390 gears

[DHolmes]

whats up guys,already had to get a new clutch in the mustang the tob went out and messed up my clutch,$511,dam stang,well my friend has some 390 gears that will fit my stang,he's selling them for $90,a steal,My questions is,how bad will they effect my mpg,What performace gains can i expect and will the car still be a good daily driver,how do gears work,Im a noob when it comes to gears,but it seems that anyone with a stang puts on gears,oh they are motive gears,still in the box,websites say to expect 1/2 a sec faster in the 1/4,thanks

[Craig 94 TA GT]

What's your overdrive gear ratio? I lost 1-2 mpg going from 3.23 stock 10 bolt to a 9" with 3.50. I went from 20-18 mixed freeway/city. That's with a .7 overdrive.

But now, I'm at 12-14, which is pretty bad.

[DHolmes]

What's your overdrive gear ratio? I lost 1-2 mpg going from 3.23 stock 10 bolt to a 9" with 3.50. I went from 20-18 mixed freeway/city. That's with a .7 overdrive.

But now, I'm at 12-14, which is pretty bad.

Im not sure,I have a 2000 mustang gt 5spd

[Craig 94 TA GT]

So you have a .67 overdrive and currently have 3.27 rear end. I'd guess going to 3.90s would decrease your mileage by 3-4 mpg, or maybe 10-15%. That's a rough guess based on my gear change.

By the way, what happened to the Bird? I haven't been on for a while. Hope you still have it along with the Mustang.

[DHolmes]

GF wrecked it, frame damage,
what performace gains would I see

http://s198.photobucket.com/albums/a...t=100_0483.jpg

[Craig 94 TA GT]

Oh man, sorry to hear that

It's all guesses for me because I'm not that familiar with Mustangs. I'd guess .2 in the quarter mile because the 4.6 torque peak is at higher RPM and would probably like the higher revs with the gear change.

[Trash man]

if the torque comes in at a higher range, then he shouldnt loose that much. i went froma 3.08 to a 3.42 rear in my old bird and saw a 2-3 mpg improvement on the highway and bout a 2 in the city, and that was with it running a constant 12:1 AFR.

[ConElite]

You should be a nice diff. thats a nice change and its going to hurt your MPG some. I say about 5-7MPG average loose. The Rustang is giving you issues already! ha ha ha

[wolfdogs]

i'd never put used gears in my ride. initial set up is too critical to noise and longevity. every pumpkin is different slightly inside.... and motive uses a bias gear pattern set up.