Front Brakes surging?
06-17-2009, 07:57 AM
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Front Brakes surging?
Hello everyone, thought I might try my luck at a problem I'm having with my '95 F150 (4-wheel drive). One day, my brakes started locking up on the rear, and the mechanic told me the drums were bad, so he replaced them. He said that everything else was fine, but that the front rotors and pads needed to be changed, so I did. I know everything was changed right, but when I pulled the rotors and pads off, they weren't that bad. A little scored, but not bad. Now the funny thing is, when I put the NEW rotors and pads on (the correct way), the calipers started "surging" and actually slapping on and off of the rotor instead of grabbing the rotor smoothly for breaking. I changed the calipers, thinking something was wrong with them, no luck. The master cylinder was my next guess, but when I changed it, no good. I thought maybe the ABS was the problem, but my pickup has rear ABS, so I elimanted that. Someone is putting a new brake booster on it today, but I honestly don't think that's the problem. I was doing some looking around on the web today and learned about combination valves (metering and proportioning valves and pressure differential switches), could that have anything to do with it?
06-17-2009, 11:00 PM
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It would seem you're right. I took it back to the garage today, and the mechanic as well as somebody else put the truck on a machine, raised it in the air, locked it into four-wheel high range, and sped it up to about 30 MPH while tapping the brakes. The rotors, they say, were warped. On the driver side, it was warped bad, and they were brand new rotors. Apparently, when you buy new rotors, they can warp from sitting on the shelf and having pressure applied to them after a long time, and once on a vehicle, the heat and pressure from the calipers can warp them even more. I'm going to take the new rotors back and exchange them for different ones to see if that fixes the problem. Thanks for the reply.
