Finding Centerline 72 GTO GM A body to square up rear end

[Mark Yacavone]

Originally Posted by FED 387

supposedly in all GM A-Body cars the engine is installed on the centerline NO offset from the factory --HOWEVER the pinion center was offset 1/2 inch to the passenger side of the vehicle--- not sure but what has been said-- might want to google it see what you can come up with

I thought is was 1 inch but one of the reasons is it centers up the mechanics of the diff
and makes both axles the same length.

[Gary Evans]

Originally Posted by Mark Yacavone

I thought is was 1 inch but one of the reasons is it centers up the mechanics of the diff
and makes both axles the same length.

It also makes a difference if it?s a bbc or sbc. BBC is offset to the drivers side for access to the heater core. Bb cars also have a different heater core with 90*fittings

[L.Fite]

Big Block Camaros are offset to passenger side...

[Greg Reimer 7376]

I now wonder if drive line C/L off set varies between models and even within models dependent on engine/trans and whatever else options may exist. If so, there probably is a factory spec for drive line offset somewhere. I've never heard of such a thing, but anything is possible. They probably don't want to crawl under cars in a line on hot pavement with some kind of center finding device in order to determine the center line of everybody's drive shaft.Let's hope they don't think of that next.

[FED 387]

GM started with the centerline of the car then offset the diff 1/2 inch to the right---because of all the available engine combos for this body they moved the Big Block engines around with engine mounts that were unique to that particular engine used ---small blocks used the centerline of the car and maybe a big block Olds might use a different motor mount on the frame than a small block Chevy would use.. It all depends on the specific engine being used whether it is a Buick- Olds -Pontiac or Chevy --SAME frame just different engine mounts and/or holes on the frame to correspond to the particular engine being used NOT the mount that bolted to the engine---that's where the off set comes in--- its the frame mount not the engine mount---Make sense?? FED 387