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

[rallye bob]

Originally Posted by CraigG

Hey Everybody,

I'm trying to find centerline on 72 GTO With stock frame for measurements

Would it be halfway between?

Outer rocker panels
Center of transmission or transmission crossmember
Center of stock frame

Thanks, Craig

https://www.chevelles.com/media/68-7...ensions.15066/

[Troy Henderson]

Originally Posted by rallye bob

https://www.chevelles.com/media/68-7...ensions.15066/

A nice way to do it is to use the holes in the bottom of the frame shown in the link above. Then, you can drop multiple points down with a plumb bob to the ground on both sides. Measure across to get centers than take a string or laser and draw the centerline thru them.

[Hacksaw]

Pretty sure the engine centerline is offset to the pass side by 5/8".

[Mark Yacavone]

I seem to remember that the factory shop manuals had those frame directions in them. If I am recalling correctly then the GTO material should be easy enough to find.

[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

[CraigG]

Thank you guys - very Helpful!

[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