Volume 1 Issue 2 - Duramax Issues and Answers

I own an 03 Duramax, and recently replaced the rear brake pads. Any tips on what tools to use to remove the top caliper bolt. The torx bit and the ratchet will not fit between the bolt head and the leaf spring. Also, I noticed the brake pads wear unevenly. This was typical all the way around. What is the cause?

Response

To answer your last question first: Uneven load on the brake pads. This is typical of a floating caliper brake system. Most do wear the inside pad more than the outside one, as the piston is located on the inside and the caliper has to “float” freely to load the outside pad with the same pressure. Several things happen that do not allow the caliper to float freely:

1. Dirt and Debris: this can severely limit caliper motion. We see the effects of this on oil field service trucks that are running in mud and gravel constantly. They will wear the inside pad metal-to-metal with very little wear on the outside pad.
2. Sliding Pin Seal Failure: if the seal on the caliper sliding pins gets damaged at all, this can cause water to get in, displacing the lubrication and corroding the surfaces. This in turn causes the pin to seize in the bore, stopping the caliper from floating properly.
3. Normal Wear-What? Normal wear? Yes, the pin and bore do wear out over time. This can cause the caliper to twist slightly on brake apply, not allowing the caliper to float properly.
   Those Torx bolts on the rear calipers are not friendly at all! What I find the easiest is to remove the entire caliper mounting frame, reposition it, and then remove the Torx bolts. The best way to break the Torx bolts loose is with a good stout half-inch drive T-55 Torx bit and an air impact wrench.

Make sure you do a good inspection of the sliding pins and bore. They should move freely and have no corrosion at all. If they are corroded, it is best to replace the pins and seals. In extreme cases you may have to replace the caliper mounting frame as well. And be sure to use the silicone lubricant that comes with the pad kit; it will extend the life of your pads and your caliper pins.

Joel Paynton

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