I need to learn all about Corvette brakes

[Greg H.]

From what I have heard, I knew this day would be coming soon. I have to learn about the Corvette braking system and how to restore it. My 70 has 37k miles and there has been limited repairs done to the brake system on an as needed basis. From what I know of the history, one of the discs has been removed and I think two of the calipers had repairs. Anything I do I want to maintain originality and meet judging standards. Here's a picture of my current issue. Please advise me on the typical mistakes that lose points. Do I need to send out the calipers or can I rebuild them on my workbench?
Thanks,
Greg

[Doug F.]

Re: I need to learn all about Corvette brakes

if your calipers have allready been sleeved you could rebuild yourself, however i've learned that if you need to buy pistons as well as the the o rings you're about as well off to just buy the finished product, lone star in texas has been helpful to me always, easy to install, but unless you have a power bleeder you may have trouble getting a good pedal, you may want to hire it out, one reason why i like my drum brake cars better, good luck

[William C.]

Re: I need to learn all about Corvette brakes

Some of the brake outfits that resleeve will (for a small extra fee) repair and return your original calipers. After that, it's a matter of making machined surfaces that might have been painted in the rebuilders hands are bare as original and reinstalling/bleeding the brakes. The real key is finding a "partner" who will take the extra time to make sure you get your parts back, as the calipers are dated.

[Jim T.]

Re: I need to learn all about Corvette brakes

In the current NCRS Driveline Corvette Stainlesss Steel Brakes INC. has an add on page 16 for a complete brake package, master cylinder, 4 calipers. brake pads, brake lines, brake hoses and retainer clips using the O-Ring Pistons. The price of $435 exchange with rebuildable cores.
Something like this 20 years ago would of cost a lot more. I know from experience of maintaining the braking systems on my 68 and 70 original owner Corvettes. I never encountered any brake bleeding problems on my 68 or 70 even when I switched to silicone. My 70 with power brakes still amazes me with its stopping performance.
If you go with a brake kit package like above recommend replacing the master cylinder first after bench bleeding the master cylinder. Then bleed the compete system from each of your four calipers getting all new fluid in the system and replace one caliper at a time and bleed it before installing another caliper.

[Patrick H.]

Re: I need to learn all about Corvette brakes

Greg,

Do you want to do a lot of work, or not much work?

If you note, your caliper there is painted silver. As originals were painted black, you already know it's a replacement and not original to your car. As such there is no benefit to saving that one caliper. However, it is likely a stainless sleeved unit and if you wish, it could be "rebuilt" at home.

At this point you could

- contact one of the major rebuilders (Vette Brakes, Lonestar, etc) and swap your used caliper for one already painted black. You then bolt it on, bleed the brakes and go

-buy a kit with the seals, take the caliper apart, and replace the seals. There is a 90%+ chance that the seal is leaking and there is not much else wrong with the caliper since it was previously sleeved. The original seal design is prone to leak (as you can see) if a car is not driven much.

- buy a caliper seal kit that has O-rings instead of the conventional seals with a lip. You are then less likely to have it leak in the future and will avoid any "air pumping" issues with that caliper.

- R&R all the calipers

Given your low mileage, I would not replace hard lines unless they are leaking or you strip one when you work on the car. I also would not replace your master cylinder if it is original. It likely needs nothing; your problem is with the caliper and its seal. Whether or not you replace the soft line from the frame to the caliper is up to you. I'd consider installing new bleeder screws when you do all of this.

If you take the caliper off and decide to reseal it yourself, I'd consider cleaning it thoroughly and painting it black so it at least appears correct.

Patrick

[Michael W.]

Re: I need to learn all about Corvette brakes

F Anything I do I want to maintain originality and meet judging standards.

As Patrick has said, this caliper does not have the original finish on it so you can do what you want.

Irrespective of what type of judging you're thinking of, please resist the temptation to replace or resurface the rotors 'just cause'. More than likely you'll induce more problems than you'll solve.

[Alan S.]

