72 Corvette LT-1 brake calipers and MC

[Dave K.]

I realize that this subject has been tossed around but I want to replace the calipers and master cylinder on this car with stainless calipers and a MC compatible with DOT 5 fluid. Can anyone advise who produces these parts with stainless steel sleeves and EPDM o-rings and seals?

Regards,

Dave K.

[Bill B.]

Re: 72 Corvette LT-1 brake calipers and MC

Hi Dave,

Years ago, (i.e.10 or so) I sent my original calipers to Vette Brakes and Products with explicit instructions to SS Sleeve my cores. (they have sleeved calipers off the shelf, and turn in yours as a core for someone else).

I think they did a fine job (no leaks 10 yrs later) but I do use DOT 4 fluid, not silicon, as I have SS brake lines.

Because I converted to P/B a couple yrs ago, the M/C came as a kit with the booster assy. Believe it was from Lone Star Caliper and believe it was SS sleeved as well.

Right after I got my calipers returned and installed, I did notice a big difference in pedal effort (much less required) to stop the car. Believe the seals and SS sleeve reduced piston friction by a noticeable amount!

[Gary B.]

Re: 72 Corvette LT-1 brake calipers and MC

[Larry M.]

Re: 72 Corvette LT-1 brake calipers and MC

There is a company out there that will, but they sell to the general public and are not Corvette specific. As such, finished appearance etc will not be correct for a judged car.

Company is Cardone. They advertise EPDM seals. I know in the past their tech department stated rebuilds were good for all DOT approved fluids. I have not done business with this company............although they are an industry leader. They appear to also offer custom rebuilding. But not certain about SS sleeving. You can call an inquire.

Raybestos states that they sell EPDM parts for brakes. Perhaps a company like Apple Hydraulics or White Post may offer a rebuild and sleeving.......and use Raybestos parts. Another avenue to check. Or get sleeved calipers and rebuild yourself with Raybestos parts.



Larry

[Patrick H.]

Re: 72 Corvette LT-1 brake calipers and MC

Raybestos parts are available on Amazon.
Generally calipers are not difficult to rebuild and detail if they've already been sleeved.

[Gary B.]

Re: 72 Corvette LT-1 brake calipers and MC

Larry,

On their website White Post says:

We fully guarantee all parts that are sleeved and/or rebuilt by us, with the exception of those used in conjunction with silicone fluid (DOT 5).

I believe Apple Hydraulics tells customers the same thing if you ask them.

Gary

[Patrick H.]

Re: 72 Corvette LT-1 brake calipers and MC

Larry,

On their website White Post says:

We fully guarantee all parts that are sleeved and/or rebuilt by us, with the exception of those used in conjunction with silicone fluid (DOT 5).

I believe Apple Hydraulics tells customers the same thing if you ask them.

Gary

I think that most rebuilders are saying this as a CYA ploy. It's easier for them to not warranty DOT5 than do anything else.
I ran DOT5 in a customer's car at his request using one of the "non-DOT5" reproduction master cylinders and had no issues.

If someone is bored you can look through old threads here regarding DOT5.
I put some Raybestos seals in DOT5 for a few months and noted no detectable difference from new seals.

[Joe L.]

Re: 72 Corvette LT-1 brake calipers and MC

I think that most rebuilders are saying this as a CYA ploy. It's easier for them to not warranty DOT5 than do anything else.
I ran DOT5 in a customer's car at his request using one of the "non-DOT5" reproduction master cylinders and had no issues.

If someone is bored you can look through old threads here regarding DOT5.
I put some Raybestos seals in DOT5 for a few months and noted no detectable difference from new seals.

Patrick------


My suspicion has been for a long time that commercial rebuilders use inexpensive seals that they purchase in bulk and these seals are the root of the DOT 5 compatibility problems. These seals perform satisfactorily when used with DOT 3 or 4 fluid but not when used with DOT 5.

As I've said previously, I do not understand how a fluid could be DOT-rated but incompatible with normal brake system elastomer components. If DOT-5 fluid was incompatible with even some normal brake system elastomeric materials, then that fluid would be absolutely unsafe for use and, consequently, would not be DOT approved.

Put another way, if DOT 5 fluid was incompatible with Corvette brake systems, then what brake systems would it be compatible with?

[Gary B.]

On Feb 13, 2013, at 8:07 AM, Apple Hydraulics wrote:

Jerry,

We strongly recommend against using silicone brake fluid (DOT5)

Problem is with seals in rebuilding kits. People who make these seals use rubber compound that is tested with originally approved fluids and that means that with DOT5 you may end up with swollen softened seal. It is especially problem with kits coming out of UK (less with American kits for American cylinders). You can google something like "girling brake silicone fluid" and see that, to say the least, it is controversial subject.

Moss Motors sells silicone brake fluid, Moss part # 220-410. We had no complaints about it (yet), but had lots of customers with bad experience with "store brand" DOT5, esp. Napa fluid.

