1995 Transmission Ratios

jadcock · Apr 22nd, 2003, 04:52 PM

In response to a discussion between me and aaronford:

4x2, 4-cylinder, 5-sp manual, 3.55:1 axle
1st: 3.321
2nd: 1.902
3rd: 1.308
4th: 1.000
5th: 0.838

4x2, 4-cylinder, 4-sp auto, 3.70:1 axle
1st: 2.785
2nd: 1.545
3rd: 1.000
4th: 0.694

4x2, V-6, 5-sp manual, 3.70:1 axle (4.63:1 LB)
1st: 3.580
2nd: 2.077
3rd: 1.360
4th: 1.000
5th: 0.811

4x2, V-6, 4-sp auto, 3.90:1 axle
1st: 2.785
2nd: 1.545
3rd: 1.000
4th: 0.694

4x4, 4-cylinder, 5-sp manual, 4.38:1 axle
1st: 3.985
2nd: 2.285
3rd: 1.415
4th: 1.000
5th: 0.821

4x4, V-6, 5-sp manual, 4.38:1 axle
1st: 4.061
2nd: 2.357
3rd: 1.490
4th: 1.000
5th: 0.862

4x4, V-6, 4-sp auto, 4.63:1 axle
1st: 3.027
2nd: 1.619
3rd: 1.000
4th: 0.694

aaronford · Apr 22nd, 2003, 05:46 PM

This would indicate that my valves are floating alot sooner than they should.... Around 5100 RPM It also answers an old question of what other rearends will bolt into my truck and have the same gear ratio. (for LSD reasons... )

jadcock · Apr 22nd, 2003, 06:20 PM

Could you post the formulas you were using earlier for rpm/tire size/speed? Like in a generic format, rpm = x * dia / y, etc.? I had a hard time following the discussion earlier.

Thanks much!

aaronford · Apr 23rd, 2003, 12:16 AM

Okay, its homebrewed, but it works. Start with what you know, ie MPH and move from there using known constants and ratios to get where you are going.
Tires=25.6 in Axle=3.55 Gear Ratio=whatever
First get the distance your tires travel in one revolution by multiplying the diameter X pi or 3.14159 = 80.4 in and divide that by 12 to get the feet travelled in one revolution (6.702)
Then
80 mil/hour x 5280 ft/mile x 1hour/60min x 1axlerev/6.702ft X 3.55driveshaftrevs/1axlerev x gear ratio = engine rev/min
This one should come out to 3729 in fourth and 3124 in 5th for my 2WD

Just basic Physics, (insert VT joke here) Aaron

jadcock · Apr 23rd, 2003, 08:13 AM

Thanks Aaron. I don't have no VT jokes...I hated physics.

I love the theories behind physics, and I love the science, but I really hated the way it was taught here, and the way they dramatized everything. Thanks for simplifying it.