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Options Abound In Aftermarket Friction


4/13/2010
By Larry Carley

Brake parts are a mainstay of the aftermarket, thanks to the fact that brakes wear out.
 
Brake parts are a mainstay of the aftermarket, thanks to the fact that brakes wear out. The more miles motorists drive and the more they use their brakes, the faster their brakes wear. Stop-and-go urban driving, mountain driving, towing and aggressive driving will accelerate brake wear, especially in larger, heavier vehicles such as full-size SUVs and pickup trucks.

Some pads may be worn down to minimum thickness and need to be replaced in as little as 30,000 to 40,000 miles, while others may last upwards of 60,000 miles or more depending on how the vehicle is driven and the type of friction materials in the pads.

Brake noise or brake pedal pulsation when braking are often the only clues that the brakes need attention.
If motorists would have their brakes inspected periodically, they could probably save some money on brake repairs. Replacing the pads before they wear down to bare metal and damage the rotors can save the cost of having to replace the rotors.

Time and environmental factors are other things that affect brake life, too.

As the brakes age, the corrosion inhibitors in the brake fluid are used up, leaving the system vulnerable to internal corrosion that can pit and damage brake calipers, wheel cylinders and steel brake lines.

Time also dries out rubber hoses and seals, causing them to lose flexibility and crack. This can lead to fluid leaks and brake failure. Wet weather and high humidity can also increase the rate at which brake fluid becomes contaminated with moisture, causing a decrease in the fluid’s boiling temperature as well as increased corrosion inside the brake system.
Add to this the complexities of today’s antilock brake systems, and it is easy to see why the brakes often need repairs.
An ABS warning light may indicate a serious problem in the brake hydraulics or the ABS control or input electronics (bad wheel speed sensors are the most common problem here).

A customer who is shopping for new brake pads is often confronted with a range of replacement options. These include low-priced “economy” pads to higher-priced “premium” pads. There’s a product for every pocketbook. Customers should be advised that they usually get what they pay for. Value-priced pads won’t provide the same longevity, braking performance or fade resistance as premium pads.

Ceramic-based friction materials have been hot for quite a few years now, and most brake suppliers have some type of ceramic pads in their product line. Just keep in mind that all ceramics are NOT the same, and some deliver much better braking performance, wear and noise suppression than others. Low dusting is another feature of ceramics that appeals to many buyers, too.

Brake rotors are another wear item that may have to be replaced when the brake pads are changed.

If the rotors are relatively smooth, have no hard spots (no pedal pulsations when braking), no cracks or excessive rust, and are not worn down to minimum thickness specifications, they can often be reused “as is” (no resurfacing). But most repair shops recommend resurfacing the rotors when pads are replaced to lessen the risk of noise and break-in problems.

In California, there has been a highly publicized case involving charges brought against a chain of repair facilities for resurfacing rotors “unnecessarily.” Consumers say they were being ripped off. But the shop owner insists that they were only trying to do the best thing for the customer so they wouldn’t have comebacks due to noise or other problems.
If rotors are damaged or worn too thin, they must be replaced for safety reasons. Rotors should usually be replaced in pairs.
  Previous Comments
avatar   Tad   star   4/26/2010   11:16 AM

You can't blame the friction mfg for the customer not machining the rotors. Yes, there's some inconsistency between pads concerning lube application (and yes, Wagner says not to lube their pads due to their integral insulation design), but You still need to machine the rotors.

The high-friction coating on EBC and Bendix pads is there to improve the pad bedding process. It cuts through the rotor surface faster than the standard friction compound. The coating is not supposed to take the place of a good non-directional surface finish, it's just supposed to speed up the bedding process. This is important because very few people, including technicians, bother to bed brake pads properly before returning the car to the customer.




avatar   Ed   star   4/20/2010   3:35 PM

Tad, you can blame friction manufacturers' for an inconsistent approach. EBC Brakes and Bendix Brakes apply a friction modifier coating on top of the friction material, that aides in the bedding of the pad initially, cutting through the thermal layer left by the last set of pads (If the rotors were not machined). There are a few other companies that do that as well, but most do not.



As for lube, some friction manufacturers', like Wagner, state DO NOT LUBE their pads, and other manufacturers' state that the lube breaks down the adhesive they have on the shim(s).



So from all fronts we are telling customers' a different way of doing things every time they come to get their brakes depending on who they buy.




avatar   Tad   star   4/17/2010   12:47 PM

I once had a customer complain to me about squeaking from the rear brake pads he bought from me for his Mercedes. After talking to him for a while about the problem and how he installed the pads, I discovered that he hadn't used any brake lube on the backing plates and hadn't machined the rotors. He just pulled the old pads off and slapped the new ones on. "I've always done brakes like this on my cars," was his excuse.



Brake friction mfg's almost always recommend machining or replacing rotors before installing new pads. Unless you have an even surface with a good surface finish, only a portion of the pad surface will be touching the rotor and it will take much longer to bed the pads into the rotor. In the meantime, that reduced friction surface area and improper rotor surface finish is going to increase the likelihood of brake noise and reduce the effectiveness of the brakes.
















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