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Discussion Starter #1
Hey Guys.....

(bike is a 99 LT with 87000 miles on it)

There's certainly been enough talk on here about the dreaded rear end to make us who have older LTs kind of keep that in the back of the mind.

Today I'm coming home from work, running about 85 mph on the interstate when I hear this grinding sound start. At first I had the radio on pretty loud but I turned that off and then I could feel a kind of rotational grinding vibrating kind of thing. I thought maybe a tire went down or maybe a brake malfunction was going on. I put it into neutral and let it coast and it seemed better. By then I had slowed down to about 40 and it seemd to have gone away so I sped back up to about 70. I was only about 10 miles from home so I was hoping to make it on home. Before I really got back up to speed it started again and this time was worse. I slowed back down to about 50 and made it to my exit. As soon as I got off I pulled off into a parking lot to give it the once over. Brake rotors seemed normal temp. Tires seemd ok. Put it on the center stand and into neutral and rolled the rear wheel and it seemd ok....BUT when rolling it I noticed some oil on the tire. Upon closer inspection it appears that a small amount of oil has slung around the rear wheel and tire. It is the heavy weight oil with the diSTINKtive smell for sure that is only in the rear end and the transmission. Given that its slung around the rear tire I am assuming it has come from the rear end.

I was 6 miles from home in that parking lot so I came on home at about 35 mph and at the slower speed the grinding action was not nearly as loud but it was still somewhat there.

I am about to go drain the rear end and check the plug for metal.

Has anyone personally experienced a bad rear drive that didnt lock up?

Needless to say, I am thankful that it didnt lock up and that I did make it home safely.

Thought I'd put this message up here before I started into it just to see if anyone had any insight.

I put it on the center stand at home and checked it some more but there really isnt a "grinding" feel in the rear wheel when spinning it. There IS a sound that is kind of rattly when I move the wheel back and forth rotationally. That sound is sort of like a burned out light bulb just a tinking kind of sound.

Is there anything else that could cause oil to sling around the rear wheel?
I will check and see how much oil is in it.....I last changed it 6000 miles ago and it was perfectly clear at that time. I refilled it with synthetic oil and I had checked it once before going up to Ironhorse a few weeks ago. I suppose its possible a seal went out and it has slung the oil out of it causing it to run dry......but there is not that much oil around the wheel.

Any insight or advice will be appreciated. If it IS the rear drive....whats the best way to get that fixed? Has anyone replaced the bearing themselves?

thanks
 

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My old 1999 didn't lookup when the rear end went bad, but was quite not easy to ride either...
That sad, there is a oil seal, inside the rear end, that could be broke on your bike, this is why you have the oil, but still riding well.
I forgot the name of that seal, but it's there. I'm sure some one will remmember which one is it.
 

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When my 99's rear went it sounded like someone had thrown a box of rocks in a dryer. There are two routes to go. Either replace the whole rear drive unit, or if feasible replace just the bearings and seal. Others have done the latter and it is much cheaper. Do a search and you will find pages on the subject. BMW replaced my whole rear drive unit which I think the dealer said would have been about $1200 with labor. I think the bearings and seal alone run about $130
 

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Pretty sure you have the common final drive bearing failure. Pull the wheel, and you will likely see oil seepage around the wheel hub, from the seal.

You are lucky you got home before the damage was too bad. Most of us did not make it to home/dealer, so had to have it towed.

As far as we know, there have been no rear lockups from the failed bearings, and possibly only one rider actually went down. Usually just a noticeable noise, getting worse, untill it is very evident that one should stop riding.

It is by far best to stop as soon as any indication of the bearing is failing to avoid too much damage to the gears, that way just the bearing and seal have to be replaced. Ride to far with the hub moving around and the gears get damaged.
 

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kip said:
BUT when rolling it I noticed some oil on the tire. Upon closer inspection it appears that a small amount of oil has slung around the rear wheel and tire. It is the heavy weight oil with the diSTINKtive smell for sure that is only in the rear end and the transmission. Given that its slung around the rear tire I am assuming it has come from the rear end.
Unfortunately, yep.

kip said:
Has anyone personally experienced a bad rear drive that didnt lock up?
I don't believe that *any* drive has locked up -- the rear wheel gets loose and handling gets squirrelly as the final drive starts to get lots of slop, but no lock-ups.

kip said:
There IS a sound that is kind of rattly when I move the wheel back and forth rotationally.
Sounds like -- don't know quite how to put this -- you have "loose balls"
Seriously, as the rear bearing starts to fail, the bearing separator cage starts to collapse and break into pieces. This allows the balls to rotate freely about the circumference of the bearing races -- the rattling sound source.

