Rear Brake Service

Warning! Do Not replace the lock nut on the hand brake screw with a regular nut! You must use the special lock nut that that was made for these screws. If that nut falls off, the caliper will fail and may jam the pads against the rotor. Lock Washers are not acceptable replacements.

The rear caliper on 84-87 Fiero is rather complicated hardware. It is no wonder many people are confused and even intimidated by it. To add to that there are two versions of piston used. This page explains how they are built and what is going on inside them. It also covers why the rear brakes regularly refuse to self adjust like they were designed to.
Inner Pad Retainer

If the clip that holds the inner pad against the piston is damaged or missing then it must be replaced. If it's not there then the pad will drag the rotor. It could heat up the rotor and cause warping. In any case you will have accelerated wear of the parts. The clip does more than prevent pad rattle.

If the pistons in you calipers don't have the notches for the pad clip then carefully pry the clip onto the piston. I do this by getting three of the ears over the piston then prying then 4th ear into place. Try not to bend the ears.

The part of the clip that holds the pad has two ears cut sharp and two ears with bent tips. The pads are easier to seat in the clips if the bent tips are toward the open side of the caliper. Push the pad into the sharp ears then snap the bent ones in place.
To compress the piston into the caliper...

If this method will not work then either the actuator screw is binding or the piston is damaged. You need to repair or replace the affected caliper as soon as possible.

GM DOES NOT recommend the use of piston rotation to retract the piston into the caliper in the 84-87 Fiero. Only 88 model Fiero pistons should be retracted by rotating the piston.

1. Work the hand brake lever on the caliper to make sure the actuator screw rotates freely. If the lever binds loosen the nut 1/4 to 1/3 turn and try it again. Don't force the lever. You can damage the screw or the caliper shell. The lever can bind from corrosion between it and the caliper. It's also possible for the screw to bind in the caliper. If the screw is jammed in the caliper then the caliper must be rebuilt or replaced.
2. Remove the hand brake lever from the caliper. Don't loose the plastic washer between the lever and seal.
3. Cover the actuator screw with a large socket to protect it. The socket MUST NOT touch the screw or seal!
4. Use a large C clamp to compress the piston. Position the clamp to load on the socket covering the actuator screw. As the piston compresses the screw will rotate under the socket. Do Not allow the clamp to damage the plug in the piston face! If need be, protect the piston with a wood block.
5. Clean away any corrosion build up around the actuator screw and on the lever. Especially on the side of the lever facing the caliper.
6. Reassemble the lever. Don't forget to put the plastic washer back between the lever and seal. The washer protects the seal from wearing against the lever. Coat the area where of the lever facing the caliper with silicone brake grease. DO NOT use petroleum products!

Here are pictures of how to position the clamp. If your clamp is in rough shape, use a block of wood to protect the face of the piston. I know some of you have clamps that are in fairly bad shape... Trashy clamps can damage the piston or the plastic plug in the old style piston.
Rotating Pistons to retract them

For safety, I have to recommend that the clamp method be used to push in the pistons regardless of type. I've tried both methods. I thought it took way more force to rotate a Fiero caliper than most of the others I've done. Most rotate and retract fairly easy. That set off alarm bells and sent me looking for the "official" method.

There are definite issues with piston rotation.

* It’s confusing to allot of people. Each piston has to be turned a different direction to retract. Someone invariably turns one the wrong way.
* The inner and outer pistons have no indexing. People have had difficulty getting the outer piston to grip the inner one tight enough to retract when they turn it.
* If you aren’t careful, you could tear the dust seal. The dust seal keeps water and dirt out of the vent hole in solid faced pistons.
* The holes in the piston face are often worn because people run them without the pad clip on them... When that happens the clamp or big pliers are your choices and pliers can really chew up the pistons.

I won’t claim the clamp method is perfect. It’s kind of a pain the in ass but it does solve the above issues. It also forces people to check over the actuator screw and arm.
Rear Brake Adjustment

The rear disk brakes require periodic use of the hand brake to maintain proper adjustment. I'm not going to try to explain why. It's just the way they are built. (It's essentially a design problem. They should self adjust but often don't.)

If you are having problems with the rear brakes then always try cycling the brake handle three or four times before tearing them apart. If the hand brake system is broken, disconnect the cables and try moving the levers with Vise Grip or other large pliers.

If you still have low pedal after rear brake work, try this adjustment procedure. (The adjustment won't cure low pedal caused by MC or Power Booster problems.)

(Low Pedal is when the brakes seem to work properly except the pedal travel is longer than normal. As opposed to Spongy Pedal that is nearly always a bleeding issue. When Fiero brakes are setup and working like they should be, the pedal will "go solid" before reaching the same plane as the gas pedal resting position.)
Hand Brake

Warning! The actuator arms and return springs must be installed on the calipers for proper operation. This applies even to cars where the cables have been removed.

Warning! You must use the special locking nut that that was made for the actuator screw! If you lost it then it must be replaced with another locknut.
Who cars about a nut...

If that nut comes off the actuator screw, the caliper can fail. It's that simple.
I need the return springs? Even with no cables?

Yes! In addition to needing the arm to perform adjustments, the arms and springs eliminate random movement of the actuator screw. Random movement of the arm/screw can bind the pads against the rotor or allow too much pad clearance.
Did your hand brake stop working after repairs to the rear calipers?

It may be that the levers in the calipers are binding. This keeps them from moving through the full operating range. You can usually pull the handle OK, but the spring at the caliper cannot push the lever all the way back when handle is released. This keeps the screws from turning enough to move the piston guts.

First off, did you put brake grease actuator arm? If not take them off, clean them, and then coat the side facing the caliper with brake grease. Doing that will lube them and prevent corrosion.

Next check the cables. You may have broken a week cable jacket while working on a caliper.

If the arms/cables are working ok and returning to the stops like they should, your problem may be too much clearance in the caliper. Try the caliper adjustment procedure above.

Copyright 2000,2001 The Ogre’s Fiero Cave, D.W.Lane. All rights reserved. Not for reproduction in any media without written permission.

Last Revised Sun, 15 Aug 2004 01:14:07 GMT.