Red Beast

Hey all, I was going to get the 8.8 rear end for my V6 soon, and was going to upgrade my gears as well. I believe i heard the 05 mustang has stock 3.55 gears and later they were bumped down to 3.35, and comparing what i experience to American Muscles data table they match the 3.55, so i was initially going to do 4.10's, but on American muscles website they had 4.56 and i was looking at that data table. realistically the RPM's in the lower gears are higher by a thousand. but even on surface streets i cruise around 55mph in 5th, i mostly stay in 5th wherever i go, surface or freeway, and at 75mph there is only a 600rpm difference between my 3.55's and 4.56.

So what do you guys think, what would you guys feel the pro's and con's are compared to bumping from 3.55 to either 4.10 or 4.56?

Sxynerd

Three things to worry about with steep gears like that, Comfort of driving everyday, Redline & Top speed in the 1/4 and traction.

If you were building a 10k RPM, 1/8th mile car I'd say sure thing but not for a Daily driver.

Ricardo

4.10s scream along @ 2600 RPM/75 MPH, 4.56 would be pretty much obnoxious on the highway.
I believe 4.56 are Motive and have not heard a single good word about those.

pdonket

600 rpm is substantial when we're talking about highway cruising...4.56 is an absurdly high gear ratio.

Norm Peterson

4.56's don't match the gearing in these trannies very well for daily use. If they had something more like a 2.5:1 first gear and 0.50:1 5th you'd have a much stronger case for going that deep.

With 4.56's you'll be struggling to run 1st gear out to 30 mph or 2nd to 50. Basically, you'll just drive the way you do now, except for being one gear higher most of the time. I'll all but guarantee you'd be looking for a 6th gear once you hit the Interstate.


Norm

daredevil95

4.56: You wouldn't have much of a 1st gear and it's way to much gear for your application. You will feel a lack of cam when reving the motor thru the gears. If you plan on modifying your cam and heads in the future I would say go for it but, be sure to match the cam. I once ran 4.56(70 Charger) and 4.88(72 Chevelle) gears in my old big block cars but, different type of cars and I would never drive on the highway....FAR. A set of 3.73 or maybe a set of 4.10s would be the most for your application. IMHO.

JIM5.0

^^^This

The stock tranny I believe already has a very deep first gear, I think 3.66:1? Maybe deeper. And if you are putting on 4.56:1 rear gears, you are looking at a total gear ratio of ~16.69:1 at the wheels. Unless you have very very tall tires and wide slicks at that, you will be spinning your wheels at launch.

Now, if you have an aftermarket tranny, a Viper spec T56 for example, your 1st gear is about 2.60:1 (I think) so for better launch, you can drop in the 4.56:1 rear gear and that will put you at around 12.13:1 total gear ratio at the wheels, which is very close to your stock tranny and stock rear gear total ratio of 12.99:1 (actually, your stock tranny and stock rear gear gives you a little better total gear ratio at the wheels).