uneven wear on front brake pads

[Jvan]

I had to change the brake pads on my 94 LSi after hearing a grinding nise while breaking. The inner pads on both sides were worn down to the backing plates while both outer pads have more 3/8 thickness left. What causes this extreme wear and what should I be checking for? Other than the grinding sound, there was no shimmy or shake while driving and the front end was aligned a couple of months ago w/new tires installed on all 4 wheels at the time of alignment.

[SVX_MY_BABY]

Originally Posted by Jvan

What causes this extreme wear and what should I be checking for?

I my experience it is usually dry / seized slider pins on the callipers or seized calliper pistons.

If either of these situations occur then the inner pads never get out of contact with the rotor, so they just wear away.

Annual lube on pins is pretty straight forward and easy to do.

[Jvan]

I creased the slider pins when I just changed the pads so that is taken care of and as far as the calipers, I installed a rebuilt left caliper about 6 months ago, Since the uneven wear is on both front calipers, I don't think both calipers would have the same problem since one is relatively new while the other is old and could have pistons that hang up.

[SVX_MY_BABY]

Only other thing I can think of is a bad surface on the back side of the rotors. If they are worn out that would cause it. I'd think there would be a lot of scraping sound though.

Edit: A lot of scraping noise for an extended time period.

[Jvan]

As far as I can see, both sides of both rotors are smooth. I've never seen such a radical difference between inside/outside pads on both rotors. Now that I've replaced the pads, I'll gave to check in a couple of weeks and every few months, unless somethings starts to shake or make noise. Thanks for your input.