I love GM brakes...

[ping64]

Just put new front pads and rotors on a '91 Lumina sedan last night (after finding a T60 Torx bit but that's another story).

Three of the four pads were about 50% and the inside pad on driver's front was worn to metal. The caliper pins were not siezed. Any thoughts about the reason? FWIW, the caliper pistons were tough to re-seat.

Also, the parking brake does NOTHING and after attempting to set it the warning lamp is on and will not extinguish. Grrr...

TIA,
Tony

[Fireplug]

Bad caliper replace it of you will destory the new pads

[ping64]

Thanks for the reply, but I'm not sure a bad caliper would just toast the inboard pad leaving the outboard pad with 50%. These are sliding calipers with two pistons on the inboard side only. Sticky caliper pins (which they weren't) would be more likely. Also, the new brakes work evenly - no pull to one side or the other on application.

FWIW, the DS caliper was easier to compress than the PS and the DS had the metal-to-metal.

Cheers,
Tony
newb on this board but not on others...

[dwalmop]

bad calipers do that. They toast one side and leave the other. Also - do your back calipers work? They sieze up all the time if you don't use your parking brake. You may have to remove your wheel and try to set the brake to figure out what is/isn't moving back there.

[ping64]

I'm not sure if the rear calipers work for the service brake or not, but for sure the park brake is NFG. With the notorious rear disc pins...

This is not my car, I'm just trying to keep repairs on the cheap for a friend. It has been poorly maintained in the past and I doubt the brake fluid has ever been flushed - 200,000km+++. If I had my way, it would be getting new calipers and flex lines all round. Penny wise, pound foolish.

Tony

[richtazz]

your caliper piston is not retracting, so that is why the inboard pad was gone and the outboard wasn't. It will not affect stopping power or cause the brakes to pull, because of teh high pressure when applying the brakes. The calipers return under only slight vacuum pressure from the piston in the M/cyl returning so they wont pull back in there bores, effectively wearing out the inboard pad. Double check the hose on that side also, as they can cause a similar situation, but it's a 95% chance of a bad caliper. As far as the parking brake keeping the brake light warning light on, you probably have a seized cable, due to most people not using their parking brake on an automatic. Normally bad calipers will cause the rear brakes to drag or no parking brake function.

[ping64]

Thanks to all. Now I get to break some bad news...

[jeffcoslacker]

Rule of thumb: Pad on piston side worn first, caliper. Pad on stationary side worn first, slide siezed.

[asm_]

Originally Posted by jeffcoslacker

Rule of thumb: Pad on piston side worn first, caliper. Pad on stationary side worn first, slide siezed.

I have read every post in this thread, but no one have explaine why the above rule holds true.

Doesn't floating type caliper has slide pin so the pressure on either pad would equal at all time?? Assuming the piston is siezed, slide pin would move in-bound to releave the pressure on the inner pad.

Comment??

~ASM

[57chevyragtop]

The slides release the outer pad pressure, but is controlled by the piston(s). If the piston(s) are not retracting due to dirt in bore, weak hose, (collapsing) or worn boot not holding vacuum, the pressure on the inner pads is greater as you still get some release if slides are even somewhat functional. When replacing Calipers you would be wise to do both sides and replace the hoses as well. Also mentioned was the difficulty pressing the piston into bore....I have found that opening the bleeder on the side you are working on does two things...relieves the pressure and allows dirt out and not back up into the master cylinder.

[theclarks1]

The above stated is all true. I have a pontaic trans-sport van(which im sure you all know is like the lumina apv but better.) it had the same issue, it was the caliper. But I agree with you guys its definatley the caliper.

[Jonn]

Originally Posted by theclarks1

The above stated is all true. I have a pontaic trans-sport van(which im sure you all know is like the lumina apv but better.) it had the same issue, it was the caliper. But I agree with you guys its definatley the caliper.

Okay, i agree too, but let me throw this monkey wrench into the works, I have replaced pads on the front of mine twice now, and both times the outer pad was toast, inner about 50%, each time i did it, i cleaned and greased the slides each time, checked them the other day, now about time for new ones, and both inner and out are worn about the same, same old calipers and slides still on it..So either the caliper pistons fixed them selves, or its just "you get whatever your decides to thow at you"
Which i do believe cars do at times.Been more than once i have found the impossible to be the only thing possibe as to a explanation.

[Jim Adams]

the problem is the brake line is colapsing and not letting the fluid bake into the master cylinder as fast as the other side,,bet if you put a new fexible brake line on it problem will be solved,,,seen this 100 times ,,working for the ford dealership.

[Jim Adams]

Brake pads can wear unevenly pending on the drivers normal braking procedures,,if the driver comes to a stop and always hits the brakes it will wear different from a driver who comes to a stop and slowley pumps the brake a few times before they stop the vehicle completely,,also if a driver uses his emergency brake everytime he gets out of the car or shuts it off for the night his back brakes will stay adjusted properly and all brakes will wear evenly if he doesnt use his emergency brake regularly then he will eat up front pads alot faster than normally ,,also it depends alot on what type of pad you are replacing it with they have semi metalic, full metalic, ceramic and then those 9 dollar pads that dont have hardly any metalic in them and you can wear then out on one long vacation.