C2 leaking brake caliper

[Richard E.]

I am working on a 1966 Corvette which has a leaking front caliper (driver side front). I plan to replace the leaking caliper. The car has a dual master cylinder, no power brakes. The brake fluid is silicone.
Does anyone supply rebuilt / reproduction calipers that have seals which are compatible with silicone fluid? If not, can the system be flushed without removing and disassembling all calipers / hoses etc.?
I would appreciate if anyone can provide a suitable flushing method to allow changing back to DOT 3 fluid if this is my only option.

[Owen L.]

Re: C2 leaking brake caliper

Elastomer of the old-school EPDM variety is compatible with silicone fluid. Raybestos Element 3 seals are EPDM.

I've not flushed my systems to convert to something other than 5, but perhaps denatured alcohol will work. Take some of your master's fluid and pour in some DNA - shake to see what happens. If it separates into layers with the silicone on top, it won't do much to flush the system and you're likely just as good using copious quantities of DOT 3 or 4. There are rumors that mixing DOT 5 with 3 or 4 creates a gel but I've not been able to cause this in informal experimentation.

[Mark E.]

Re: C2 leaking brake caliper

I was going to suggest contacting Lonestar Caliper and ask them, but I can't find their website. Are they still around?

[Patrick B.]

Re: C2 leaking brake caliper

I was going to suggest contacting Lonestar Caliper and ask them, but I can't find their website. Are they still around?

Try Muskegon Brake, they sell Lone Star stuff for a good price.

[Mark L.]

Re: C2 leaking brake caliper

I had a conversation with Ken at the Lone Star booth. He believes the silicone fluid is today's problem as something was changed in the past 10? years. If you can find old fluid it might work.

[Paul S.]

Re: C2 leaking brake caliper

FWIW, I went down the road of trying to use DOT 5 when I converted my 67 from standard to power disk brakes in 2013. I initially bought new calipers, MC, lines and brake hoses everything from CSSB, Inc. and could not get the right front caliper to stop seeping brake fluid at the hose connection, and the master cylinder seeped brake fluid from the rear. CSSB replaced the caliper and MC, same thing, and then took all the parts back for a full refund. I then started over with new parts from Lonestar, this time using DOT 4. I flushed the entire system with denatured alcohol prior to removing the calipers and MC to return them, so that I knew there was no DOT 5 in the lines, and used new rubber hoses front and rear. No issues. So that's what I would recommend Richard do.

My experience likely led to what you read on CSSB's website about DOT 5 voiding all warranties.

Your only other option would be to go with an aftermarket caliper (there's one who's name I cannot recall but search over on the Corvette Forum C2 discussion board to find it) which won't look correct but which have seals that work with DOT 5. Or I guess rebuild your caliper using the DOT 5 friendly seals. Good luck.

[Gary B.]

Re: C2 leaking brake caliper

Elastomer of the old-school EPDM variety is compatible with silicone fluid. Raybestos Element 3 seals are EPDM...

Raybestos

[Kurt K.]

Re: C2 leaking brake caliper

Richard, I have had calipers leak. I just take them apart and clean up the bores and seals, put them back together and the leak was fixed. I have Dot 5 in mine and the seals all look good, just a little crud gets up under seals and starts them leaking. Easy fix. Worth a try and you can save the trouble of switching back to Dot 3.

[Richard E.]

Re: C2 leaking brake caliper

I'm sure my calipers have SS sleeves, but they have been on the car a long time, probably from back in the day when changing to silicone fluid and SS sleeving was all the rage (1980's?). Taking the calipers apart and cleaning them is a reasonable option, I will look into that. I would still like to hear if there is any seal kit or caliper replacement that can withstand silicone. Thus far it appears none exist, but I expect many Corvettes still operate with silicone fluid regardless.
I'm old enough to have lived through the silicone craze! Prior to SS sleeves and silicone, I repaired a number of leaky calipers by lightly honing the caliper bore and replacing the seals and pistons with factory originals purchased from the local chevy dealer. That usually worked for a while, but here in Upper Michigan where a Corvette can sit for 6-7 months of the year waiting for the winter streets to clear it wasn't long before a caliper would leak again.
Thanks everyone for your input and suggestions. I hope this thread continues to generate comments, I did not expect this situation to become the issue that it has!

[Owen L.]

Re: C2 leaking brake caliper

Owen,

Correct me if I’m wrong, but I believe the intent of your statement is that Raybestos Element 5 seals are compatible with DOT 5 based on the EPDM composition and its perceived DOT 5 compatibility. However, back in January 2023 posting, Ed DiNaploi said he spoke with Raybestos Tech Support and Ed reported this:

“I just called the Tech Dept at Raybestos and asked about their rubber products compatibility with DOT 5. The lady was very straight forward and said their brake product are NOT compatible with DOT 5.”

If what Ed was told by Raybestos is true, then I am not aware of any source for DOT 5 compatible seals for our C2/C3 calipers.

Gary

Now that you mention it, I do vaguely recall this. If the representative is correct, I wonder if Raybestos is putting any sort of notice on the packaging now. My spare boxes of seals from a couple years ago don't have it. Unless they changed from EPDM, the seals should be just fine.

[Gary B.]

LOT of other people.

Gary

[Mark E.]

Re: C2 leaking brake caliper

Years ago, someone at Lonestar Caliper told me the seals will last longer if I depress the brake pedal 2 or 3 times a month when the car is stored and flush the fluid every 2 years regardless of miles. I usually do this but have suffered one seal failure since then...not too bad.