Is there one cause for all these FD failures?

[cmattingly]

I was thinking about this on my way home from my paying job this morning. I see alot of talk about replacing bearings. Is it the material they've used or the actual design? I have a custom gunsmith shop and have lathes and a mill. I can find better material and make bearings. Has anyone tried this?
If it's a design flaw, someone is bound to have an idea. This is going to require more research.

[Hackercraft792]

I don't know if there is any one single cause. What is needed is a control study and that is going to be hard. There seems to be a group who think it is a lube problem and another that think bearing/design flaw. I am in the lube group and run Lucas products in everything I own, but I have also purchased a spare final drive from a company that trikes LT's.

[bigbear]

Another thought on why some fail and some don't is improper assembly or preload adjustment.
1) During assembly when the bearings are installed they maybe getting pushed on the outer race as well as the inner race. This could cause small indents in the bearing races.

2) Preload adjustment: To much preload could cause the balls to indent to the races slightly. This may be agravated by shipping with bike weight bearing on the rear tire. Bearing is not turning so that any bumps would also transmit load in constant location.

Roy

[mtrevelino]

I see alot of talk about replacing bearings. Is it the material they've used or the actual design? ....
If you do a through reading of all of the postings, it seems to be related to assembly problems. I do not think that the bearing has changed from the 99 model year LT.

[cmattingly]

So properly installing replacement bearings with ones that have not been previously installed might be an answer? Are there incidents of FD failures after an initial failure, and a new FD had been installed? (lightening striking twice)

Back to the lube aspect. I replaced all the oil in my tractor with Sheffield (sp?) oil and noticed a huge difference in running temperature. It was so much better with Sheffield's oil. I know there's 1,000 oils out there with just as many opinions. But I may try that.

[BobShirley]

Are there incidents of FD failures after an initial failure, and a new FD had been installed? (lightening striking twice)

I had the original FD fail at 33,000 miles. It was replaced with a completely new unit by a BMW dealer and that one failed at 49,000 miles. Again replaced with a new unit and am now at 75,000 miles and still going. Both were replaced at BMWs expense.

Bob Schrader
'00LTC

[swanny]

I spoke with my mechanic this past saturday .asked him about the FD problems and what he thought was the cause for them. He stated that alot of them he saw were trailer pullers /some he felt were clutch slappers and the fact that when he recieves new bearings from BMW') the source of the bearings has been from several countries / not always from the mother land! This leads me to believe that some of these inferior bearings are placed in new bikes during production as well as repaired FDs.To sum it up / just like many other companies throught out the world BMW is trying to save pennies through cheaper suppliers and we as consumers get screwed :( :(

[wilbar00c]

Take a look at this thread!!! http://www.bmwlt.com/forums/showthread.php?t=34385

[BecketMa]

You can scan the threads and see that few rear bearings have failed in LTs towing trailers.

Not sure what a clutch slapper is?

If you need someone to diagnose why something has happened to your LT, you might think about asking a different BMW mechanic.

So far, no one knows why the bearing fail. Anyone who is asserting a fact about it is simply guessing.

Enjoy the nice wx.
Bob, 0hOh LT

[dshealey]

------------------------- I have a custom gunsmith shop and have lathes and a mill. I can find better material and make bearings. -----------------------------------------------
You can MAKE BEARINGS???? This I gotta see. Ball bearing manufacture is an extremely involved, VERY high precision venture, with balls and race contours measured in microns, not thousandths or even ten thousandths of an inch. Just the race and ball grinding operations are leagues away from what any machinist, tool maker, etc. could ever hope to even think about, requiring equipment costing hundreds of thousands of dollars. Even the inspection/measuring equipment is way out of reach for just about any individual.

[cmattingly]

When I first wanted to make barrels with integral sights and ejector rod housings, someone asked the same question. My response was "if someone else is making them, then I can too." No, I haven't attempted to make bearings yet, but someone is making them. Unfortunately for us, not very well or we wouldn't be talking about this. Only thing I can do is try to do better than them.

[tkramer]

You can MAKE BEARINGS???? This I gotta see. Ball bearing manufacture is an extremely involved, VERY high precision venture, with balls and race contours measured in microns, not thousandths or even ten thousandths of an inch. Just the race and ball grinding operations are leagues away from what any machinist, tool maker, etc. could ever hope to even think about, requiring equipment costing hundreds of thousands of dollars. Even the inspection/measuring equipment is way out of reach for just about any individual.

