front fork stiff after new seals

[Tom Andersen]

I just replaced the fork seals on my '78 for the third time since new, now 102K miles. I used oem seals and the front fork action is very stiff. I don't remember it being this way in the past after replacing the seals. I'm sure the front wheel is positioned correctly as I have had the bike since new and had the front wheel off many times. Could this just be "stiction" because of the new seals? I am open for suggestions.

[bikerphil]

Yes, sometimes new seals will be stiff until they are broken in. Make sure your fork tubes are paralell in the trees. A piece of plate glass against the front of both tubes will tell you. Did you use 10W oil and how much? Recommended level is 212cc's IIRC.

[Tom Andersen]

Yes, sometimes new seals will be stiff until they are broken in. Make sure your fork tubes are paralell in the trees. A piece of plate glass against the front of both tubes will tell you. Did you use 10W oil and how much? Recommended level is 212cc's IIRC.

bikerphil yes the tubes are straight, I used 10w BelRay fork oil, 212cc's. Thanks for the suggestions.

Tom

[cywelchjr]

I know mine are a little bit stiff, but I expected it since I used 15w silkolene in them. I actually wanted to stiffen them up what with my weight and the fairing and all, so I'm not unhappy with the results, but I'm surprised that properly fitted and lubed seals would be stiff at all, that would make me worry that they were TOO tight on the inner tube.

Did you bounce the forks before tightening the cap on the non-bolted side? I know you can get stiffness if you don't because the inner and outer tubes CAN be out of alignment.

[motoman]

If everthing else is all together correctly, spray a bit of silicone on the tubes and work forks up and down......may free movement up a bit.....

[Tom Andersen]

cywelchjr yes I bounced the forks with the cap loose, first with the brakes applied, then after a test run I tried it without putting the brakes on, no change.

motoman I will give the silicone a try.

[natemoen]

Silicone can cause rubber to swell, so there is a chance that it could make the seal tighter.

[bikerphil]

Double check the size of the seals, make sure they are not 36MM, ours are 37MM. Only other thing I can think of is that they weren't driven in all the way squarely.

[Tom Andersen]

Thanks for the suggestions everybody, I'll see what I find.

Tom

[motoman]

hope you find the issue.........and no, silicone won't cause the rubber to swell....

[cywelchjr]

hope you find the issue.........and no, silicone won't cause the rubber to swell....

I would agree, I have never seen silicon swell rubber parts. I have used it in several applications where you want to slip a rubber part over metal parts, just don't use it where something needs friction to work. I used to work as a piano technician and we thought the stuff was great at first, until it made parts that were held in place by nothing other than friction slip out of place. The stuff WILL migrate to anything else nearby, although I have found it often doesn't migrate upwards, so it works on tachs and speedos pretty well.

[natemoen]

I have had it happen, and I have heard others say that it can cause swelling. Who knows maybe it is the propelant used in some cans that really causes the swelling.

[Rasputin]

I have never heard of a new seal causing a moving part to be stiff. I would definitely recheck everything. The newer fork oil or some gunk still in the forks could cause it but no, I do not believe new seals would cause this. Even without silicone they should move properly.

[Cobia]

JAT - Could it be that the teflon/plastic 'guides' that are in the lowers, just below the seals have been compromised?