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Topic-icon '76 R90/6: How do you stop leaking forks

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2 weeks 4 days ago - 2 weeks 3 days ago #6417 by 14517
I just rebuilt the drink forks on my 1976 R90/6. Changed all the seals, damper springs, bushings and springs. Fork leaks a few droops over several days. Anyone know a secret to stopping/preventing leaking forks?
Last edit: 2 weeks 3 days ago by Wobbly. Reason: Mods altered title

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2 weeks 3 days ago #6429 by 895
It depends on where your fork leak is located.

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2 weeks 3 days ago #6430 by 14517
Replied by 14517 on topic '76 R90/6: How do you stop leaking forks
Its leaking out the bottom of the forks. It appears to be coming from the damper to fork cap interface, through the rubber cap - not around the seals where the fork cap connects to the fork tube.

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6 days 6 hours ago #6483 by Wobbly
Replied by Wobbly on topic '76 R90/6: How do you stop leaking forks
1976 models have a stud on the bottom of the internal shock. On the inside of the leg, around that stud is a "sealing washer". The original washer was most probably aluminum. The Germans seem to be crazy for aluminum washers. The old washer probably hopped off the stud when the forks were being disassembled or drained in a previous life. Being aluminum, the part (if it's still inside the fork) is most probably mangled beyond re-use.

This part is no longer available from BMW, but a plain nylon flat washer is all that's required to give years and years of service. You can get 1/4" ID nylon flat washers at almost any hardware store, or from Amazon.

Hope this helps.

Don't hide 'em, Ride 'em !!
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6 days 6 hours ago #6485 by 14517
Replied by 14517 on topic '76 R90/6: How do you stop leaking forks
Thanks. That’s very helpful.

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6 days 3 hours ago #6487 by Wobbly
Replied by Wobbly on topic '76 R90/6: How do you stop leaking forks
Sorry it took so long, but until today I had never disassembled BMW forks and didn't want to make a wild guess.
After replacing the seals in an '81 model this morning, now the diagrams make sense.

Don't hide 'em, Ride 'em !!
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