Final Drive Failure??? Seeking questions advice???

[Michael Derby]

Hi all - While weekending with my wife in Highlands NC from Atlanta strange thing happened. '01 RT 22k miles, have done all my own wrenching with expereinced friend. Anyway on way into town to have dinner last night I have my face sheild open and I start to hear a slight RUOO RUOO RUOO noise. Almost as if tire is rubbing or something. But no vibrations or anything. After dinner on way back to Inn I hear it more strongly and I keep pulling in the clutch to let the bike coast and I can hear it clearly now. When we stop the final drive seal leaks about a silver dollar worth of goo onto rear rim. I realize now, something not right. Break news to wifey that we are in for an interesting Sunday, and may not make it home. I start out this morning and by the time I get to down town highlands it is making a prounounced RUOO RUOO RUOO noise rather loudly and I can really begin to feel some vibration. SOOooo decide I am not going to make it down War Woman Road stop, and sure enough more final drive fluid leaks out. When I put bike on center stand, remove rear caliper and rotate tire and it is sort of "gravely" in there as I rotate it around. Luckily Randy Cono comes to rescue and drives up to trailer me and not so happy wife home. She is on her way to dealer tomorrow.

 

So question, do you think this is final drive or rear bearings or what you all think? Is there anything I should also have dealer check or get taken care of etc.. from anyone expereinced that I should be aware of??? I am getting ready to ride accross country next month and after 22k completely worry free miles I am now a bit spooked!

 

Any thoughts appreciated as well as any thoughts about what maybe should be done preventative while at dealer before I ride cross country -

 

As always thanks so much in advance - you guys on this site are the best

[ShovelStrokeEd]

Wife is going to be less happy. New final drive is about $1100, installed. Final price will depend on condition of swing arm pivots. You are probably going to need new brake pads as well. The individual parts needed to do a proper rebuild plus the added labor make it impractical to try and save the old drive.

[cgdR]

Wife is going to be more happy. She will find how smart her husband is when you save $1000. Simply change the crown bearing ($110), and probably the seal.

Illustrated instructions by Master Steptoe here:

Crown Bearing Replacement

 

Total time for replacement: 2 hours if you have the right bearing puller (with small grips), or 3 hours if you do it with chisels. Post any questions: "been there, done that."

[ShovelStrokeEd]

Maybe.

 

If bearing parts have not migrated between gears or into other bearings. A seized rear drive is no joke. At the very least, a tear down and inspection is in order.

[smiller]

Excellent link Carlos, thanks. It's hard to tell from the pictures... does replacing the crown bearing affect the preload on the tapered roller bearing at the opposite end of the assembly? Is there any clearance checking or shimming necessary after the repair?

[Joe Frickin' Friday]

Wife is going to be less happy. New final drive is about $1100, already installed in the FD. Final price will depend on condition of swing arm pivots. You are probably going to need new brake pads as well. The individual parts needed to do a proper rebuild plus the added labor make it impractical to try and save the old drive.

 

I bought a new FD from Chicago BMW for $725 delivered. It included new pivot bearings. OP sounds like an experienced DIY mechanic (or at least has access to one), so this should be an easy shadetree replacement job.

 

New FD gets you back on the road faster, and includes a 1-year warranty that you won't get if you rebuild your own.

[4wheeldog]

I am with Mitch on this one. No one has been able to definititively tell what falls first.....Gears or bearing. Either way, neither will survive bits of the other. New final drive is the way to go, and it is a DIY job for anyone that does their own work. Good Luck!

[cgdR]

No one has been able to definititively tell what falls first.....Gears or bearing.

I have not heard of gear failures. Crown bearing failures, on the other hand, are too common. I think that the company considers this repair so simple and inexpensive and the failure so benign that they have used the same bearing on virtually their entire line for a decade. If my experience is typical, bearings will rumble for several thousand miles before they fall apart. The rumbling can be felt by spinning the rear wheel by hand.

 

The gears are extraordinarily tough and normally survive bearing failures unscathed because there is a baffle that keeps dirty oil and debris at the bottom of the drive.

 

The delicate part of the bearing replacement procedure is the shimming of the crown bearing. Shims determine the correct preload on the bearing. However, bearings are so precisely machined that you can count on the replacement bearing to be identical to the failed one, so you can re-use the old shims.

 

The pinion bearing is much more difficult to change, but it is completely independent of the crown bearing and unaffected by the crown bearing replacement. If that bearing seems rough too, I would seriously consider tossing the FD.

 

As I said before, the crown bearing replacement is easy except for the removal of the old bearing. The problem is that there is not enough room between the back of the bearing and the gear for a standard bearing puller. I had success with two large chisels and a hammer which is what Steptoe, a BMW mechanic, recommends.

 

Carlos D.

[Alan D]

- RUOO RUOO RUOO RUOO RUOO RUOO

Perfect description! Got the same noise yesterday about 100 miles from home. I made a right turn and it started. I made it home. It's going to the dealer tomorrow AM. I have 46,500 on this bike.

