Rattle From Front End Over Bumps - Gone With Light Brake Apply - clunk suspension

This PI was superceded to suggest biasing the caliper guide pins rather than replace the pins and brackets. Please discard PIC3585G.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

A customer may comment about a muffled rattle noise from the front end of the vehicle when driving over bumps or rough roads. The noise will stop if the brakes are applied lightly. The cause may be movement of the front brake caliper guide pins in the caliper bracket.

Bias the front caliper guide pins in the caliper brackets as required using the following procedure.

1. Remove the wheel from the front brake corner(s) that produce the noise.

Notice: In severe cases the rattle can be reproduced by tapping on the caliper with your hand. Tapping on the caliper before and after this adjustment procedure can aid in determining if the adjustment was done correctly.

2. Loosen the brake caliper guide pin bolts and small amount.

Important: Care must be taken to NOT over bias or bend the guide pins causing them to not slide freely. This could result in the caliper dragging.

3. Using an open end wrench on the guide pin locking nut (1), rotate/push the wrench up for the bottom pin, and down for the top pin so the outer edge of the wrench contacts the caliper biasing the guide pin in the bracket away from the other guide pin (increasing the distance between the upper and lower pins a very small amount). This will take up clearance between the pins and the bracket. Tighten the guide pin bolt to hold the pin in the biased position (2).



4. Reinstall the wheel(s).
5. Inspect the front brakes for drag. With the vehicle suspended on a hoist, brake drag can be identified by rotating each wheel several times and observing whether more force is needed to rotate the left wheel or the right wheel.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.