Questions and Answers

Replacing Ford Bronco Front Brake Pads Q. Hi, very good web site. I'm trying to do brake pad replacement, my first. I have a 1996 Ford Bronco, the big one, 4x4. Front brake pads are low. I don't know if this model has the floating caliper or the other type, the type with the pin. I did see two bolts on back of caliper with small rubber boots around the bolts but, not sure. If I take these bolts out and use the C clamp to push in piston, will I be okay??? Michael Nevada

A. Let's hit upon some basics first, then I'll get into the specifics.

When Removing the Caliper, Remember...

• Prior to removing the calipers, remove/siphon brake fluid from master-cylinder until the reservoir is only 1/3 full.
• Brake fluid will remove paint and damage electrical connections. Use a drip pan and fender covers to protect the vehicle's finish and electrical system.
• Always replace all brake linings on an axle. Never replace only one wheel. Unequal lining thickness between wheels on the same axle will result in a strong steering pull when the brakes are applied.
• Work on one side at a time. If you forget how to reassemble the parts you can always use the other side as a model.
• When forcing the piston back into the caliper, open the bleeder valve first. Corrosion and other deposits accumulate inside of the caliper. If the bleeder valve is not opened when the piston is forced back into the caliper, these deposits will be forced back through the brake lines and into the master-cylinder.
• When pushing the pistons back into the caliper with the bleeder screw open, a stream of brake fluid will be expelled from the bleeder screw for 2-3 feet. Use a drip pan and be careful not to "shoot" brake fluid onto the vehicle's finish. A cleaner method is to use a piece of clear plastic hose and a glass or plastic jar to catch the expelled fluid.
• Upon removal, Do Not allow the calipers to hang by the flexible brake hoses. The brake hoses can be damaged easily by this practice. These hoses are double walled, damage to the interior pressure hose will not be visible.
• Do not depress the brake pedal with either caliper removed from the rotor. The caliper pistons will be inadvertently expelled from the caliper. If this occurs rebuild or replace the caliper, do not attempt to insert the piston back into the caliper.

WHEN INSTALLING CALIPERS AND PADS, REMEMBER...

• Clean and lubricate caliper slide joint/pins with high temperature silicone grease

Unlike drum brakes, disc brakes do not utilize a spring to withdraw the pads/linings when the brake pedal is released. Disc brakes rely on the elasticity of the piston seals, and the unrestricted movement of the caliper slide assemblies to release the brakes.

If the slide joints/pins are not cleaned and lubricated properly the disc brake linings will drag upon the release of the brake pedal. This will result in overheated brakes and premature brake wear.

Disc Brake Mechanical Force Diagram

NOTE: Floating calipers require free and unrestricted movement on the caliper mounting. Floating or sliding calipers have pistons only on one side of the rotor. The first part of the piston's travel forces the inner pad against the rotor, then further travel forces the movable part of the caliper to pull the outer pad against the rotor.

High temperature silicone lubricant must be used. Low temperature grease can melt and contaminate the pads and rotors, or can bake into a very hard substance which binds the slides. Petroleum based grease can cause the slide boots to soften and swell.

• Work on one side at a time. If you forget how to reassemble the parts you can always use the other side as a model.

Anti-squeal Coating

• Apply an anti-squeal coating to the back side of the pads/linings. This coatings acts as an insulator to dampen high frequency vibrations that are generated during normal braking. These compounds are highly effective in preventing brake squeal.
• Many professional repair shops recommend always rebuilding or replacing the calipers when replacing the brake linings, because:

When the pistons are forced back into the calipers, the piston seals are dragged across any corrosion or abrasives that may be deposited on the inside of the caliper.

Damage to the seals may not be initially evident. As the new brake linings begin to wear, the piston is gradually withdrawn from the caliper. This results in the piston seals again being dragged across the layer of corrosion and deposits.

Calipers which are not rebuilt or replaced have a higher probability of sticking or leaking.

• Check to ensure the bleeder screw is not frozen prior to reinstalling caliper. Freeing a stuck bleeder screw is much easier with the caliper removed from the vehicle.

Specifically for your vehicle, it's pretty much a straightforward job. You seem to know what has to be done. Removing the two caliper bolts (1) will allow you to remove the calipers, (2) and (3).

Ford Bronco Front Calipers

Since this is your first front brake job, you might want to read my article DIY: Disc Brakes