The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: MR.E on August 29, 2011, 01:58:23 PM
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hello
can anyone tell me how much fluid goes in to the forks on a 1981 r65?
I'm using 5wt oil
thanks
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If only draining the fork fluid rather than a disassembly and cleaning, add 190cc. It is not possible to drain all the fluid from the fork lowers as the drain hole is a bit above the interior bottom of the slider leg. 200cc is a good start with "dry" forks.
5wt fork oil is very light and may not provide damping perform to your expectations. BWM recommends 7.5wt but some peeps, myself included, use a 10wt. YMMV.
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Monte's volumes are what I use. For real accuracy side to side I also check the oil height using the dipstick method down the centre of the spring. From memory the oil height above the damper piston should be 35mm + or - 15mm which allows for a slight bit of tuning on the amount of dive. And it does make a perceptible difference to the feel as well. I've found that oil height at the higher end will firm up the forks a touch if the oil is a bit thinner than ideal and the lower height will soften the forks slightly if the oil is a bit too thick. Minor stuff which won't correct oil that is way off being the right viscosity but regardless the levels should be equal side to side.
I also found 5wt too thin but it will depend on which brand as they can be so different in viscosity that one manufactures 5wt is thicker than another's 7.5 wt. Most people seem to say BMW's own 7.5wt is spot on. If the 5wt is too light you can always drain some off and blend in some heaver oil if needed. Stick to one brand if you are going to blend.
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ey up
thanks for the replies, not done the forks as yet, decided to do a complete carb rebuild instead!
I'll let you know how the forks go tomorrow
Elliott