Author Topic: Front Forks C12 not Damping  (Read 907 times)

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Offline AdminPete

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Front Forks C12 not Damping
« on: November 24, 2008, 05:32:46 pm »
Hello, I was wondering when you put fresh oil on the front forks of a C12 is there
anything special you need to do than just put oil in them? I had oil leaked out of
the fork/forks when I bought the C12 and transport to my house, we pull down on
the handlebars to strap in and some oil came out. Then I empty or replaced the oil
in the forks, the forks seems to not damper very much seems only the spring is working. If I used the front brake only it nose drives. Just wondering if I need to replaced the seals on them? Where to get some seals for the forks?

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From: thomasjasper Sent: 16/05/2006 19:26
The seals only affect damping inasmuch that if they have 'gone', then oil leaks out eventualy from the top of the sliders. Your bushes may be rather worn, springs probably pretty weak or just maybe the incorrect grade of oil in the legs; should be 142cc, (5 fluid ounces) sae 20. Suggest you try in order of cost; oil, seals, bushes and springs although I suspect the latter. Bear in mind that they are not exactly Marzocchis, but 50 year old BSA's. All these items available from Dragonfly, Autocycle Engineering or C& D and probably others. You might need a tool to shift the oil- seal holders, preferably not a wrench; try a strap wrench- the type used for removing auto oil filters, one with a fabric strap, NOT a chain, Joe

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From: zepol2006 Sent: 16/05/2006 20:43
Hey, Joe
Thanks for that info. I have already replaced the oil with the right stuff SAE 20 fork oil. It did not seem to help much. It looks like it dampers the same with the oil and with out the oil in the forks. I think it may be the seals. I also understand about the 50 year old machine. It seems that it was damping a little more when I bought the machine at the guy house that I got it from. Anyway Thanks!

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From: zepol2006 Sent: 18/07/2006 14:32
Just in case anyone is interested.........I did finally replace the fork oil seals. I had to buy the special tool to break the tube apart. The oil seals were very hard not soft and
would not hold oil in place. I did have to make a special tool to install them back. I bought a top nut that goes on top modified it and used it to make this tool along with a long piece of thread rod. Worked very nice and did not cost alot. The replacement of the fork oil seals made a big differance, now it seams to damper right. First time I have rebuild forks on a motorcycle, it was very interesting specially when the removing them, that kind of spring out, so if anyone is doing this be careful.
Texas USA