I have a 2009 HHR SS with the Brembo front breaks and the rear disc breaks with the solid rotors, I am looking to update the rear Disc Break Rotors with 2009 Cobalt Vented rear rotors I am looking for someone that has done this swap I think if I buy new cobalt rotors and calipers they might fit on my factory rear Axle Beam. Can someone give me some direction ?

 

They are probably the same item, unless you mean drilled. Vented BRAKES is the vented area between the braking surfaces.
Are you planning on road racing? Otherwise there is no benefit past appearance for drilled rotors, especially the rears. The rear brakes do about 10% of the stopping.

Some Cobalts have 4 lugs.
Why not just buy drilled and slotted rotors made for your SS?

 

RockAuto has them.
Ask me how I know

 

Yes we are going to auto cross the SS and need the better rear rotors any help would be appreciated

 

Well, then Lonwane says Rockauto has them, if they do then others do.
Why would Cobalt brakes be better? it is a lighter vehicle.
Try GoOgle "autocross brake rotors".

 

HHR SS rear rotors are solid metal , the Cobalt SS rear rotors are vented.
I’ve always thought 14” rotors up front from ZZP and 12.6” rotors in the back also from ZZP with Brembo calipers. In race trim who needs emergency brakes?

 

Yes that would be real nice but ZZP just don't want to sell them at a fair price we are trying to stay within a budget we were told several guys have used the Cobalt SS rear vented rotors and calipers and the breaks last a lot longer with the Cobalt set up and will improve the breaking I don't know but thought I would ask you guys and see if you could help me understand if these parts will fit on my HHR SS ?

 

B-r-a-k-e-s

 

They’ll fit others have done it.

 

OK, who knows for sure? What's the difference between HHR SS brakes and Cobalt LNF brakes? I heard something is large diameter, but I don't remember if it's the front rotors, or the front Brembo rotors, or the rear rotors.