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Final drive pivot bearings


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I removed the pivot bearings from the final drive today and soaked them. The inner race looks OK but when they are assembled with a little pressure, they feel like the rollers and running through small indentations (like detents). I was told earlier that they would likely have to be replaced. I think someone mentioned that they used plain bearings for this instead of needle bearings?

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I removed the pivot bearings from the final drive today and soaked them. The inner race looks OK but when they are assembled with a little pressure, they feel like the rollers and running through small indentations (like detents). I was told earlier that they would likely have to be replaced. I think someone mentioned that they used plain bearings for this instead of needle bearings?

 

Ditto with mine. I was told by others on the forum that these things seldom last longer than 20-30K miles, and that an oilite bronze bushing was a much more appropriate part for the task. The bushing rides on the pin and replaces the needle bearings, and it comes with a new race which replaces the OEM race in the final drive (i.e. the one that now has wear marks). The bushing mates to the race, and since there are no needles, there is no needle bearing wear. I'm told they will likely last the life of the bike.

 

I got a set of two from Tom Cutter when I had my transmission repaired. The bushings are pricey, about 2x the cost of OEM.

 

It's a very doable repair. I popped the final drive shaft off of it's mount, and then used heat and a socket with extension to remove the races, i.e. placing the socket inside and against the left race, putting the extension through the right race and attaching it to the socket, and tapping on the extension with a plastic mallet until the left race popped free. Same procedure in reverse for the right side. I installed them by making a race of a 5/8" bolt, two nuts, and two sets of washers (3-4 on each side for strength). Just heat up the final drive case near where the race fits, pull the race out of the ice box and insert it, then turn the bolts until the race seats in the final drive. The bronze bushing seats tight around the pin, but fortunately, my pin was a bit worn so it was a relatively easy fit. grin.gif

 

Good luck with the repair.

 

FInalDrivePress2.JPG

 

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FInalDrivePress1.JPG

 

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I just did that repair on my bike using oem bearings, the previous ones had totally failed. (I discovered they were bad when I checked the boot and 3 bearings fell out) I would be interested in knowing of the source and part number of the oilite bearings. Thanks Greg. cool.gif

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I just did that repair on my bike using oem bearings, the previous ones had totally failed. (I discovered they were bad when I checked the boot and 3 bearings fell out) I would be interested in knowing of the source and part number of the oilite bearings. Thanks Greg. cool.gif

 

Tom Cutter can be found at The Rubber Chicken Racing Garage.

 

Andy

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carquestman1

What would the symtems be for bad bearings. I seem to have slack under acceleration and deceleration and was wondering if this could be my problem.

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The symptoms for these bearings is side-to-side play at the rear pivot. What you describe sounds like normal BMW drive-line lash. The nature of the big twin and complete lack of flywheel, coupled with the required transmission clearances makes this feel jerky.

 

With time you find this diminishes because you subconsciously learn to be smoother with the on-off throttle transitions.

 

Andy

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The plain bearings look good, but they do seem pretty expensive. If the Hammersley pricing is correct, the stock needle bearings are two for $27.

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What would the symtems be for bad bearings. I seem to have slack under acceleration and deceleration and was wondering if this could be my problem.
I swapped ours out for the Rubber Chicken bushings. What I/we noticed before and after the swap was the noticable "hinge" feeling of the rear end disappeared with the bushings installed. I sort of mashed mine getting them in and since the bronze is so soft they loosened up on me after a few 1000 miles and I had to go in a re-torque them down. The increase in the "hinge-y" feeling was slow and very subtle, but the difference post replacement/adjustment was clearly noticable. The rear wheel would seem to bounce around a bit during braking especially whilst cornering at all or downhill--the bike feels so much more solid now.
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SAAB93driver
I sort of mashed mine getting them in and since the bronze is so soft they loosened up on me after a few 1000 miles and I had to go in a re-torque them down.

 

I think this might be fairly normal with the bronze bushing, I have not installed mine yet but the instructions say to retorque at 500 miles.

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So, I assume that to re-torque after ~500 miles, one must reheat to soften the locktite, remove the left pivot bolt, clean out the old locktite, re-apply the locktite, re-insert the left pivot bolt, and then torque the pivot bolt and then the locknut?

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Or just not apply the locktite the first time. Mark it with some fingernail polish so you can check it from time to time to make sure it isn't working it's way loose.

 

Considering the amout of torque (160 Nm if I remember correctly), I can't imagine these coming loose.

 

Thats what I did when I needed to replace a damaged pivot pin while waiting for the part.

 

Stan

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I sort of mashed mine getting them in and since the bronze is so soft they loosened up on me after a few 1000 miles and I had to go in a re-torque them down.

 

I think this might be fairly normal with the bronze bushing, I have not installed mine yet but the instructions say to retorque at 500 miles.

That may well be, but I didn't heat mine enough before I started wailing on it with a hammer and socket/drift. I got that sucker in there, though! thumbsup.giflmao.gif
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So, I assume that to re-torque after ~500 miles,
There is no re-torque after xxx miles requirement that I am aware of. Once installed you're good to go.
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Ken,

The instructions do caution you to re-torque them at 500 miles. A buddy installed these and took off to the east cost without doing that and ruined the bushings. Both were grooved . He put the stock needle bearings 33 17 2 311 091 $30.00 Ea back in till he can reorder the bushings.

 

Mick

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SAAB93driver
So, I assume that to re-torque after ~500 miles,
There is no re-torque after xxx miles requirement that I am aware of. Once installed you're good to go.

 

The instruction sheet I got with mine about a month ago says to retorque at 500 miles.

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Ken,

The instructions do caution you to re-torque them at 500 miles. A buddy installed these and took off to the east cost without doing that and ruined the bushings. Both were grooved . He put the stock needle bearings 33 17 2 311 091 $30.00 Ea back in till he can reorder the bushings.

 

Mick

OK, I stand corrected.
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So, I assume that to re-torque after ~500 miles,
There is no re-torque after xxx miles requirement that I am aware of. Once installed you're good to go.

 

The instruction sheet I got with mine about a month ago says to retorque at 500 miles.

I bought mine a few years ago so it's conceivable that Tom might have added that caveat more recently after finding that they do/might loosen up after installation (or if you whack on them too hard with a hammer! wink.gif )
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