Is there a noticeable performance improvement going from the stock 3.31 to a 3.73 rear? Is it worth the money?

 

You'd be adding 12.7% more torque multiplication to the wheels so your car will feel faster, though the actual 1/4 mile ET and trap may only marginally improve.

 

Do you have an auto or manual? It has been pretty much established by many users that 3.73 is the best overall gear for an auto and 4.10's are the best overall gear for the manual.

 

One of the first mods I did on mine was get rid of the 3.31's in my manual for 3.73's. You will notice a difference, you will like it, and you will wonder what idiot at Ford though even putting 3.31's in this car was a good idea.

While I like my 3.73's it seems like I could have went 4.10's and been perfectly happy as well. The old general rule was if you thought you might add boost them 3.73 was the sensible option, if not then 4.10's are the way to go (again, for the manual)

Long story short, just do it.

 

Probably the same idiot who thought that 3.31's would be good for highway fuel mileage so that Ford would meet ever more stringent CAFE standards.

 

When I went to wider and shorter tires for road course track days, the difference was very close to what I'd have got by swapping 3.55's out for 3.73's and staying on OE-height tires . . . and even that was clearly noticeable. I can't imagine anyone not noticing the change from 3.31's to 3.73's.


But there is a downside. You are forced to shift at lower speeds and I'm getting very close to having to shift up to 5th down the main straights at my home track (NJMP). 3.73's make having to grab 3rd at autocross more likely, which kind of sucks for that activity. Could be that some of Ford's powertrain engineers spent some of their spare time on the kind of tracks where the corners are driven at least as hard as the straights instead of where there's just one slow turn onto the return road. It's even worse for the guys with MT-82 transmissions.


Norm

 

I love my 4.10's and run a 275/40-18. I am looking to go a bit larger for the tire. Right now my gears max at red line at these speeds:

1st - 37 MPH
2nd - 63 MPH
3rd - 95 MPH
4th - 126 MPH
5th - 185 MPH

I've not done any road/track courses so I don't know what type of gear/speed you would want (depends on specific track) but I love my set up.

Unfortunately, at the strip, I will have to grab 4th gear to finish out (losing time in each of the three gear changes).

 

Your rev limiter must be set at 6600rpm.

 

With much experience at all, at NJMP's Thunderbolt track you will either have to grab 5th or coast along at your redline in 4th for a couple of seconds. NJMP/Lightning and maybe Mid-Ohio aren't quite as fast, but you'd be getting close.

There are a couple of places on T'bolt where it'll be better to short-shift into 4th before a 90+ mph turn than find yourself at redline in 3rd somewhere in the middle of it and needing to upshift.


Your speeds in gears table is very close to mine (I have shorter tires, 3.55's, and a lower redline), and I'm pretty sure that you have a bit more power, so you're going to run into those limitations even sooner than I did.


Norm

 

You will gain speed and lose some gas mileage.