gear debate

[uhoh5.0]

What is the steepest set of gears you could go with in an auto if you are planning on possibly doing a power adder (supercharger) down the road? 3.90? ALso, I know there is always a debate about what gear to go with, but in my last mustang (in sig) the 4.10s made interstate driving kinda rough. I got horrible gas mileage and I was around 3500rpms at about 60ish mph. I just don't want to lose driveability, but I still want the seat of the pants hp feeling that gears give you. I went from 2.73s to 4.10s in the last stang and that was a HUGE difference. And finally, does FRPP make a 3.90 ratio or would I have to go with motive, which leads to my final question: Are any gears other than FRPP ok? I've always heard to stay away from other brands.
Thanks,
Sean

 

[Kilgore Trout]

What is the steepest set of gears you could go with in an auto if you are planning on possibly doing a power adder (supercharger) down the road?

3.73, maybe 4.10

ALso, I know there is always a debate about what gear to go with, but in my last mustang (in sig) the 4.10s made interstate driving kinda rough. I got horrible gas mileage and I was around 3500rpms at about 60ish mph. I just don't want to lose driveability, but I still want the seat of the pants hp feeling that gears give you. I went from 2.73s to 4.10s in the last stang and that was a HUGE difference.

Do not fear the gear

And finally, does FRPP make a 3.90 ratio

No, FRPP does not make a 3.90

or would I have to go with motive, which leads to my final question: Are any gears other than FRPP ok?

It is not about the brand of the gear it is about the quality of the install. However, FRPP gears are easier to install because you can use the MHD (master housing depth) method.


Also, you could have found the answer to these questions by doing a quick search...

 

[04YELLOWGT]

I have a SC and have 4.10. They work perfect because it gets you into the boost quicker.

 

[helty]

at 60 mph w/ 4.10s you will not be anywhere near 3500 in a 4.6. 3.73s or 4.10s in your case? I dunno. Do you go to the track a lot?

Here: http://www.youtube.com/watch?v=0lccqtF15Gc

EDIT: Oops, forgot you have an auto and not a 5-speed.

 

[DeathMetal]

With 4.10's you should be at 3220 at 60mph in 3rd gear, and 2254 at 60mph in OD for an automatic if you have the stock tire height.

 

[Cantslowdown]

I have 3.73s and i have automatic and I am right at 2400rpms doing 70..I think 3.73s in automatic is a good combo alot will say 4.10s but if ur car is a dd then 3.73s is just right..

 

[04YELLOWGT]

my car is a dd

 

[04gtdrop]

I say go with the 3.73's.....I got 3.73's in my DD and I love them.

+1 for 3.73's

 

[uhoh5.0]

What would I tach in OD with 4.10s? 3.90s? 3.73s?

And most importantly, if I am correct (and please correct me if I am wrong) a set of 4.10s should add roughly 2 to 3 tenths in the quarter mile.

So, with going from 3.27 to 4.10 thats a difference of 0.83 in gear ratio. So, as a percentage 3.90s should add roughly 75% of that 2 to 3 tenths which would equal somewhere between .15 and .225 sec and 3.73 would be roughly 46% and somewhere between .1 and .15 seconds. So, to round and make it easy you could say 4.10s=.3 tenths 3.90s=.2 tenths 3.73s=.1 tenth ???

Don't know if thats an accurate way to predict performance gains, but it make sense at least on paper.

 

[BurningRubber]

I rode in a buddies GT with 4.30's in an auto today. Wow...

He definatly doesnt fear the gear, and that car friggin pulls.

 

[the98stang]

I have a SC and have 4.10. They work perfect because it gets you into the boost quicker.

4.10's wont be good with kenne bell S/c's. 4.10's work with your set up because you have a centrifugal SC.

I'd stick with 3.73's if you plan on using a power adder..

 

[the98stang]

What would I tach in OD with 4.10s? 3.90s? 3.73s?

And most importantly, if I am correct (and please correct me if I am wrong) a set of 4.10s should add roughly 2 to 3 tenths in the quarter mile.


.

.3-.5 off your quarter mile. Depends on the tires you have and how well you hook...

 

[Cantslowdown]

I can say this i really like my 3.73s..I live kinda out of town and they do well for me..I plan on doing a power adder just dont what i want to do yet..

 

[Pennywise2]

 

[uhoh5.0]

Is that a neon?

 

[hognutz]

to me this is the bottom line.

if you keep the stock 6000rpm limiter you will have like 112mph trap speed if you go 4.10's.

you will have like 120mph of trap speed with 3.73's.

so based on that info is how I would pick the gears.

If my wife quits spending my money I am getting the kb 9psi kit. so i went with 3.73's because I feared getting really close to redline in 4th by the end of the quarter mile.

if the blower you are going to buy does not give you enough power to trap over 110 or more you may consider 4.10's. if you plan on making say 400hp at the wheels or so you may consider 3.73's. you don't want to have to use overdrive before the end of the 1/4mile it will hurt your et.

 

[the98stang]

If my wife quits spending my money I am getting the kb 9psi kit.

Is that possible for any woman?

 

[03ghoststang]

4.10's for a centri blower or N/A

3.73's for a KB

that is what i would do

 

[Rocketman]

I have 3.73s and i have automatic and I am right at 2400rpms doing 70..I think 3.73s in automatic is a good combo alot will say 4.10s but if ur car is a dd then 3.73s is just right..

4.10's Auto in OD. Stock tire size. 4.10's are perfect in an auto!

 

[Cantslowdown]

4.10s arent bad for a auto but for me i really like 3.73s and they seem to be working good for me..My car will see alot of hwy driving..And i love how they pull i bet 4.10s pull even harder but i am happy..