Fork Seals??

[Rebel]

Question for fork seals. My '88 R-100RS is leaking from both seals. I ordered new seals (31-42-2-310-199) and installed them oriented the same way as the leaking seals were removed from the bike. Upon completion, I noticed the new seals were leaking. I noticed the rubber boot of the seal was folded over and removed the forks once again, removed the seals from the fork leg and installed the seals once again on the tubes making sure the rubber seal was not folded over again. Success. I then installed the sliders and tapped the seals down into the sliders flush, and re installed the rest of the bike. Alas, the seals are STILL leaking. I don't know how or why. I am now suspecting the seals may be installed upside down. Does any one know the proper orientation of the seals for the later style mono bikes? Does the spring side of the seal face up or down?
Thanks!!

[Major Softie]

Spring on the wet side.

[Rebel]

Thanks,
I have done it spring side down twice now, and was still having issues and thought maybe I was wrong.

[ME 109]

New seals shouldn't leak.
Check the stanchions for wear/stone chips. Check the slider where the seal sits for damage from po's.
How much fork oil did you use?

[Major Softie]

Yes, ME's point is important. Whenever I replace fork seals, I assume that they are leaking because of damage to the tube damaging the seal (although, if you have gaitors, this shouldn't be able to happen). The little chip can be hard to even feel sometimes, so I rub the tube with a cotton ball and see if it snags on anything. If it does, knock that down with superfine wet/dry paper: like 1500 - 2000. I like to use a hard rubber sanding block for that kind of work.

[Rebel]

I did check the fork tubes and no signs of dings. The bike now has 123,000 miles, and the tubes are worn to a mirror finish from the seals. I used 320 cc of ATF for fluid in each leg, which to my knowledge is correct for that model. I have installed many sets of seals over the years, so I think I have a "feel" for what I'm doing, and I have never had issues with other bikes in the past. Maybe I just got lucky with a bad pair of seals.

[ME 109]

Hmmm, so the forks were leaking before, and after installing new seals.
Stanchion chrome can wear out. Maybe a good idea to check for spec.

Maybe clean around the seals very well and dust a little flour or something around the seals. I'd expect a worn slider to weep around x circumference, where a ding or burr or damage to the seal would show as a small spot first.
I think.

[khittner1]

I used 320 cc of ATF for fluid in each leg, which to my knowledge is correct for that model. I have installed many sets of seals over the years, so I think I have a "feel" for what I'm doing, and I have never had issues with other bikes in the past.

I think the monoshock front ends are the same from '85 until the end of production. The Haynes manual says the fluid capacity of each fork leg is 270cc, so you may be overfilling them. I don't know about using ATF as a fork fluid. I'd look at the owner's manual for guidance, but I think I'd start presumptively with BMW's 7.5 weight fork oil. I suppose that the seals may not care much which sort of lube you're using.

[jagarra]

Since you say the seals are leaking I am assuming both of them are. ATF has a lower viscosity than oil, if you are overfilled
plus the lower viscosity that may be the cause.

[Rebel]

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.