Disc Brake Squeal when hot!

NdeVente · Post by **NdeVente** » Tue Apr 02, 2002 10:48 am

Hi my 78 bus brakes are new rotors, calipers, pads, and i repacked the bearings with grease. I used the graphite lube that came with the calipers. and when i drive it the brakes start to squeal really bad when they get hot! i don't know if anyone else has had this problem, if you have pleae help me in fixing the problem. IT IS REALLY ANOYING!!!

rich2481 · Post by **rich2481** » Tue Apr 02, 2002 1:44 pm

Did you put the anti squeel goop on them it is a thin layer of silicone i think I dont know what it is made of Autozone and Checker ( most auto parts store ) sell it you put it on the pad and it stops the noise
good luck

Rich

ray greenwood · Post by **ray greenwood** » Tue Apr 02, 2002 2:57 pm

What rich suggested...may help you totally...but here is what may be happening. There are several things that expand when heated. (1) You may still have some air bubbles that are expanding at the calipers...and causing the discs to not retract as far when hot.(2) Pull the pads when its cool...and grind off the powder coating or paint on the top and bottom edge of the pad backing plate. if its a tight fit in the caliper...the metal expands and drags a bit on retraction. (3) The pad material itself may be swelling up when hot. Are you using semi-metallic or organic? There is a whole world to brake pads. One last thing. I just changed pads on my front end this last weekend. I had repco metalmaster pads on it...Superb heavy metal pad! I changed to an excellent extremely high friction semi-metallic canadian made pad (they were out of stock on the metal master..and I needed it fast). These new pads are even grabbier. You can feel the instant they get hot in a moderate stop. They triple their friction. But...they are a little softer than my last pad...and I have cross drilled rotors. You can hear the noise as the pads are compressing into the holes. I have found that where the holes are...it swells a little less than in the other areas....so I get an occasional squueek..when they are heated up. Watch this if you have cross drilled rotors.Last important thing. If you have all new brakes...check the freeplay of your brake pedal. If you are compressing the primary piston of the master cylinder even 1/16"..then you will be blocking a compensating port partially...and will have killer pedal...with killer stopping...but not full retraction on the discs...causing them to drag when they heat up. Ray

david thomas · Post by **david thomas** » Sun Apr 14, 2002 5:45 pm

try removing the pads and smearing a thin layerof copper grease on the backs (not the braking surface!). that usually does the trick