SOHCman

Since the axle in our 4.0 Mustangs is the standard 7.5" shouldn't we be able to switch gearsets?

* Has anyone used taller gears than the 3.31/3.73/4.10 that everyone seems to have?

I used to run a 1970 Cougar with 2.75 gears and slightly oversized tires. With a 351W I was able to run approx 2000RPM at 70MPH (3spd tranny)... My pony has the 3.31 and runs approx 2500RPM at 80MPH(in 5th)... Might be good for gas mileage if I can use a taller gear from a previous Ford model????

* Any idea about reprogramming the computer to taller gears than the 3.31??

Cruisin' at 2000RPM at 80MPH would be nice... hmmm... that would mean 100MPH would only be around 2500RPM... Redline is 5500... The rev limiter hasto go!

Thanks for any input or gear options and programming!

mustangman02232

uhhh, any 7.5s will fit, but why?[&:] the fact taht the 4.0 is SOHC and is rev happy that just makes no sense

8cd03gro

what do you consider rev happy? LOL the thing will grenade at 7k im sure! i do agree tho, there is really no reason to go any taller. Most people go shorter for better acceleration. You will not get a higher top speed with taller gearing than you would just removing the stock speed limiter, without massive power improvements, you will be drag limited even if you remove the speed limiter.

plus our driveshaft blows and starts going crazy higher than the speed limiter.

mustangman02232

the 4.0 has alot better top end pull then the 3.8 IMO doesnt have the low end torque like the 3.8 but will rev and make power higher, taller gears will make you wait longer to get to the top end and slow you down considerabley, if that makes no sense, then idk its hard to type right now but i think you get what im saying[8D]

fazm

doesnt have the low end torque? i made more torque downlow than any 3.8 ive seen with just bolt ons.

and im spooling 9psi at 3200 rpm now

fazm

oh and it wont grenade at 7k, i can tell you that from experience.. didnt sound great, but held together.

mustangman02232

well from my opinion, the older 3.8s have more down low power, maybe it was just the 05 i drove was stock and had the throttle lag still[8D]

8cd03gro

you actually wound it out to 7k? that doesn't seem like too great of an idea...please tell me that was not with the snail on!

8cd03gro

was it an auto? i mean...the 4.0 makes 15 more ft lbs only 500 rpms higher...

fazm

no it wasnt with the turbo on, it was on a burnout at the track, i had the limiter at 7k and it hit the fuel cutoff twice before i backed it down