Lazar
Apple Hydraulics

http://applehydraulics.com

1610 Middle Road, Calverton NY 11933
800-882-7753, 631-369-9515 (voice 8:30-4:00 Eastern, M-F)
631-369-9516 (fax 24x7)

[Joe L.]

Re: 72 Corvette LT-1 brake calipers and MC

I found this on a Triumph car forum. I thought it was interesting to hear the perspective of a caliper/master cylinder resleeving company. I’ve previously read that some manufacturers make less problematic DOT 5 than others. But as Joe states, the problem could be the composition of the seals. Or a proem with both the seals and the fluid. Lot of mystery and voodoo in this topic.

On Feb 13, 2013, at 8:07 AM, Apple Hydraulics wrote:

Jerry,

We strongly recommend against using silicone brake fluid (DOT5)

Problem is with seals in rebuilding kits. People who make these seals use rubber compound that is tested with originally approved fluids and that means that with DOT5 you may end up with swollen softened seal. It is especially problem with kits coming out of UK (less with American kits for American cylinders). You can google something like "girling brake silicone fluid" and see that, to say the least, it is controversial subject.

Moss Motors sells silicone brake fluid, Moss part # 220-410. We had no complaints about it (yet), but had lots of customers with bad experience with "store brand" DOT5, esp. Napa fluid.

Lazar
Apple Hydraulics

http://applehydraulics.com

1610 Middle Road, Calverton NY 11933
800-882-7753, 631-369-9515 (voice 8:30-4:00 Eastern, M-F)
631-369-9516 (fax 24x7)

Gary------

What we need to find are vehicles that are specifically approved for DOT 5 fluid. Then, we need to find out how the brake system elastomeric components (seals, etc.) differ, if at all, in composition to the Corvette seals.

If there are no vehicles approved for the use of DOT 5 then why is it sold, at all, and why does it have a DOT rating? As I've said previously, if fluid is labeled as DOT 5 then it has to meet the set of standards applicable to that rating. It would not matter what brand it is, it would have to meet the standards for DOT 5. Obviously, the DOT 5 standards must include, in one form or another, specifications on what type of rubber compounds that it is compatible with.

[Ed D.]

Re: 72 Corvette LT-1 brake calipers and MC

All Post Office and most Fed Gov vehicles use DOT 5, and use Jasper DOT 5 fluid. I did my front brakes with Bair rebuild calipers and Jasper fluid 1 year ago, no leaks yet. My rear calipers were rebuilt 35 years ago, still dry.
Ed

[Terry M.]

Re: 72 Corvette LT-1 brake calipers and MC

Around 25 years ago I got several papers from SAE (Society of Automotive Engineers) regarding DOT 5 tests. The tests that were reported in these publications revolved around seal material compatibility and moisture pooling in brake systems using DOT5. One of the papers also dealt with conversion from DOT 3/4 fluid to DOT 5 without thoroughly cleaning the brake system. The short story was that the seal material used at that time was compatible with the commercially available DOT 5 fluid. Tests in tropical environment yielded no moisture pooling in the military vehicles used. Additionally using DOT 5 to push out DOT 3/4 resulted in a dark sludge accumulating in the brake system over extended time, but no reduction in brake efficiency was noted.

I wouldn't be surprised that these publications are still available from SAE.

At that time Harley Davidson and US Military vehicles were the main production users of DOT 5 fluid.
That was then & this is now.

[Mark F.]

https://www.govinfo.gov/content/pkg/CFR-2012-title49-vol6/xml/CFR-2012-title49-vol6-sec571-116.xml

In the context of these regs, Brake fluid means a liquid designed for use in a motor vehicle hydraulic brake system in which it will contact elastomeric components made of styrene and butadiene rubber (SBR), ethylene and propylene rubber (EPR), polychloroprene (CR) brake hose inner tube stock or natural rubber (NR).

S5.1.12 Effects on cups.

[Patrick B.]

[Larry M.]

Re: 72 Corvette LT-1 brake calipers and MC

Pat:

Good information. Military testing with various brake fluids and elastomers indicates that for all DOT 5 fluid tested, EPDM is fine. However if SBR rubber is used, some DOT 5 fluids can create issues. That is why I feel it is important to purchase a DOT 5 fluid that also meets military specs. These fluids apparently are a better quality with less impurities, etc.

DOT 3/4 fluids seems to be fine with both EPDM and with SBR.

Agree, that with our car parts often being made overseas, it is anyones guess what rubber compounds are being specified........and even if the correct rubber is specified, what is actually supplied.

But for DOT 5 and brakes: buy EPDM rubber brake components from a reputable company and buy DOT 5 fluid from an established company that meets military specifications as well as SAE/DOT specs. This can be done, but it is time consuming and frustrating for many of us. The default is to use DOT 3/4 and flush system every 3-5 years.

Larry