Final drive gone south

[alke46]

Had a nice 60° day here on Monday so I decided to go for a little ride. 145 miles later and I got back home, parked in the garage and went in the house for a cup of coffee.
Went back out to the garage and found what this collection of photos show. I guess I am lucky to have made it home.

IMG_20230213_165537462 by Larry Alkire, on Flickr

IMG_20230213_165713528 by Larry Alkire, on Flickr

IMG_20230213_165717142 by Larry Alkire, on Flickr

IMG_20230215_153222817 by Larry Alkire, on Flickr

IMG_20230215_153113135 by Larry Alkire, on Flickr

What's next? Is this something that can be reconditioned, or replaced? When I removed the drain plug it had quite a bit of shiny metallic particles on the magnet.

I'm thinking the seal went bad and just let the gear oil out or did a bearing in the FD give up the ghost and go out causing the seal to leak?

Suggestions appreciated as I know this is not the 1st time for this to happen to others.
TIA.

 

[senseamidmadness]

I'll preface this by saying I am NOT an expert on these final drives -- I will defer entirely to Anton Largiader's knowledge if he sees this thread. Pretty much everything I know comes from the excellent documentation on his website.

It's not clear to me from the pictures whether the seal failure caused bearing damage or the other way around but I haven't seen a lot of dramatic seal failures personally. The bearing directly behind that big seal, I believe, is the crown bearing -- the biggest bearing in the whole bike. It carries (almost) the entire load of the rear end so it sees a whole bunch of force when you ride. Pop what's left of that seal out and you should be able to get a decent look at that crown bearing.

If the damage isn't obvious there, the final drive will have to come apart to find out where it is. And if that gets done the whole thing might as well get rebuilt. The "taking it apart" isn't terribly complicated but it does require heat, special tools, and patience. It's the "putting it back together" part that's really easy to screw up because of the need for precise shim-adjusted preload on the tapered roller bearings.

Did you take any pictures of the drain plug magnet? That would also provide some clues as to where the metal came from.

It would also help to know how many miles are on this machine, what final drive oil you typically put in it, how often you change it, and how many times you've done that on this bike.

 

[41107]

Just looking at that oil that is on the rim tells me it wasn't changed often enough.With the little bid that is in there I change it every 3th oil change with the hope of never having to go through this.

 

[Bdiver]

On my 3rd

I'm on my 3rd now. The first one the bearing went belly up (113k), you could put the bike on the center stand and move the wheel all over the place side to side. I actually rode it 600 miles home gently that way (the seal did NOT leak) then got one off ebay. My 2nd was feeling squirrely for about 500 miles (I suspected the crown bearing was going bad) and then 150 miles from home riding gentle I started sliding in the curves, when I pulled over there was fluid all over the back tire (36K + whatever was on it before I bought it). I took it apart and will rebuild it but found another on ebay from a 1996 with only 11k miles on it (I can't believe a company would part out a basically brand new bike but........) I still plan to rebuild one of my old ones but got the one off ebay for a reasonable price.

Good luck!

 

[riderr1150gsadv]

How many miles and what year? Age/miles have to do with what failed first.... Sounds weird, but if the OP got around 100K miles on the bike, then the bearing wore out and took out the seal. If the bike has around 25K miles, the bearing was shimmed wrong and prematurely destroyed itself taking out the seal too..... In any case it isn't that hard to repair depending on the shimming situation, as for that you need some measuring tools... Yes, seals wear out too, but they usually last longer than the bearings in the FD's.... YMMV

 

[jrogers]

Good ones and bad ones never now until failure. I'd be betting the bearing was the problem if not more things worn when you open it up. Seal usually hold up fairly well until something else causes problems.

 

[saddleman]

That is definitely the classic crown bearing failure on this style of BMW final drive. Hopefully you didn't ride it to far after the bearing failed and it can be rebuilt. Sometimes the black seal housing that the bearing is in gets ruined & it is not worth rebuilding then. A new housing cover alone can cost over $400 the bearing is $185 & the crown bearing seal cost $50. The bearing debris from your failure means to rebuild it correctly so all of the metal shavings can be removed the entire final drive needs to come apart. I have tools & instructions that I loan out that details how to remove & properly install this style of final dive. Message me & I'll be happy to help you.

 

[alke46]

Thanks to all

Thanks for all who responded, I will try to fill in some information that I personally know about the bike.

I am the 3rd owner of said bike. I purchased it from a friend I have known and worked with for over 50 years. He unfortunately has been dealing with short term memory loss and I believe the bike sat unattended for possibly 6 years. Garaged.

My friend bought the bike from the original owner in Denver, Co. who put only 20,900 miles on it. I have no idea of what items the 1st owner addressed but the bike is 2001 R1100RL. I have been told the "L" stands for limited edition. It came to me with a plexiglass windscreen and BMW side cases (saddlebags). It also has the black tank with white pinstripes on it. Again, from what I have been told is part of the "L" designation.

