Piston seals for 1st design brake calipers

[Gary B.]

I'm contemplating getting a set of the original 1st design calipers for my '66. In terms of the piston seals, what is considered state-of-the-art? Some vendors claim that O-ring seals are superior to the original GM-style lip seals. My first question is, are the O-ring seals really clearly superior to the alternative (lip? seals)?


Secondly, I was told by an e-bay seller who restores 1st design calipers that the the insulator pistons cannot use O-ring seals, i.e., only pistons without the insulators can use O-ring seals, and the insulator pistons have to use the original GM-style lip seals. Does anyone know if what I was told is universally correct? Or is that vendor basically saying that he can't match up O-ring seals with insulator pistons?


Thanks,


Gary

[Larry M.]

Re: Piston seals for 1st design brake calipers

Gary:

This topic has come up before, and you should find some good info in the archives. I like the concept of the o-rings, but after reading all the pros and cons of each design, I decided to stay with the lip seals for my car....and also use DOT 5 fluid in the system to help improve longevity.

FWIW...............Larry

[Edward J.]

Re: Piston seals for 1st design brake calipers

Gary, The lip design seals provide better brake pedal feel. I read a article once on Zoras 4 piston caliper design.I don't remember everything about the article, and he touched on the O-ring design and really had nothing positive to say about them. I know that there are thousand of the o-ring type seal calipers out there and some may think theres likely nothing wrong with the braking on there o-ring seals.


I think that the lips seals where engineered for Corvette calipers and for many years have proved that they work well without problems.My two cent is get the calipers sleeved and use the lip seals.Using dot 5 may help with longivity for the fluid but not sure on the calipers seals, unless someone has done some testing that proves other wise. Dot 3 fluid has an ability to absorb mositure in the system and Dot 5 does not. Corvette systems are not a 100% sealed system. routine Dot 3 fluid service is needed every 2/3 years to flush out the mositure.

[Dick W.]

Re: Piston seals for 1st design brake calipers

I'm contemplating getting a set of the original 1st design calipers for my '66. In terms of the piston seals, what is considered state-of-the-art? Some vendors claim that O-ring seals are superior to the original GM-style lip seals. My first question is, are the O-ring seals really clearly superior to the alternative (lip? seals)?


Secondly, I was told by an e-bay seller who restores 1st design calipers that the the insulator pistons cannot use O-ring seals, i.e., only pistons without the insulators can use O-ring seals, and the insulator pistons have to use the original GM-style lip seals. Does anyone know if what I was told is universally correct? Or is that vendor basically saying that he can't match up O-ring seals with insulator pistons?


Thanks,


Gary

They. Manufacture a different piston for use with O rings. Original will not work

[Ronald L.]

Re: Piston seals for 1st design brake calipers

Gary, they were state of the art design, why would you think some half baked aftermarket probably less tested design is better, stick with what was original and use the silicone brake fluid. It was not available in '66 but by '80 it was and one of my cars got it installed in 85 and its never been changed, like brand new.

[Justin A.]

Re: Piston seals for 1st design brake calipers

Well that is not all the case, each has it pros and cons. The lip seal I agree has a better design while in use. The more pressure in the system the tighter the seal on the back of the lip. However the huge con with the lip seal is sitting which most of these cars do allot. The o-ring will not weaken over time and allow brake fluid to leak. I have driven lots of both and truthfully can't really tell the difference except that I will not see brake fluid on the inside of the wheel after sitting for extended periods. I am sure the aftermarket does not test as much as GM, because of money and resources, but being a aftermarket manufacture I can assure you we test parts to the best of the ability that we have. This also add cost as test labs are not cheap and this reflects into the price of a product which is sometimes why someones parts are more expensive than another companies. No the gentleman that talked about the 1st design setup is correct, I do not know anyone making a o-ring piston for a 1st design caliper. You can't just put the o-ring on a lip seal piston so I don't think the o-rings will be an option for you. Lip seals will be fine, just if the car is going to sit make sure you are pumping brakes as well as starting up often.
Justin

[Timothy B.]

Re: Piston seals for 1st design brake calipers

The OEM Chevron type seal is a very good seal for the calipers. What happens is when the cars sit the seals flat spot and start slightly leaking. Go out to the car and push the brake pedal once or twice a week, this may help.

I agree with DOT 5 silicone.

[Michael W.]

Re: Piston seals for 1st design brake calipers

as well as starting up often.

Disagree strongly here. Let it sit undisturbed.

[Gary B.]

Re: Piston seals for 1st design brake calipers

Thanks to everyone. Sounds like if want to have the original style guided pistons with the insulators I'll have to take the lip seals. I'm OK with that.

Gary

[Terry M.]

