SHAKE AND BRAKE
| 2003 Chevrolet Silverado Hot Hot Heat Z
Question: My 2003 Silverado 1500 has 85,000 miles on it. I am having a problem with it shimmying and shaking when braking. It happens at all speeds, but only when I brake. It drives smoothly otherwise. I have replaced all the brake pads and rotors, thinking there was a hot spot, warped rotor, etc. Could it really be the bearing or tie rods?
Answer: I'm assuming you're feeling the brake pulsation up front (through the steering wheel). But, front or rear, there are some basics that apply to both. First, be sure all front suspension components are in good condition (including but not limited to tie-rod ends). Then jack both front wheels off the ground and rock them side to side and up and down. There should be no play at all. If there is, look from behind the wheel to narrow down what's loose. If it's the wheel bearing (hub assembly), it must be replaced. Play in the bearing can cause a brake pulsation. Then remove the rotors and inspect the hubs (where the rotors mount). A common issue is rust and debris on the hub mating surface, which prevents the rotor from fitting perfectly flat. This will cause the rotor to wobble and produce a pulsation just like a warped disc. Clean the hub surface with a scraper, wire wheel, etc. There's also the possibility of a hub being bent from impact with a curb or pothole. The hub runout must be measured with a dial indicator to be sure it's in or out of specifications. And a bent hub will cause the wheels themselves to spin untrue, which is also noted as a shimmy without applying the brakes. With some hard-to-fix brake pulsation problems, the use of an on-the-car brake lathe often solves the problem. Resurfacing the rotors while still bolted to the hub compensates for irregularities. Last be sure the wheels where torqued to specifications in a star pattern. Improper torque can distort the rotor.
If you have a technical question regarding your pickup, SUV, or van, feel free to contact Alex, a master technician with the National Institute for Automotive Service Excellence. Send a letter to him in care of Truck Trend Garage, 831 S. Douglas Street, El Segundo, CA 90245, or e-mail us at trucktrend@sourceinterlink.com. Please include the VIN with your question. Due to the volume of questions received every month, we cannot guarantee that everyone's question will be personally answered or will appear in the magazine.
Can't wait for help with a problem you're having with your Truck or SUV? Ask the expert we trust here at Truck Trend Garage -- visit Alex Steele at www.RealWorldAutomotive.com.
