Rear Wheel Drive removal

[BevBeng]

Hi Folks,

 

I've been hit by the final drive gremlins, & forcing me to remove the Rear Wheel Drive for further investigation. Thus I have 2 prelimenary questions:

 

1) Is there a trick to removal of the rear wheel ABS sensor? I am having a heck of a time trying to slide it out (shims & screws already removed);

 

2) On the final drive housing, what is the size of the socket wrench for the removal of the locknut for the pivot bolts and the size of the hex wrench for the pivot bolts?

 

Many thanks,

Ben

[SAAB93driver]

read this thread

 

final driver R&R

[biometrics]

Locknut is 30mm and the pivot pin hex is 12mm. I will start taking mine apart this weekend for a bearing/seal replacement...

[dirtrider]

Afternoon Ben

 

To remove the wheel speed sensor you can try soaking the sensor hole (not the bolt hole) in the final drive with just a bit of penetrating oil (very sparingly as you JUST want to lube the sensor OD to hole ID not the wire entry. Then with the bolt removed try using something like the end of a very dull screwdriver or plastic rod in the bolt hole (in the sensor part only) to drive the sensor in a twisting direction. You might have to drive it one way then back the other way but eventually you will get it loose enough to twist by hand then you can work it out with a twisting & pulling motion.

 

Before removing the entire final drive why not take it apart in place? Mounted in the bike is a great holder for the final drive housing. Unless the pinion bearings are bad you can easily replace the crown bearing (the usual failure point) & even check the shimming with the drive still mounted in the bike.

 

The side cover with ring gear & all should just slide out to the L/H side of the housing with a bit of tapping once you remove the cover bolts.

 

I usually do the first or initial inspection with the drive still in the bike. If only the crown bearing or carrier R/H bearings I never remove the entire drive from the bike.

 

[Danny caddyshack Noonan]

As usual, what Dirtrider says. You can also, gently, grab the ABS sensor with pliers and twist and pull...within reason. They get dry on the seal and stick.

There's a good Youtube video of a LT FD R&R that shows how to do the preload. I didn't save the link but, it starts out with a screen shot indicating that it is for something about horses. It isn't.

You'll need a drop or dial gauge and base or, kluge up something that'll serve with reasonable accuracy.

 

[Michaelr11]

There's a good Youtube video of a LT FD R&R that shows how to do the preload. I didn't save the link but, it starts out with a screen shot indicating that it is for something about horses. It isn't.

You'll need a drop or dial gauge and base or, kluge up something that'll serve with reasonable accuracy.

Here are link to two videos for final drive R&R. The long one is the LT R&R mentioned above and it includes measuring and setting the shim preload. The shorter clip is just a disassemble. Both of them are shown with the FD taken off the bike, but as said you can do most of this with the FD left on the bike. I just replaced my FD big bearing on my 1100RT with the FD left on the bike. Not a bad project for DIY.

 

Final Drive Disassembly (short version):

 

Final Drive Rebuild (long version):

http://www.bmwlt.com/uploads/lt_final_drive_rebuild.wmv

[biometrics]

Both great videos...

 

After reading this thread, I am very tempted to try and change the big bearing and seal with the drive still mounted on the bike. I will let you know how things turn out on my repair... thanks to all -John

[Steve W.]

Afternoon Ben

 

To remove the wheel speed sensor you can try soaking the sensor hole (not the bolt hole) in the final drive with just a bit of penetrating oil (very sparingly as you JUST want to lube the sensor OD to hole ID not the wire entry. Then with the bolt removed try using something like the end of a very dull screwdriver or plastic rod in the bolt hole (in the sensor part only) to drive the sensor in a twisting direction. You might have to drive it one way then back the other way but eventually you will get it loose enough to twist by hand then you can work it out with a twisting & pulling motion.

 

Before removing the entire final drive why not take it apart in place? Mounted in the bike is a great holder for the final drive housing. Unless the pinion bearings are bad you can easily replace the crown bearing (the usual failure point) & even check the shimming with the drive still mounted in the bike.

 

The side cover with ring gear & all should just slide out to the L/H side of the housing with a bit of tapping once you remove the cover bolts.

 

I usually do the first or initial inspection with the drive still in the bike. If only the crown bearing or carrier R/H bearings I never remove the entire drive from the bike.

 

D.R.

A quick question: What method do you use to check the preload of the big bearing?

Thanks

Steve

[dirtrider]

---

A quick question: What method do you use to check the preload of the big bearing?

Thanks

Steve

 

Afternoon Steve

 

I use & have used a varity of methods.