kip said:
Is there anything else that could cause oil to sling around the rear wheel? ... I suppose its possible a seal went out and it has slung the oil out of it causing it to run dry.
Not that I'm aware of :( The seal usually gets cut up almost every time the separator cage elements fall out of the bearing.

kip said:
Any insight or advice will be appreciated. If it IS the rear drive....whats the best way to get that fixed? Has anyone replaced the bearing themselves?
Before you consider whether to replace the bearing, you need to look inside the housing to see whether the bearing is just starting to go, or whether it's *really* torn itself apart, sending bits all through the housing (including bits in the pinion gear and its bearings and the small outer bearing). There are several threads about how to do this.

If the bearing isn't far gone (and I'm not convinced yours is too far gone), bearing replacement is do-able at home -- again, a couple *good* threads.
 

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I have an 03 and I have ridden 6K+ miles in the last 4 weeks including an SS1K and BB1.5K. When I went to a friends to do service on our bikes. I had ugly oil drain out of the rear drive with glitter. I figured that it was starting to go. I reinstalled the plug and forgot to add crush washer, so I removed the plug, only to find part of the keeper on the magnet. Just so happened to have a trailer and hauled it to the dealer, which was discovered that warranty expired last month. Dealer quoted me a price for parts and labor, I agreed and rode "The Beerburner" home 2 hours later. I was very fortunate to discover this when I did, or it could of been worse.

BTW I kept the bearing for a paperweight!
 

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Discussion Starter #7
thanks

i appreciate it....ill pull the rear wheel and check it out

lookin at all the scoop now
 

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I have a 99 with 12K. I just replaced the rear drive seal and bearing because the seal started to leak. I think the rubber had gotten hard and lost its sealing capability. I had the old 19 ball bearing and while I was in there, I replaced it with the new 17 ball bearing. So far, all is well at 1500 miles into it. After I pulled the old bearing off, cleaned and dried it, I spun the race and I could feel it was not as smooth as it should be. It was obviously beginning to spall and it was a matter of time before it would loosen up. I inspected the tapered bearing and it looked perfect.

If I were you, I would replace the crown bearing and the seal for starters. Peel back the driveshaft boot and see if there is any oil in there. If so, the pinion seal needs replacing. Mine was dry, so I left it alone.

Good Luck!

-Larry
:bmw:
 

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Discussion Starter #9
the dirty truth

pulled the rear wheel.......pulled off the brake caliper......rear end definitely AFU......feels like it has a hand full of gravel in it......seal leaking for sure....

got to study up on how to take it apart from there.....and how to determine if its fixable or throw-awayable ........

if anybody in north ga has been into one and knows how to tell the difference between not too far shot and shot .....let me know.....maybe i can bring it by .......

anyhow.....thanks for all the info and im sure i will e asking for more help soon
 

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I know somewhere, someone listed the part #s for the bearings and seal but I sure can't find them in search or files or technical. Thanks in advance.
 

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Kip,

The rear drive is not very hard to take apart. Do a search on the site or the HOW for rear drive bearing replacement, and you will find a heap of info. I did mine myself and was pleasantly surprised at how easy it was.

I didn't remove the whole drive, just the crown gear.

Good Luck!

-Larry :bmw:
 

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BMW MOA magazine has an article, in the May issue (I think it was May), detailing how to replace the main bearing.
 

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Discussion Starter #13
a man has got to know his limitations :)

It was a pretty quick and easy job to pull the rear drive off.....
being basically clueless from there, I made a few phone calls and discussed it with my new buddy Nathan who owns Boxerworks in Watkinsville....he was nice enough to meet me in Athens where I handed over my rear drive and he is going to break it open today and see what the damage is.....

He will let me know if he can deal with it or not and then I'll go from there....

On the positive note, assuming I either get it fixed right or have to get a whole new one.....at least that will be one thing I don't have to worry about for a while......having read everything about the rear drive failures on this site, and having a 99 bike with 87000 miles on it .....and generally driving like a bat out of hell.....I've been kinda of paranoid about that anyway.......

And.....at least it happend within 10 miles of home!

A couple of questions: Does anyone know right off hand the bwm numbers for the preferred bearing and the correct seal?

Are all rear drives interchangeable?

Is there anything else I ought to do as far as reassembling things?

<ok...that was 3 questions :)>

thanks
 

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kip said:
Are all rear drives interchangeable?
No -- the '99-'01 have an extra hole in the outer face of the top half of the drive for the speed sensor. '02-on use the ABS sensor for both ABS and speedo functions. There were also minor post-'02 final drive ratio changes.
 
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