SpectreH

I have a good friend who is a mechanic and excellent drag racer. He always swaps out the rear gear on manual Mustangs, but says leave the 3.15 in the auto alone.


I trust his advice and he is the only person I will let work on my car besides myself.

fahvzero

Yes I have the 91 and 93 Steeda. They are awesome tunes. Completely changed the cars character. I would recommend them to anyone. Also have the Steeda intake. It's all about gearing. 3rd 4th and 5th are really tall 1st and second really short. Outside of second gear the gears wind up slow that's when I'm in the corners 3rd and 4th. I want it to 'feel' faster.

fahvzero

The manual has a 1.69 3rd gear a 1.34 4th and a 1.00 5th. The Auto has a 1.52 3rd a 1.14 4th and an .87 5th how can going to a shorter gear not be better?

fahvzero

We can all agree 1st gear is gone quick no matter what rear gear there is, but even 2nd gear in a 3.73 auto is multiply second gear by 3.73 in an auto is 8.73 and the manual 9.06. So being the characteristic of how an auto shifts would be 'like' a manual. Why not put a 3.15 in a manual? 3rd 4th and 5th in a manual with a 3.15 would be numerically shorter than the auto.

SpectreH

Basically, if you go with too tall of a rear gear, you make 1st and 2nd pretty much worthless in the auto. I've never driven an auto with a taller gear. It seems some here have and regretted it.

fahvzero

I say 'like' a manual because a 4.10 gear auto 3rd 4th 5th is numerically close but an auto shifts quicker so a 3.73 auto though numerically longer shifting quicker would most probably be equal in acceleration because of the lack of the pause a manual driver simply can't avoid. I originally thought about 4.10s but being how the auto shifts quicker it might he too much gear.

fahvzero

Car A is a manual 3.73 in 3rd gear
Car B is an Auto 3.15 in 3rd gear
We are both in a corner which car is going to be better? Coming out of a corner which car is going to accelerate faster? The manual it has shorter gearing.

fahvzero

Car C is an Auto 3.73 in 3rd no shifting yet the manual still would accelerate quicker through the corner shorter gears. But coming into a straight out of the corner the auto might have an advantage because there's no pause when shifting to 4th like even the best manual driver can't avoid. I using the select shift as an example.

fahvzero

Also I just want to say thanks to all of you guys for this friendly debate, no sarcasm on my part with my posts and I appreciate your advice.

SpectreH

No sarcasm detected


It sounds like if you really want to swap rear gears, the 3.31 is safer with the auto.

GrabberBlue5.0

A couple of things. The Steeda is avergage at best. Nothing wrong with them but you leave a lot on the table with them.

You reference 5th gear but that's an overdrive gear so it's a moot point. For performance purposes you want to focus on 1st-3rd and possibly 4th. But mostly 1st-3rd are the gears most utilized.

I mentioned a converter already but that makes a HUGE difference in these cars. Even from a roll.

2014GHIGGT

I would definitely recommend not going any steeper than 3.31 in an auto. Regardless of the purpose. These cars will see way more street time than track time. That said, you also need to keep in mind around town drivability. If it were an older 4R70W, AOD-E, or AOD, I would agree that a 4.10 is the best gear for those older transmissions.


Don't re-invent the wheel. These new 5.0's build some serious power and if you are thinking of going forced induction soon, then I would stick to the 3.15 and not even consider anything else. The engine will build enough HP to go through gears quickly.

fahvzero

Any advice on a good tune? If Steeda is average I can't imagine what really good is :-)

GrabberBlue5.0

Mike Rousch from Mid Atlantic Performance is one of if not the best going. AED and Lund are also very good.

fahvzero

How much more can they safely get out of this engine? Steeda makes the car a beast already, I believe you they are good I have heard good things about AED.

momogt

what ever you do don't get 4.10,s like grabber said a converter is the way to go if your budget allows it.i like 3.55,s I had a chance to drive a friends 5.0 A6 with 3.55,s and the car felt good no wacky shifting like the 4.10,s my 4.10,s are coming out as we speak I would have went back to 3.15,s but got a deal on a set of new ford racing 3.55,s 60.00 to good to pass up and free install.

fahvzero

I was looking at the F150 5.0s they have the same transmission and they have 3.73s I know it's a truck but more gear = more torque I agree though 4.10s are too much for your 1st and 2nd gear. 3rd 4th and 5th should be a blast with 3.73s

GrabberBlue5.0

A truck is much heavier than a Mustang which is why it would need a steeper gear. Your car doesn't need it.

momogt

if I had the money right to get a converter I would I every time I have the money something else comes up just life I guess.my friends car with car with just a tune and 3.55,s had great torque

fahvzero

I don't live a 1/4 at a time on the roads I like driving on I'm in 3rd and 4th gear on twisty roads 1st gear is dang near useless even with the 3.15 plus I shift manually always. I never let the car shift that's boring. A 3.73 in 3rd and 4th will wind out quicker making it more fun to drive. I don't care about 60 ft times and 1/8 mile times I'm a corner carver