95 Accord Front Brake Problem

[MEJA]

I was having excessive shimmy in front end when braking. At 200K I replaced the rotors with new after market from NAPA and installed new ceramic pads. I was disappointed that the shimmy was still there. 25K later the front end shimmies really bad when braking hard and I want to fix it but I would like to know why replacing the rotors the first time didn't help. Any Suggestions?

[jeffcoslacker]

2 possibilities...

When you replace rotors you have to be sure the mating surface where it interfaces the hub is clean, no rust or dirt, otherwise the rotor will not be bolted true to the hub and have some runout, which will cause shake like that...

But the more common explanation is that you are dragging brakes for some reason, building enough heat to warp the rotors. In this case you might notice it gets worse the farther you drive, because the warpage increases the longer it drags the brakes.

Typical causes are worn or corroded caliper slide surfaces, pins, sleeves and bushings, or brake hoses that have failed internally. Or the caliper piston itself can be seized and dragging

If it seems to get worse the longer you drive, there's a couple of things you can try.

Drive the car at highway speed for a few miles, then come to stop in a safe place using only the emergency brake (so the front are not being used) get out and feel the front wheels and brake calipers. They should be fairly cool if everything is working right. If warm or even hot (be careful touching calipers), you're dragging.

To tell if a brake hose is involved, what I'll do is get a wrench that fits the bleeder screw, take a ride and get the brakes good and hot. then get out quickly and open the bleeder screw on the suspect caliper...don't worry about air getting in, not gonna happen while the system is static.

If the drag is caused by a caliper or slide problem, you'll just see a little brake fluid drool out. If a hose is involved, it'll shoot a shot of fluid under pressure when you open it, because the failed hose holds pressure just like you had your foot on the brake.

If you suspect the caliper itself, replace it. There are ways to free them but it takes time to explain and is rarely a permanent solution anyway.

If the piston seems to move fairly easily, like when you changed the pads, then look hard at the slider pins, sleeves and bushings...a missing or egged out bushing can cause the caliper to cock into a position that is not normal and drag, and those pins have to be straight and well lubed. The pin must move inside the sleeve...if they are corroded together it's sliding on the bushings instead, which will drag that brake.

When you put the caliper on, with the piston pushed back into the bore like when you replaced the pads, you should be able to easily glide the caliper back and forth on it's mount with two fingers and a thumb...if not, you've probably found the problem. Determine the cause and correct it.