Reminds me of a quote from the movie Fast Times at Ridgemont High:

Jeff Spicoli (after he wrecks Jefferson's car): Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.[/QUOTE]

[BikerBob]

I have A 2002 with only 43k no problems with the final drive yet still better then a drive chain time to ride cya.....

[RonKMiller]

This is going to require more research.

:rotf::rotf::rotf:

..and a wad o cash. ;)

[cmattingly]

Before this gets ugly with replies and questions about my abilities as an engineer/machinist/motorcycle repair dude, I just want to clarify that the original point here I'm trying to find out is if there is one dominating cause for FD failures. Apparently BMW refuses to admit there is a problem. But with all this experience on this board, I'd like to take a proactive approach about it and gets some ideas. I'd rather do something about it now, than be stuck out in BFE with a new membership card into the FD Failure Club. It's a machine folks, someone designed the dang thing. But that doesn't mean we can't tweak it. Come on, you've never changed anything on your bike to make it better.... One of these days someone is going to come up with a fix for it and everyone else is going to say, "I wish I'd thought of that!"
I probably can't make a bearing on my equipment. Maybe the aircraft parts manufacturer right down the road can. If not, who the heck can make a decent bearing? Is that the whole problem? Is it the oil? Who's done a study on the different lubricates to find out? That's why I came here to ask y'all! It was not my intention to come on and boast of my capabilities, but to engage in conversion with some experienced and knowledgeable people.
Thankyouverymuch (done in my best Elvis impersonation).

[RonKMiller]

Nah, it ain't gonna' get ugly - it's just that this has been discussed about - oh - maybe ten thousand times over the years by some extremely qualified engineers, metallurgists, bearing specialists, oil engineers, etc. Bearings have been carefully examined for all potential failure points and sent for analysis several times. Some have failed at 5K, many others have lasted much longer. There are several members (including myself on my first LT) that have gone well over 100K.

The conclusion is: There is no conclusion

Collectively as a group we have not been sitting on our asses. Well, maybe I have - but it's part of my job description.

I can guarantee you that the combined engineering expertise of members on this board is at least equal to and probably far surpasses anything BMW has. Yeah, they're THAT good.

Plenty of suspects but no smoking gun.

Personally, I think the Butler did it....;)

[CharlieVT]

I know why they are failing, but I'm not telling.

[Dman]

I know why they are failing, but I'm not telling.

Heh, heh :D
You rascal! :D

[grifscoots]

Before this gets ugly with replies and questions about my abilities as an engineer/machinist/motorcycle repair dude, I just want to clarify that the original point here I'm trying to find out is if there is one dominating cause for FD failures. I have faith in ya, man! And thanks for looking out for us.

Come to our RTE tomorrow and bring weapons.

[CharlieVT]

Entertaining thread, this one. :)

I am reminded that I waited for years for someone to come up with a way to measure for crown wheel bearing preload without the BMW special tool. As a service to those who might consider rebuilding their own final drive I will refresh the collective memory here that it was "Dman" who posted the techique that requires no special tools and is elegant in its simplicity:

http://www.bmwlt.com/forums/showthread.php?postid=118116#poststop

[OU812]

When I first wanted to make barrels with integral sights and ejector rod housings, someone asked the same question. My response was "if someone else is making them, then I can too." No, I haven't attempted to make bearings yet, but someone is making them. Unfortunately for us, not very well or we wouldn't be talking about this. Only thing I can do is try to do better than them.
Please do. Then I can sleep at night and ride with out the FD keeping me looking back.
Really, I always believe anything can be made better. Why not the FD?

[gbob]

Has anyone measured how much of a "sweat" fit the inter race is ?
The NTN site has a list of shaft diameter measurements that their 61917c3 single row deep groove ball bearing can be mounted on .Short story is the listing shaft size is from 3.3465 " to about 3.349? (cannot remember) thats about 0"to .0025" sweat ,2.5 is a lot, I cannot remember ever mounting any bearing of any
size with more than .0015" .
I have read that the "c3" is a clearance spec.is clearance to be taken up by
sweat fitting on a oversize shaft to give a solid mounting and still have enough clearance for oil lube .
Has anyone measured this ball to race clearance after mounting ?
I have done this when installing large printing machine cylinder bearings ,with brass feeler gauges ,these bearings have a tapered mount and bezel nut that is tightened to reduce the clearance to .002 .004 " oil lube clearance.