Re: Piston seals for 1st design brake calipers

Gary, they were state of the art design, why would you think some half baked aftermarket probably less tested design is better, stick with what was original and use the silicone brake fluid. It was not available in '66 but by '80 it was and one of my cars got it installed in 85 and its never been changed, like brand new.

Ron,

You used the key word. What was state of the art 50 years ago, is no longer.

I am convinced if our hero came out with these brakes today all those multi-lettered government agencies that the small government people love to hate would be all over Zora like stink on do do. The problem isn't the lip seals, but the poor dust boots that let moisture into the space between the aluminum piston and the cast iron bore. Let the corrosion begin.

But all of that is aside from the original question of this thread. If the OP wants to use first design pistons, he has no choice. In the process he should check for post-1963 TSBs regarding updates in dust seal installation.

[Gary B.]

Re: Piston seals for 1st design brake calipers

Ron,

... In the process he should check for post-1963 TSBs regarding updates in dust seal installation.

With regard to the dust seals, do you think Lonestar or CSSB is doing something that is not state-of-the-art?

Gary

[Terry M.]

Re: Piston seals for 1st design brake calipers

With regard to the dust seals, do you think Lonestar or CSSB is doing something that is not state-of-the-art?

Gary

Gary,
I don't know. My last experience with sleeved calipers was over twenty years ago, so it isn't relevant. I have learned not the assUme anything.

[Ray K.]

Re: Piston seals for 1st design brake calipers

Gary,

I had my original calipers sleeved about 10 years ago by Lone Star. I used the original pistons with insulators and GM style lip seals.

My experience with Dot 5 was not good . Tried twice to install Dot 5 silicone fluid and both times it had an adverse effect on the master cylinder seals and the caliper seals. The rubber would swell and resulted in no brake pedal!! Ask my wife!! I tested a new master cylinder rubber seal in a jar of Dot 5 --- same result -- the rubber would swell. After two complete rebuilds of the calipers and the master cylinder I decided that I was " convinced " and then did the third rebuild and installed Dot 3 fluid. No problems then and is still fine today. I start and drive the car every 30-60 days. I would have liked to have used Dot 5 - but it can create problems -
" FYI "
Ray

[Terry M.]

Re: Piston seals for 1st design brake calipers

Gary,

I had my original calipers sleeved about 10 years ago by Lone Star. I used the original pistons with insulators and GM style lip seals.

My experience with Dot 5 was not good . Tried twice to install Dot 5 silicone fluid and both times it had an adverse effect on the master cylinder seals and the caliper seals. The rubber would swell and resulted in no brake pedal!! Ask my wife!! I tested a new master cylinder rubber seal in a jar of Dot 5 --- same result -- the rubber would swell. After two complete rebuilds of the calipers and the master cylinder I decided that I was " convinced " and then did the third rebuild and installed Dot 3 fluid. No problems then and is still fine today. I start and drive the car every 30-60 days. I would have liked to have used Dot 5 - but it can create problems -
" FYI "
Ray

Ray,

What brand were the rebuild kits you were using, and what brand of DOT 5.

I rebuilt my master cylinder with GM rebuild kit (about 30 years ago) and used STP brand DOT 5, however the labeling on the brake fluid can makes me think DuPont made the brake fluid. No brake issues for me since, and just for S & G I flushed the DOT 5 about fifteen years ago using the same brand of DOT 5 (I have a lifetime supply that I purchased in the mid-1970s). A number of us on this board have reported converting to DOT 5 and yours is the first issue of swelling brake parts I have heard of.

Before I converted to DOT 5 I purchased and read several SAE (Society of Automotive Engineers) booklets on DOT 5 test results and conversion from DOT 3 & 4 issues. The latter report was based on testing by the US Army on vehicles stored in Panama, and was a very rigorous series of tests over a long period of time. Nowhere in that literature were there reports of brake system seals swelling using DOT 5. Something sounds very wrong with your situation.

[Gary B.]

Re: Piston seals for 1st design brake calipers

Gary,

I had my original calipers sleeved about 10 years ago by Lone Star. I used the original pistons with insulators and GM style lip seals.

My experience with Dot 5 was not good . Tried twice to install Dot 5 silicone fluid and both times it had an adverse effect on the master cylinder seals and the caliper seals. The rubber would swell and resulted in no brake pedal!! Ask my wife!! I tested a new master cylinder rubber seal in a jar of Dot 5 --- same result -- the rubber would swell. After two complete rebuilds of the calipers and the master cylinder I decided that I was " convinced " and then did the third rebuild and installed Dot 3 fluid. No problems then and is still fine today. I start and drive the car every 30-60 days. I would have liked to have used Dot 5 - but it can create problems -
" FYI "
Ray

Ray,

Thanks for the feedback. I had really hoped I would be able to use DOT 5. It does make me wonder what those who do use DOT 5 do in order to achieve that success. And I know there are some folks who love DOT 5 and swear by it. Different composition of the seals?

Gary