swap 3.90's for 3.73's???

SaleenGT2001

Well-Known Member
Jul 18, 2005
2,811
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Four Oaks NC
i have a friend that works at a ford dealer. they got a car with 12,000 miles complaining of a whine in the rear. they replaced the gears which were fine. anyways he will give me the gears for free. while i have the rear end apart should i swap out my 3.90's in favor of the 3.73's. i know i will lose some 1/4 speed, but i like to play on the roads a lot better! i just hate having to shift out of 4th gear at 115mph! i get my doors blown off every time i go to 5th gear. i was considering 3.55's but i'm not sure.
 
I dont know. It seems like there is a very small difference between 3.73's to 3.90's. Most people say that the difference between 3.73's and 4.10's isnt that big either, but obviously larger.

I know someone who is putting 4.10's in his blown GT, hes making a little less power than you are. Hes aiming to get the gears done by Mustang Week.
 
I used to think there was a small difference between 3.73 and 4.10 until I drove a car nearly exactly like mine with 4.10's and holy crap it was crazy. I felt like I didn't know how to drive lol.. Downshifting was the main difference I noticed tho
 
So having not driven in a re-geared car except for once, but it was a 5.0 LX, I will ask how big of the ass dyno factor comes in when switching from stock gears to 4.10's.

How much of a difference? I know someone going 4.30's in their auto GT, 4.10's in their blown 5 speed GT... People with 4v's going 4.30's and higher. Damn!!! I would like to be able to comfortable cruise down the interstate at like 70 without taching really high. I would also like to be able to rip balls off the line, which is a MAJOR flaw with stock gears. Trying to punch it from anything below 3500 RPMs feels like a waste of gas to me.
 
i like top end better than out of the hole performance. you will NEVER get me to even consider anything over a 4.10 in a 5 sp blown car. i think that the 3.73s would be more fun. i have PLENTY of power for the street so really low gears just make me spin a lot more!