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'81 RS Fork Rebuild - Parts missing?

Posted: Mon Jan 31, 2011 11:31 am
by Rapid Dog
Reason I decided to do this besides the maintenance this bike needed, was that it's got a 'topping out' clunk that goes on randomly.
I was told by Gary at RPM Cycles that it could be that the internals weren't shimmed properly.
Compression srole seems to work fine, but it definitely was clunking.

So, I pulled it apart and like everything else on this bike, I find little surprises.
The right side fork 'absorber' tube was all unscrewed and in pieces. Left side was intact.

Mucho gunk in the bottom of the slider. Some rust on the 'valve housing' thingie. Basically kinda messy.

My question is, does it look like I'm missing some parts?

I ordered up what I figured was missing that a did see in the MAXBMW fische:

#10 - 31422301724 GUIDE SUPPORT
#15 - 07119932660 SHIM - 22X30X0,5
#16 - 31421242646 LOCK RING - 30X1,2
#18 - 31421241737 INTERMEDIATE RING


Insight on this is very welcome....

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Here's the parts as they came put of the bike:

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...and the MAX fiche:

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Re: Thisplaceishottoday!

Posted: Mon Jan 31, 2011 5:26 pm
by Rapid Dog
...could somebody mebbe even tell me what #18 is made of? Bumper material. What's it do? If I can cobble something up maybe I won't have to wait 1-2 weeks to get it all back together.

Re: '81 RS Fork Rebuild - Parts missing?

Posted: Tue Feb 01, 2011 12:21 am
by ME 109
I don't think part no 18 is on my 81 RS.
There really aren't many parts in our forks compared to other models.
The random clunk you mentioned happens on my bike too.
We had a discussion on this 'clunk' a while back and no one had a definite answer as to what caused it.
My forks don't even have that middle length spring in your pics.

Re: '81 RS Fork Rebuild - Parts missing?

Posted: Tue Feb 01, 2011 10:15 am
by Rapid Dog
Looking closer at the spring (middle length) that came out of the very bottom of the slider, it looks to be home made. A spring brazed to a washer. I have the sneeky suspicion that this is a 'bottoming spring' like we use to make up for the earlier ATE forks. That said I can see that PN#17 is not there either. The PO must have tossed that part/parts in replacement for the spring dealie. Guess I'll cancel my order for #18 as it's a $15 part that has too come from BMWAG (Germany).

Re: '81 RS Fork Rebuild - Parts missing?

Posted: Tue Feb 01, 2011 11:43 am
by Rapid Dog
This in from ADVRider:

"#18 is a spacer made of aluminum. These were an add-on part made to counter RS/RT fenders hitting the fairing. #17 is also missing, because it/they were removed to install the anti-dive spring in your 5th pic, just above the slider.

The snap ring you have is an early one, which was replaced by a conventional one and shims (15 & 16) to keep the valve body from moving in the fork tube. The clunking comes from the valve body-once you get it shimmed properly, the noise will go away. "


Question is...how do I knkow if it's shimmed properly. There are 3 shims available.