The leaning ride height is an excellent observation and it should have been a red flag to the alignment specialist. If ride height is not in specs, even if the car is level, it adversely affects the steering and suspension geometry. At a minimum, that will cause accelerated tire wear even though the numbers on the alignment computer appear to be okay. Most newer alignment computers have provisions for measuring ride height and will warn the operator if it's incorrect. When ride height is incorrect, or especially when it is altered on purpose, the control arms go through the wrong arcs as the car goes up and down over bumps. That makes the tires slide sideways across the road as the body goes up and down.
Before replacing or suspecting warped rotors, use a dial indicator to look for a bent wheel. If excessive runout is found, it doesn't necessarily mean the wheel is bent, but that's where you have to look to see why the wheel is wobbling. A bent hub on front-wheel-drive cars is always the first thing thought of, but it's more common to find proper procedures were not followed during a recent brake service. There's access holes in hubs to get to the bearing mounting bolts. Water splashes up there and causes round spots of rust to form on the back side of the rotor. Those rust spots have to be cleaned off before the rotor is machined. If an old rotor is installed in a different orientation, those rust spots prevent the rotor from sitting squarely on the hub. That holds the rotor and the wheel not parallel with the hub, so they wobble as they rotate.
Also be aware that if Chinese rotors were used, it is common for them to warp after a month or two. A light machining will take care of that. There's nothing wrong with the quality of the parts. When we make parts from cast iron, we set them aside for 90 days to age before they get their final machining. The Chinese cast 'em, pack 'em, and ship 'em, then they age on your car and often warp a little. That will give you a pulsation in the brake pedal while braking, but that's all.
Front inner cv joint housing can develop wear that causes a shimmy in the steering wheel during acceleration. The load on them makes it hard for the rollers to run back and forth in their grooves over those wear spots. That's a hard one to find but your car doesn't have front cv joints. I don't know if your rear inner joints are of the same design and can cause that but the clue is the shimmy goes away at any speed when you let off the accelerator. Even if your cv joints do have worn spots, being on the rear, they won't cause the steering wheel to shimmy.
I'm pretty sure your mechanic overlooked something, and he sure should have noticed it on the final test drive. Even something as stupid as a broken tire belt is real common. There's two things to look for related to tire belts and one is not very obvious. You may identify that by switching the tires front-to-rear. If you only feel the shimmy in the seat after that, suspect a broken tire belt.
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Thursday, May 7th, 2015 AT 9:13 PM
