Gear help.

R

rich1223

Founding Member

Jul 6, 2001

69

0

6

NYC

Dec 23, 2012

#1

• Dec 23, 2012

• #1

I just picked up a 97 GT 5 speed got it from a used car dealer but the previous owner did a few upgrades that i can tell, Trick Flow upper plenum,pullies,BBK cold air intake,etc.My question is i am trying to find out what gears i have i looked on the door and the code is M which i know is 2:73's but i think they might have been switched a 70 mph i am at 2000 to about 2100 rpm's with the stock 16 inch rims and tires.Thanks!

 

84Ttop

They make new pistons every day, so why worry?

5 Year Member

Jul 2, 2009

5,222

3,254

204

South Jersey

Dec 24, 2012

#2

• Dec 24, 2012

• #2

Put the car up n jack stands, in neutral count the number of revolutions the driveshaft makes with one revolution of the tire. Voila the number of turns the driveshaft makes is the same as your rear gear ratio.

 

blacksheep-1

Member

Oct 21, 2006

322

4

18

Dec 24, 2012

#3

• Dec 24, 2012

• #3

Put the car up n jack stands, in neutral count the number of revolutions the driveshaft makes with one revolution of the tire. Voila the number of turns the driveshaft makes is the same as your rear gear ratio.

Click to expand...

Ding ding ding...winner

 

trinity_gt

10 Year Member

Jan 31, 2003

3,125

81

99

Canada

Dec 25, 2012

#4

• Dec 25, 2012

• #4

Or you can avoid going out in winter conditions, jacking it up, crawling around underneath it by just doing some math.

You know the car's speed and the diameter of the wheels so you can calculate wheel RPM.

You know engine RPM and the gear ratio in the transmission so can calculate driveshaft RPM.

The rear gear ratio then is Driveshaft RPM/Wheel RPM.

In this case it works out to ~3.27:1.

 

blacksheep-1

Member

Oct 21, 2006

322

4

18

Dec 25, 2012

#5

• Dec 25, 2012

• #5

http://www.corral.net/tech/gearcalc.html