1966 427 425 Brake Caliper Markings

[Barry J.]

I am restoring a 1966 that has been parked in our garage since 1971. Anyone ever seen caliper markings still on the calipers. Car has 30,000 miles on it over a 4.5 year period.

Looking to restore the master cylinder (non power breaks) as well as the calipers. Any recommendations on re-sleeving, buy new, etc.

see attached photos of markings still noticeable on the calipers, not to bad for 44 years old.....

[Mark D.]

Re: 1966 427 425 Brake Caliper Markings

Barry,

Nice PIC. Do all four have similar markings? Outside or inside portions...or both?

Thanks,

Mark

[Barry J.]

Re: 1966 427 425 Brake Caliper Markings

I just pulled these out of a tub after taking it over to the restoration shop.


I have attached the inside view of the same caliper....and the other side.... I only have two off at this time...the other two are still on the car so I don't have access....

[Steven S.]

Re: 1966 427 425 Brake Caliper Markings

White Post or Apple Hydraulics are popular choices for m/c sleeving.

[Joe L.]

Re: 1966 427 425 Brake Caliper Markings

I just pulled these out of a tub after taking it over to the restoration shop.


I have attached the inside view of the same caliper....and the other side.... I only have two off at this time...the other two are still on the car so I don't have access....

Steve------


I have seen such inspection marks on other calipers. However, for the most part they are the exception and not the rule.

One other thing: these calipers don't appear to have been ever painted black. I have contended for a long time that some calipers were never originally painted black and these seem to support that. I can see no evidence, whatsoever, on these calipers that they were ever painted black. I believe that the original calipers on my 1969 were never painted black, either, although I do not recall any inspection marks such as those seen on these.

These calipers are the correct casting numbers for 1965-E67 and are the 1st design calipers. I would recommend having these stainless steel sleeved by a firm that can do it on 1st design calipers without machining out the piston guides and converting them to 2nd design. The work and the pistons will cost more but, in my opinion, it's the way to go.

[Barry J.]

Re: 1966 427 425 Brake Caliper Markings

Joe, can White Post or Apple Hydraulic repair 1st design calipers?

[Joe L.]

Re: 1966 427 425 Brake Caliper Markings

Joe, can White Post or Apple Hydraulic repair 1st design calipers?

Barry-----

As far as I know, both only do brass sleeving, primarily for master cylinders. A source like Stainless Steel Brake Corporation of Clarence, NY, Corvette Stainless Steel Brakes of Florida, Vette Brakes of Florida, Carters Corvette of Livermore, CA or Lonestar Caliper in Texas can stainless steel sleeve 1st design calipers.

[Michael G.]

Re: 1966 427 425 Brake Caliper Markings

Barry,

Might speak w/Ken @ Lone Star Caliper. They did my early '66 calipers and master cylinder. Had my calipers converted to the o-ring type piston. No issues.

[Steven S.]

Re: 1966 427 425 Brake Caliper Markings

Barry,

Might speak w/Ken @ Lone Star Caliper. They did my early '66 calipers and master cylinder. Had my calipers converted to the o-ring type piston. No issues.

Do they still use the piston insulators?

[Michael G.]

Re: 1966 427 425 Brake Caliper Markings

Do they still use the piston insulators?

Unsure. Ken would be best to answer that question.

[Joe L.]

Re: 1966 427 425 Brake Caliper Markings

Do they still use the piston insulators?

Steve-----


All 1st design pistons use piston insulators, originally as well as now.

If you are talking about o-ring pistons, I know of NONE that are 1st design. To use o-ring pistons in 1st design calipers the piston guides have to be machined out and the calipers effectively converted to 2nd design.

[Steven S.]

Re: 1966 427 425 Brake Caliper Markings

Steve-----


All 1st design pistons use piston insulators, originally as well as now.

If you are talking about o-ring pistons, I know of NONE that are 1st design. To use o-ring pistons in 1st design calipers the piston guides have to be machined out and the calipers effectively converted to 2nd design.

That was why I asked Michael if his did, I didn't think anyone was making the o-ring pistons for an unmodified 1st design.

Unsure. Ken would be best to answer that question.

Michael, the insulators would have been fairly obvious if you installed the calipers on the car. There is roughly a 1/4" thick "spacer" attached to the end of the piston which was supposed to keep the heat from transferring from the pad. Must not have been much of a success though considering they didn't use the design very long.

Steve

[Joe L.]

Re: 1966 427 425 Brake Caliper Markings

That was why I asked Michael if his did, I didn't think anyone was making the o-ring pistons for an unmodified 1st design.



Michael, the insulators would have been fairly obvious if you installed the calipers on the car. There is roughly a 1/4" thick "spacer" attached to the end of the piston which was supposed to keep the heat from transferring from the pad. Must not have been much of a success though considering they didn't use the design very long.

Steve

Steve------

The 1st design calipers and insulated pistons were quite effective. I expect the reason that they were discontinued in favor of the 2nd design was cost. The 1st design calipers are more complex to machine, the pistons are more complex in design and, undoubtedly, more costly and the insulators resulted in additional cost yet. I expect that Chevrolet came to the conclusion that the 2nd design was "almost as good" for street applications and less costly.

Actually, some 2nd design pistons did use insulators. These were the L67-75 J-56. These pistons were "unguided" but did use insulators. These insulators were more than twice as thick as the 1st design and, undoubtedly, were more effective in reducing heat transfer to the brake fluid.

[Steven S.]

Re: 1966 427 425 Brake Caliper Markings

Point taken. I do sometimes forget that cost is a more powerful factor in vehicle design/engineering than is performance and or functionality, this is likely one of those cases.

Steve

[Joe L.]

Re: 1966 427 425 Brake Caliper Markings

Point taken. I do sometimes forget that cost is a more powerful factor in vehicle design/engineering than is performance and or functionality, this is likely one of those cases.

Steve

Steve-----


I think that what may have happened here was that it was adjudged that the 1st design insulated pistons were more than was necessary for street applications (which is what the VAST majority of Corvettes were destined for) and not really enough for racing applications. So, for L1967-75, the non-insulated 2nd design pistons were used for the vast majority of Corvettes and improved insulated pistons were used with J-56 which was supposed to be primarily for off-road racing. The J-56 option cost almost $400 during the 1966-69 period and I'm sure that most of this cost resulted from the special brake pads and insulated pistons. Keep in mind that during this period of time, 400 bucks was a LOT of money. In fact, the L-71 engine option cost about that much then.

After 1975, J-56 (as part of special performance packages only for 1970-75) was dropped. I guess they figured there was no further need for a racing brake package for Corvettes at that time.