euromay

I don't know if its just my car, but I justswaped my gears to 3.73 ratio last week and while driving down the highway my rpm's seemed way to high. Also, does anyone know what gear I might be finishing at on a 1/4 mile run with these new gears? Need some ideas guys..Thanks!

Rajun_Cajun

Well, Im at 2800 when doin 80mph with 4.30's. If your speedo gear wasnt corrected, the your mph is gonna be off. The faster you go, the more off the reading is going to be.

Albizo66

yeah with my 3.73s, my speedo is off by right about 10mph

gearbanger

you will finish in fourth... i got 3.73's and around 2400 is 70mph

5spd GT

Gear Calculator:

http://www.allfordmustangs.com/Detailed/608.shtml

Reference with T5 transmission/stock tire size/16in. wheel, in 5th gear cruising rpm at 70mph (Interstate Speed):

2.73:1 - 1696 RPM
3.08:1 - 1914 RPM
3.27:1 - 2032 RPM
3.55:1 - 2206 RPM
3.73:1 - 2318 RPM
3.90:1 - 2423 RPM
4.10:1 - 2548 RPM
4.30:1 - 2672 RPM
4.56:1 - 2834 RPM

euromay

Follow up questions: What RPM should I set my shift light at? Also, what RPM do I take off to not spin my tires so much? Sorry for all the questions but I'm really getting some good answers.

gearbanger

your stock dont take it past 5500 because your not realy going anywhere.. as for take off we cant realy tell how because every track is diffrent. just keep trying diffrent rpm ranges and see where your car hooks

Albizo66

just accelerate untill you feel it stop pulling, look at the tach, and there you have it, your shift point...thats how i got mine

nitrous_bob

i always liked a 5200 chip, by the time you react, and actually complete the shift your right where you wanna be (5400-5500)

i have 4.10's and tach 3000 doing 80-85

on street tires you'll need to either launch off idle and ease into it, or launch high slipping the clutch all the way. i like launching off idle so to keep undue clutch wear to a minimum, but to be honest .... you need cheaters, some mickey thompson DR's will do it. 3000 launch will hook rigth up, spin just enuff to clean 'em off.

Jfsram

I've ran my best times launching off idle and shifting at 4800rpm.

On 235 45 17 Dunlop all seasons 2.0 60'

14.0@100 shifting at 5200rpm.
13.8@101 shifting at 5000.
13.6@102 shifting at 4800rpm.

Stock engine BBK cold air, meter, long tubes, Flowmaster, e fan, underdrives, 3.73 and al driveshaft.


As for high rpms on the highway. One major reason not to go with low gears for highway driven cars.

I'm presently searching for 3.27 gears for my commute to work.
I'm confident the taller gears will not slow my track times down too much since I'm traction limited anyways.