The final solution was the right front rotor. Once I replaced that, my braking became smooth again. Thanks for all the help.

 

A new friend told me they had an HHR and loved it but couldn't keep the front end from shaking when braking so they got rid of it. There is a simple fix. I found it by trial and error but have owned several and hightly recommend it. Here's the problem. The toe-in factory specification is incorrect. They actually need a tiny bit more toe-in. It stips the shimmy and clears up the uneven tire wear. It only needs the slightest tweak, and it isn't easy to get the alignment shop to go outside the spec but it works. I believe the problem is that the alignment is too close to centered. It begins with a slight wobble that causes a minor slapping of the front hubs against the pads. This creates hotspots that cause warping of the rotors. The warped rotors creates more shimmy and before you know it the problem is out of control. The heavy shaking damages the rubber bushings and wears tie rods and ball joints and after an expensive repair it all starts again. Upgrading the hubs can help but they still wear the tires funny and the problem eventually returns. The only factory adjustment for alignment is actually toe-in, and they aren't quite towed in enough. Of course there are many things that can get blamed (rear brakes included) but all of those problems are exacerbated by the original problem. The scalloped side wear actually quits when toe-in is moved one more point past the inside limit of the toe-in scale. It won't fix the warped rotors and repair other damaged components but it will prevent it from happening again. (Just turning it in a bit will actually reduce the shimmy from damaged rotors, but will not reverse the damage) I've done it on four HHRs now.

 

Warped rotors are best addressed by properly adjusting the rear drum brakes and upgrading the front rotors and caliper brackets to SS non Brembo 11.6 inch rotors. I’ve done this to several HHRs and it cured the brake shake

https://www.chevyhhr.net/forums/brak...ard-hhr-42938/


and some go to the extent of swapping the rear drum brakes for SS rear disc brakes

 

I spent $2700 replacing control arms and bushings, rear brakes, front brakes and struts, all the same day, but at the same time I asked the Goodyear service manager (Retired GM service manager) to also increase the toe-in and explained my experience with it. He did. Problem never returned. It often returns according to my experience and my review of the recurring statements by people looking for solutions. I now start with adjusting the toe-in and replacing the rotors on the used HHRs I purchase. I no longer have a shimmy problem. One member noted that his car doesn't always shake. It will not shake if the engine is assisting in the braking. You can actually prevent the shaking by downshifting to third (as if when exiting a freeway) The engine deceleration seems to pull the front of the tires together (increase toe-in) and I have read that acceleration decreases tow-in (lengthens distance between the fronts of the tires) on front wheel drive cars (coming from the race drivers dealing with oversteer and understeer).

Slightly increased tow-in also reduces the need to rotate and balance on the HHR. I never rotate and balance anymore. The rear tires last at least twice as long as the the front tires so I just replace the front tires as needed.

Saving brakes: I'm not reccommending this for every driver, nor for wet or slick roads, but I live in hil country and often gear down one notch when going downhill, exiting freeways, or in other situation where there is a long stopping distance involved. I prefer compressing air in lubricated engines to replacing brake pads, rotors, shoes and drums. It also reduces potentially harmful brake dust to the atmosphere and build up on the wheels. Watching people apply the brakes on long downhill runs doesn't make physics sense to me. Just remember that it should only happen on dry roads. This also transfers braking friction to only the front tires on the HHR (and other front wheel drive cars) causing the front tires to wear down quicker and the rear tires to last longer. I replace front tires twice as often as the rear, but never need to rotate or balance. All methods of braking causes friction between the tires and road, so the amount of overall tire wear remains the same. Gearing the HHR down one notch results in a smooth downshift and transfers more wear to the front tires.

 

Easy to gear down with manual transmission, not so much in an automatic. Never balancing tires is not recommended as the balance effects tire to road surface adhesion, depending on the amount of weight the tire is out. Most of us drive in multiple weather, sun, wet, snow and ice, having your car in good condition and safe is highly recommended. To each their own,

 

If the rears last twice as long as the fronts something is very wrong. I rarely rotate and usually need a full set a few thousand miles past the warranty. I do keep the rear brakes adjusted.

My personal experience (more than 400,000 miles) with the "brake shimmy" is the LCA bushings and rear brakes out of adjustment. As an experiment, I loosened the rears up a bit lots of shimmy, tightened back up no shimmy, also more shimmy when the rears are too tight. YMMV.

 

I drive lots of highway miles and they often result in better rear tire wear and always have. I also remember getting 100,000 miles out of the original rear brakes on a 1991 Impala that I drove almost all highway commutes in Southeast New Mexico because brakes were rarely used. Front wheel drive cars wear the frontvtires on accelleration and braking. Not so back tires, but if you rotate them you don't really recognize how much more the fronts are wearing. I never rotate.

HHRs have been shimmy shaking since forever with some people experiencing it as early as 5000 miles and taking it back to the dealer again 5000 or so miles later after the warranty repair.
Worn or improperly adjusted back brakes and other worn parts can definitely cause shaking, and put more wear on the front brakes, but I think the improper tow-in is the initial culprit that leads to many of the other necessary repairs. For instance, if the front is shimmying you can bet more brake pressure is going to be required to stop. Some of that pressure is going to get applied to the back brakes causing them to wear, and we probably couldn't build a much better bushing destroyer than shimmying the front wheels of the vehicle. I have experienced the "...starts as a tiny vibration shortly after new rotors and pads and gets worse over time..." described by one member. One retired GM engineer (I think I remember) even suggested replacing the caliper brackets and rotors with the ones from the HHR SS because the brakes were under designed. I haven't experienced weak brakes since eliminating the shimmy with a small toe-in correction and it requires no expensive parts.

Gaylon Ponder