[pwillia]

Same thing happened to my '98 1100RT on Sunday morning while on the way back from Lima, OH to Atlanta. 9am on a two line backroad in Kentucky, when I heard the noise. At first I hoped it was road surface bumps or a flat tire. Not to be... small oil drips on rim, etc... I wasn't able to get a Uhaul lined up until Monday morning and then dropped it off at the dealer Monday evening.

 

Dealers diagnoses was final drive bearing failure and recommended complete replacement $875 for the drive itself plus installation.

 

Hopefully the new one will last a lot longer than the 29K I got out of the first one. Does anyone know root cause of these failures, and is there something different about the design of the new final drive that will prevent this type of failure in the future?

 

Thanks

[Eschelon1]

Divorces are even more expensive... but worth it!

[Alan D]

I bought a new FD from Chicago BMW for $725 delivered. It included new pivot bearings. OP sounds like an experienced DIY mechanic (or at least has access to one), so this should be an easy shadetree replacement job.

 

New FD gets you back on the road faster, and includes a 1-year warranty that you won't get if you rebuild your own.

 

My bike has been getting a suntan in the dealers lot, they have not looked at it yet and don't know when they will.

How big is the job to replace the drive as a unit? Need any "special" tools?

[impilot]

It is pretty simple, actually....you will need a heat gun (loctite needs to be heated up on the rear drive bearing journals), a 13mm hex driver, 30mm socket, and a pretty good sized torque wrench capable of 150 NM. You may also need some additional ABS sensor shims. I could not find a 13 mm hex driver, so I bought a 13 mm hex key, used a power band saw to cut it off, and then inserted it into a 13 mm deep socket.

 

The procedure is pretty straightforward. Put the bike on its center stand, and stap the stand to the front wheel to keep it from collapsing. Remove all luggage. Remove the rear brake caliper and tie it to the upper frame. Remove the clamping strap on the larger gaiter, and pull it back to expose the drive shaft. You may get a table spoon of oil or so...no biggie, but if you get a lot of oil, you probably have a seal issue. You will then heat the locknut side of the bearing journal for about 4-5 minutes, remove the locknut and break the hex carrier free from the loctite. Heat the other side about 5 minutes, break the loctite so that you can back out the carrier journal. Also, remove the bolt on the torque bar where it attaches to the rear drive, and loosen the bolt where the torque bar attaches at the front. Once the carrier journals can be removed on both sides, fully back them out and remove. The rear drive will then pull straight out. It is usually easier to first drain the rear drive oil, or you will need to keep the drive upright. You will also probably see that the inner races on the bearings are loose or have come out. Don't worry about it, other than to account for them. Sometimes they stay on the carrier journal.

 

Installation is pretty easy. Using a wire bristle brush, clean off the threads of the bearing journals to remove the old locktite. Also, clean the threads in the paralever housing. Lube the splines on the new rear drive with something like honda moly 60 and insert the new drive into the paralever housing. It may be necessary to insert a screwdriver through one the of the holes on the paralever to hold the drive shaft upright while mating the rear drive small shaft into the main shaft splines. Once they hook up, you can remove the screwdriver. Also, you will want rotate the rear drive so that the U-joint at the rear drive is aligned in the same phase as the u-joint at the front of the shaft. A flash light comes in handy to see the position of the front u-joint.

 

Once the drive is inserted into the paralever housing, eyeball the alignment and insert the bearing journals and tighen enough to support the rear drive. Then attach the bottom of the rear drive to the torque arm, and loosley tighten the bolt. You will fully torque these later. Now, apply blue locktite to the right side (as you sit on the bike) threads of the bearing journal and torque to 150 NM. Then apply red locktite to the threads of the left side bearing journal and tighten to 7 NM (seven is correct). Then tighten the locknut (also with red locktite) to 105 NM. It is important that those threads are clean so that the correct torque is applied to the bearings. Now tighten the two bolts on the torque arm to 43 NM. Replace the gaiter and tighten the strap. Fill the rear drive with .25 Litre of hypoid SAE 90 gear oil (BMW recommendation....other opinions will vary). Install the rear brake caliper, and torque those bolts to 40 NM. Insert the ABS sensor into the rear drive, apply the old shims and tighten. Check the gap between the sensor and the ABS ring with the feelers in your BMW toolkit. The gap should be between .45 and .55 mm. I checked mine about every 20 degrees of tire rotation. Due to runout, you may get different readings at different locations. Here is where the extra shims come into play. You will need to add/remove shims to get the sensor to the correct depth. Apply rear brake a couple of times to deploy the brake pistons, check that it is functional, ride and enjoy.

 

BTW, it actually sounds worse than it is. Someone that has a bit of mechanical aptitude can do this in a couple of hours.

 

Regards,

 

John

[270]

My record for R/R is 45 minutes...

 

My (long) record is three hours. It's very straight forward. You'll need to sit with the drive in your lap, legs straddling the swing arm while seated on the floor. It's not hard, just a little tricky to line everything up. I prefer to run the bolt through the lower arm for lateral support. Bolt 'er up and go.

 

I prefer the Valvoline full synthetic lube. It seems to stick better. Good luck.

[impilot]

I prefer to run the bolt through the lower arm for lateral support.

 

Doh ...that's what I ment to say!

 

John

[Alan D]

Thanks guys!