I have a pair of Standard Duty Dual Piston brake calipers off of my 91 Vette and wanted to know if anyone has bolted these onto an 88 Fiero GT's 9" rotors?

The Corvette caliper brackets look like they will bolt right onto the stock 88 front spindles if I could buy or fabricate an adapter.

I was thinking that the Corvette dual piston calipers mounted to the 88 Fiero GT's standard 9" Rotor, would be a good upgrade without having to buy new rotors, concentric hub rings and adapter plates. Thanks

[This message has been edited by GKK1 (edited 10-26-2009).]

I think that you already have enough pad area on the 88 and you wouldn't gain anything from that sort of swap.
It was the 87 and before that were a bit more marginal, no?

My son installed 17" wheels and although the brakes stop very well, they won't lock up, (I changed all pads, flushed the brake fluid and bled the system). I was thinking that the dual piston Corvette calipers should be able to lock up the larger wheels.

quote Originally posted by GKK1: I was thinking that the dual piston Corvette calipers should be able to lock up the larger wheels.

I would be very careful about making arbitrary changes to the braking system of your car. It could be very dangerous and fatal. The dual pistons working with your existing master cylinder could result in half the braking power.

It would be far better to make a change that you already know works, like larger rotors using your existing calipers.

The C4 Corvette dual piston Calipers are the same ones used in all the Fiero brake upgrade kits sold by Fiero Addiction and West Coast Fiero so, I would think this would work OK since both upgrade kits don't require a Master Cylinder upgrade.

[This message has been edited by GKK1 (edited 10-26-2009).]

Oh okay...but most people just use the 88 calipers since they will also work. But if you have the Corvette calipers laying around and you are convinced it's safe then go for it.

quote Originally posted by jscott1: The dual pistons working with your existing master cylinder could result in half the braking power.

Why do you think this would happen?

quote Originally posted by Will: Why do you think this would happen?

Just a guess...but if the fluid has twice as many places to go with the same stroke on the master, it's possible that the total braking force could be less even though the theoretical clamping force is increased.

well they could do a master cyl. upgrade as well like the S-10<?

quote Originally posted by revin: well they could do a master cyl. upgrade as well like the S-10<?

In my simple mind you should upgrade the master as well. Otherwise the stroke on the calipers is going to be half what it was. By the time you factor in the slop in the system between the pads and the rotor, you might not get double the clamping force as expected. That's just my opinion, I haven't tried it though.

the fiero MC is pretty large, so I would try it using the original MC, considering wilwood and the rest of the aftermarket suppliers don't have much to choose from above 1" (while the piston areas of the majority of their calipers exceed that of the fiero calipers).

jscott1: while the fluid has twice as many places to go, does it need to fill twice the volume? I don't know the piston diameters for the vette calipers, so I really don't know. Don't know the MC piston diameter for the vette MC either... Does anyone have any details on vette brake systems? It seems we all accept the need to go with a vette MC when upgrading to vette calipers but we don't have the info to back that decision up.

I don't know what you expect to gain with Corvette calipers. If you do it, at least use the same two-pot ones all around...

Unless you're anorexic, you shouldn't be unable to lock up the wheels with stock brakes.

quote Originally posted by jscott1: In my simple mind you should upgrade the master as well. Otherwise the stroke on the calipers is going to be half what it was. By the time you factor in the slop in the system between the pads and the rotor, you might not get double the clamping force as expected. That's just my opinion, I haven't tried it though.

You will only experience less clamping force than predicted by comparison of the total piston areas if you're bottoming out the master cylinder.

quote Originally posted by pmbrunelle: Unless you're anorexic, you shouldn't be unable to lock up the wheels with stock brakes. You will only experience less clamping force than predicted by comparison of the total piston areas if you're bottoming out the master cylinder.

I guess you should also add stock brakes and stock tires. There is no way in the world for me to lock up my 19s or 20s with the stock brakes.

I don't know the total piston areas. The bores on the dual Corvette calipers are probably smaller than the single bore Fieros. But my brakes is one area that I would not want to be guessing. The whole point of my original post was to do something that is known to work and known to be better and be careful experimenting... That's all.

Basically, all I want to do is replace the 88 GT's Front stock single piston calipers with the C4 Corvettes Dual piston calipers that I removed from my 91 Vette.

My son's 88GT hasn't locked the brakes up since he installed the 17" wheels but, it does stop very well.

quote Originally posted by jscott1: I guess you should also add stock brakes and stock tires. There is no way in the world for me to lock up my 19s or 20s with the stock brakes. I don't know the total piston areas. The bores on the dual Corvette calipers are probably smaller than the single bore Fieros. But my brakes is one area that I would not want to be guessing. The whole point of my original post was to do something that is known to work and known to be better and be careful experimenting... That's all.

