Fork Cap Problem

[Mick Milakovic]

Hi All,
I need to fix my fork caps.  Sometime in the past a previous owner drilled out the spring-and-ball pressure release and replaced it with an air valve.  The threads are now too big for the stock screw.  I think the pressure build up is why my seals rarely last a season.  Other than getting new caps, does anyone have a suggestion for fixing the issue?  Thanks in advance,

Mick

[Daniel P. McEntee]

Don't have one at hand to see how much "meat" you have to work with, but maybe a keen-Cert of the proper size can restore the threads for the screw, if the ball and spring will still work underneath. Got a few other ideas of fabricating the system outside the cap and then installing into the cap, but need to look at one first. Maybe even welding up the hole back to solid metal and rebuilding that way? Gotta be a way!
   Type at you later,
    Dan McEntee

[Mick Milakovic]

Dan, the guy drilled the hole all the way through, so filling the hole is the only way to fix it.  In the meantime, I suppose bleeding any air pressure built up after each ride?

Mick

[Daniel P. McEntee]

Yeah, you can still do that with a Schroeder valve.  If a length of aluminum rod could be drilled, and tapped for the mechanism, and then the rod cut to length, and pressed into a proper size hole in the cap, then welded around the bottom. I don't have easy access to a cap right now, so just can't visualize it. But if they made it at the factory, you should be able to duplicate it in a piece of material and add it to the cap, I would think.
  Dan

[G Ellis]

You will Have to get new caps.

[Richard Colahan]

Just a thought...I've put Shraeder air valves into a number of my vintage XC race bikes. I use them to either bleed out excess air pressure, especially when the bikes get tied down for transport...or in other cases to add a few pounds prior to a race.
I have not had problems with blown fork seals that I'd attribute to the air valves.

Perhaps...perhaps...your issue is not the air pressure, but the fork oil level being a bit too high?

Richard Colahan
1969 V1225
Upper Black Eddy PA

[Mick Milakovic]

I've always put 185cc per leg (about 6.5 ounces) on a complete rebuild, according to the Penton manual, using ATF.  I've been considering going to real fork oil on this rebuild.  I weigh 175 pounds and am an intermediate rider.  Suggestions on fork oil weight?  Could the ATF be too thin and cause the early leakage?

Mick

[Daniel P. McEntee]

Don't have one at hand to see how much "meat" you have to work with, but maybe a keen-Cert of the proper size can restore the threads for the screw, if the ball and spring will still work underneath. Got a few other ideas of fabricating the system outside the cap and then installing into the cap, but need to look at one first. Maybe even welding up the hole back to solid metal and rebuilding that way? Gotta be a way!
   Type at you later,
    Dan McEntee

[Mick Milakovic]

Dan, the guy drilled the hole all the way through, so filling the hole is the only way to fix it.  In the meantime, I suppose bleeding any air pressure built up after each ride?

Mick

[Daniel P. McEntee]

Yeah, you can still do that with a Schroeder valve.  If a length of aluminum rod could be drilled, and tapped for the mechanism, and then the rod cut to length, and pressed into a proper size hole in the cap, then welded around the bottom. I don't have easy access to a cap right now, so just can't visualize it. But if they made it at the factory, you should be able to duplicate it in a piece of material and add it to the cap, I would think.
  Dan

[G Ellis]

You will Have to get new caps.

[Richard Colahan]

Just a thought...I've put Shraeder air valves into a number of my vintage XC race bikes. I use them to either bleed out excess air pressure, especially when the bikes get tied down for transport...or in other cases to add a few pounds prior to a race.
I have not had problems with blown fork seals that I'd attribute to the air valves.

Perhaps...perhaps...your issue is not the air pressure, but the fork oil level being a bit too high?

Richard Colahan
1969 V1225
Upper Black Eddy PA

[Mick Milakovic]

I've always put 185cc per leg (about 6.5 ounces) on a complete rebuild, according to the Penton manual, using ATF.  I've been considering going to real fork oil on this rebuild.  I weigh 175 pounds and am an intermediate rider.  Suggestions on fork oil weight?  Could the ATF be too thin and cause the early leakage?

Mick