Fork Seals??

[barryh]

I spoke to the dealership this morning and the mechanic verified the 320cc of oil for each leg. He asked me what oil I was using, and I told him ATF. He said it may be too light and to try a heavier viscosity oil. ATF is about 4 weight oil, so I will get some 10 weight fork oil and before disassembly, simply try changing the oil once again.
Thanks again for the tips.

Maybe I'm not up to date with modern ATF but I've never known it to be 4 cSt. ATF always used to be 7 Cst which is a lot thicker than BMW's fork oil spec for the early forks but very close to typical 7.5 cSt fork oil.

You can't really compare fork oils at their label weight because forks don't operate at 100 Deg C but that's another story.

[khittner1]

Your mechanic and Snowbum are singing from the same hymnal on the fork oil capacity, Reb, so it must be so, and, once again, Haynes is found to be wanting. I don't know why Haynes doesn't issue an updated edition, or offer an errata sheet/volume . . . presumably, it's a money thing.

[jagarra]

Reb,

I made the mistake of using too heavy of an oil in my forks once. It was 15 wt, they just didn't work at all, they compressed and stayed there. The weight that seems to work the best is 7 wt, thinking 10 may be just a bit too heavy and may cause a different issue.

gg

[barryh]

There is one thing that can be tried on leaky fork seals although you have to very careful not to introduce too much stiction.

The garter spring that provides tension in the seal can be shortened by unscrewing the joint, cutting a little off the end and rejoining it. This will increase the tension in the seal. Doesn't always cure the leak but might be worth trying before chucking a new seal that leaks. This is is a highly magnified view of the joint. If you are getting on like me you'll need your very best reading glasses just to see the join. It's doable though.

[pmonk]

BMW fork oil is 7.5 wt, and made by Spectro. Or it was made by Spectro. Who knows nowadays.

[Rebel]

Thanks all, I picked up some 10 weight spectro fork oil, so I will change it over the weekend and hopefully resolve the leak.

[Rebel]

Problem resolved. I ordered parts from Max BMW this time, and they had an updated part number for the fork seals. The new number is: 31 421 458 341 for those needing them. These were different in design than the original kind in the bike. The seals were designed where they would not fold over like the old ones and worked like a charm!! I am using Spectro 10 weight fork oil and about 300 cc per leg. Bike handles great again!!