I did a search on it over at the corvetteforum and it seems the caliper piston diameter is about 45mm for the C5 rear and 40mm for the C5 front. haven't found anything on the MC...

I see your point, but then someone has to be the first to try a new upgrade, so I'm still wishing him good luck. I'm sure he will make sure to test it where it's safe as opposed to just heading straight for the rush hour traffic

I shouldn't have generalized - the 19/20" wheels are a case where the stockers wouldn't be adequate.

According to Rockauto:
C4 Vette: twin 1.5" pistons, 3.53"^2
88 Fiero: 1.889" piston, 2.80"^2

There's no luck involved with brake upgrades. The results of a brake upgrade can be predicted pretty easily...
If you don't know what's going to happen, you're just not qualified to be guessing.

It's not because a part has the "Corvette" name on it that it's going to perform well on your car. Corvette calipers on the front only are going to suck the first time you have to emergency brake...

The Corvette rotors with stock calipers are a good choice. Are Corvette rotors really that much more expensive than 88 Fiero rotors? The only difference is the adapters, which are not a consumable.

If you just want less effort, and the same fade resistance, I believe there is a brake booster available which can provide more assist.

quote Originally posted by GKK1: My son installed 17" wheels and although the brakes stop very well, they won't lock up, (I changed all pads, flushed the brake fluid and bled the system). I was thinking that the dual piston Corvette calipers should be able to lock up the larger wheels.

Most people often over look the master cylinder and brake booster when there are problems with the brakes. You have to remember that these parts are now 21 years old if they are the original parts in the car and rubber seals do not last forever.

I had the same problem with not being able to lock up my brakes on my 88 and it turned out to be a problem with the booster. However if you want to install the Corvette calipers on the car, knock yourself out - just remember if they work, you are not solving the problem, just masking it.

quote Originally posted by Mickey_Moose: just remember if they work, you are not solving the problem, just masking it.

There is No Problem with the Brake system.

The Stock brakes will lock up the Stock 15" wheels just fine but, my son just installed 17" wheels and the stock brakes no longer lock up.

[This message has been edited by GKK1 (edited 10-28-2009).]

quote Originally posted by pmbrunelle: It's not because a part has the "Corvette" name on it that it's going to perform well on your car. Corvette calipers on the front only are going to suck the first time you have to emergency brake...

would you mind elaborating this a bit? I would think if he disabled the prop-valve he would get a pretty good balance (with the C4 calipers up front) for an emergency stop. as long as the road is dry that is. but as I said, please elaborate and tell us how one would remedy the problem.

quote Originally posted by PerKr: would you mind elaborating this a bit? I would think if he disabled the prop-valve he would get a pretty good balance (with the C4 calipers up front) for an emergency stop. as long as the road is dry that is. but as I said, please elaborate and tell us how one would remedy the problem.

As long as the road is dry, and the prop valve was removed, sure. But emergency stops never happen in the wet?

A prop valve is a necessity on a street-driven car. Similarly sized calipers all around, with a prop valve, would provide good braking in a variety of conditions.

It's not because you have a set of Corvette calipers laying around that you should find a use for them.

quote Originally posted by pmbrunelle: As long as the road is dry, and the prop valve was removed, sure. But emergency stops never happen in the wet?

depends on how you use the car.

would replacing the original prop-valve with an aftermarket prop-valve (wilwood or similar) help or would those have to be adjusted as soon as the weather changed (let's say you adjusted it to work fine in the wet, would you have to adjust it again when the weather improved)?

quote Originally posted by PerKr: would replacing the original prop-valve with an aftermarket prop-valve (wilwood or similar) help or would those have to be adjusted as soon as the weather changed (let's say you adjusted it to work fine in the wet, would you have to adjust it again when the weather improved)?

The aftermarket valve works on the same principle as the stock one.

They are both rough approximations to get the optimal bias in any situation.

You wouldn't need to adjust it any more than a stock valve. Set it, and forget it.

quote Originally posted by jscott1: Just a guess...but if the fluid has twice as many places to go with the same stroke on the master, it's possible that the total braking force could be less even though the theoretical clamping force is increased.

You could try figuring it out instead of guessing randomly.

quote Originally posted by Will: You could try figuring it out instead of guessing randomly.

Where is the fun in that?

didn't want to contaminate the excellent vette brake upgrade thread with this question: does anyone have the specifics for the C4 master cylinder? like bore diameter and mounting hole pattern?