thrust rod broken

[spo123]

In my OPINION, it seems, that when you adjusted the clutch "properly".......The correct and proper FREEPLAY of the clutch/ thrust rod/ bearing, was incorrectly set.
IF, too tight, the later /6 and up....bearing (which are extremely thin.....Unlike the earlier 4 speed, which has a substantial Ball Bearing assembly) WILL get chewed up quickly!

[ThompsonJP]

Hey, I'm back at this problem. I've figured a few things out but not enough to solve the problem yet.
I've chewed up another needle bearing in the clutch control assembly. This time I pulled the thrust rod out a bit to get a look.
The first question I have is about the thrust ring. I can't tell whether the bevel is supposed to be facing toward the front of the bike like it is now. The Haynes manual shows is should be. However, I feel like the bevel should be facing the rear, maybe to facilitate the oiling of the bearing.
In working on this, I shot some compressed air in the cavity for the clutch control and some gunk and congealed grease flew out. I suspect that it had clogged the slot where the oil is supposed to lubricate the needle bearing. I included my simple drawing of how I think it works.
Anyway, I'm going to order another bearing and try again. Any advice or observations would be appreciated.
It's still a 1974 R90/6.
Thanks

[schrader7032]

I wouldn't think the thrust ring orientation wouldn't matter. To me, #3 and #5 are there to sandwich the thrust bearings. That said, maybe the bevel edge should not be on the side with the needle bearings...if it was, some surface of the ring wouldn't be working on the bearings.

On this page near the top, Brook shows the thrust ring with what appears to be the bevel towards the front of the bike:

https://brook.reams.me/bmw-motorcycle-r ... nsmission/

[malmac]

Part 3 has a groove on one side where the balls run in and is flat on the side that faces forward. Hard to get it mixed up if paying attention.


Mal

[schrader7032]

The problem can be that the bearing itself was changed over time. Early on, the bearing cage was indeed balls...a better design. But then it was changed to needle bearings that are arranged like rays of sunshine from the center. The problem with that design is that the outer part of the needle bearing has to...or wants to...turn faster than the inner part but it's impossible for that to happen. So, what happens is the needle bearings skip or scuff along. So with the later design, the two surfaces on either side of the needle bearing must be flat.

Anton shows the two different bearings on this page:

http://largiader.com/articles/throwout/