 

With the drive out of the bike & on my granite plate I use digital height gauges & precise gauge blocks. (this is very precise & exacting & takes a bit of time not to mention somewhat expensive gauges & gauge blocks).

 

With the drive in the bike I have used a few different ways all with decent success.

 

-The first way is to install the carrier in the cover with no shim & seated all the way into the cover. Then install the cover (no "O" ring) & bolt it tight. Then install a dial indicator reading on the spool center hub, then heat the cover & push the spool all the way in. The indicator movement is total so then need to add needed pre-load to the closest shim thickness to set it correctly. This worked OK but I always doubted the exact accuracy as heating the cover also heated the indicator, indicator stinger, & indicator stand. I finally made a bridge using long bolts & tube stands to hold the indicator out away from the side cover with a long stinger passing through a hole in the bridge. This kept the indicator itself cool & pretty well eliminated stand deformation but I still questioned the long stinger heat expansion so I would let it cool before taking the final reading. (worked but cumbersome)

 

-My current in-bike method has evolved a bit so I will give you the current iteration:

I install the new crown bearing then install the spool in the cover re-using the old shim PLUS an additional .5mm shim. Then very lightly bolt the cover on without the "O" ring using the stock bolts with springy wavy washers (you could use "O" rings) under the bolt heads. I hold 4 evenly spaced .025" feeler gauges between the cover & the housing to get an even gap all the way around to start with.

 

Once I have an even gap I pull the feeler gauges out & see if the cover is too tight or too loose (bearing play or lack of bearing play). If too loose I slowly work the bolts down (light finger tight) while using smaller & smaller feeler gauges to work down to an EVEN gap all the way around the cover. I want just the lightest amount of finger tight torque on the cover bolts (just enough to take the movement out of the cover).

 

With an EVEN gap all the way around the cover I know the cover to housing gap by inserting feeler gauges until I have a gauge that will just push into the gap all the way around the cover. With that known gap & knowing I have an extra .5mm shim under the bearing it is a simple matter to figure the correct shim thickness including desired pre-load.

A bit fiddly first few times but once you have the process down it is really pretty quick & not as bad as it sounds to do precisely.

 

[Steve W.]

Thanks for the reply.

I'm going to check mine soon (01 gs with 50k). I have a few questions to clarify. On the feeler gauge method: I understand you are getting the bearing assembly to a zero preload / zero clearance position and taking the resulting gap measurement. But don't you need the gap measurement with the housing fully closed to compare to the first measurement? The bearing "crush" would be the difference? I read somewhere a similar method where the housing is assembled "empty" and torqued then measure the gap. Then with the shims tightened to a zero/zero position, the difference is the preload or crush. Do you add the .5 shim just to be sure you do not have clearance? Have you compared results with the dial indicator method? Have you tried a crushable median such as solder? Do you check the preload before replacing the bearing and are they usually too tight as susspected?

I apologize for all the questions, I'm just educating myself before I dive in. I AM NOT trying to question your methods or second guess your reply, I appreciate and applaud your contributions to the forum.

Thanks

Steve

[dirtrider]

Evening Steve

 

No I don't check the preload before replacing the bearing as once the bearing goes bad there is no usable measurement attainable.

 

I don't need the measurement with the housing fully closed as I know the cover gap at zero preload (so fully closed would be minus the thickness of the gap). That is what that .5mm extra shim is for. That moves everything away (or out) that .5mm thickness.

 

OR, using that (extra) .5mm shim & having a .5mm cover to housing gap should yield a zero preload with the .5mm shim removed. Once I know what zero preload is I shoot for about .075mm (about .003") tighter for bearing preload.

 

I'm not sold on the solder method, it might work but with only a few thousands bearing preload I'm not sure the cover isn't flexing that much to crush the solder correctly.

 

On your 50K final drive-- If you haven’t trashed a bearing in 50K your original preload must have been pretty good.

 

[biometrics]

 

On your 50K final drive-- If you haven't trashed a bearing in 50K your original preload must have been pretty good.

 

DR,

 

You are not the first rebuilder I have spoken with that believes that if you got past 50K miles before the breakdown that you can likely just reuse the existing shim without measuring because the preload must have been pretty good. MY RT-P made it to just shy of 64K miles. I have the service records and the bearing had not been replaced before...

 

As I am about to attempt a DIY replacement of my big bearing and seal, I intend to use a digital caliper to try an measure the space (because I don't own a dial indicator) and combine it with the measurement technique used in the long version of the FD repair video (the one that starts with the horse footage)... I am hoping that my measurement results in a requirement for the same size shim that I will find when I open the FD case... If not, I have a handful of shims that were lent to me by Georgeinva...

