DOT 5 compatible caliper o rings

[Gary B.]

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[Gary B.]

Re: DOT 5 compatible caliper o rings

Patrick,

While I have your expert knowledge handy, this is what came in the NOS GM master cylinder rebuild kit I recently bought.

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[Ed D.]

Re: DOT 5 compatible caliper o rings

This goes back to the question, if anyone knows of anyone offering lip seal EPDM seals for calipers? I have only seen o ring seals.
Ed

[Gary B.]

Re: DOT 5 compatible caliper o rings

Ed,

I’m guessing the answer is no. The peroxide-cured EPDM O-rings, such as the ones now being sold on eBay, apparently by one individual, are likely being sourced from a company that makes or sells O-rings for hundreds or thousands of different applications. Unless you can find a comparable company that does the same for lip seals of the correct diameter and geometry, then I think we’re stuck dealing with the brake caliper and master cylinder resleeving companies. And clearly they are not stepping up and offering EPDM lip seals or we wouldn’t in the position we are in.

Gary

PS - I should clarify that my guess of no one making EPDM lip seals was for companies not specializing in brake caliper resleeving. Who the heck knows about what the the resleeving companies use unless they tell us. Which they seem reticent to do for reasons that escape me.

[Owen L.]

Re: DOT 5 compatible caliper o rings

Ed,
I believe the Raybestos Element 3 lip seals (WK452 & 453) are EPDM. I use them in my calipers and have had no swelling/leaking issues for years. I sent an email to their tech department asking if EPDM and which curing method is used. Will post their response.

[Gary B.]

[Owen L.]

Re: DOT 5 compatible caliper o rings

I did a similar test as Patrick's about a 1.5 years ago:
https://www.corvetteforum.com/forums...ot-5-test.html
My issue was that a newly installed caliper from Lone Star was leaking and I could not return it under warranty (due to DOT 5 use). The message initially had to do with the quality of the caliper machining and secondarily I wanted to test the brake fluid disclaimer. The kit I used was the WK452.

[Patrick B.]

[Gary B.]

Re: DOT 5 compatible caliper o rings

Patrick,

Thanks for the follow-up. Any idea what the white stuff is on the loose rubber item? The rubber seal on the other end of the piston has no hint of white.

Gary

[Gary B.]

Re: DOT 5 compatible caliper o rings

Owen,

Thanks for that link to your posting in the Corvette Forum. Nice work. That makes me feel good about the Raybestos lip seals. Unfortunately, my calipers have O-rings.

Gary

[Terry M.]

Re: DOT 5 compatible caliper o rings

FWIW, and it is probably not much, I will share my experience. I have on other threads of this nature so it will not be new news to many of you.

About 40+-years ago I rebuilt the entire brake system in my 1970. I replaced pistons, lip seals, dust boots and MC kit. Lone Star sleeved the calipers (I bought them through Brushy Mountain Corvette - Dick Whittington) and used the then-available over the counter rebuild kits from Chevrolet. DOT5(Dow Corning) has been in there since with NO issues.

I did flush the brake lines with denatured alcohol even though the SAE papers of the time, which quoted military tests, stated that removing all the DOT3/4 was not necessary. Bleeding the new fluid was difficult -- now we all know that should have been no surprise, but it was to me in those pre-internet days. I finally settled on over-might gravity bleeding for the win. I doubt the brakes have been significantly heated since then, but the system has been trouble-free since. I'll never know if it is the brand of fluid or the material of the seals, I just want to duplicate those results on another car. I too am looking for a solution. My thanks to Pat and Gary for their well-done research and the fortitude to continue and not settle for less than 100% success.

[Patrick B.]

Re: DOT 5 compatible caliper o rings

Patrick,

Thanks for the follow-up. Any idea what the white stuff is on the loose rubber item? The rubber seal on the other end of the piston has no hint of white.

Gary

I have not seen white stuff before. It may be residue from a mold release agent that turned white over time. I would clean it off with soap and water and then wipe it with lacquer thinner if necessary.

[Joe L.]

Re: DOT 5 compatible caliper o rings

I have not seen white stuff before. It may be residue from a mold release agent that turned white over time. I would clean it off with soap and water and then wipe it with lacquer thinner if necessary.

Patrick------

I don't think I'd use lacquer thinner. As I recall, this is a petroleum derived solvent. I think I'd use something like BrakeClean solvents.

[Gary B.]

[Gary B.]

Re: DOT 5 compatible caliper o rings

Dish soap, water, dry, then lube with DOT-5 worked well.

Gary