alright so a i have 2007 hhr lt 2.4 liter and i'm getting a mechman 240 amp alt which has a smaller pulley so need a smaller belt. I was talking to summit racing to see what my belt size was and that i ether need a .5 inch or 1 inch smaller belt and they said depending on the shape of my ac compressor my factory alternator belt is ether a 40 inches or 40.5 inches is there any easy way to find out would the vin number help ?

 

The tensioner should take care of a half inch.

 

My thoughts too Don, I can't recall any pulley size differences based on whether the compressor is the Sangean(sp?), or the Delco unit.

They take different clutches, but that's it I believe.

 

ttN will not help !!!

Suggestion.......difficult, but can be done if you are careful and precise.

Use a ladies sewing tape and stretch/string it around the existing belt of the car. You could also use string or another idem and measure it afterward. However, understand that this provides an outside measurement.

 

Easiest way is to buy 2 belts. One 1/2" shorter and one 1" shorter.
Once you change out the alternator, one of the 3(counting your current belt) should fit. Then just return the one(s) that doesnt fit and exchange it for a backup spare. I always keep a spare belt in all my vehicles for emergency's.

 

I'd go with firemangeorge's suggestion on this one