The speed limit for 61917c3 bearing is 6300RPM oil lube and we are maxing out at 2 to 3K RPM and a load limit of 6000LBS (I think someone said on this site)
so it looks like this bearing is not out of it limits in this use . With proper and clean install / clearance setup it looks like it should give a good service life.

My WAG is that the failures are from rough install or improper fitting.

I have 50K on my 99LT FD ,am 3rd owner and the lube comes out clean and on a hot day of fast running it gets good and warm to the touch, not too hot

[dshealey]

When I first wanted to make barrels with integral sights and ejector rod housings, someone asked the same question. My response was "if someone else is making them, then I can too." No, I haven't attempted to make bearings yet, but someone is making them. Unfortunately for us, not very well or we wouldn't be talking about this. Only thing I can do is try to do better than them.

There is nothing on a gun that requires the accuracy of a ball bearing (unless it is a ball bearing IN a gun) ;) Guns are relatively crude in comparison as far as precision is concerned. Just how would you make a hardened steel ball, ground to roundness of a couple of microns? I was a tool and die maker for many years before becoming a design engineer, and have toured two bearing factorys. I do not see how ANY one person could come within miles of making a functional precision ball bearing. Even the BIG manufacturers sometimes mess up, as is evident in the problems FAG had with some runs of the final drive bearings, which also seems to no longer be an issue now that reported failures for '05 and up seem to be pretty non-existant. Seemingly the problem may already be solved by BMW, probably just a big batch of bad bearings from a normally well respected bearing company. They switched to SKF for a short time, but now have gone back to FAG, so they must also feel assured that FAG has their quality act back together.

Go ahead and try to make a bearing for a final drive though, and let us know how long it lasts. You should know within a day or so after installing it. :rotf:

[KYchris02]

has anyone considered "planned failure" as a possibility for FD failures. perhaps keeping customers coming back led to a few (4%) of the FDs to be faulty. there is definitely a cottage industry around this "flaw".

conspiracy! HMMM. now if we can just get the memo from motorrad that documents residual earnings potential from a perceived random failure of a major drivetrain component.

My vote is bad design. drive 'em long enough, with enough torque... they're gonna fail.

[cmattingly]

There is nothing on a gun that requires the accuracy of a ball bearing (unless it is a ball bearing IN a gun) ;) Guns are relatively crude in comparison as far as precision is concerned. Just how would you make a hardened steel ball, ground to roundness of a couple of microns? I was a tool and die maker for many years before becoming a design engineer, and have toured two bearing factorys. I do not see how ANY one person could come within miles of making a functional precision ball bearing. Even the BIG manufacturers sometimes mess up, as is evident in the problems FAG had with some runs of the final drive bearings, which also seems to no longer be an issue now that reported failures for '05 and up seem to be pretty non-existant. Seemingly the problem may already be solved by BMW, probably just a big batch of bad bearings from a normally well respected bearing company. They switched to SKF for a short time, but now have gone back to FAG, so they must also feel assured that FAG has their quality act back together.

Go ahead and try to make a bearing for a final drive though, and let us know how long it lasts. You should know within a day or so after installing it. :rotf:
I'm done with this conversation sir. I've explained the purpose of my original post and you've taking one part out of context.
[/QUOTE]Before this gets ugly with replies and questions about my abilities as an engineer/machinist/motorcycle repair dude, I just want to clarify that the original point here I'm trying to find out is if there is one dominating cause for FD failures. Apparently BMW refuses to admit there is a problem. But with all this experience on this board, I'd like to take a proactive approach about it and gets some ideas. I'd rather do something about it now, than be stuck out in BFE with a new membership card into the FD Failure Club. It's a machine folks, someone designed the dang thing. But that doesn't mean we can't tweak it. Come on, you've never changed anything on your bike to make it better.... One of these days someone is going to come up with a fix for it and everyone else is going to say, "I wish I'd thought of that!"
I probably can't make a bearing on my equipment. Maybe the aircraft parts manufacturer right down the road can. If not, who the heck can make a decent bearing? Is that the whole problem? Is it the oil? Who's done a study on the different lubricates to find out? That's why I came here to ask y'all! It was not my intention to come on and boast of my capabilities, but to engage in conversion with some experienced and knowledgeable people.
Thankyouverymuch (done in my best Elvis impersonation).[/QUOTE]

You win..... In the meantime, I rode into work this morning and the FD held up. I'll cross my fingers for the ride home.