I purchased the bike last July with 40,294 miles on it and it had a LOT of issues to address just get it road ready. I changed all the fluids in it and used Belray Hypoid gear oil SAE 90. The same stuff I used to use on a Honda ST1100.

I also am surprised the drained gear oil was so dirty as I have only put 1,500 miles on it. When I changed it I did not notice any metal shavings on the drain magnet, but in my defense, I did not know about the FD issues that came with it.

So, I hope I have given enough information about the bike. It is again, a 2001 R1100RL with 41,759 miles on it.

 

[alke46]

@ Saddleman, a PM will be coming soon. Thank you.

Here's a couple of pics of the bike. The 1st two are of the bike as I received it. After taking off the bags and windscreen and finally the bike with rear drive exposed.

IMG_20220707_130617610_HDR by Larry Alkire, on Flickr

IMG_20220707_130606759_HDR by Larry Alkire, on Flickr

IMG_20220827_160912619 by Larry Alkire, on Flickr

IMG_20230217_113723020 by Larry Alkire, on Flickr

Also, I believe it was the original owner who changed out the front wheel to a larger 19", painted (non matching), one probably for more choices of tire size????? Anyway, there is a chrome rear wheel and a black or really dark blue front wheel.

 

[riderr1150gsadv]

It is hard to say exactly what caused the failure but seals do dry out from just sitting, and it makes me think now that this is what likely happened as, sadly, that bike has been somewhat neglected over time. Sometimes it is better to deal with a higher mileage vehicle than a barn find that sat around for ages.... Just my 0.02 cts..

 

[alke46]

It is hard to say exactly what caused the failure but seals do dry out from just sitting, and it makes me think now that this is what likely happened as, sadly, that bike has been somewhat neglected over time. Sometimes it is better to deal with a higher mileage vehicle than a barn find that sat around for ages.... Just my 0.02 cts..

Yeah, that's my weakness, I just wanted to help out a good friend who could no longer ride and needed it gone.

I agree with you that the bike had been neglected and we all know what happens to rubber that gets dried out and OLD!!!
The tires alone "looked" good but the date code showed they were 16 years old. And, they were really hard to get off. Came real close to using my sawzall to remove them.

 

[pglaves]

I have seen several cases of failure on this generation of final drives. In all of the cases I have seen in various stages of failure the cause has been pretty clear. The very thin but very brittle hardening on the big ball bearing races get a small crack or pit. This irregularity damages one or more balls. The damaged balls further damage the races. In the most advanced cases a ball will jam in the damaged races. This damages the cage surrounding the balls and the remaining balls pile up on one side kind of like railroad cars do in a train derailment. In various stages of failure metal particles in the oil and wobble of the crownwheel rapidly destroys seals.

I am convinced there are several reasons these bearings might fail. I have seen wear tracks in the races that were off-center, indicating the bearing was shimmed too tight. This means that cushioning lubricant is too thin between the balls and races. I know of several cases where owners and dealers mistakenly used out-of-spec gear oil that was too thick. This can under just the wrong temperature and speed conditions cause the gear oil to wedge up ahead of the rolling balls, again providing insufficient cushioning between the balls and races. Some may have been shimmed too loose, which can allow hammering and thus chipping of the outer race.

Also bear in mind that the big ball bearing used in these final drives was originally specified for the lean and fairly light weight R80GS back in the early 1980s and was continued to be used through the later models including the porky R1150 bikes and the still porkier K1200LT.

 

[gsaddict]

I'm on my 3rd now. The first one the bearing went belly up (113k), you could put the bike on the center stand and move the wheel all over the place side to side. I actually rode it 600 miles home gently that way (the seal did NOT leak) then got one off ebay. My 2nd was feeling squirrely for about 500 miles (I suspected the crown bearing was going bad) and then 150 miles from home riding gentle I started sliding in the curves, when I pulled over there was fluid all over the back tire (36K + whatever was on it before I bought it). I took it apart and will rebuild it but found another on ebay from a 1996 with only 11k miles on it (I can't believe a company would part out a basically brand new bike but........) I still plan to rebuild one of my old ones but got the one off ebay for a reasonable price.

Good luck!

When you do rebuild, you must check the shimming or you will eat another bearing.
Many were shimmed too tight from the factory.

Also use 80w90 gear oil as per BMW spec for that generation of bikes.
Avoid synthetics, that is for the next generation.
Tom Cutter from Rubber Chicken Racing is adamant the synthetic oil contributes to bearing failure.

 

[alke46]

When you do rebuild, you must check the shimming or you will eat another bearing.
Many were shimmed too tight from the factory.

Also use 80w90 gear oil as per BMW spec for that generation of bikes.
Avoid synthetics, that is for the next generation.
Tom Cutter from Rubber Chicken Racing is adamant the synthetic oil contributes to bearing failure.

This is something I was wondering about especially since the 1st owner only put 20k miles on it and the 2nd owner only another 20k.

On a side note, I know a guy who had a '02RT that was serviced twice by a dealership and after the 2nd service, his FD went out and left him stranded 400 miles from home. I don't know if his was an 1100 or an 1150.

