this site and others. Invariably, the bearing showed no symptoms, clean oil on a recent final drive oil change then a failure a short time after. An oil analysis might reveal impending failure if the oil is compared to fresh oil and then again, it might not.

 

I wouldn't go so far as to exchange bearings at some arbitrary interval until I found a history on a particular final drive. Once the bearing has failed, a prudent mechanic would have changed all the bearings anyway which brings back the issue of fit and proper assembly. Since the assembly requires a fixture to set the pre-load on the opposing tapered bearing, it is best left to someone who has the proper tools and experience/training to use them.

 

This is exactly what I do not want to do (create a history of failures on my final drive) as you have stated there is very little if any indication that a final drive is going to fail. After the failure I seriously looked at other motorcycles that do not have the paralever design but there is no other bike that can replace the RT IMOHO. Checking the shimming is a good suggestion and I will have this done. The investment of the bearing plus labour is in my opinion cheap insurance against having a catastrophic FD failure.

Thanks for your comments

Keith

[Stan Walker]

I’m guessing here but would imagine the BMW bearing is a C-3 bearing

 

The BMW supplied 17 ball crown bearing is marked as follows:

 

SKF 61917/C3 FRANCE

 

I heard a rumor that BMW had returned to the 19 ball crown bearing.

 

Stan

[Keith S]

Stan

Thanks for the bearing info...this will give me a starting point to do some research. My comment on the rumour "you have to be kidding!".

hmmmmmm let me see..... where was that artical on belt drive

[Keith S]

I’m guessing here but would imagine the BMW bearing is a C-3 bearing

 

The BMW supplied 17 ball crown bearing is marked as follows:

 

SKF 61917/C3 FRANCE

 

I heard a rumor that BMW had returned to the 19 ball crown bearing.

 

Stan

 

Stan

Would you know the SKF part number for the 19 ball crown bearing?

 

Thanks

Keith

[Stan Walker]

Stan

Would you know the SKF part number for the 19 ball crown bearing?

 

No.

 

The only reason I know the 17 ball crown bearing is that I have a brand new one sitting on my shelf.

 

Stan

[Keith S]

Local bike shop gave me these numbers for the crown bearing and the main seal.

seal 33127663482 $43.00 CDN

bearing 33121451188 $53.00 CDN

 

Pretty darn cheap insurance.

 

Keith

[RFW]

f my new crown bearing also measures within spec of the old bearing then I will just install it without reshimming……comments/thoughts??

ABSOLUTELY NOT!!!

 

You MUST reshim the shim on the bearing (but not the one on the taper roller at the other end).

 

The axial tolerance of the large ball bearing is greater than the shimming tolerance. You cannot easily measure this. The main reason for the shims is to take up the differences in axial bearing tolerance (which you cannot measure easily).

 

If you assemble the FD with what SEEMS to be a bearing with identical dimensions, you can easily end up with with either axial play in the FD, or an excessively high interferance fit. Either will result in a very short bearing life.

 

Note that the shim at the taper roller end controls gear tooth engagement, which although critical, will not have changed if you have not replaced the taper roller. The shim at the big ball bearing end controls preload.

[Anton Largiader]

You MUST reshim the shim on the bearing (but not the one on the taper roller at the other end)....

Note that the shim at the taper roller end controls gear tooth engagement, which although critical, will not have changed if you have not replaced the taper roller.

Seeing that the title of this thread contains the word 'proactive' I will say that anyone reshimming a final drive should check ALL of the shimming. The backlash isn't likely to be correct either, especially on a drive that's already darkening the oil. If you pull it apart, check it all. Tooth contact, backlash, and preload. Then you have a really good shot at the thing lasting indefinitely. My RS has gone 150k miles on the original 1993 bearing. Meredith's '98 GS has gone about 135k miles, same deal.

 

If weight was an issue, well, we ALL know people who should have had multiple failures by now but haven't, right? These FDs are capable of being very durable. You just need to make sure yours is capable. Sad but true.

[Keith S]

Bob

I took a closer look at the failed FD. The crown bearing indeed has 19 balls. The crown bearing had started to fail, which caused resistance to rotation and heat. This led to the outside race spinning in the main seal housing. Aluminium debris is what I saw in the oil not metal fillings. After searching other sites for FD failures and repairs I found out that I am not the first one to consider replacing the crown bearing at a fixed mileage. I even found one post where a guy on a GS had a crown bearing failure out in the boonies. He used a drift punch to remove the failed bearing and heated up the new bearing on the exhaust crossover pipe. He admits that this is a field repair, which is only good enough to get you back to civilization. Who would have thought of using exhaust pipe heat! What I also found amazing is the number of FD failures out there. There have been a few people that replaced just the crown bearing without shimming but I have to agree with you that it would be a crapshoot at best. I reviewed the shimming procedures, they look tedious but straightforward and makes sense. The gears in the failed FD look pretty good so I am thinking of rebuilding the failed FD and replacing all of the bearings. This would entail shimming for backlash and preload. I will post the rebuild process once I start and see if anyone wants to work with me online. It could get interesting!

 

Bottom Line.

If you replace just the crown bearing without shimming, it is a crapshoot.

 

Keith

[Stan Walker]

bearing 33121451188 $53.00 CDN

 

This is the tapered roller bearing part number, not the crown bearing.

 

Stan

[RFW]

Bob

I took a closer look at the failed FD. The crown bearing indeed has 19 balls.

Usually the 19-ball bearing fails because the retainer disintegrates. Too many balls and not enough space for a robust retainer. The 17-ball bearing is apparently more robust.... at least its retainer is.

 

These bearings (both the ball and the taper roller) are standard items and are available at bearing suppliers at a lot lower price than BMW charges.

[RFW]

[quote

Stan

Would you know the SKF part number for the 19 ball crown bearing?

You do not want the 19-ball bearing!! BMW originally used a 17-ball bearing made by SKF. It lasted forever. Then they switched to a 19-ball bearing made by Fischer AG (FAG). This bearing had problems with retainer disintegration. I understood they switched back to the 17-ball bearing.

 

Note that the new final drives (the ones with the big hole through the middle) are of a totally different design.

[Keith S]

You do not want the 19-ball bearing!!

 

Bob

 

I wanted to look at the spec differences between the two bearings. I will use a 17 ball during the rebuild.

 

Keith

[Tipover_Bob]

And for goodness sakes, use a 90wt oil.

Tipover Bob

[Keith S]

bearing 33121451188 $53.00 CDN

 

This is the tapered roller bearing part number, not the crown bearing.

 

Stan

 

Figures!

Spend 10 mins with this guy from Blackfoot Cycle telling him that this bearing was closest to the wheel. I thought the term "main crown gear bearing" would have been enough, oh well. After a second call the price is $88.00, still pretty cheap!

 

Keith

[A-Red Bill]

Another proactive approach is the ST1300. They don't seem to fail.

[Keith S]

Another proactive approach is the ST1300. They don't seem to fail.

[Keith S]

I started doing searches on rebuilding the FD and here are some of the links I found. this is the best one for understanding the dynamics of shimming and this shows you how to make a paralever installation tool and the rest #1 and #2

 

From what I have seen so far the installation of the crown bearings is pretty straightforward but the pinion gear shimming looks a little intimidating.

Going on a 3 day ride tomorrow so I will be away from the computer for the weekend.

 

Keith