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Old 04-21-2014, 04:15 AM   #1
Mal S7 OP
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Joined: Mar 2012
Location: Central NSW
Oddometer: 92
R100/7 fork internal components

Does anyone have a pic of R100/7 or R100S fork damper components?

I have mine apart at the moment and, studying the fische, and workshop manual, and motobins parts I am not sure that I have all the parts.

Certainly don't have the black washers shown above the alloy ring in this picture. (acknowledgements for the pic linked from a post by chasmbmw)



The manual depicts these but says they were fitted on "later models". I have spare damper rods from a 78 R100S and they don't have the black washers either.

And how many rings should there be between the two threaded rings that screw into the bottom of the fork tube? I have a plain alloy ring that appears to be the dampening ring Motobins Part No.29082, but not the "stiffening ring" Part No.29080 (BMW Part No. 31 42 1 234 506) that appears in the fische (but not in the workshop manual!)

http://www.motobins.co.uk/bmw-parts....20valve%20Twin

http://www.maxbmwmotorcycles.com/fic...1&rnd=04302013


Thanks
Mal
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Old 04-21-2014, 06:20 AM   #2
SculptD
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It sounds like you are fine. The dark plastic ring shown in the pic was added to reduce noise. Maybe there was some clicking sound? I have never noticed. If I had such a plastic ring, personally, I think I might discard it. In any case, it's not required for performance afaik.

And, you only want one damping ring. BMW like to depict all options that were offered on the same drawing. So nice of them. The "stiffening" ring is very slightly smaller in inner diameter, increasing rebound damping a little. It is identified by an incised ring around the outside. I always run with this "sport" ring.
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Old 04-21-2014, 07:06 AM   #3
chasbmw
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Quote:
Originally Posted by sculptd View Post
it sounds like you are fine. The dark plastic ring shown in the pic was added to reduce noise. Maybe there was some clicking sound? I have never noticed. If i had such a plastic ring, personally, i think i might discard it. In any case, it's not required for performance afaik.

And, you only want one damping ring. Bmw like to depict all options that were offered on the same drawing. So nice of them. The "stiffening" ring is very slightly smaller in inner diameter, increasing rebound damping a little. It is identified by an incised ring around the outside. I always run with this "sport" ring.
+1
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Old 04-21-2014, 08:06 PM   #4
Mal S7 OP
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Thanks fellas!
that's why these forums are invaluable; you get the sort of advice that you can't find in the manuals, or the fisches.

cheers
Mal
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Old 04-24-2014, 05:31 PM   #5
Mal S7 OP
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Joined: Mar 2012
Location: Central NSW
Oddometer: 92
I've just been testing and notice the damper rod rings do add noticeable drag. I slid the oiled rod into the fork tube and pushed it back and forth, they certainly wouldn't fall out on their own.

I've seen where chas (I think) has had them machined to take the later style plastic ring. I think that's a great idea but don't have time to get that done right now. (oh to have a lathe in my shed!)

Any other ideas out there to make 'em slippy? I replaced the rings once ... about 40 thousand kms ago. Afterwards I read that you shouldn't replace with new for some reason I can't recall. They never wear in? I've also replaced both fork tubes over the years.

cheers
Mal
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Old 04-24-2014, 07:03 PM   #6
SculptD
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Yeah, there is friction there. They are what they are, steel on steel. Mine have never slid down of there own weight. Have others? I've seen some pretty corroded fork insides, but it sounds like yours are in good shape.

I would love to do the mod for the later wiper, and someday I probably will. But those plastic rings are pricey!

I think stiction is the enemy, not so much friction (within reason).
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