[fpmlt]

I think I understand where you're coming from. Seems, though, that if the original bearings were replaced with another mfg., than back again, and still the failures, the bearings themselves are likely not the problem. I'm betting that BMW has the info. With all the data, including the VIN of each vehicle worked on by an authorized BMW dealer/service center, BMW knows where each was assembled. If we had that same info, we would have one more piece of the puzzle. For now I'm leaning toward the lube, and still playing with boundary lubrication properties of various gear oils. Now my tests are no more scientific than anyone's ability to build a better bearing, but it does get interesting. So far I've only tested Lucas, ******, and Schaeffer's, but I'll be buying more to continue the testing. At the very least, I think the better lube will get me a couple of extra miles.

[Jerrym]

If it is lubrication why wouldn’t other bikes like the Gold Wing have rear drive problems? My 2005 LT rear drive was replaced at 41,000 miles. When I had the oil analyzed 12,000 miles later it had no metal or aluminum in it at that time but it was showing high wear, which it did with the first rear drive. They told me at that time it is not going to last to long with that high of wear. From the time the bike was new the rear drive oil was changed every 3,000 miles. The first rear drive, I used Mobil 1 Synthetic Gear Lube 75W/140. After replacing the rear drive I used Red Line Gear Oil, which there is probably no better gear oil. It still showed high wear. In my new Gold Wing I do not even worry about the rear drive. I will change it every 24,000 miles or every season. It has to be the design of the rear drive or material they are using. The rear drive should last with any good gear oil of today. BMW is the one that is going to have to come up with the fix.

[grifscoots]

Folks it's not just the LT that has had failures. The RT, GS and GT, all with the new style rear (the one with the hole in it) have had failures. Not a lot, but they've happened

(HI JOE!)

[paalao]

Bearings do fail for many reasons, but improper lubrication is there at the top of the list. And rests are the following:

43% due to improper lubrication;
27% due to improper mounting;
21 % due to other causes and
9% due to reaching the fatigue limit of the metal.

Reasons for lubrication failure are following:

1) Incorrect selection of the grease base for a particular application.
2) Use of static or circulating oil in a improper manner.
3) Insufficient lubrication either in quantity or in required viscosity.
4) Deterioration of prolonged service without proper intervals.
5) Contamination of the lubricant and the bearing with foreign materials.

http://www.uniweldbearings.com/faq.shtml

[Jerrym]

Bearings do fail for many reasons, but improper lubrication is there at the top of the list. And rests are the following:

43% due to improper lubrication;
27% due to improper mounting;
21 % due to other causes and
9% due to reaching the fatigue limit of the metal.

Reasons for lubrication failure are following:

1) Incorrect selection of the grease base for a particular application.
2) Use of static or circulating oil in a improper manner.
3) Insufficient lubrication either in quantity or in required viscosity.
4) Deterioration of prolonged service without proper intervals.
5) Contamination of the lubricant and the bearing with foreign materials.


http://www.uniweldbearings.com/faq.shtml

If this is the case why is it not happening in other band of motorcycles with the same type rear drives? Other bikes occasionally have a rear drive fail but nothing like BMW. Like I said before I don't even look at the rear drive on my Gold Wing but when I had my LT every gas fill I would put it on the center stand and feel the rear wheel. Change the gear oil every time I serviced the bike. Had the oil analyzed every 12,000 miles. Always worried on every long trip.

[Moonshine]

Have you looked at all of the new model BMW bikes FD with the exception of the LT? They all have a completely redesigned FD using a different bearing style and with a large hole through the main ring gear shaft to provide some cooling effect. And they were originally designed to be a lubed for life operation but as we now see they are recommending the original lube be replaced to remove any manufacturing Debris from the assembly. However BMW bikes are still suffering from occasional FD failures and these BMW bikes are significantly lighter than the LT. No question BMW is making an improved FD, but me thinks they still have some work to do in making the FD bullet proof.