Final Drive

[nbarab]

Mercedes went through a similar flat spot in QC a few years ago, they learned quickly to dig their way out of that hole.

clever people..

[Lost Rider]

I have not had any major issues yet but can't help be somewhat concerned when traveling far from home. Over 20 years ago I switched to BMW from other brands because I saw the others as disposable bikes. Ride alot and sell after 2 years, repeat as needed. If BMW keeps it up I will have to go to another brand.


Dereck

So you've never had a problem, and 99% of the owners in here have never had a problem, but somehow you feel concerned to travel far from home on your roadster? Take your balls out of your purse.
If we were talking about the version 1.0 F800GS I would tend to agree, there's issues with the all-new model, and I'm not all that happy with BMWNA right now, but your statement about the 1200R or any other current boxer seems a little strange considering the millions of miles that must have been ridden already on the hexhead platform with proven reliability.

[Mollygrubber]

+1 on that Joe.

I feel more confident riding this bike long distances than I do about just about anything else.

Of course, I'll probably try to avoid 45 degree inclines covered in skull sized boulders, but as far as reliability goes, I think the boxer record speaks for itself.

And if you have an issue on the road, that's when the adventure really begins! Ted Simon said when he got bored on the road, he'd run out of gas on purpose...

Peter

[tinytrains]

Of the 268 FD failures listed at http://www.bmwfinaldrive.com, none of them are an R1200R.

Lots of RTs and GSs. I have read about one R1200R with a wheel bearing failure, but that is all I can find.

Given its light weight and road-only use, the FD has a pretty easy life. Plus the new models (08 and up) have some improvements.

Sure someone out there has had a failure, but it is not common place on this model.

My only real concern is my battery leaving me stranded without warning.

Scott

[rutheugene2]

I agree. The inside wheel bearing is of a type designed for precision machine tool spindles that have preload adjusted with fine thread nuts. Made by SKF, these are very high quality, angular, 15 degree contact angle, ball bearings, with dynamic load ratings (about 5000 pounds), far beyond anything seen on a motorcycle wheel. They are not lube sensitive at motorcycle speeds, so any clean decient oil will do. The only problem I see is, they are preloaded with a shim system that is very unforgiveable!! I can see how they could easily be preloaded incorretly. Since the final drive axle and case are very stiff, even a smallest amount of insufficient shimming will put excessive preload on the bearing, greatly reducing it's life. If preloaded correctly, the bearing should last the life of the bike. Shim tolerance by the book is quite generous. Personally, I would prefer the shimming be more accurate, to within +/-.00050. Few shops have the ability to shim this accurately.

The only other design problem I see is, this bearing has steel cages that are going to scuff off some wear particles. I would prefer fabric reinforced resin cages. Wear particles from the steel cages should be picked up by a magnetic drain plug. Changing the oil at reasonable intervals will keep the debris particle count within reason.

This explains why failures posted on the web are across the board and very random. It isn't about lube, bike model, or anything else. Life is going to be related ONLY to shim accuracy, and that is not something the average rider is going to be able to check. Worse yet, this makes rebuilds a very iffey situation if not done very, very carefully. One bike might go 1000 miles and the next one go 150,000 miles, depending on preload.

I think this explains a lot about an issue that has had a lot of opinions.

Eugene Arnold. Retired professional product development Mechanical Engineer

[Mollygrubber]

In addition to all of the above, which I am hardly qualified to debate, I have a gut feeling that at least some of the reported problems were the result of ... ahhh... searching for the right phrase here ... less than rigorous adherance to 'proper' maintenance schedules, lubricants and or procedures.

If you're concerned, do some research and find out what fails and when. Then take preventative measures by servicing said parts early. You'll be likely to catch something in the throes of failure before it happens, and have documented proof for a warranty claim.

My 2¢

After all that, I'll probably ignore my own advice...

[tinytrains]

... ahhh... searching for the right phrase here ... less than rigorous adherance to 'proper' maintenance schedules, lubricants and or procedures. :

While true, it was BMW that said it was "maintenance free" originally.

They later changed their tune.

[Mollygrubber]

... ahhh... searching for the right phrase here ... less than rigorous adherance to 'proper' maintenance schedules, lubricants and or procedures. :

While true, it was BMW that said it was "maintenance free" originally.

They later changed their tune.

Indeed. Why they would publicize that, without being 100% confident (mathematically speaking, a 'certainty' - hard to achieve in the mechanical world I'm sure) is a mystery to me. One of those hanging yourself with your own rope scenarios. I tend to take blanket statements like that with a grain of salt. Another example is the 'zero maintenance' drive belts on the 800 twins. In a perfect world, OK I guess. But why put it out there for the vultures to feed upon? If I was involved in the marketing, I would have suggested saying 'Extremely low maintenance', not 'Zero maintenance'.

[gibbo111]

The independent mechanic I use for the things I dont do(other than oils) recently said to me " Please change the final drive oil every10000km/6000m as 180ml isnt a lot of oil" , I will do it!

