Leaking Mollies (fork seal)

[ryonker]

I installed leak proof pro-moly fork seals on my 78 last summer. They leaked a little the small amount of time I road that bike.

I have been riding that bike a little more this year, and they still leak. No gushes, just gradual leaking, leaving rings on the inner fork legs and small drips on the dust covers.

I really didn't want to take them apart again but it looks like that is inevitable. I have maybe put 100-200 miles on those seals.

When I took the forks apart there were no noticable dings on the inner legs. But I did not sand them.

Is that about my only option, other than just putting in different seals?

Thanks!

Rick

[bwringer]

With Pro Moly seals, if you hammer the new seals in instead of gently working them in with your fingers, they will leak. (Guess how I learned this... )

If that's not the case, perhaps you can pop the seals out and clean them. You can remove and reinstall Pro Moly seals without damaging them if you're careful.

[bonanzadave]

It does not take a very big pit to make em leak. I have one fork that Ive had 3 seals in and the old seals I took out looked perfectly good. This last time around I saw the couple small pits and sanded them down to 1000 grit. Its holding 15psi but it still leaks oil . This newest seal is a genuine S part from the dealer.

[ryonker]

With Pro Moly seals, if you hammer the new seals in instead of gently working them in with your fingers, they will leak. (Guess how I learned this... )

If that's not the case, perhaps you can pop the seals out and clean them. You can remove and reinstall Pro Moly seals without damaging them if you're careful.

I put them in totally by hand, and very gently. So, I should take them out, clean them and sand the inner fork tubes? I think I have read somewhere about cross hatch sanding with 800 grit? Just the lower 2/3 or the whole inner fork tube?

Thanks for the help!

Rick

[DanTheMan]

Rick, on my fork tubes I used a fine whetstone then 400 grit paper, then some 0000 steel wool. I've got no leaks except the inner o-rings that I didn't replace, so they don't hold air pressure, which it turns out is no big deal as those unidentified springs I put in appear to be Progressives or something similar.

[ryonker]

Rick, on my fork tubes I used a fine whetstone then 400 grit paper, then some 0000 steel wool. I've got no leaks except the inner o-rings that I didn't replace, so they don't hold air pressure, which it turns out is no big deal as those unidentified springs I put in appear to be Progressives or something similar.

Thanks Dan;

I'd be a little nervous using a whetsone, but how about 400,600, 800 or something like that.

Rick

[DanTheMan]

The finer grit wet/dray paper or crocus cloth in those grits should work fine. I just smoothed mine out around the scratches/dents to make sure there were no raised/sharp edges. It's worked out fine so far.

Oh, the parts bike is a 1980 just like mine year wise, and I might even be able to title it after researching the vin#. Right now I'm just using it as parts, but no telling what I might do with it. Hey, where are the pictures of the trunk?

[ryonker]

Oh, I totally forgot about the pictures .

My charging system issues starting consuming my brain power.

I'll try and get them up soon. I love that trunk...now to just get the bike back on the road so I can use it.

Rick

[ryonker]

The finer grit wet/dray paper or crocus cloth in those grits should work fine. I just smoothed mine out around the scratches/dents to make sure there were no raised/sharp edges. It's worked out fine so far.

Oh, the parts bike is a 1980 just like mine year wise, and I might even be able to title it after researching the vin#. Right now I'm just using it as parts, but no telling what I might do with it. Hey, where are the pictures of the trunk?

Dan, would you sand them wet or dry?

Rick

[DanTheMan]

If using wet/dry paper, sand them using something real lightweight like penetrating oil as the lube, then wipe them down real good. Be sure you don't go too far and make flat spots, it becomes counterproductive then.

[mike_of_bbg]

Can't answer for Dan I sanded mine wet (w/WD40) using 600 grit. No need to go past your 6-8 inches of travel except to practice, unless you're really paranoid about cutting your seal on its one pass in. I started with a small circular motion, went to a cross-hatch, then a circumferential finishing pass.

[bwringer]

Last time I reinstalled a pitted fork tube, I used my polishing wheel (cotton buff on a bench grinder, loaded with polishing compound) to smooth out the pitted areas. It was there, it was easy, but it seemed to do the job.

[ryonker]

Last time I reinstalled a pitted fork tube, I used my polishing wheel (cotton buff on a bench grinder, loaded with polishing compound) to smooth out the pitted areas. It was there, it was easy, but it seemed to do the job.

Thanks Brian.

The funny thing is, the legs looked really clean and nice, with no obvious evidence of pitting. Maybe I didn't look carefully enough.

Rick

[bwringer]

Thanks Brian.

The funny thing is, the legs looked really clean and nice, with no obvious evidence of pitting. Maybe I didn't look carefully enough.

Rick

Maybe it's just dried bug guts or something that got in the seal. It's also common to find that the spring clip has rusted and the rust flakes are getting into the seal. There are lots of ways to spring a leak.

Exposed fork tubes was just about the dumbest thing the motorcycle industry ever did, yet this idiotic fashion is with us to this day. Back when fork tubes were shrouded, fork seal leaks were fairly rare.