4th Gen Rearend

[Mike Mans]

Here's my question: The rule says it must be a stock width rear end with all of the details everyone has outlined. I've searched the classification guide high and low and I can't find anywhere that they note just what a stock width rear end should be for every car in competition. Anyone able to point me to that? If it's not documented in the NHRA classification guides at this point - it seems like a pretty unenforceable rule.

[Michael K]

Classification guide won't have this info.


The rule book talks about wheel base. Since there are production line assembly tolerances, there is an allowable variation from factory specifications (I can't recall exactly...3/4 inch?). The rear axle width is not addressed, other than stock mounting points and stock width (between backing plates) must be used. I have factory rear housings that vary up to 5/16 inch for the same model of car.


In the spirit of the rules, it would seem that the factory tolerances should be factored in within reason. When asked, division tech would only say that they would not allow stock mounting points to be moved.

[Rob Petrie E395]

Since no one posted it. On a 4 gen F body. If you have a stock length rear end. Using a 10 inch wide wheel you need 7 1/2 inches of back space.

[mannymen]

The trick is to use an 82-92 F-Body “STOCK WIDTH” rearend. It’s a complete bolt-in for a 93-02 F Body. The 82-92 is approximately 4” shorter than a 93-02 rearend. This is what u r seeing in the pics u posted. Now you can use a 15x10 wheel with a more common 5.5 backspace.