[rutheugene2]

See my message of 4/11. As for lubrication, these bearings are ball bearings that roll, not journal bearings that slide. Therefore, lubrication is not so important for a ball type bearing. That is why similar rolling bearings on car or truck axles require no lubrication change for the life of the bearing. They are lubed with either grease or oil. In the case of trucks, the volume of oil is very, very small and they can go for millions of miles. This same exact bearing, preloaded with a fine pitch nut, on machine tools, lasts for many, many years in the industrial environment. Many of the bearing failures have been on bikes that have been carefully taken care of. Unfortunately, you can't tell if a bearing has been improperly preloaded. That will kill the bearing regardless of lube. I can understand why BMW wanted to go to a zero maintenance schedule. With correct preload, that would be fine. After all the uproar, they changed their mind, more due to customer pressure than engineering reasons. Again, if the bearing preload could be adjusted with a fine pitch nut rather than shims, this wouldn,t be an issue. I am surprised that BMW used this design in the first place. Not the way I would of designed it and I have been designing bearings into machinery for over 40 years.

Eugene

[Mollygrubber]

See my message of 4/11. As for lubrication, these bearings are ball bearings that roll, not journal bearings that slide. Therefore, lubrication is not so important for a ball type bearing. That is why similar rolling bearings on car or truck axles require no lubrication change for the life of the bearing. They are lubed with either grease or oil. In the case of trucks, the volume of oil is very, very small and they can go for millions of miles. This same exact bearing, preloaded with a fine pitch nut, on machine tools, lasts for many, many years in the industrial environment. Many of the bearing failures have been on bikes that have been carefully taken care of. Unfortunately, you can't tell if a bearing has been improperly preloaded. That will kill the bearing regardless of lube. I can understand why BMW wanted to go to a zero maintenance schedule. With correct preload, that would be fine. After all the uproar, they changed their mind, more due to customer pressure than engineering reasons. Again, if the bearing preload could be adjusted with a fine pitch nut rather than shims, this wouldn,t be an issue. I am surprised that BMW used this design in the first place. Not the way I would of designed it and I have been designing bearings into machinery for over 40 years.

Eugene

Interesting point Eugene. If the 'flaw' in the design is in the adjustment mechanism, then BMW has an opportunity - every year! - to revise it. One wonders why this hasn't happened yet. It would seem that a one-time redesign would have solved this issue completely and prevented the many FD failure posts on forums like this. I can't help but think these scared away potential new buyers from the marque, however strong the sales figures are.

Peter

[celticus]

... ahhh... searching for the right phrase here ... less than rigorous adherance to 'proper' maintenance schedules, lubricants and or procedures. :

While true, it was BMW that said it was "maintenance free" originally.

They later changed their tune.

Indeed. Why they would publicize that, without being 100% confident (mathematically speaking, a 'certainty' - hard to achieve in the mechanical world I'm sure) is a mystery to me. One of those hanging yourself with your own rope scenarios. I tend to take blanket statements like that with a grain of salt. Another example is the 'zero maintenance' drive belts on the 800 twins. In a perfect world, OK I guess. But why put it out there for the vultures to feed upon? If I was involved in the marketing, I would have suggested saying 'Extremely low maintenance', not 'Zero maintenance'.

BMW can call it "Maintenance Free" because they are going to insist that did not malfunction even in the face of irrefutable evidence to the contrary.
I read in maybe Cycle World that BMW had finally fixed the oilhead surging problem even though BMW had never admitted that there was a problem. Wink wink.
That's my story anyway.

Mark

[rutheugene2]

Mark,

Lighting The Fire

You have a good point regarding the surging. Again, BMW got themselves into a design corner going back many years. Emission requirements drove them towards lean mixtures. Because they monitor only one cylinder (TPS), and all injectors are not perfectly matched, things can sometimes get a little out of control, at part throttle, light load, having marginal ignition of the air/fuel mixture. We call that surging. When a spark plug fires, the air/fuel mixture must be within certain bounds, between too lean or too rich, to start the fire. Once started, the flame front moves in all directions towards the corners of the chamber. (no, it doesn't "explode"; it burns rapidly, but evenly, out from the source of ignition), That is why plug position is so important to engine design. You want the flame front to reach all edges of the chamber at about the same time, to achieve greatest cylinder pressure in the shortest amount of time. I.E. more grunt on the piston.

Engines with more cylinders, running lean mixtures, all have the same problem, except you don't feel it as much as you add cylinders. Chrysler had the problem for a while and had to tweak things a little bit towards the rich side. Modern, very hot, ignition systems have also helped.

One has to do whatever it takes to be sure there is enough fire to ignite the lean mixture on both sides. That's why different plugs, different plug indexing, etc., sometimes helps and sometimes doesn't, depending on what works best to start the fire. I suspect it is also why they went to two plugs for each hole in 2004. It also gives just a bit more power because two flame fronts don't have as far to go, increasing cylinder pressure a bit faster and higher, for more push on the piston. Just that more insurance that the fire is going to get lit well and surging is eliminated. All piston aircraft also have two plugs per hole, not only for safety, but for the increased performance also. They run richer mixtures so they don't have the surging problem.

