Uneven Brake Pad wear?

[Jomama]

I have done the searches.. It appears the most likely culprit is a sticky caliper piston. I'm just checking to see if anyone thinks I may be missing something...



Late this spring I notice a lot of "brake squeal" while driving down the road.. I heard it most when it could be reflected back at me.. And had a friend stand outside it as i drove around him.. Both of us thought it was a very "typical" brake squeal sound... It disappears when I actually apply brakes. I dont hear it till i start to roll...

Front brakes were given new pads in June 04.

I originally assumed it was one of two things..

1) Rear brakes? (drum brakes on my 93) I was just going to do these preventatively since I'm not sure of the maintenance of these. Parts are on hand.... and my first searches for "brake squeal" suggested that there is a compound in break pads to make them make noise when they get closer to being used up... I thought this might explain the squeal...

2) Brake dust and such on the Front rotors...


Well I finally got to check out my front brakes this weekend... And I was dissappointed to see extremely uneven wear on the pads... Inside pad is damn close to gone, outside pad appears to be about the wear I would expect after 2 yrs (and less than 15K miles).. With the tire off, I spinned the rotor by hand and I do get the rubbing/grinding noise fromt he rotor ...

I did clean the rotor of all the pad dust on it.. but the squeal is still there...


"Uneven brake wear" searches here on mud results in a majority of posts about sticky caliper pistons... And a suggestion or two that a rebuild of these is not really worth it.. and replacement is more cost effective...


Any other thing I should check out before just picking up new front calipers?

Any other general cause for the uneven pad wear??

 

[semlin]

is the wear even across the individual pad surfaces on both sides? if uneven acorss the pad then it's pistons for sure, if wear is even but unequal between the two pads check first to see if your rotor thickness meets spec and that your caliper bolts are tight enough.

i got a decent deal on rebuilt calipers locally. the rebuild kit is cheap though and if you don't have corrosion issues it should work.

 

[Heffenoche]

Calipers can be rebuilt and the OEM kit is not that much. If you follow the FSM it's not that hard. You will need compressed air and a wooden block to get the pistons out. Some say you can get them out w/o copressed air but I think it would be difficult.

Then you clean up the pistons and replace the seals and boots. Getting the boots and spring clamps back on can get a little tricky but very doable.

 

[semlin]

btw, do you have a poverty pack 93 with rear drum brakes and no abs? did you adjust your lspv when you went to a j lift?

 

[Jomama]

No compressed air currently, so that was a reason I was shying away from the rebuild.



The pad wear appears even on the given pad.. The uneven wear is the inner pad, which has worn about 2/3 more than the outer pad.

Rotors are grooved, and look like rotors on a truck with 150k (in my limited experience). I have not had excessive wobble, or pulsing, or pulling when braking, before or after the front break job 2yrs ago, so I just assumed they are alright..

I did notice, that on the rotors there is a small lip on the outer edge of the rotor (mabey 2mm, or a little more) where the rotor is not contacted by the pad (no wear). This lip appears to indicate how much the rotor has worn from its original width.

So now I'm thinking mabey try new rotors and pads? And see if I still have issues...?

If I tear it down to put new rotors and pads on it, is there a way to check the caliper? Will I not be able to push it back?

 

[Jomama]

btw, do you have a poverty pack 93 with rear drum brakes and no abs? did you adjust your lspv when you went to a j lift?

Yes rear drums and no abs.

I did adjust my lspv, but it was a complete guess based on the lspv writeup.

I could be slightly over or under the recommended adjustment. I tried to err on the side of not adjusting it TOO FAR..

 

[semlin]

ok, well the fast wear makes more sense. my friend's 1991 went through stock pads in 10k and also saw faster wear on the one side of the rotor (I think inner). my 93 pads seem to wear evenly side to side. don't know if that is abs or better balance front to rear with rear discs.

If you have grooves on the rotors they are going to eat pads and be far less efficient.

I'd definitely go with new rotors and 100 series pads. then i'd adjust the lspv to try to get all 4 brakes to lock up at the same time.

 

[Jomama]

Ok, that sounds like a good course of action. I really appreciate the input.

 

[lovetoski]

One thing to check is whether the pad that's less worn has a seized piston. Pop off the brake resevoir cap and push the pad away from the rotor. If both sides push back easily that's a great sign. A caliper rebuild kit is ~$30, and easy to install.

However, if one piston is siezed into the caliper, you might find it necessary to purchase a reman'd caliper.