 

I will report back and let you know what success I have, if any...

 

Thanks for all the repair advice and encouragement you provide to the forum members here...

[Steve W.]

Evening Steve

 

No I don't check the preload before replacing the bearing as once the bearing goes bad there is no usable measurement attainable.

 

I don't need the measurement with the housing fully closed as I know the cover gap at zero preload (so fully closed would be minus the thickness of the gap). That is what that .5mm extra shim is for. That moves everything away (or out) that .5mm thickness.

 

OR, using that (extra) .5mm shim & having a .5mm cover to housing gap should yield a zero preload with the .5mm shim removed. Once I know what zero preload is I shoot for about .075mm (about .003") tighter for bearing preload.

 

I'm not sold on the solder method, it might work but with only a few thousands bearing preload I'm not sure the cover isn't flexing that much to crush the solder correctly.

 

On your 50K final drive-- If you haven’t trashed a bearing in 50K your original preload must have been pretty good.

 

Thanks D.R. I'll probably try the dial indicator method to check the preload of the old bearing (if it last till winter) and check with the feeler gauge method to see if I can get a repeat value. Then after I get a "fuzzy feeling" for my measuring, install the new bearing and start over.

Thanks

Steve

[AndyS]

 

On your 50K final drive-- If you haven't trashed a bearing in 50K your original preload must have been pretty good.

 

DR,

 

You are not the first rebuilder I have spoken with that believes that if you got past 50K miles before the breakdown that you can likely just reuse the existing shim without measuring because the preload must have been pretty good.

 

Unless I am mistaken DR DID NOT say you could just use the same shim with the new bearing. He said that the pre load on the existing bearing must have been OK.

On a new bearing the pre load is essential to be checked or you may well be having a failure 4000 miles down the road. I am sure Kevin will back this up from experience too.

 

Andy

[biometrics]

AndyS,

 

DR DID NOT say you could just use the same shim with the new bearing. He said that the pre load on the existing bearing must have been OK.

 

I have done days of research and believe I have read just about all that has been put in print on the Internet regarding Final Drive failures and the repairs of those units...

 

I do thank you for your input, and the anecdotal history from others, but I have decided to chance reusing the original shims. On Saturday last I did all the work myself, and made sure everything was scrupulously clean before assembly. The results were gratifying... The online videos were very helpful.

 

In my experience, everything in the machine world is built to tolerances. What that means to me is that every FD case is an individual set of tolerances.

 

That being said, I don't think there is much room for change of tolerance in a FD case. Bearings are also made to a tolerance specification, But I think much closer tolerances than the FD case is made.

 

I feel that if the original shimming provided in my FD case was sufficient to allow for just shy of 64K miles of service before failure, it will likely repeat that level of service. I must admit that I didn't change the final drive lubricant as often as I had planned. I think that when the FD failed I had almost 6000 miles on the lube. In spite of all that, I believe that I will likely be safe reusing the original shims. Only time will tell. BTW< my ball bearings were not part of the failure. The entire failure was the ball bearing cage that keeps them equidistant from each other... There was no perceptible damage to the balls or races themselves except for the pieces of the cage that got in the way... The failure was almost instantaneous for me after a 75 mile run... the pieces of bearing cage tore through the oil seal and dumped the entire contents on my rear tire and parking space... There was no warning for the failure, not sound or vibration.

 

The new Crown Wheel bearing, FD oil seal, and the FD Case O-Ring cost me about $135 total, plus a full Saturday of my time to replace them. Well worth the investment to me to intimately know how the final drive works.

 

Outside of the parts costs, I spend about $50.00 on tools that I didn't already own (heat gun from Harbor Freight - $10, gear puller from AdvanceAuto-$24.00--modified slightly for pulling off the big bearing, and the rest of the $ for a 30mm socket, the loctite, and Honda 60 moly paste for lubricating the drive shaft splines) all of which are re-useable for the "next" failure should it happen to me, or anyone I know. So for less than $200 my R1100RT-P is back on the road and running smooth as silk... My only problem during the repair is that one of the 2 screws that holds the rear brake disc to the hub sheared during removal, but drilling a small hole through it, and applying additional heat allowed an "easy out" extractor to remove the broken screw once the loctite was defeated by the heat. I was fortunate that I didn't have to use a machine shop to remove the broken screw shaft.

 

I consider it all an investment in the bike, and in myself... I will religiously check and change the FD fluid with every oil change, and check 9-3 and 12-6 wheel movement when doing my own preventive maintenance just to be on the safe side.

 

Wish me luck... but I am confident that I don't think I will need it...

 

-John