One last Brake Caliper Question

[Mark P.]

Dana, Joe and others

I pulled the caliper apart and have included a picture. I would say that the caliper has definitely been sleeved. When I placed a magnet against the piston there is no magnetic attraction. When I place the magnet against the sleeve there is some attraction but no where near the attraction of the casting. In years past I have seen stainless steel with some magnetic attraction, so I believe as one on the previous owners has stated that these brakes are stainless. Do you agree?

This does not appear to be a complex rebuild. That said can you recommend a supplier that can provide a seal kit? Any hints or things that I need to be aware of when rebuilding these calipers?

Thanks--Mark

[Joe L.]

Re: One last Brake Caliper Question

Dana, Joe and others

I pulled the caliper apart and have included a picture. I would say that the caliper has definitely been sleeved. When I placed a magnet against the piston there is no magnetic attraction. When I place the magnet against the sleeve there is some attraction but no where near the attraction of the casting. In years past I have seen stainless steel with some magnetic attraction, so I believe as one on the previous owners has stated that these brakes are stainless. Do you agree?

This does not appear to be a complex rebuild. That said can you recommend a supplier that can provide a seal kit? Any hints or things that I need to be aware of when rebuilding these calipers?

Thanks--Mark

Mark------

This caliper has definitely been converted from the 1st design with guided pistons to the 2nd design. You can easily see where the piston guides have been machined out. Also, they appear to be stainless steel sleeved from what I can see of them. The stainless used for these sleeves usually has very weak magnetic attraction although some of the "cheapies" use decorative stainless which has more magnetic attraction. You will also get some magnetic attraction due to the proximity of the sleeves to the native cast iron material.

The pistons you have are definitely not GM pistons. If they are stainless pistons they may be ok for re-use. If they are aluminum, I doubt that they will be ok for re-use. The stainless pistons were a very expensive item and I don't know if they are available anymore, or not. They were NEVER available from GM, though.

There may be a small stamping somewhere on the calipers that indicates the name of the firm that installed the sleeves. If there, it's usually very small and just a logo, not a full name.

You can get rebuild kits from just about any of the Corvette parts sources. If you need to replace pistons, they have those, too.

[Timothy B.]

Re: One last Brake Caliper Question

Joe,

Can you explain where to look for the evidence of grooved pistons like first design.

[Joe L.]

Re: One last Brake Caliper Question

Joe,

Can you explain where to look for the evidence of grooved pistons like first design.

Timothy-----



You will note that at the rear of the caliper bore pictured there are two "semi-circles". This is what remains of the piston guides that once protruded into the caliper bores and into which the guide pins that were part of 1st design pistons inserted.

When 1st design calipers are converted to 2nd design, the piston guides are machined out and this usually leaves only the very short "stubs" seen in the photo.

Stainless steel sleeving caliper rebuilders often machine out the piston guides and convert them to 2nd design configuration. In fact, I expect that the vast majority of originally 1st design calipers are now 2nd design.

[Timothy B.]

Re: One last Brake Caliper Question

Thanks Joe,

I see what you are talking about. I have a hard time picturing guide pins, I assume this is part of the first design piston..

If someone has a picture of first design piston and bore I would like to see.

[Joe L.]

Re: One last Brake Caliper Question

Thanks Joe,

I see what you are talking about. I have a hard time picturing guide pins, I assume this is part of the first design piston..

If someone has a picture of first design piston and bore I would like to see.

Timothy------



Yes, the guide pins were part of 1st design pistons. Here are photos of a 1st design front caliper half showing the piston guides that remain in their original configuration. These calipers have been stainless steel sleeved. In the following post I'll show photos of 1st design pistons.

[Joe L.]

Re: One last Brake Caliper Question

Thanks Joe,

I see what you are talking about. I have a hard time picturing guide pins, I assume this is part of the first design piston..

If someone has a picture of first design piston and bore I would like to see.

Timothy------


...and here are NOS examples of the front and rear 1st design pistons:

[Timothy B.]

Re: One last Brake Caliper Question

Joe,

Thanks for the great pictures, now I understand. What are the black things screwed to the top of the pistons, I read about them before but can't remember.

I want to locate a set of first design calipers for my 67. It was built September 66 but the brakes were changed out before I purchased the car. Now I know what to look for in my hunt.

[Jim T.]

Re: One last Brake Caliper Question

Dana, Joe and others

I pulled the caliper apart and have included a picture. I would say that the caliper has definitely been sleeved. When I placed a magnet against the piston there is no magnetic attraction. When I place the magnet against the sleeve there is some attraction but no where near the attraction of the casting. In years past I have seen stainless steel with some magnetic attraction, so I believe as one on the previous owners has stated that these brakes are stainless. Do you agree?

This does not appear to be a complex rebuild. That said can you recommend a supplier that can provide a seal kit? Any hints or things that I need to be aware of when rebuilding these calipers?

Thanks--Mark

Mark I recently rebuilt my 68's front calipers and bought my parts locally at O'Reilly Auto Parts. Caliper kit #CK46454 list price $28.80/net price $16.99. I selected the caliper repair kit from O'Reilly's because it was made in America. The caliper kit from Auto Zone was made in China. This is the first service repair on my stainless steel sleeved calipers installed in 1983.

[Mike M.]

Re: One last Brake Caliper Question

Info & Pics.....Priceless.
Great pics, Joe.
HaND

[Joe L.]

Re: One last Brake Caliper Question

Joe,

Thanks for the great pictures, now I understand. What are the black things screwed to the top of the pistons, I read about them before but can't remember.

I want to locate a set of first design calipers for my 67. It was built September 66 but the brakes were changed out before I purchased the car. Now I know what to look for in my hunt.

Timothy------

The "black things" are the piston insulators. These are made of "Pyroceram" material and are found on ALL 1st design pistons.

2nd design pistons have no guide pins and no insulators except for 2nd design J-56 pistons which do have insulators. Those pistons have insulators that are much thicker than the 1st design pistons.

[Kenneth T.]

Re: One last Brake Caliper Question

Timothy------

The "black things" are the piston insulators. These are made of "Pyroceram" material and are found on ALL 1st design pistons.

2nd design pistons have no guide pins and no insulators except for 2nd design J-56 pistons which do have insulators. Those pistons have insulators that are much thicker than the 1st design pistons.

Joe,

Those pictures take me back a way. I have not seen caliper pistons with the "hockey pucks" on them in many, many years. I remember having to be careful not to break off the screw in the pistion....

[Ryan V.]

Re: One last Brake Caliper Question

This was a very interesting explanation of the difference between the 1st design and 2nd design calipers. Thanks for sharing.

Can anyone explain why GM switched the design? For those of us restoring original 1st design calipers, is there safety or performance reason for us to have them switched to 2nd design during rebuild?

- Ryan

[Patrick N.]

Re: One last Brake Caliper Question

Timothy------


...and here are NOS examples of the front and rear 1st design pistons:

Joe,
Is there a bit of dichromate on the pistons?

[John H.]

Re: One last Brake Caliper Question

Is there a bit of dichromate on the pistons?

Patrick -

The aluminum caliper pistons are anodized.