Aftermarket replacement pads should be the same composition as the original. For example, if the vehicle’s original brake pads were semi-metallic, the replacement pads should also be semi-metallic. The same applies for factory-installed NAO or ceramic pads.
Full-line suppliers like Honeywell Friction Materials specify the OE composition type in Bendix® and JURID® catalogs. While we also list other types of pads that fit the vehicle’s calipers, the catalog will always single out the pads that match OE composition type as the part number recommended for use.
Many SUVs, minivans, and even some cars utilize a load sensing proportioning valve, located near the rear axle. The valve senses if ride height is lower than normal due to increased weight. If so, the valve directs more hydraulic pressure to the rear wheels to equalize braking forces. If the valve is out of adjustment or defective, the front brakes will perform too much of the braking and wear out prematurely. Check the service manual for your vehicle to find the correct valve adjustment procedure.
Easy, bring the suds to the rotor. Fill plastic spray bottles with soapy water and spray both sides of the rotor. Scrub the surfaces. Then spray them with rinse water. Dry with clean paper towels (not shop rags or compressed air). If the vehicle has ABS, use shop air to remove any machining deposits from the tone wheels (wear proper eye protection when doing this).
The odds of finding a rotor that can be reused without machining is next to impossible. Surface smoothness, lateral run-out, minimum thickness, machine-to, and maximum thickness variation measurements must pass manufacturer’s specifications. The best way to achieve proper burnishing, the least amount of noise and dust, longest life, and best performance is to restore the rotor surface to like-new condition when installing new friction.
The best method is to isolate the brake system circuits and components by installing temporary brake system block-off plugs. Never clamp off a flexible brake hose—that can permanently damage the hose. By removing the plugs one at a time and from side to side, you can easily determine which component is at fault.
The easiest method is to deplete air from the vacuum booster by pumping the pedal until its hard (engine off). Next, hold your foot firmly on the brake pedal and start the engine. If the power booster is operating correctly, the pedal should drop slightly with engine vacuum and become firm. If the hard pedal condition still exists, check for binding linkage or over adjusted drum/shoe assemblies. Check the vacuum check valve at the inlet of the booster. It should allow the engine to draw a vacuum on the booster, but not let air flow occur in the opposite direction.
Some manufacturers recommend tightening the parking brake cable to ensure full engagement after just three clicks, while others require a full pedal pump. Consult the service manual for your vehicle to find the exact procedure. After adjusting to the manufacturer’s specifications apply and release the parking brake several times to ensure correct operation.
DOT 3 and DOT 4 are both glycol-based and hygroscopic. But DOT 4 fluid has higher wet and dry boiling points. It’s easy to tell which type of brake fluid a vehicle maker specifies because it’s listed right on the master cylinder reservoir cap.
Although DOT 4 fluid can work in place of DOT 3, DOT 4 has a higher boiling point so it absorbs moisture faster. And, changing to a fluid that is a better “sponge” means the fluid change intervals should be sooner with DOT 4 than DOT 3. **NOTE: Never use DOT 3 fluid when DOT 4 is recommended because its boiling point protection won’t meet the vehicle manufacturer specs.** To avoid any potential issues, we recommend that you always use the factory recommended fluid type for your vehicle.
DOT 5 is silicone-based and non-hygroscopic and is specifically not recommended for use with ABS/traction control systems because they may aerate during system operation. Since silicone-based fluids have different lubricating characteristics than glycol-based fluids, DOT 5 is not interchangeable with DOT 3 or DOT 4. To avoid any potential issues, it’s always best to stay with the fluid type recommended by the manufacturer.
Brake noises generally fall into three categories: (1) squeaks, (2) squeals, (3) grinds and growls. Rapid clicking noises, motor/pump humming, cycling or pulsing are normal during ABS operation. 1. A high-pitched squeal that appears when you first apply the brakes but goes away as you apply more pressure can be caused by a wear indicator. 2. If the high pitched squeal doesn’t go away with increased braking effort, or the noise sounds more like a squeak, check for a missing or rusted-out shim(s), a stuck caliper, or worn friction material (rivets rubbing against the brake drum). 3. Grinds and growls can be caused by stuck calipers or metal-to-metal contact between the friction material backing plates/shoes and the rotor/drum. Make sure there’s smooth caliper movement on the slide pins (floating calipers only), even pad wear, and no deep grooves on the rotor face.
Anyone that works on brakes is sure to run across “brake pull” complaints sooner or later. It’s just part of the business. Here’s a short list of the most common causes: (1) sticking caliper, (2) restricted pistons or delayed piston retraction, (3) friction material contamination, (4) unequaled side-to-side brake fluid pressure.
Although tire-related and suspension issues are less common causes of brake pull, don’t discount them. If you’ve already checked the most likely causes of brake pull noted above, swap the two front tires. If the vehicle then pulls in the opposite direction, that’s a sign of a tire-related issue. Take a look at uneven tire pressure, alignment, worn suspension parts, uneven tread wear (caused by out-of-spec camber), tire-size mismatches or belt separations.
Sticking caliper. Most vehicles use a floating caliper design that pulls the outboard pad in contact with the rotor during brake application. The caliper “floats” on slides. However, if the slides become corroded or the wrong lubricant is used, the caliper can’t release the hydraulic pressure and the outboard pad remains in contact with the rotor, causing a brake pull. Start your diagnosis with the slide mechanisms. Caliper pins must be corrosion-free, smooth, and lubricated with a high-temperature synthetic brake grease. The bores they ride in must also be in good condition, and the protective rubber boots must be intact and flexible. Be sure to clean any corrosion or old lubricant deposits from the pin bores.
Restricted pistons or delayed piston retraction. This is fairly common on higher mileage vehicles and those with brakes that have severely overheated. The square-cut piston seal rolls slightly forward during brake application and back in place when released. If the piston seals are old and hardened, they may delay caliper release or not release at all. So the caliper clamping force keeps the pads in contact with the rotor, causing a pull. Rebuild calipers with new seals to eliminate the problem.
Friction material contamination. Brake fluid, engine coolant, chassis or CV grease, and engine oil can contaminate the pads on one side of the vehicle, altering their friction characteristics – making them grip either more or less than the opposite side. Most often the contamination is permanent and replacing the pads is the only real fix (after you’ve eliminated the source of the leak and cleaned off all the contaminants). When replacing the pads, be sure that both sides are using the same friction material. Differences in formulations can create pull issues.
Unequal side-to-side brake fluid pressure. Tube blockage, hose damage, master cylinder wear, malfunctioning proportioning/combination valve, and stuck ABS valves can cause these kinds of unequal pressure problems. The easiest way to find and isolate the problem is to measure rotor/hub temperatures with a non-contact infrared thermometer. The problem wheel will be much hotter than its axle companion and the thermometer will also show the brake that’s not functioning.
Probably, diesels don’t produce manifold vacuum, so they can’t use vacuum brake boosters. Instead they use hydraulic boosters. The hydraulic boosters are usually pressurized by fluid from the power steering pump. So the hard steering and erratic braking definitely may be related. If both steering and braking are affected, and the vehicle uses one pump, then there is a good possibility the power steering pump is low on output. If the pump is showing signs of wear, these symptoms can usually be felt when the brakes and steering are used at the same time. A power steering pressure check will show if the pressure release and maximum pump output are functioning properly.