91 Legacy 180K Miles

 

Wife comlained about the brakes squeeking. I replaced all the pads and only drivers side front inside pad had any signs of wear. The pad was worn to the wear indicator, but not evenly acorss the pad. More on the lower side of the pad than the upper side. Not down to backing, no metal showing.

 

No other pads showed any noticeable wear.

 

Car still squeeks while light breaking.

 

Thoughts/Advice?

[...]Thoughts/Advice?

Seems like the caliper is sticking, not sliding. At a minimum, disassemble, check for corrosion, clean, lube.

Seems like the caliper is sticking, not sliding. At a minimum, disassemble, check for corrosion, clean, lube.

 

Uneven wear makes you think the caliper is sticking?? Thanks I'll take apart and lube. Now I would be lubing the pins that the caliper slides on???

 

Why would it be squeeking?

Its not squeaking. What he's suggesting is that because corrosion has the slide pins sticking, not allowing the pads even and free movement when the brake pedal is released, the pad is squeaking at that location. While you're at it, check to see if your cailper pistons move freely in and out, and are not sticking. Pull the caliper on one side, have someone give a moderate push on the brake pedal while you watch the piston move, and then push the piston back in using a large C clamp. You should be able to do so fairly easily. Reinstall that caliper and then do the other side. If not you would be wise to either rebuild the calipers or replace them. I would also suggest a complete brake flush and bleeding when done. Good Luck!

Uneven wear makes you think the caliper is sticking??

Yes. If the caliper can't slide, it won't self-center over the rotor, and the outer pad won't apply as much pressure as the inner (therefore the inner will wear more).

 

 

Thanks I'll take apart and lube. Now I would be lubing the pins that the caliper slides on???

Yes. Make sure the boots are in good condition, that the pins aren't corroded (or possibly even bent), and that you use a proper high-temperature brake lubricant. Also, verify that the pad tabs/ears are able to move within the anti-rattle clips without excessive force -- if not, there may be corrosion, or the pads' dimensions may be out of specification (especially if they're not OEM).

 

 

Why would it be squeeking?

Originally, when the inner pad was severely worn, you may have been hearing the pad wear-indicator rubbing (it makes a noise to alert you). After the pads were replaced, it might be caused by several factors, including no or improper lubrication of the pad back plate where it contacts the pad clip/shim.

 

You could start with checking what I've already mentioned, and let us know if the problem persists.

[...]While you're at it, check to see if your cailper pistons move freely in and out, and are not sticking.

While it's not a bad idea to verify that caliper pistons aren't sticking, if that happens the inner versus outer pad wear is usually relatively even (assuming the caliper slides readily), although excessive.

 

 

Pull the caliper on one side, have someone give a moderate push on the brake pedal while you watch the piston move, and then push the piston back in using a large C clamp. You should be able to do so fairly easily. Reinstall that caliper and then do the other side. If not you would be wise to either rebuild the calipers or replace them. I would also suggest a complete brake flush and bleeding when done. Good Luck!

If you decide to do this, be very careful about depressing the brake pedal while the caliper is not mounted; it's easy to "pop" a piston that way. At the very least, place a block of wood where the rotor (and pads, if removed) would normally be, to limit the piston travel.

Does the locking bolt act as one of the piston slides?

 

Boots are in good condition.

 

I was able to push the piston back easliy (w/ C clamp) when opening up for new/larger pads.

 

Pads went into anti-rattle clips easily and didn't take much force to get the new pads to slide into place.

 

I'll eventually get to all these suggestions.

 

Thanks,

D

Does the locking bolt act as one of the piston slides?[...]

I assume you were referring to the lock pin and caliper slide. Both the guide pin and lock pin outer surfaces have to be properly lubricated for the caliper to slide correctly. The pin boots should also be greased at the inner "grooves". Again, be sure to use lubricant specifically meant for the purpose.

The boots and rubber ring on the tip of the lock pin can swell up and soften if you use a petroleum based caliper grease, though your car may not come equipped with the latter. For the guide and lock pins, I use a synthetic permatex grease that the manufacturer says is safe even for the caliper piston seals. In my locale, it's available at Autozone in little green packets and 8-oz. bottles. A silicone grease will also work, and I believe OEM Subaru caliper grease is just this. Petroleum caliper grease is fine for the contact surfaces of of the pads.

 

However, also avoid contaminating the friction surfaces of the pads and rotors with grease, which can also cause squealing and grabby brakes.

Yes, I meant the lock pin and caliper slide.

 

Thanks for all the tips.