R90/6 front fork question

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Joined: Sun Nov 16, 2008 7:26 pm
Location: Big Bar, Ca.

R90/6 front fork question

Post by wbmoore »

Hey….I’m rebuilding the front forks on my /6. Does any body KNOW the answer to this three scraper rings (#13) alignment question ?

A Very good builder (by my estimate) says to align the gaps of the 3 scraper rings in a straight line… unlike the oil scraper rings on a piston in an engine, which are staggered.

Are the three rings placed in a straight line to allow oil to flow down the tube ? Or should they be staggered as in an engine ?

Thanks for the input.
Brad Moore
1960 R69; 1975 Norton MKIII; 1976 R90/6; 1992 K75S; 2000 Hayabusa
Big Bar, Northern California

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Joined: Thu Jul 22, 2010 1:05 pm
Location: Victoria, BC. Canada

Re: R90/6 front fork question

Post by sblaylock »

Interesting question.

Every picture I've seen shows them spaced like piston rings - 1/3rd, 1/3rd, 1/3rd i.e. 120 degrees apart. Whenever I rebuild forks, including the R90/6 I'm doing now, I do the 120 degree spacing. I believe the scraper rings are exactly that, scraper rings. They are not part of the "shocking" system. The dampner rod holes and the "ring", 9 in the diagram, control the compression and rebound... as I understand it.

So, I would say, 120 degrees apart, but I'm always open to insight as to why my understanding is not 100% correct.

Scott Blaylock
Stoney Peak BMW Service
Victoria, BC. Canada
BMW Classic and Vintage Motorcycle Service and Restoration

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