P-30 Brake Squeal

[Bill_Carry]

My 1994 P30 chassis M/H has always been fussy regarding brake squeal. I bought this M/H new and have over 220,000 miles on it. Found from experience that only Delco (GM) pads would not squeal. Now have a bad squeal from L/R brake coming to stop. Six months ago the pads,rotors, calipers and hoses were replaced in the rear by a very reputable truck shop (I'm getting to creaky to do this stuff myself like I always used to). Recently this bad squeal developed. The shop that did the work last spring replaced the rear pads again. They didn't find anything on the L/R brake suspicious. The squeak is reduced, but still happens. It takes a half hour of stop and go driving to get things hot enough for the noise to occur when coming to a stop.

Any thoughts or experiences that might help would sure be appreciated.

[enblethen]

No adjustment on disc brakes!

[Passin_Thru]

Usually means one brake is out of adjustment. You hear it on Class 8 trucks. Adjust them until they are against the metal and back off 1/4 to 1/2 turn.

[enblethen]

My shop runs new rotors through the lathe. The ones for my rig was out very slightly on both sides.
Another thing they did was to wire wheel brush the hub to remove the old paper liner that GM used during assembly line operation. They use some lube on the face of the hub to rotor

[turbojimmy]

enblethen wrote:
turbojimmy: Was the new rotors checked to insure they were not warped?

No - I assumed they weren't warped because they were new. Bad assumption I guess.

EDIT: And I just realized that I said left front. It's actually the right, but I doubt that's relevant.

[enblethen]

turbojimmy: Was the new rotors checked to insure they were not warped?

[turbojimmy]

My left front does the same thing when it heats up. Loud squealing. I assume that wheel is getting hotter than the rest for whatever reason. Subscribing for more info. Some good advice here so far. My pads, rotors, calipers and hose are new on that wheel. Lubed the slide points on the caliper but NOT where the pads meet the caliper. I'll try that next.

[Gjac]

I would focas on why the pads would wear out so quickly. You said you just had them replaced last spring. New pads will squeel for a while. I would use an IR gun to see if the LR is much hotter than the others, which would indicate that the caliper is hanging up, the piston sticking, or maybe the brake line swelling closed not allowing the caliper to release.

[enblethen]

Another issue that I ran across is the piston needs to be metal and not bakelite.
I would not use the spray. It needs to be something that will last.

[midnightsadie]

X2. things need to slide very easy in the pad guides. there is a brake spray lube to try a easy fix.

[enblethen]

Outside pad to caliper is one of the places that should be lubed with proper high temperature lube. The ends of the pads, both inner and outer, must be lubricated. The face of the piston where it contacts the pad must be lubricated. The retaining wedge on the bottom must be lubed as well as the track where it goes in. The high temperature is not the same as used on drum brakes.

[Dr_Quick]

One thing that you could try, if it has not been done. They make a lubricant that goes on the back side of the pads between the caliper piston and the out side where the outer pad sits. I have know this to help with a squealing sound.

[enblethen]

Another issue I had, was not the proper lube used on the slide locations on the calipers.

[More_To_See]

I would be interested in knowing the temperature of the rotors between the two sides since you say the squeal starts after it has had time to heat up.

[enblethen]

What kind of pads?
Did they check the new rotors?