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Posted by Hemimech on Wednesday, April 02, 2008 at 15:04:39 :
In Reply to: W250 warped rotor help posted by Don in Missouri on Wednesday, April 02, 2008 at 10:55:36 :
What must be mentioned is that a warped rotor can occur with a small amount of heat over a length of time. Jack the truck up and spin both tires by hand. If you don't feel a bad spot anywhere during the rotation have someone lightly depress the brake pedal. Often you will find that a rotor is only warped on one side of the vehicle. This would indicate that there is a problem with a caliper slide or piston retraction or even an internally swollen brake hose. On older vehicles its seams that the caliper slide surface is often the culprit. Newer vehicles have stainless lined surfaces or pins sealed in grease. On older brake systems the calipers sat cast surface of caliper to cast surface of knuckle. If you have a fair amount of wear on these surfaces the caliper will tend to take a set. So as the pads wear the caliper should automatically center itself as the brakes are applied. But what happens is the caliper tends to stay loaded inboard upon piston retraction. On a long drive this off center caliper holds the outboard pads against the rotor with a light pressure. Even light pressure creates heat, and most notably heat on one side of the rotor(bad condition, great for warping rotors). This condition can be observed in the old brake pads you removed. The outside pad will be an appreciable amount thinner that the inboard piston side pad. So then your challenge is to true up the slide surface and use quality caliper grease.