Also check for rotor thickness variation. With a bad hub it is not so much the run out but the thickness variationm of the rotor as it wobbles. The thickness will vary at point aound the rotor and this is what compresses and releases the caliper piston to create the pulse.

This is what the GM TSB recomended to look for a while back. I think it is in that thread somewhere.

 

I checked the rotor thickness with my micrometer and the thickness varies by about .0005 which is less than the .001 spec. I've made an appointment with the dealer for Friday to have the hub checked out/replaced. Thankfully I'm still under the powertrain warranty on this.

 

If you want your brake plusation to go away, you will have to change your front hub assemblies. Also, check into switching to semi-metallic pads instead of ceramics. I know most newer cars come with the ceramic pads like the HHR from the factory but semi metallics don't transfer as much heat into the rotor as ceramics do. Ceramics are very good pads, but I have had a really good expereince switching from the ceramic pads to the semi metallics on my HHR, the braking just feels stronger and there is more bite,if you will, to the brakes. I also replaced my hubs and rotors with the semi metallic pads about 14,000 miles ago and my pulsation has not returned.

 

It is not Ceramic pad but the quality of Ceramic pads and how much filler they have.

Generally any pad can advertise Ceramic or Kevlar material but they do not have to say how much material content the pads have.

Cheap ceramic pads can have low ceramic % content and a lot of cheap fillers that mess with the rotor. OE pads for the most are cheap and the high dust on my SS is proof of a lot of cheap filler.

Now if you use a higher quality pad like a Red EBC or Hawk Ceramic and if it is installed properly on a hub bearing that is with in spec you should not have much issue. The EBC red and Hawk both have high ceramic content to the point where there is little dust and great heat trasfer from the pads.

Most Semi Metalics can work pretty well too but they are horrid for heat and fade. They are cheap to make and buy. They also can make more noise and wear the rotos. The wear is not a big deal on wear for people like me who just change rotors vs cutting them anymore.

The bottom line is all pads are not equal and generally the price paid is to the kind of quality you get. It is like anything else you get what you pay for.

I have made the change to Ceramic EBC and Hawk and have never had another issue with pulse. I had it start on the SS but it wore away as it was just material on one spot of the rotor that cleaned up after some hard stops. I also am sick of the dust on my SS so I may go to the EBC reds soon.

 

I hope things are going smoothly today. Please, let me know if they were able to get this resolved for you.

Michelle, Chevrolet Customer Service

 

I got the car back from the dealer today and I am less than pleased. The tech "looked" at the rotors and said that they didn't look good and needed to either be turned or preferably replaced, and the pads aren't very good and would merely cause pulsing again (the pads are new Wagner Thermoquiets). Just turning them is $139. I told them to just put it back together as I could replace both rotors for less than that. I also fail to see the sense in paying to put notoriously cheap GM rotors on the car.

I think they merely didn't want to touch the car unless they did everything themselves. I don't even think they checked the right hub runout. At least I greatly appreciate the fact that they didn't charge me anything. They said that since they didn't do anything there is no charge. I was expecting a diagnostic fee or something. So I'm none the worse at this point.

I decided that since many seem to recommend the NAPA Ultra Premium rotors, I'd buy a set and mount them and then see what the runout is as they are guaranteed to be .002". If I mount the one on the right and it is still out of spec which is what I am expecting, then let them tell me that the rotor is the problem. I also bought a set of NAPA's best brake pads, the Adaptive One ceramics. I'm planning on putting them on in a few days and we'll see what happens.

 

voigtsga-

Good luck with that, & be sure to 'bed the pads' as recommended..

I still have no complaints on my oem rotors..(hope I didn't jinx myself)..

 

Like he said bed then in properly as most auto techs do not do this.

The first mistake is many want to blame the GM rotors as cheap, They are to the same satandards as any other on the market. The real issue is finding the cause of the issue. This is where bearing bedding in is key.

Also the bearing play is also key as it takes so little to be out to cause issues with todays brakes. The major issue is few techs ever check out hub play. If the bearing is out a little it is going to wobble and you will have issues again in 5K-7K miles.

I have not had issues in years just by checking the hubs and bedding in the pads.

Note the techs do not want to do just part of a brake job as if they do it all they can take responsibility for it. If you do part and they do part it could turn into a bunch of finger pointing.

Best to do the whole job yourself or just let them do it all.

The greatest key to brakes anymore is just because someone can change the pads does not mean they know what all needs to be done or checked for a proper brake job.
Many goo mechnaics that have not kept up make a lot of mistakes anymore. Things are not like they used to be and new things are important for long good brake function.

 

I have learned to bed in the brake shoes whenever putting on new rotors/pads. I did this with the rotors I have on the car now. Thanks for the reminders however.

I am beginning to think that a big part of the problem is that the braking system is simply too small for the car. I've read long, long threads about people who have repeated braking problems with HHRs. No other car I've owned has ever had issues like this.

If it wasn't for the fact that the hub bearings are under the powertrain warranty, I wouldn't go to the dealer at all with this. I don't want to pay $200+ for a hub that is under warranty. I've worked on my own cars for over 20 years, and I'm not going to pay the dealer 3 times as much to put rotors on the car when putting on pads and rotors is a stupidly simple job. If the new rotor still shows excessive run-out, then there will be absolutely no doubt that the hub bearing is at fault as there is simply no other possibility. I'm planning on putting them on Monday morning so we'll see what happens.

 

If you are not anti-chinese you can get new front hubs for $65 or so. In the 70's I used to run Karmann-Ghias 40K a year same problems with "rotor warping", but they ran around $200 each back then, it was easy to ignore.

And please check the rear bearings.