gear size?????????

[DHolmes]

I decided im going to get gears,What size do u guys think i should get,Im thinking 3.90's,my car is a daily driver,I want the most performance ,but i still want the car ti drive good on the freeway,and dont want the mpg to go down that much,thats why im leaning towards 3.90's,because there in the middle of 3.73's and 4.10, thanks

[Wild Willy]

I don't think you would go wrong with any of those- I used to run 4.10's in an LT1-powered Caprice, 4400 lbs. worth- and it really woke that beast up. I seldom drive more than 75 or 80, so RPM's weren't an issue for me. Turned around 2800-2900 revs there, right in the middle of the power band- and, it would chirp 3rd at about 70 or 75, when I was on it-

Currently running 3.42's with my auto, and I wish they were a little bit deeper- probably 3.73's would be better, but not a high priority for now- still plenty quick

[Jeff_in_Atl]

5th gear in a Mustang is about the same as 5th gear in a 6 spd f-body. I had 3.73 gears in my old 85 Mustang at one time. when I broke a tooth off them I went back with 3.55 gears and I was happy I did. 3.73 is pretty high for highway speeds in a Mustang 5 spd. If it were the Cobra with a 6 spd you could go with 4:10s.

[MN6WS6]

3.90's are notorious for whining in the 12 bolts, and I don't even think you can get them for the stock 10 bolt. I'm going with 4.10's, but I have a spare rearend that I'll put them in. I think it will help mileage since 6th will actually be useful below 75MPH, but in another thread on here currently a member is going back to 3.42's for better mileage. So, in this instance, Your Mileage May Vary can be taken literally! I look at it like this. In town, I'm getting 13 MPG; the 4.10's cannot possibly make it any worse than that, AND it will wake the car up.

[DHolmes]

what rpm would I be at going 75-80mph in 5thgear with 3.90's
with 3.73's
with 4.10's

Im leaning towards higher gears because mustangs are slow,And I need some go,it just seems like everone with a stang just puts superchargers on,And i dont have money for that,So gears seem like the next best thing

[Jeff_in_Atl]

Go here http://murray.faithweb.com/formulas.htm
and scroll down to "Find RPMs"

[DHolmes]

well i dont know what my tire diametere is,My gf has my car right now
I have 18' cobra r wheels,
3.90's
with a daimiter of 25.5???????
going 80 my rpms would be 3042,does that seem high,I dont think thats that bad,comments please
sorry im bothering u guys with mustang Q's

[ConElite]

Your cars going to be screaming in that town tha you need to be on the freeway all the time. I would not recommend it. ha ha ha. I was thinking of going to 4.10's but I have a decent 6 speed , but then again with Gas prices, forget about it. Its bad enough Im getting around 10-15 MPG. All i drive is city and my foots damn heavy!

[DHolmes]

just called my shop and they told me $387 for the install,does that sound like a decent price,And he recommeded 3.73 cause my cars a daily driver

[ConElite]

Thats about right. Its expensive to install gears. Thats why I did them myself. lol