If you changed to EBC Rotors/pads it's no longer a GM issue. Rotors can warp if heated to that point. I started gettin a little shake at 38k miles on my panel. It's a fact of life, it's a machine and that happens. Driver braking style or habits can contribute to it as well.

Is this an issue with SS's too? I have an SS now, but no shake at 12k miles.

 

It sounds as uneven wear or material got embeded on the rotor after a realy hot stop.

If it is material sometimes it will go away but if it is uneven wear the rotors need a light cut.

I do not know what kind of miles you have but I suspect uneven wear as that is so common on all FWD cars anymore.

It was not too long ago normal driving would wear front pads out at 30K-35K miles on many cars. Now with higher miles many people see the uneven wear because of this.

 

What a long read. I just went through this entire thread. Being that this '07 HHR is the newest car I've driven in a long time, I would like to know how to check the hub bearing end play. I am looking everywhere for something that shows how exactly to determine if the hub bearings have too much play, but am simply finding nothing apart from just stupidly trying to wiggle the wheel. How exactly do you do this?

 

As far as I can figure, using a run out gauge to check for ANY sloppiness, or listen for the roar of bad bearings. I asked the same question a while ago and that was the roundabout consensus. Since they are ball bearings not rollers "end play" as we dinosaurs know it does not exactly apply.

Don

 

Ok, I must admit that I don't even know what a "run out gauge" is, nor have I ever used one. Yes, I am displaying my ignorance here.

I've been driving old cars so long up until now that all I know are the old tapered bearings. Nothing replaces that manly feeling of having wheel bearing grease squooshed all through your fingers...

 

Old School I like it. I know the feeling of Grease too.

Run out gauges are really old school too and have been around for years. Just in the past few people had them since hub play was not as critical and but also it was needed to kick the brake pads back.

Today with the new brakes and hubs the calipers pull the pads back so they do not ride on the rotor or create any drag. The truth if a hub has enough play to feel it may be too much. The Run Out gauge is really like a dial indicator that measures movement. The generally accepted play on most [not I did not say all] is .001 to .002. It is best to check the spec with a dealer for manual based on what you are working on as it can vary.

The warp feeling is most times either material embedded in a spot on the rotor surface. Also most times it is the play that lets the rotor wobble enough to wear a rotor thinner ins spots than others. This is why when you cut the rotors they cut like there is high spots as if it is warped. This is where Rotor Thickness Variations is often mistaken for warp. This is also why people try to correct the issue they think is warp and often repeat the same problems.
Similar symptom but not the same problem.

Brakes in the past used to be able to hold up to a lot but pads usually did not last as long as today. But on the other hand the bearing today are just not as good. Getting more MPG from these bearing has a price to pay vs the old tapers.

 

I've just spent a good bit of time hunting around online for exactly how to do this. The gist I get is that you somehow mount the gauge, put it up against the hub assembly, and just rotate the assembly and read the gauge.

I feel kind of stupid having to figure this out, but when its new to you, oh well.

It makes a lot of sense that if the hub bearings have too much play, it will cause brake pulsing and hence people keep getting rotors resurfaced and replaced over and over again without fixing the problem.

 

Ok, Magnetic base Dial Indicator: You mount it on a piece of steel (that won't move) & adjust the dial needle to the rotor wear surface, Zero out the gage & slowly turn the rotor, while watching the run-out on the gage..

 

Thank you. I'm going to pick up one of those gauges. The one you pictured looks to me to be a Grizzly G9849 Dial Indicator, and is only about $30 shipped.

 

The indicator has to mount on a part of the spindle like the brake caliper mount, not the brake caliper. You would also try to pull the rotor toward the indicator and push it away to check for bearing play.

I've come full circle on wheel bearings. My first cars had ball bearings which required frequent adjustment. Roller bearings don't really need adjustment as they usually have more rollers than the ball bearings have balls and a roller contacts in a line while the balls contact at a point so roller bearings have more contact area. That larger contact area creates a little more drag so they went back to ball bearings but these can't be adjusted.

I hadn't heard about brake calipers that pull the pads back. I'll have to look at a set to find out how they do that and keep the pistons from backing off so far that you have to pump the brakes to get them pushed out again.