Len Sholes

Has anyone any feed back on the Power slot rotors. I have a 07 HHR with 53000 miles and have had the dealer turn the rotors twice and install a set of pads and it is now back doing the famous chatter again so am wanting to install something that will last and elimante the chatter. I would be interested in any comments that you have on these rotors.

hyperv6

Might so a search here on rotors as they have been debated often.

This is the basics of it all.

The pulsing or as you say chattering rotor is one of the biggest misunderstood issues.

The truth is it is often a bad hub bearing with too much play that created what is called Rotor Variation Thickness. This is not warp but a uneven wearing of the rotor that creates a variation of the thickness of the rotor.

The hub having .001-.002 of play will create this issue.

Also brakes can create hot spots and areas of the rotor where pad material will stick to the rotor in one or several spots and make the gripe uneven making this pulse feel.

Generally Rotor do not warp but they can distort with uneven lug torque on the wheels. Most take 100 FT LS. If you crankem harder they can distort a rotor.

As for rotor quality it is best to stick to the OE as they are as good as you will find. Some after market rotors can use less metal and this robs the rotor of metal that works as a heat sink.

Look at the fins in the center and see how much space between the two side there is. The less space means there is more metal. Most name brands are to OE spec but some of the cheaper imports can put more space and make thinner rotor surfaces. This just makes the brakes fade faster due to less heat transfer.

Also holes, slots and dimples are cosmetic. In the past they did out gas the pads and save unsprung weight. But the new pads do not out gas. And again holes and less surface will only give less metal to absorb the heat away from the pads.

I would have the hubs checked for play for the most you should not feel any and the mechanic can put a run out gauge to see how much you have. Also I would use a good quality name brand pad. You pay $20 for a set of pad you get cheap pads. With good pads they are not cheap but the more expensive ones will use better quality materials.

The Pulse and Chatter is a common problem on many vehicles today because of the type of Ball bearing hub they all use. THey are used for more MPG but they do not last as long and can be damaged more easy vs the old taper bearings. GM, Ford, Honda, Toyota, Hyundai, Chrysler etc all have this issue with most of their hubs.

The hub play is something even many good mechainics never check but should.

As for thw Power Stops they should work fine if everything else is in spec. My company sells them. But keep in mind a OE quality replacment is cheaper and will work just the same if not better if it is a solid rotor. My work also sells Bendix OE replacments and that is what I will use on my when it is time.

The key is to fix the real cause the hub or rotor surface and not the symptom which is the uneven worn or hot spotted rotor.

Len Sholes

Thanks hyperv6 for your reply. With regards to your reply I have to ask you this, if what you say is correct about a loose wheel/hub bearing them why don't you get chatter or pulsing with cold rotors. Mine only start to act up after using them on a long hill or after they get hot from a lot of stop and go city traffic, once they have cooled they are OK again. If like you say the bearing is loose wouldn't this dimension decrease as the hub heated up? I had a 92 Cadillac with the same problem and once I changed the rotors to an after market heavy duty one I had no more problems.

voigtsga

I bought a dial indicator, but am not sure what surface to use to check the hub bearing play. Do you check against the rotor surface by the lug nuts, or do you take off the rotor and check against the rotor mounting on the hub surface? Sure enough now that I've been driving my '07 more, I've noticed that it does have some brake pulsing. Its not real bad, but it is noticeable. I've got 65k on the car, so I want to make sure I know whether or not the hub bearings have too much play before I go putting on new rotors/shoes.

It goes without saying that even though the hub bearings are covered under the Powertrain warranty according to the list in the sticky, I don't trust dealers to do the right thing and replace them if they are going bad. I'd like to go there armed with having measured them first if they are bad. If they aren't, then I can just go ahead and replace the rotors/brakes.

hyperv6

Odds are it is the rotor surface has pad material embedded in it. Some pads can get hot and leave material on the surface when you stop and this will make a spot that will grab or chatter the brakes. Heat on the rotor will effect the grip of the brakes and when it is cold you do not have the grip you would have till they heat up.

Might try a Ceramic pad of good quality.

Often a hard stop on a off ramp will get the pads and rotor hot. When you sit at the light with the max temp the clamping force on the pads will help transfer the material into the metal. It does not clean off with a few stops. Some time it may get better but often it will only get worse.

Changing the rotors will remove the spot just as if it was turned.

Odds are the time on the caddy was cleared up due to better pads were installed would have to be my guess.

The whole thing boils down to heat transfer. You need remove the heat from the pads and let the rotors soak it in and disipate it.

hyperv6

You need to mount the indicator on a solid surface and then pull out and in on the rotor to checl the pay. .001-.002 is not much.

In the past you wanted the rotor to have a little play to kick the pads off but that is no longer required.