Brake caliper seal failure...AGAIN

[Mark F.]

Howdy

I have been a member for 18 years, but this is only my second post. I have two 65 convertibles.

Two months ago, as the weather got hotter here in southern California, both of my front brake caliper's piston seals failed within one day of each other! The calipers were converted to SS many years ago by the previous owner. I have owned the roadster since March of 2003 and this is the second time I have had to replace caliper piston seals. I am using DOT 3 synthetic brake fluid. Is this correct?

Has anyone else experienced caliper piston seal failure "regularly" due to temp or humidity?

Thanks,

Mark Francois
26312

[Patrick H.]

Re: Brake caliper seal failure...AGAIN

Mark,

what type of seals are you using? The original style with a lip, or the O-ring type?

The O-ring variety was developed partly because of the exact problems you are experiencing. Air pumping is the other problem they help you avoid.

So, if you're reinstalling original seals and your car doesn't get driven much, it will happen again. Check out some new O-ring seals such as those sold by Vette Brakes.

Patrick

[Joe L.]

Re: Brake caliper seal failure...AGAIN

Mark,

what type of seals are you using? The original style with a lip, or the O-ring type?

The O-ring variety was developed partly because of the exact problems you are experiencing. Air pumping is the other problem they help you avoid.

So, if you're reinstalling original seals and your car doesn't get driven much, it will happen again. Check out some new O-ring seals such as those sold by Vette Brakes.

Patrick

Patrick and Mark-----


The o-ring seals have "pluses" and "minuses". However, one of the "pluses" is that they are generally longer-lived in the case of cars which see little use. One of the "minuses" is they are not as good as the chevron-seal when high performance braking is a requirement.

To install the o-ring seals, though, the pistons also have to be changed. One cannot install o-ring seals on stock pistons.

DOT-3 brake fluid, synthetic or otherwise, should not be a factor in your problems; it should work fine. High ambient temperatures and humidity shouldn't be factors, either.

[Mark F.]

Re: Brake caliper seal failure...AGAIN

Patrick / Joe

Thanks for the info. First, let me correct my initial post. I have been a member for 15 years, not 18. I have owned mid-year cars for 18 years. Got a bit confused in my old age.

Yes, I am using the standard seals because I still have the stock set up on my red 65. The source of the seals the past several years has been ebay since they are cheap at about $10 per caliper compared to NAPA which cost $25 per caliper. Perhaps it is a case of you get what you pay for.

Here's the only explanation I can think of. As Patrick suggested, the car is driven very little. Maybe 200 miles per year, maybe not even that much and it does sit for long periods, i.e., for months without being driven.

I don't know this to be a fact, but it would occur to me that the seals probably need to stay in contact with brake fluid to keep the rubber happy. Long periods of sitting combined with a sudden increase in temperature may dry the seals out just enough to allow some shrinkage and allowing some of the fluid to pass. I literally had one front caliper fail when the weather turned hot and the very next day the other front side of the car failed.

At least it's a simple repair job that I have now done about half a dozen times in 18 years, so the process is quick. And the wife really enjoys spending an evening in the garage helping me bleed the brakes....NOT!

Thanks again guys!

Mark