Which Gears Are Best For My Roush Mustang?

427RStangg wants to know: “In my s/c Roush, what gear ratio would you recommend? I have friends who say that 4.10 gears are way too steep for my car? It’s a manual.”

When choosing aftermarket Mustang gears (or any aftermarket mod), it’s important to consider what type of driving you do/want to do with the car, how much power you currently make, and how much power you intend to make.

Aftermarket rear-end gears are designed to get you off the line faster, so you’re going to burn through first gear (and second… and third…) much more quickly than with your stock gears. This isn’t as much of a hassle with an automatic transmission because you aren’t the one shifting, but if your Mustang is a stick and you do any kind of driving in a city or heavy traffic, you’d be wise to avoid the steeper ratios. Considering your pony is already super charged, I would have to side with your friends and recommend the 3.73 gears; they’ll give you the extra kick off the line that you want without making driving a chore.

When installing aftermarket gears, it’s always a good idea to get a bearing kit and replace the shims, bearings, and other items that wear out over time. This will complete your rear-end rebuild and make sure you keep that rubber burning for a long time.

About Heather

Heather is a Customer Service Team Lead and blogger at AM, but outside she is a jack-of-all trades. A Ford enthusiast since birth, she credits her love of all things mechanical to her father, a mechanical engineer who really just needed free labor for his weekend car projects. Surprisingly, Heather began her post-secondary education as a Music major, but alas – she was not destined to be eternally dubbed “Band Geek”. Instead she attended Automotive Training Center in Exton, PA where she found her true passion, and worked as a mechanic until her grease monkey career was cut short by a shoulder injury sustained in motorcycle accident. Outside AM, Heather still works on her own 1985 Ranger (Pepe, Le P.O.S.) and Lola, her 2004 V6 Mustang; and although neither of her current vehicles are race-worthy, she is no stranger to the quarter mile. “Girly” is probably the last word you would use to describe Heather, yet she moonlights as a model to fund her addiction to car parts. While she has many talents and interests, she has truly found her dream job at AM. More posts by Heather

http://www.newyorkmustangs.com NY Mustang Club

I went with 3.73′s as well and love them. When I was N/A I wanted 4.10′s but with the blower 3.73′s is perfect.
http://yahoo Dylan

hey while we are on the subject, i was wondering what size would be good for my stang its an 03 GT auto with CAI,plenum and throttle body, i dont want to kill gas but i really want to improve acceleration
http://www.americanmuscle.com AMChrisRose

If I owned an auto, I would go with the 3.73′s as well. I think that they’re a perfect auto gear, no matter what your plans are for the future, Naturally Aspirated or Forced Induction.
Steven

No way… 4.10′s for automatic without a doubt. Don’t fear the gear man. Can’t decide then go for the middle man, the 3.90. 4.10′s in an auto will get you into the blowers powerband much quicker.
Bill

03 GT auto here and I put 3.73′s in. Their great. I would recommend those or the 3.90′s, but if you do alot of long driving I’d stay away from the 4.10′s.

Dylan

thanks alot, i think the 3.73s are probably the way im goin to go

http://same Tuts

I have a 2010 Mustang GT with the track pac option,they come with 373s standard from the factory.I,m installing 456s I don,t do any highway driving and love the get out of the hole feeling these gears will give me.