Question about rearend gearing for my situation

JT15601

Registered User
I have a 1989 sc i got not too long ago. 5 speed transmission stock rearend. I dont know exactly whats done to the car besides and exhaust and a tune but its doing 0 to 60 in 4.5 seconds which im pretty sure is a lot quicker than stock. At any rate, I was told the stock rearend is basically a ford 8.8 center section with IRS and 2.73 gears. well i dont like the fact that my car will do 145 in 4th gear and 5th is just way too high to use. Ill go out and say it im into a lot of like casual street racing (i know its illegal) i really cant help it. but i dont need the car to do more than like 150mph. i want better acceleration in 3rd and 4th gear. but i dont really know if having to shift to 3rd to get to 60 will effect the 0 to 60 time if i put a lower geared rearend. so basically what gearing should i get? i heard most people use 3.08 and theres also like 3.23 (or close to that) and 3.73 which i heard is like really slow. so idk what would be best for me. any suggestions?

Thanks, Jake
 
and will my speedometer be off if i change the final drive gearing?

If you don't change the speedometer drive gear, yes.

If you pick up a 3.08 or 3.27 out of the boneyard to rebuild / add a TrakLok or equivelent to, grab the VSS out of the same car.

If you don't, there's several places that sell the VSS drive gear to compensate, you just need to figure out which one you need.

As a note - the aluminum Mark VIII diffs came in 3.08 (standard) or 3.27 (LSC).

The 3.08 and 3.27 TLs came on auto MN12s. A 3.31 came on late 1994/1995 SC autos (and possibly others.)

The diff codes (for the door sticker) can be seen at this link.

(Note: The two vendors I link to are in my metroplex, that's all. There's a bunch of OTHERS that sell the gears - Summit, Jegs, the usual suspects.)

RwP
 
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