Brake Calipers

General Information

Info - 1984 model pistons

"I have two sets, one with a rubber plug in the centre and the other without it. Which set is better/newer?"

The one without the plug is the new style.

From: Scott Backer

Info - 1988 models

The wrench for the calipers is different than the Torx on pre 88 cars. It is a large Hex - wish I could remember the size, but is the same as most GM cars of that year and beyond.

A caliper piston rotating tool (about $12) sure does make the job a lot easier for servicing the rear brakes on 88s.

From: Randy Agee

Removal and Installation

Removal - front and rear - 84-87 models

1. Remove the wheels.
2. Using a Torx T-50, remove the two Torx bolts that hold the caliper on.
3. Pull the two bolts out. I find it easiest to use the T-50 socket to hold onto them by pushing it towards one side while pulling outward.
4. You can now lift the caliper up, over the rotor. DO NOT let the caliper hang by the rubber brake line! Use a coathanger or piece of wire to hold it to the springs, when you are not holding onto it.

From: Sketch

Installation - front - 84-87 models

1. Use a C-clamp over the caliper to compress the piston back into it's bore.
2. Coat the bolts with some lithium grease. This may help prevent broken bolts.
3. Put the caliper in place, and replace the bolts.

From: Sketch

Installation - rear - 84-87 models

Installation is the same as the front calipers, except that to compress the piston back into its bore you will need a special tool. I believe it is called a "disc brake caliper tool" or something like that. What it is, is a little round piece of metal the same size as the piston. It has a 3/8" drive and two notches sticking out of it. You will notice that the piston has two indents into it.

Take your new tool, and attach it to your ratchet. Push it against the piston and turn. It will be dificult to turn, but after you get started, you will get the hang of it and it will become easier.

Note that this is only necessary if you have not removed the parking brake cables from the calipers. If you have, you should just be able to push the pistons back in easily, without the need to rotate them back in.

From: Sketch

Removing broken banjo bolts

"Sure enough, the first front caliper saw the banjo bolt shear right off. I don't know the best approach to removing this bolt to ensure that it doesn't shear, but I was left with a hollow copper bolt in an aluminium caliper and decided _I_ didn't even want to think of drilling out such a critical bolt myself, so I took it to a machine shop."

The banjo bolts usually do break and the best way to get broken part out is by means of an "Easy-Out" screw extractor. This is little thing which looks like wood screw with a very coarse TAPERED LEFT HAND thread and head like a thread cutting tap (ie. a little square machined on the top on which you use a tap handle). It is hardened to about Rc55-60 so it will cut most bolt materials quite easily.

Easy-outs are generally available in little sets with about 4-6 different sized units for lest than $20. I am sure that Binford sells a set. If you are going to work on older cars you ought to have a set of these little monsters.

To use them, you just tap one into the hole in the broken banjo bolt and then gently turn it in the "unscrewing" direction. Because of the LEFT HAND thread and the TAPER the Easy-out will screw its way into the softer banjo bolt until the bolt loosens the then the whole thing will come out. You then mount the assembly in a vise and turn the Easy-out the other way to get it out of what's left of the banjo bolt. Be sure to use an appropriate sized Easy-out. Too small and it will break, too big and it won't get into the banjo bolt enought to break it loose.

From: Peter Frise

Rebuilding - 84-87 models

I have a few Rear Fiero (1984 through 1987) Caliper rebuilding tips.

Once upon a time there were Fiero Brake Calipers. There was no competition as the Fiero was a new car and the aftermarket didn't see any money competing with GM. Life went on and warrentees began to expire. Now the aftermarket was interested. They saw big money, but there were many of them. As a result, comptition was formed. Now all of the Brake Caliper rebuilders started looking for ways to cut corners.

Here are some of the methods they used:

1. The ratching piston was re-used. This was after GM determined their design had many problems and a recall was issued. The recall included a new piston, seals, internal springs, fluid, brake levers, etc. Unfortuneatly they sold a story to the Feds which allowed the recall to only be installed on manual transmission equipped cars. Those with automatic transmissions were on their own. The explanation was so bizzare that even I will not repeat it.
2. A dis-similar metal bleeder valve was used. After a couple of years the internal corrosion prevented the bleeder from coming out. Period. All conventional removal methods will probably fail Something as simple as bleeding air from your bakes will result in you buying two new (rebuilt) calipers..
3. Corroded pistons bores are used. GM changed the design of the Fiero rear calipers from all others in that the "O" ring is lodged in the piston bore and the piston sides on the square "O" ring, not an "O" ring sliding on the caliper bore.. The corrosion can continue, especially when the old brake fluid (the entire system was not flushed) is still in use. When a piece of corroded material is floating in the caliper bore, it will take out the caliper (leaks).
4. The old Line to claiper body feed through bold is reused. Dirt and corrosion have already collected here. Its hard to clean them out.
5. The guide pin's sliding "O" rings are reused.
6. The attaching bolts are replaced with internal hex head bolds instead of the GM TORX bolts (T-50). Not a problem, just an inconvience as you will need an extra tool.
7. The piston is not positioned properly in the bore. I mean rotational position. Some piston bores (new GM, some aftermarket bores) have up to six slots cut into the piston faces. Only two are correct for the inboard pad to be properly seated. If any other pair is used, the pads will be pitched and not parallel to the rotors. This not only accelerates wear, but it reduces braking force.

Not all of these conditions will exist with any given rebuilder, but they are things you should watch out for. Personally, I reccomend the GM rebuild kit, levers, bleeders, and feed through bolt and then rebuilding them myself. I am putting together an article which will describe the rebuild process in detail.

From: Joe Wynman