Wheel offset... What determines it??
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 935
Likes: 2
From: Beverly, NJ
Wheel offset... What determines it??
What exactly is different in 84-87 vettes that makes the offset different of that on an 88-96 vette? Is it the rotors? This offset thing is really racking my brain. Thanks!
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Believe it is in the design and size of the control arms after 1987. The 84-87 cars use 38mm offset wheels and the 88-96 cars use 56mm offset. The 88 standard wheel was a 16" size and the 17" wheels were an option but the offset was the same for both.
The hat thickness of the rotors is different over the same years but the diameter changed at the same time. That may be because of the differences in the suspension.
The hat thickness of the rotors is different over the same years but the diameter changed at the same time. That may be because of the differences in the suspension.
1st Gear
Joined: Dec 2004
Posts: 1
Likes: 0
Wheel Offset
Imagine you are sitting in front of your car, and you can see through the bodywork, and into the suspension. Draw an imaginary straight line from the center of the upper ball joint through the center of the lower ball joint, to the point where this line intersects the ground. The distance from this intersection point to the centerline of the wheel, as that centerline is projected vertically from the centerline of the wheel to the ground, is the offset. If the centerline of the wheel is outboard of the contact point of the imaginary line and the ground, this is positive offset. Negative offset is the other way around. This is what an old MGA SCCA racer from the '50 once told me. Can't say if it's true or not.
Drifting
Joined: Oct 2004
Posts: 1,477
Likes: 80
From: Hawaii
From what I understand on offset is the amount of rim (wheel) back spacing. A 38mm has less back space than a 56mm rim.
The way that they figure the back space is, say a 11" inch rim, get the centerline point which is 5.5". They add the 5.5" and the 38mm, and the rim lip say 1/4" = total back space.
This would mean that the 84-87 mounting position (rotor) is more inward than a 88-96
The way that they figure the back space is, say a 11" inch rim, get the centerline point which is 5.5". They add the 5.5" and the 38mm, and the rim lip say 1/4" = total back space.
This would mean that the 84-87 mounting position (rotor) is more inward than a 88-96
