What size gears should i use?

[Gearbanger 101]

I thinking about changing my stock gears in my 02 AOD GT, But I'm not certain on what size. I cruise at 2200rpm in overdrive @60mph and 2800 with the overdrive off. A friend of mine said 3.73 will raise the r's in o/d to about2800 and gain ample amount of power and drop considerable time in the ET aswell as gas mileage.(.40/h/w9gal. less)

Your friend’s math calculations are out a fair amount.....and by the sounds of it, so is your stock tach or speedometer. With the stock 3.27's and stock 245/45/17’s, you shouldn't be seeing more than about 1,800rpm. With 3.73 @ 60mph, your engine would be spinning at around 2,100rpm....not 2,800rpm. Even with 4.10's like the other recommend, you won't see more than about 2,300rpm @ 60mph. So don't sweat the gear change. For the record, I'd go with the 4.10's as well, unless you had a power adder in the future....and even then it's not so bad.

 

[jasonh_86]

4.10's

 

['13_ImpactBlue_GT]

I have 4.30's in my 01 GT w/ the 4r70w automatic, and I love them.

Is your GT a DD or just a weekend car? If its your DD how is it on gas?

 

[ponysarepretty]

You don't have stock gears bro, stock gears rev about 2000(+/- 100) RPM at 65.

 

[Dark Knight GT]

Is your GT a DD or just a weekend car? If its your DD how is it on gas?

My car is my daily driver. Around town, I won't lie, its a gas hog, but then again its always been a gas hog around town. On the open interstate, it can still see around 20-21mpg. Not too bad considering all the crap I've got done.

 

['13_ImpactBlue_GT]

What bolt ons do you have DK?

 

[Dark Knight GT]

K&N FIPK
FRPP polished 70mm throttle body
Ported and polished upper plenum
Intake spacer
Mac Long tube headers
Mac prochamber w mac cats
Mac catback(I'm turning it into dumps)
Steeda u/d pullies
Cobra R power steering pulley
Colder plugs
Steeda transmission cooler
PI stallion torque converter
Jerry mod shift kit
Aluminum driveshaft w safety loop
Ford 4.30 gears
31 spline Ford differential
31 spline moser axles
Moser rear differential cover
UPR DA upper control arms
Maximum motorsport lower control arms
HPM subframe connectors(weld in)
SCT custom ECU program w/ advanced ignition input

Some other mods I'm waiting on is the new intake setup(both upper and lower) from HPS. I'm thinking about adding a throttle body spacer. I've also got some adjustable shocks and struts waiting to go in, and I'm hoping for a new tubular k-member with coil overs. I think I'll draw the limit there, and do motor work when the motor develops internal problems.

 

[GTIF]

I will double check the rpm's in the morn. and give a much better ACTUAL result.

I lost my time slipsamnit:
Better go get new ones.

 

[GTIF]

Ok i went on the freeway to see what my rpm's are running about.
60Mph in overdrive rev's at 1800 and w/o o/d on it reads 2600/2700.
All done with the cruzzzze on and stock tires.

 

[MEandmyKB]

Are you sure you've got stock gears GTIF? The math isn't working out with the RPMs and speed your showing above. What size tire are you running?

With stock gears and tire size at 60mph in OD you should be about 1800 rpm and 2550 rpm with OD off. The attached calculator will help you figure out what rpms you'll be running at different speeds with different size tires.

http://www.wcfords.com/stuff/calcs/EGTcalc/egtcalc.php

I was thinking the same thing, because his rpm's were getting pretty close to what my 4.10's run.

And my 4.10's don't feel like too much gear, even with the KB.

 

[Jackie Chan]

4.30's
tranny cooler
sctxcalibrator
stall

do it once, do it right

 

[Gearbanger 101]

Ok i went on the freeway to see what my rpm's are running about.
60Mph in overdrive rev's at 1800 and w/o o/d on it reads 2600/2700.
All done with the cruzzzze on and stock tires.

Though so. In which case, check out my original post to see what your RPM would be at with the gear swap.http://forums.stangnet.com/showpost.php?p=5589030&postcount=21