Seal heads and anodizing



3 replies to this topic
  • DaveJ

Posted November 27, 2000 - 10:28 PM

#1

I'm looking for a suspension shop in California that can do teflon anodizing and possibly make some modifications to my fork seal heads?

I'm assuming someone down in So. Cal. does this.

Thoughts?

  • Scott_F

Posted November 28, 2000 - 06:51 AM

#2

I believe Pro Circuit and Race Tech offer the teflon anodizing service through a subcontractor. I personally don't recommend this. Also, your forks do not have seal heads like a shock does. Perhaps you are referring to the bottom of your outer tubes. What are you trying to do?

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  • DaveJ

Posted November 28, 2000 - 10:02 PM

#3

Scott,

I'm talking about the caps that screw down on top of the fork compression tubes. They are made of aluminum, usually have a bronze guide, a small seal, and a shim stack. It's what the cylinder tool holds on to when you're un-doing the compression valve. The whole head is peened together and locked into the compression tube via four press points.

My problem is that I appear to be getting excessive oil that is flowing past these. I replaced these about 50 hours ago.

When they were new, all worked well. When I was on the track last weekend, the front wheel had excessive oscillation. I set the compression and rebound screws just about all the way in which helped a little, but it was obvious that something internal was failing.

So I pulled them apart and did some testing via a tank of oil. It appears that about 1 to 2 ounces of fluid flows past these on each up or down stroke. Obviously not all of the oil passes through the valving, but I don't think this much oil should flow pass the heads.

I'm not sure what's wrong or what is causing this since the only mod at this point are some minor changes to the high-speed stack, and synthetic oil.

I spoke with GP Suspension the other day and they are offering to rebuild these, which includes some mods to the bushing and stack, as well as renewing the factory Teflon coating. But since they are back East, I thought I could perhaps find someone closer.

The only thing that I can think of is that perhaps I have bottomed the bike too much with all my bad landings. But you'd think they would design for that.

Thoughts?

Dave

  • Scott_F

Posted November 28, 2000 - 08:27 PM

#4

Dave, I have some thoughts and the solution to your problem. I am in LA, and I can fix your forks. I thought you may have been referring to the cartridge, but wasn't sure. You are right, the shims in there could be weak and you could be losing pressure in the cartridge. I believe the trouble you are experiencing is what the magazines call midvalve failure. I have replaced those seal heads and found that if the drilled holes are too big, the threads can leak fluid. So here is the fantastic solution:

Bottoming cones.

I have installed these in all of my YZF forks, and they work great. They eliminate the shims, but most importantly, they eliminate the bottoming.

Send me an email if you want to get together.





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