I wish there were an easy way to richen things up a tad without spending a lot of money on off market controllers. Until then, we (and the dealerships), are stuck with just a few weak options.

Eugene

[deilenberger]

See my message of 4/11. As for lubrication, these bearings are ball bearings that roll, not journal bearings that slide. Therefore, lubrication is not so important for a ball type bearing.

Snippage..

I am surprised that BMW used this design in the first place. Not the way I would of designed it and I have been designing bearings into machinery for over 40 years.

Eugene

Eugene,

I was a bit puzzled when I read your original posting on the final drive, but figured I must have misunderstood something.. I'll admit to never having one of the Hexhead rear drives apart.. but my understanding is - the large inner bearing isn't even touched by the oil in the rear drive. And it is not preloaded. It lives outside a seal, and is a sealed greased bearing. The outside end bearing, which is a needle bearing with no axial restrictions on movement is lubed by the lubricant.

http://www.realoem.com/bmw/showparts.do ... g=33&fg=10

Theoretically - the bearing should last just as long as the ones used in cars.. It does appear there is some adjustment of the cover by the spacers used under the inside cover (what they call in the diagram "adjusting washer") but in reading the factory service manual - these are used to adjust the tooth engagement positioning between the pinion and crown gears, not for adjusting preload on this bearing.

Basically - the inside bearing is not side loaded.. due to the floating design on the outer end of the axle.

I've uploaded a copy of the page from the manual to my website: http://www.eilenberger.net/temp/rear_drive_repair.pdf

The type of design/adjustment you're describing sounds more like the older rear-drive design used by BMW on the oilhead bikes.. is that possible? (I see you own an 1150 - which used the older design, and you may not be aware that the new design is nothing at all like the design in the 1150..)

FWIW - the failure mode most seen on the Hexhead final drives is one of the seals going bad, heating up occurring due to the loss of lubricant (just the oil-less tooth contact is enough to do this) which eventually causes the seal on the large bearing to fail, leading to it loosing lubricant and failing. My understanding is - (and this mostly is from discussion with some very knowledgeable people who also have some contacts within BMW) BMW's likely determined two things were happening: (1) The original manufacturer did not clean the assemblies adequately when they were assembled - causing contamination of the factory oil fill that leads to the seal failure - perhaps due to inadequate cooling/lubrication of the tooth contact area, causing the contaminated oil to heat and expand - and since the housing is sealed - the oil had to go somewhere (2) the original quantity of oil didn't leave enough of a compressible air-space in the housing if the oil was contaminated, causing the pressure buildup to exceed the capacity of the seals - causing fluid loss and subsequent bearing failure.*

Take those ideas for what they're worth - I have had no personal confirmation from any of my contacts in BMW that this is the case (nor have I asked.. since I suspect I wouldn't be told.) What I found interesting is when I did an oil change on my rear drive at 24,000 miles - on a bike that had received the 600 mile change of fluid - the oil that came out looked EXACTLY like the oil I was putting in. It's BMW's 75W-90 Synthetic gear oil - which looks like cherry cough syrup.. and the oil coming out showed NO contamination at all (I drained it into a brand new baking tin just for that reason) - so I suspect BMW's original supposition that the fluid was "lifetime" fill wasn't too far out of line - IF the original assembly had been done correctly. BMW doesn't make the rear drive (or transmission, or lots of other parts on the bike..) I believe it is made by ZF, but it's also possible Getrag may have made it - they are the two companies BMW uses for this sort of thing.

So - to me - the rear drive is a non-issue. It's nothing I'll stay awake worrying about..

* - I personally have talked to three people who suffered rear-drive failure on a hexhead. In all cases there was indication that some fluid loss had taken place before the actual rear-drive bearings failed. In two of the cases where the riders were observant - there was some evidence of overheating of the rear-drive before bearing failure occurred. In one of these cases - the rider (a good friend and local club member) was about 1,000 miles from home when he observed there was leakage. It was a Saturday evening and he had to be home by Monday AM. He actually called a friend to ask what to do - and then ignored the advice to park the bike for the weekend and have it looked at on Monday. He rode it home, and commented on the burning smell he noticed for a good part of the trip. He actually did make it home, but mentioned the last 20 miles were kinda hairy since the back wheel didn't want to turn again whenever he came to a stop.. (BMW covered the drive..)

Best,

[rutheugene2]

Yes, I was referring to the older oil head designs. I drive a R1150R. A lot of thought has gone into the newer design. That design has spacers available in .050mm increments (which would never be small enough for proper preload adjustment), but are fine for gear alignment.

Although there is a lot of talk on the web over this issue, I also am not convinced that it is really that big of a deal, considering the number of bikes out there ---- except if you do have a failure, then the rebuild of the older design is very, very sensitive to preload and must be done carefully.

I also suspect that BMW has fine tuned their assembly procedures as well as their design. They don't want to lose any customers for any reason. As for the American segment, the local BMW dealer told me that only 10% of BMW production is sold within the United States. If true, that isn't a good thing. I would hate to see them leave us.