Doc brown

Of course there has been much discussion and debate over the issue of pulsating brakes. Conventional wisdom is that the rotors are warping. I've never bought into that myself, but I've also never been 100% convinced that 2mm of bearing run out can cause the issue over a long period of time. If 2mm is that hard on the brakes, why don't we feel at least some pulsating when new rotors and pads are put on? And why does changing or cutting the rotors fix it, at least for a period of time? It really doesn't make a lot of sense to me. Now before anyone gets offended that I'm challenging their knowledge or experience, please read on and then think about it.

My rotors were cut and pads replaced once under warranty. The second time, in Oct of 2009, I replaced them myself with Napa Premium rotors, and "mid-level" safety stop brake pads. Almost exactly 10k miles and a year later, the pulsating came back. It got pretty bad so I reread the threads about bearing run out and considered all my options.

Then one day on the way to work (early November) I was in one of those hairy situations on the freeway where I had to hit my brakes really hard. In that split second I got scared because I didn't know how the pulsating was going to negate my ability to stop. Guess what? It was smooth, firm, and safe. I was very surprised. So I began to experiment a little. I started waiting an extra second or two to apply brakes, then hit them harder. It still pulsated, but certainly was better than gentle pressure. As time went on it seemed to get smoother, which of course I was not expecting.

This week I can confidently say that the pulsating is gone. No matter if I press the petal gently or hard, no more pulsating. In my mind that completely throws out the warped rotor theory. It also makes me wonder even more how the 2mm bearing run out could be in play here. I'm going back to what I said all along, that something about the brake design is causing the pads to get too hot and are leaving material on the rotor. Firm braking prevents this because they are applied for a shorter amount of time and generating less heat. Cheaper pads? Maybe, its been discussed before. I didn't use the NAPA Premium pads, I just didn't want to shell out $90 in case they'd get replaced again anyway. I would love to try good quality semi-metallic pads to compare against the ceramic ones, but no one makes good ones for the HHR. Unfortunately, I also don't have 6 HHRs to test out these different thoerys on, and waiting a year or more isn't practical.

Again, I'm not challenging anyone's experience or expertise here, but I did want to share what's been happening and see if anyone has a thought as to why this happened. Of course I'm thrilled that I don't have to spend any money on it.

LawDog88

Interesting note there, Chuck.

pontiacgt02

I also bought the Napa routers but I also purchase the medium grade pads, i have very little if any pulsing now. I have also notice to if i have a little pulsing and hit the brakes hard it does go away. Also spraying the brakes with high power wash to clear the dust seems to help also. So there is some logic here. Glad I'm not the only one noticing this, but just for the record everyone is having this problem no matter what brand of car. I have a friend who has wife who has a honda Pilot and her brakes are pulsing with just about 20,000 miles.

Old Lar

The only time I've had pusating brakes (not in the HHR) was brake rotors warpage. Or maybe something with the anti lock brakes. I've had no pulsation with my HHR and I'm still on the original brakes at 76K miles. Mine is an '06 and came without anti lock brakes also.

the_shmoo

Good point Doc brown. I have a 97 Saturn and when I returned for service the mechanic suggested when applying the brakes (on a light car) to apply with extra force (no lock-up) as this cleans the pads and rotors eliminating pulsation. It has worked for me for 10 years on the Saturn and 4 yrs on my HHR.
Take it for what it's worth.

843de

Yeah Doc I think you were/are experiencing a condition where some of the pad material is deposited on the rotor. I had this issue with the stock pads and rotors and went down the whole resurface/new pads route only to have it crop up again. I found that an occasional hard stop would clean the rotors and calm things down for a day or two. Since the change/upgrade to NAPA rotors and full ceramic pads the problem hasn't returned and my stops are smooth as glass. Even though I was pounced on before for saying this, our beloved HHR's are under braked from the factory in my opinion.

hyperv6

Yes you had material on the rotor.

Often a hot rotor will pick up material after a hot stop and leave a pad material deposit on the rotor. It will grab in that one spot and feel like it is the so called warp issue.

It can go away depending on how much material is on the rotor and how abrasive you pads are to clean it off. Sometimes a hard stop will do it. Or sometime just more time and use will wear it off.