Re: I need to learn all about Corvette brakes

Hi All,
About how much brake fluid does it take to fill a completely dry system, and to bleed the system?
Regards,
Alan

[Doug F.]

Re: I need to learn all about Corvette brakes

I just changed mine over to silicone. Part of the change over was installing a new master cylinder. I removed and drained all four brake calipers and did not "re-use" any of the fluid pumped through the system during bleeding. You will need just over a quart.

[Alan S.]

Re: I need to learn all about Corvette brakes

Thanks very much Doug!
Regards,
Alan

[Greg H.]

Re: I need to learn all about Corvette brakes

Guys,
Thanks for all the advice. It appears both sides have been switched out. I'm going by the maintenance records I have for the car, one repaired in '75, the other in '94 and the date codes look like 312 and 437. So I don't have to worry about keeping these exact calipers and won't be searching for date coded replacements. I can't be sure both of them are already SS lining (or can I?)

I think I'll go with buying rebuilt and do both fronts so I know they are good.
Greg

[Patrick H.]

Re: I need to learn all about Corvette brakes

Guys,
Thanks for all the advice. It appears both sides have been switched out. I'm going by the maintenance records I have for the car, one repaired in '75, the other in '94 and the date codes look like 312 and 437. So I don't have to worry about keeping these exact calipers and won't be searching for date coded replacements. I can't be sure both of them are already SS lining (or can I?)

I think I'll go with buying rebuilt and do both fronts so I know they are good.
Greg

If they're silver, they were sleeved. Many rebuilders paint their cores silver as a quick wasy to tell they've been sleeved.

A 72 I'm working on has GM calipers from the 80s (?) on it, and they're black.

If it was me, I'd pull both front ones and exchange them with Vette Brakes for 2 black calipers already done with O-rings. End of problem.

Patrick

[Tom D.]

Re: I need to learn all about Corvette brakes

Fellow members:

Are the clips to hold the pistons back sold by the Corvette vendors? Anything similar to tool number J-21938 (shown at the end of the disk brake section - 1966 Service Manual.)

More general question: I know just a little about the company that supplied a lot of these tools to GM. I wonder if anyone is "dedicated" to reproduction of such tools?

Thanks in advance and Happy Holidays.
td

[Gerard F.]

Re: I need to learn all about Corvette brakes

Greg,

I replaced all 4 of my original calipers on my 67 about 8 years ago, with one of the rebuilt SS core kits, hoses and all. Glad I did, no problems since, and if you paint them black they will probably judge well.

Couldn't bear to send in the original cores, and also pay the heavy shipping charges, so my originals sit in a box in the garage for future restoration (or a future restorer ).

The biggest problem I had was trying to get the original caliper bolts off, working in my miniscule garage on jackstands. Tried Liquid Wrench, PB Blaster, finally resorted to a propane torch on the bolts to heat, cool, heat again. Was afraid I was going to burn the garage down.

If you are going to do it yourself in your garage, get the car as high as possible on the jack stands so you can get some leverage under. Use a 6 point socket (I think a 5/8" spark plug socket works best), with a 1/2" breaker bar and pipe extension. Use the propane torch as a last resort.

While you are in there, you should probably change all the rubber hoses, and steel tubes to the rears, and the brake line clips. Might as well do all 4, so that you are not back on it on the ones you haven't replaced, in the future. It's kind of a nasty job, and a PITA bleeding them. Once is enough.

Have fun,

[Bill I.]

Re: I need to learn all about Corvette brakes

And a word of caution. DON'T get any fluid on the paint. Bill.

[Greg H.]

Re: I need to learn all about Corvette brakes

Lots of great info. given here. I've received the two front calipers rebuilt by Vette Brakes. Every thing looks good and the bolts to remove the old ones were no issue at all. I am having trouble with the steel line connection to the flexible hose. My craftsman wrench is not very tight fitting at all. I'm wondering if it's the wrench. I've been through this before with many Mustangs but I really want to avoid changing the steel lines. Any good tricks to loosening these? I've already tried heat but nearly lit the car on fire and I don't want to take chances on that!
Thanks,
Greg