3.31 Rear Gears Anyone?

90lxwhite · Jan 12, 2015

I'm not digging the 3.73's, I'm not finding them to be a very pleasurable drive and I don't think 3.55's would be enough difference to justify the money spent on the swap. I don't want too high a gear but I'd like to not have to shift out of first within 3 feet after pulling out of the driveway anymore and cruisng on the highway in the powerband is growing pretty irritating.
Do any of y'all have experience with 3.31 gears? Thus far the only experience I have is with 2.73's and 3.73's. What would be a good compromise between the two?

89oem · Jan 12, 2015

I really liked my 308's with my t-5 but they wont match my new transmission gearing..
308 may be a little tall for you - it does give a nice highway and plenty of wheel spin at launch if you want it to...... 308/t-5 is same as 93 Cobra and I think SSP.

A5literMan · Jan 12, 2015

3.31 and a blower for the street would be a good combo. 3.08 are to tall imo. 31 or 55's would be my advise.

rbohm · Jan 12, 2015

i personally think that a rear gear in the 3.25 - 3.40 range is great for the street.

90lxwhite · Jan 12, 2015

Thanks y'all.

A5literMan said:
3.31 and a blower for the street would be a good combo. 3.08 are to tall imo. 31 or 55's would be my advise.

is there that much difference between 3.73 and 3.55? Back when I had 2.73's and was looking at gears I was trying to decide between .55's and .73's. I probably should've went w the 3.55's originally but now my concern w them is I'm afraid they will be pretty much what I have now. Am I wrong?

A5literMan · Jan 12, 2015

You're not wrong in that there is very little difference on the highway. With the t5's 3.35:1 1st gear is still short. For everything that I think you want you'd be best served by the 3.31's. You also probably wouldn't see much drop off in performance. You have to remember that if we are talking about just performance or a compromise for the highway/DD ability of your vehicle there is an ideal ratio. Also 1st gear helps get you out of the hole but I always found that 2nd gear was my "pull" gear when racing. If I didn't have the race won by the 2-3 shift I was toast. Now there are calculators online that will show you the rpm @ mph for a given combo. I would expect a 20% drop @70mph. Just off the top of my head roughly around 21-2200rpm @ 70 or so.

srtthis · Jan 12, 2015

maybe its just me... i loved my 4.10's with the T5... wish i could have run 4.56's

now with the C4... i wish i could turn more RPM.

A5literMan · Jan 12, 2015

srtthis said:
maybe its just me... i loved my 4.10's with the T5... wish i could have run 4.56's

now with the C4... i wish i could turn more RPM.

Oh I agree! I've been contemplating changing my 3.73's for 4.10's. I just had to draw a line somewhere and I also may some day add a forced induction 363. A few hundred extra cruise rpm is no big deal to me. But op has always posted his dislike for them and I believe would be happier with the 31's

A5literMan · Jan 12, 2015

srtthis said:
maybe its just me... i loved my 4.10's with the T5... wish i could have run 4.56's

now with the C4... i wish i could turn more RPM.

What rpm were you turning at the stripe? And what size tire/and was it the b cam engine? Sorry for thread jack 90lxwhite.

90lxwhite · Jan 12, 2015

A5literMan said:
What rpm were you turning at the stripe? And what size tire/and was it the b cam engine? Sorry for thread jack 90lxwhite.

no worries and I think maybe 3.31's might be for me.

srtthis · Jan 13, 2015

A5literMan said:
What rpm were you turning at the stripe? And what size tire/and was it the b cam engine? Sorry for thread jack 90lxwhite.

never got a clean pass on 4.10's i made a lot of changes and it didnt like something. i lost 10mph out the back going from 3.73's and 28" radials to 4.10's and 26" slicks. i also took over 100lbs out of the car and it went slower

Mustang5L5 · Jan 13, 2015

I dislike my 3.73's and as soon as I get motivated enough, they will come out for some 3.27's or 3.31's.

