Had a guy ask me today about 68 & 69 442 optional dual piston and 4 piston calipers. I was totally lost because I didn't know there was a dual piston caliper optional on these cars never mind 4 piston. He wanted to know if I knew anything about a 4 piston caliper. He was positive they made dual piston calipers but was curious about 4 piston. Any of you guys verify or have info on this?

Thx

 

1967 and 1968 disc brakes were 4 piston there was no dual piston. There are 2 pistons on the inboard side of the caliper and two pistons on the outboard side of the caliper. The two sides are connected through a short metal brake line. This was a similar design to the corvette brakes that came out in 63. In 69 the caliper was changed to the single piston design I assume due to cost savings but I am not sure. I have a set of 4 piston brakes on one of my 67 GTO project cars. These systems were basically the same across A and F bodies and only used in 67 and 68. This design uses a two piece rotor design that was very hard to find until they started reproducing them a few years ago. My 68 Toronado uses a very similar design but while the A and F body cars use 11 inch rotors, the E body cars use a 12 inch rotor. The 67-68 two piece E body disc brake rotors are VERY difficult to find if you need to replace them. Here is a pic of my Toro disc brake setup. For the A body, imagine a slightly smaller rotor and no axle coming through the center.

 

Thx, I didn't think 4 piston would be an option. Never seen dual piston for that matter.

 

Interesting. Good stuff

 

Yes disc brakes were fairly rare in 67 and 68 so most don't realize they were 4 piston. Just about everyone who adds a disc brake upgrade to a 64-68 A body uses a 69-72 single piston set up as they are readily available as used "take offs" and new after market and will bolt right on.

 

Very nice! How well does your Toro stop?

 

The Toro stops great! The dust seals were torn on the original calipers and the pistons had some pitting so I put on a rebuilt set (still have the originals). I also made all new steel lines for the whole car (a few months after I finished the car I saw that inline tube came out with brake line kits for these cars) and rebuilt the original proportioning valve (small cylinder mounted on the passenger side of the master cylinder) using parts from a reproduction 67-70 A body valve. The castings are just slightly different between the A and E body valves as far as the way they mount. The rear hold off valve for these is on the outside of the driver side frame rail just behind the front wheel well and just needed cleaned up.

 

The '68 four piston calipers did not use the external brake line. It was machined internally.

 

Thanks, you are correct. I guess I have not looked at the ones on my GTO in a while.

 

Were the 4 piston used an A body cars?

 

1967 - 1968 Factory Disc Brakes were Four (4) piston caliper set ups ONLY.... There is No such anything else in 1967 - 1968. And in 1969 , they all became single piston calipers.

Full Size cars, and A Body cars both had a very small percentage of vehicles that had factory Disc Brake Set Ups..... Both very different.

And the Tornados were different yet again.

And incidentally -- I have N.O.S. +++ Asbestos +++ Brake Pads for All of these --- which are
+++ Critical +++ such that you don't RIP UP these Rotors to smithereens..... Because all of those Rotors are virtually "Unobtainium".......

Always best to simply call me --- Craig --- 516 - 485 - 1935.....

 

I wonder how many of the Corvette parts are the same. They were 4 piston for a few years later, at least.

 

ABSOLUTELY NOTHING about Corvette is the same.
Corvette used the same Calipers, Rotors, and Brake Pads from 1965 - 1982 --- and they are
Corvette Exclusively and ONLY.

 

Not sure if the Olds calipers, were designed like the Corvettes, but I had Vetts 30 40 years ago, and every one sooner or later, leaked, because of rust, and had to have stainless steal sleeves, in them, and that cost about $400- 500 then, not sure what it would cost now? Wondering if that is why Olds changed the design, so they would not have a warranty problem?

 

Pretty sure the rare Camaro 4-piston, 4-wheel disc brake option JL-8 used Corvette parts.

The "Corvette" 4-piston calipers were responsible for kick-starting the aftermarket performance-brake industry. They got their start shoving stainless-steel sleeves into failed/seized 4-piston calipers, and grew from there.

Far as I know, Corvette, Camaro, A-body used Delco 4-piston calipers.

I think the Toronado/Eldorado, and perhaps the B- and C-bodies had Kelsey-Hayes 4-piston calipers. Thus the difference between the Toro calipers having the fluid transfer tube while the others were just drilled internally.

At any rate, just about everything except 'Vette and maybe the Camaro option, dropped the rigid-mounted 4-piston calipers for the '69 model year. After that, it was single-piston, floating caliper.

 

^^^You can also include Firebird with Camaro and A body.

 

I recently upgraded my spindles and they required disc brake system from an 83 caprice. They're so much shittier than the 68-72 disc brakes I had on before...

 

The A-body four piston calipers use larger pistons than do the Corvette calipers.

 

What do you mean by "shittier"?
Low pedal? Poor stopping power? Grabbing/skidding? Noisy? Alignment problems?

 

The 4 piston calipers between Firebird and Camaro were different because the Pontiac had a thicker disc.

 

The brakes on the 77-90 B-body cars use exactly the same 10.75" rotors and D52 calipers with exactly the same pads and the same 2.9" piston as were used on the 69-72 A-body cars. Any difference in braking force has to come from some other problem.

 

Low stopping power. I was able to get a small screech and a harder stop with my old calipers. Now it just feels soft (but not in a "needs to be bled/adjusted" way.

 

There's a whole bunch of things that could cause that, and none of them are related to the basic design of the system.

Loose wheel bearings in front
Glazed or low-friction (poor quality) pads/shoes
incorrect master cylinder-to-wheel cylinder diameter ratio
Partially-seized calipers
Failing brake hoses
Failing master cylinder
Overly-tight park brake adjustment
Failed brake booster (I had this problem on TWO early-'90s Luminas) In both cases, the booster "tested" good via the usual methods--there was just very little assist.)

No doubt there are other factors that would cause similar symptoms.

 

There's a whole bunch of things that could cause that, and none of them are related to the basic design of the system.

Loose wheel bearings in front
Glazed or low-friction (poor quality) pads/shoes
incorrect master cylinder-to-wheel cylinder diameter ratio
Partially-seized calipers
Failing brake hoses
Failing master cylinder
Overly-tight park brake adjustment
Failed brake booster (I had this problem on TWO early-'90s Luminas) In both cases, the booster "tested" good via the usual methods--there was just very little assist.)

No doubt there are other factors that would cause similar symptoms.[/QUOTE]

Yep. Assuming everything else was new (due to the spindle swap), then my first reaction was different pad composition as one more variable in the system.

 

^^^ I had to edit my previous post to add a bracket " [ " in front of Coastie's second quote. That'll fix the formatting on your post, too.

 

I have a 68 sport coupe that came with the 4 piston calipers and the host of options including the T3 rear. I am using DOT4 synthetic brake fluid which does not absorb water like the alcohol based fluid does. This will help to keep the brake pistons and sleeves from pitting which is the major cause of the corvette issues. Some guys think that the silicone brake fluid is the answer but it does not remove the moisture from the system, the two mix together and you cannot have a working hydraulic system with water in it as water does not compress. You may have a stiff pedal but you won't have any braking power. The synthetic fluid repels the water and keeps it out of the system.
That plus stainless lines that don't rust helps. I was asked by a customer once " where does the moisture come from", the simple answer is heat from braking. You heat up the fluid and it cools, you now have condensation in your system. Bad for any ferrous parts. I have had the synthetic fluid and stainless lines on for ten years now and the fluid is still clear, not red like old alcohol based fluid. It is something to look into if you want to avoid a rusty brake system and brake fail.