SVThis

A friend of mine just bought a 2011 5.0 with Brembo Package and 3.73's. The question I have is, can you legally downsize to an 18" wheel with the same width and offset and still be legal in SCCA F stock? I should know this but I don't. Thanks for the help. I get to co drive the car this season. Should be a hoot.

Sam Strano

No. Must run 19x9's, offset between 36 and 48 to be legal. And 3.73's are not the gear you want..... I have (and found out that it's best to have 3.31's unless you are running postage stamp lots.

Signed,

Sam 2010 FS National Champion in a 5.0/Brembo car Strano

jahudso2

The tire diameter plays a huge effect on overall gearing though. Sam do your auto-x tires measure the same height as stockers, or are they shorter? If you have shorter tires, his 3.73s might be equivalent gearing with stock height tires.

Sam Strano

My tires are shorter than stock... but if you want to be competitive you need R-comps, and I was running the tallest tire I could. Which means any other car will be on the same tires, but with the deeper gearing too.

SVThis

Thanks Sam. What's second gear with 3.73's good to mph wise?

Sam Strano

You'd have to run numbers on the tires you will be using. My car w/3.31's on 265/35 or 295/.30-19's is good to right @ 65mph.

SVThis

Since I'm most familiar with 4th gen F bodies, I was wondering how much negative camber you can get from a stock S197 chassis?

Sam Strano

No adjustment in stock form. There is a Ford service procedure that gets you some adjustment which would put you at just about -2.

justjim

Check this... http://i319.photobucket.com/albums/m...-ratios_97.jpg

The 3:31 is the ratio of choice, unless you like lots of shifting on an autocross course. My 2006 with a 3.55:1 axle works pretty well on the autocross courses I run on, and the (2011 with a 3.31) is about the same as a (2006 with a 3:55).