Alternate caliper seals

[CU Zcar]

Did a track day in my 280Z, noticed that the heat has scorched/cracked the bellows seals around the caliper pistons. What do ITS cars (and others forced to race with stock-type calipers) do about this? Just frequent replacement, omission of the bellows seal (and frequent clean/rebuild), or is there a scraper-type seal available?

 

If I understand correctly, the bellows really just keep dust out of the caliper and another seal takes care of keeping brake fluid in...yes?

[MONGO510]

Primary job is to keep dirt and moisture away from the piston. It has another sael inside that takes care of sealing the piston.

You could assemble the caliper without the bellows but when it comes time to replace the pads you may have to dissasemble the caliper to make sure the piston is clean. If the piston is dirty, when you retract it it may damage the inner seal, causing leaks.

Hope this helps!

[CU Zcar]

Hrm. A caliper teardown to clean the pistons at every pad change. Sounds like fun! Surely there's a better way.

 

Thank you for the response though, you did confirm my suspicions.

[CU Zcar]

Anyone else have input? Anyone else do trackdays/race on stock calipers? Maybe others don't have this issue?

 

Should I maybe take this to improvedtouring.com or a similar race-based forum?

[zcarnut]

Make sure you are using the thin metal sheet (or shim) that is located between the pad and the piston. Although the primary function of the shims is as a dampening device to reduce vibrations (brake squealing), they are also useful in reducing the heat flow from the pad backing plate into the piston.

 

The stock shims are usually stainless steel which will reduce some of the heat flow. An improvement (as some racers are doing) is to use shims made from titanium. Titanium has roughly 40% the thermal conductivity of stainless steel. It’s fairly easy to cut out the correct shape from some titanium sheet stock.

[JMortensen]

Anyone else have input? Anyone else do trackdays/race on stock calipers? Maybe others don't have this issue?

 

Should I maybe take this to improvedtouring.com or a similar race-based forum?

If you're going to run without the dust seal, extend the pistons out further, clean as much as you can, THEN push them back in. According to people using Wilwoods, getting all the dirt and grit off the piston before you push it past the seal pretty drastically reduces the need to replace the seals every time you change pads.

[CU Zcar]

Make sure you are using the thin metal sheet (or shim) that is located between the pad and the piston.

I am using a set of those I got from Nissan, though the ones I have are only a half-sheet with a circular cutout ... a picture would help me describe, suffice it to say I am using one. The titanium shim sounds like a good idea, I may have to look into that.

 

If you're going to run without the dust seal, extend the pistons out further, clean as much as you can, THEN push them back in.

So this is common practice in racing circles? If I find I burn up another set of dust seals, I may switch to this method.

 

Thanks for the replies so far!

[mom'sZ]

What do ITS cars (and others forced to race with stock-type calipers) do about this? Just frequent replacement, omission of the bellows seal (and frequent clean/rebuild), or is there a scraper-type seal available?

In ITS, the brakes have always been considered the weak link for Zcars. Frequent replacement of major components are the rule. Multiple brake ducts are nessasary, not practical on a street car, but a prerequisite on a track bound stock braked Zcar. Also, adjusting and using the rears to their max potential helps. Hopefully a certain championship winning crew chief will chime in with more direct experience.

good information on the shims, thanks zcarnut!