After hard stops at the end of a off ramp or the like I will often try to release the pads so they are not clamping hard on the rotor and transfering material to the hot surface.

As for the bearing being out it does happen and is much more real than the so called warp issue.

More often than not the the material embeded it a common issue. Many times it will not go away unless you clean or cut the rotors. Some people will even put on very abrasive pads to clean the rotors off and remove the material after track time.

What you discovered is on many of the brake web sites tech info. I really recomend to read or visit many of these sites. Bendix even has some really good videos that show you what happens in the pad material issue and the Run Out wear.

Cheap pads are very prone to the material sticking on the rotors.

Brakes are a very misunderstood item and many people really need to read up on present problems and technology. Things have changed a lot on braking systems and materials.

You also get what you pay for.

Note seating in pads is very very important also helps prevent the material from sticking as the entire rotor will have material evenly spread on it. This will prevent a hot spot or a place where it will grab the pads every time the rotor goes around.

No mystery here just info people really need to learn.

Doc brown

Hyper I hear what you're saying, and I've said that the issue is caused by pad material since I've been on this forum. However, I backed off a bit when the run out issue seemed to be the agreed on cause. After my experience, and reading lots of other threads on various other forums, and reading a lot of manufacture info, I believe that the bearing run out issue, while very real, is also quite rare. I'm starting to think that even if one has cheap pads, replacing the rotors or hub is an unnecessary expense. Seating pads is critical, so maybe I just didn't seat mine properly. Admittedly I don't follow the so-called "correct" procedure. A short drive firmly apply the brake 5 or 6 times is how I do it. Yes, things have changed a lot in brakes, but not so much in cars and trucks in the last 10 years or so. I've followed this bedding procedure on my 2003 Trailblazer, '99 Catera, '00 Pontiac Montana, and daughter's '98 Lumina. Never had the same issue as the HHR. And I've used cheap pads from time to time as well. The mystery is why is the HHR so prone to this?

hyperv6

No you are very correct on the pad material sticking issue. It may account for 3/4 of the complaints. The bearing issue is not rare. Just look at how many failed bearing we see here and they do not account for the ones that should be replace but are not making noise.

Now often the times where rotors are tuned and you hear the lath cutting on and off. People assume that is warp. The truth is that is Rotor thickness variation.

Too often today cars are getting the embedded material. Like you if it is minor it will go away but too often it will not.

Higher brake temps. Smaller lighter brake rotors tha retain more heat and too often cheap pad material can really take a set in the rotor surface.

In the past here I discribed it as like spilling coke on the kitchen floor and then trying to slide over the floor in your socks after it dries to the floor. It will grab and stop the slide. Well the pad material is doing the same. Clean the coke off the floor and all is well. Same for the rotors.

Bedding is a major key. Since I started to bed brakes properly and used quality pads I have never had an issue since. I am not alone and I am not the only one who knows what to do. The information is out there but so much other poor info is too. I am not any smarter than anyone here just in some cases better informed. It is important to keep up with todays cars as they are changing faster in technology than many realize.

As for this being a HHR issue it is not. The brake complaints are on most web sites. I see it on Honda, Toyots, Ford, GM,Chrysler and many others. The same complaints and often the same advice that seldom addresses and corrects the issue.

I just did the brakes on my 04 GTP last week. They went around 50,000 miles and nary a pusle. I went with Hawk pads and Bendix rotors and seated them per Hawks recomendation. I should be good for 60,000 more miles.

I did away with the slotted rotors. I hated the noise. I only used them for looks and it was not worth the noise they make and I feel they cut down on the miles I normally would have gotten out of regular rotors.

Either way you have the right idea. I just preach bedding the pads in. THat is key. THere is more than one way to do it but the key is to do it. So many fail to.

sleeper

Another often overlooked aspect is adjusting the rear brakes properly.
If they are out of adjustment, then the fronts have to work extra hard.
Because they have self adjusters does not mean they are set to proper adjustment, as I found out when I pulled mine apart to clean, inspect & paint the drums & calipers.

I'm still on stock rotors/pads, shoes & drums & stop smooth as glass..

Edit: When I'm at a stop light, I throw it into neutral & get my foot off the brake pedal.