Hi, hope this is the right place.

New (to me) 2011 HHR.

Wheels were balanced, alignment done.

Above 60mph there is a vibration. Frequency is akin to driving on a rumble strip, but a lot less "volume". Just an ever so slight feel in the ass and wheel.

And, it's intermittent. Seems to start after a few miles at speed, and then sometimes it goes away for a (short) while....

Riddle me that one Batman......

 

Bad Balance or lost wheel weight.

Bad wheel mounting, especially if you have aftermarket wheels. Some aftermarket wheels do NOT have the relief for the production washers that are installed on the rotors (generally 2). If this is the case, remove the wheel and then remove the production washer that is in tight contact with the rotor and drum, and reinstall the wheel. The washers are thin metal and can be cut or pulled off.

If the vibration started just after the work you listed, the problem would need to be something in that process.

You are not speaking of vibration when applying the brakes....correct.

 

Check to make sure your lugs are tight....just a thought

 

You don't give the car mileage or the tire mileage.
My guess. If the tires are balanced and alignment is good. Maybe a bad strut or shock. Or a tire slightly out of round. Long shot: a warped rim

 

Factory steel wheels with genuine plastic covers.

23k Miles, tires look original.

Vibration was there before they balanced/alinged which is why I made them do it.

I don't suspect the wheels because that would not be intermittent......

 

I went round and round on this awhile back..different rims..tires..balancing ..didnt quit until brakes were changed..suspect rotor out of balance, no they werent pulsating. Only thing left after that would have been hubs....

 

Ah yes, forgot, brakes not pulsating. But new rotors may still be the ticket.

As I said, it's intermittent, so there is some sort of harmonic vibration going on.
If the rotors are part of that "game" then replacing them may break the chain.

I'll think about it.

 

For grins and giggles..if you are feeling it in the front do a rotation first to confirm its NOT in the tire/wheel package...if its still in the front then look at rotors..

 

Is it an automatic? If so you could be experiencing a torgue convertor shutter. It would be intermittent and fit your symptoms.

 

I like the rotation idea.

Yes it is an automatic. Tell me more about the torque converter shudder?