I don't drag race much, so i'd prefer a gear better suited to highway cruising.

90lxwhite · Jan 13, 2015

Mustang5L5 said:
I dislike my 3.73's and as soon as I get motivated enough, they will come out for some 3.27's or 3.31's.

I don't drag race much, so i'd prefer a gear better suited to highway cruising.

The other day I think I was doing around 5k rpm in 4th somewhere between 100-110 mph. Back when it was new and had 2.73's it'd do 70 mph in 2nd at redline. Was slow moving though...

89oem · Jan 13, 2015

well the 410's are in my axle now at the shop so hope I like it, hoping the t56 gears will mate well
2.97 2.10 1.46 1.00 .74 .50

Modern Driveline has all the t5 gearing ratios by year here

http://www.moderndriveline.com/Technical_Bits/tremec_t5.htm

Heres the tremec calculator

http://www.tremec.com/calculadora.php

Put it together and you can arm chair your RPM and Speed

Noobz347 · Jan 13, 2015

I don't like gear ratio questions. It really comes down to the fore-mentioned Tranny gearing, Power/Torque output and curve, application, ability to put power down to the ground, and driving style.

That last variable makes the question a crap shoot for nearly all street vehicles. It's mitigated quite a bit when track is the priority.

srtthis said:
maybe its just me... i loved my 4.10's with the T5... wish i could have run 4.56's

now with the C4... i wish i could turn more RPM.

Track guy with track mentality, driving style, and habits.

rbohm · Jan 13, 2015

srtthis said:
never got a clean pass on 4.10's i made a lot of changes and it didnt like something. i lost 10mph out the back going from 3.73's and 28" radials to 4.10's and 26" slicks. i also took over 100lbs out of the car and it went slower

in other words you violated the hard and fast rule about making ONE change at a time when tuning the car.

90lxwhite · Jan 13, 2015

89oem said:
well the 410's are in my axle now at the shop so hope I like it, hoping the t56 gears will mate well
2.97 2.10 1.46 1.00 .74 .50

Modern Driveline has all the t5 gearing ratios by year here

http://www.moderndriveline.com/Technical_Bits/tremec_t5.htm

Heres the tremec calculator

http://www.tremec.com/calculadora.php

Put it together and you can arm chair your RPM and Speed

If I had the $ I'd stick w the 3.73's and add a 6 speed but I don't. @89oem Oh hey I got the headliner in. Tried to take a pic but it looked like a black screen.

srtthis · Jan 14, 2015

rbohm said:
in other words you violated the hard and fast rule about making ONE change at a time when tuning the car.

other than weight the only change was gearing and tire height which the tire size change would have just compounded the gearing change.

now that i think about it more i might have had to put a new TFI module in the car at the time also

89oem · Jan 14, 2015

my headliner folds into my trunk

Did it turn out nice?

rbohm · Jan 14, 2015

srtthis said:
other than weight the only change was gearing and tire height which the tire size change would have just compounded the gearing change.

now that i think about it more i might have had to put a new TFI module in the car at the time also

read what you wrote again, you said you made a lot of changes, not two changes. and yes going to 4.10s and shorter slicks did kill your top speed. the 28" slicks should have been used with the 4.10s, or the 26" slicks with the 3.73s.

3.31 Rear Gears Anyone?

90lxwhite

I'm kind of a She-Man

89oem

Mustang Master

A5literMan

At least it is lumpy...

rbohm

90lxwhite

I'm kind of a She-Man

A5literMan

At least it is lumpy...

srtthis

the guy doing it does every local racers rear end

A5literMan

At least it is lumpy...

A5literMan

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90lxwhite

I'm kind of a She-Man

srtthis

the guy doing it does every local racers rear end

Mustang5L5

That is…until I whipped out my Bissell

90lxwhite

I'm kind of a She-Man

89oem

Mustang Master

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

rbohm

90lxwhite

I'm kind of a She-Man

srtthis

the guy doing it does every local racers rear end

89oem

Mustang Master

rbohm

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