 

[oldcamper]

I have seen several cases of failure on this generation of final drives. In all of the cases I have seen in various stages of failure the cause has been pretty clear. The very thin but very brittle hardening on the big ball bearing races get a small crack or pit. This irregularity damages one or more balls. The damaged balls further damage the races. In the most advanced cases a ball will jam in the damaged races. This damages the cage surrounding the balls and the remaining balls pile up on one side kind of like railroad cars do in a train derailment. In various stages of failure metal particles in the oil and wobble of the crownwheel rapidly destroys seals.

I am convinced there are several reasons these bearings might fail. I have seen wear tracks in the races that were off-center, indicating the bearing was shimmed too tight. This means that cushioning lubricant is too thin between the balls and races. I know of several cases where owners and dealers mistakenly used out-of-spec gear oil that was too thick. This can under just the wrong temperature and speed conditions cause the gear oil to wedge up ahead of the rolling balls, again providing insufficient cushioning between the balls and races. Some may have been shimmed too loose, which can allow hammering and thus chipping of the outer race.

Also bear in mind that the big ball bearing used in these final drives was originally specified for the lean and fairly light weight R80GS back in the early 1980s and was continued to be used through the later models including the porky R1150 bikes and the still porkier K1200LT.

I’m not a mechanical engineer but even so suspect a conventional ball bearing designed for radial loads is simply a poor choice to deal with the side thrust loads generated by a pinion and crown gear. When I Google “crown and pinion thrust bearing” it shows mostly tapered rollers and a few other special purpose bearings. Considering the frequency of BMW FD failures it seems obvious there is a deficiency somewhere in the fundamental design. I wonder how other MC manufacturers have addressed this problem. Does anyone here know?

 

[pglaves]

I’m not a mechanical engineer but even so suspect a conventional ball bearing designed for radial loads is simply a poor choice to deal with the side thrust loads generated by a pinion and crown gear. When I Google “crown and pinion thrust bearing” it shows mostly tapered rollers and a few other special purpose bearings. Considering the frequency of BMW FD failures it seems obvious there is a deficiency somewhere in the fundamental design. I wonder how other MC manufacturers have addressed this problem. Does anyone here know?

You are correct. The deep groove ball bearing BMW used will tolerate mild axial loads but an angular ball bearing or tapered roller bearing would be far superior. I was told this by an engineer for FAG, a bearing manufacturer.

That is one key reason why shimming which is too tight may rapidly damage the bearing.

ADDED: The design of the final drive is such that the gear mesh pushes the crown wheel axially into the ball bearing and away from the tapered roller bearing. When I told this to that FAG engineer he told me I must have that wrong. So I emailed him an image from the parts fiche. I got a 5 word reply: "Holy $#!+ you are right."

 

[Omega Man]

I’m not a mechanical engineer but even so suspect a conventional ball bearing designed for radial loads is simply a poor choice to deal with the side thrust loads generated by a pinion and crown gear. When I Google “crown and pinion thrust bearing” it shows mostly tapered rollers and a few other special purpose bearings. Considering the frequency of BMW FD failures it seems obvious there is a deficiency somewhere in the fundamental design. I wonder how other MC manufacturers have addressed this problem. Does anyone here know?

You are correct. The deep groove ball bearing BMW used will tolerate mild axial loads but an angular ball bearing or tapered roller bearing would be far superior. I was told this by an engineer for FAG, a bearing manufacturer.

That is one key reason why shimming which is too tight may rapidly damage the bearing.

I wonder if the /2 generation had this problem? When I look at this single side swing arm setup, as Paul mentioned, the axial load becomes more complicated. I think this is especially true with the increased weight and horsepower of later (than say a /2) bikes especially when ridden in high-torque situations.
I don’t know if there has ever been a study on riding styles/conditions as they relate to driveline failure?

OM

 

[20774]

In reality, how much is there in the way of side loads? The beauty of a motorcycle is the leaning part which transmits loads vertically through the chassis. Granted there will be some side loads, but if as Paul suggests, the design can tolerate mild side loads, it might be fine. I thought one of the bike series, maybe the KLT, also had issues with rear bearing failures but the issue was being properly set up with shimming.

My R69S has tapered bearings in the wheels, as well as the swing arm.

 

[senseamidmadness]

Axial or side load may not be the right term, but I'm no engineer either. It seems to me that because the crown bearing is offset from both the center of the tire and from the load-bearing pivot points of the swingarm, the load it experiences isn't a direct axial load, but a torsional load. My guess is the forces on the tire attempt to twist it (and the hub assembly it's bolted to) relative to the swingarm, as you would with your hands at "12 and 6" when checking the crown bearing for play. This would be two axial loads at once in different directions, one on each side of the bearing, right? Does that count as axial load?

 

[dieselyoda]

Vent plugged?

When I saw the OP pics, right away I went to a plugged diff vent.

For sure, bearings, loading/lubricant could be good reasons but in just around 45 years of being a pro-wrench, didn't matter to me who made what/when or where it worked, if I saw a fast diff/tranny failure that blew the seal out, I went to the vent.