93 Z71 disk brake problem

[mattman]

I'm posting this for a friend of mine. I know it's off subject (93 Z71), but I was curious if any ran across the same problem since I think the disk brake systems are similar.
About a year ago, he changed the front disk pads. Both the inner and outer pads on both sides were worn evenly. A couple of days ago, they started grinding. He picked up a new set and changed them out. The problem is only the outer pad on both sides were worn all the way down. The inner pad was barely worn. Any ideas since both sides did the same thing? Only other thing of note was that he said the bolts that hold the caliper on were real tight.
Any guesses?
Thanks for any help.
Thanks for any help.

90 GMC Jimmy, 350 TBI, 700R4, 32's
84 Bronco II 204,000 miles and counting...........that's 207,000 and counting now

 

[mattman]

toppin'

90 GMC Jimmy, 350 TBI, 700R4, 32's, D.O.D.
84 Bronco II 210,000 smoking and going.........

 

[Twiz]

O.K., sounds like the calipers draging and/or binding up.

First, have someone depess the pedal while inspecting the piston movement. The piston should pull back into the caliper when brake pressure is released. Very slightly, but noticable. It should be tthe same left and right.
Second, Check the caliper movement. It should slide back and forth freely. If it sticks at all or is stiff, you have found the problem. (check it as is, then compress the piston and recheck)

Third, check caliper clearence between the caliper and steering knuckle with a feeler gage. (at the moment, I can't remember the exact specs.Combind, something around .020 or .030" or so seems to ring a bell, but don't hold me to it) Check and compare left and right, they should be the same or close.

Forth, remove the calipers and inspect the caliper to knuckle contact surfaces (the slides), they should be free of rust and corrostion, also make sure there is not any casting flash on the caliper (a problem w/A.M. calipers), this can be removed and adj with a flat file. Clean both surfaces with emmery cloth and lubricate with silicone grease (supplied w/G.M. brake pads).

In a nut shell, the most proable cause to out-board brake pad wear would be;
Caliper "slides" and/or bushing sleves binding or sticking and making the caliper out-board brake pad drag on the roter.

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