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Gear and 4x4 Calculators

The 4x4 and Gear Calculator will help you find any one of the below values. To use this, fill in all the blanks and leave the one you are calculating for empty and then hit "Calculate". This calculator will help you find your Tire Diameter, Transmission Ratio, T-Case Ratio, Engine RPM, Gear Ratio, and MPH. With some automatics, there will be some slippage but this should still get you in the right ballpark.

4x4 and Gear Calculator
Tire Diameter:	Transmission Ratio:	Transfercase Ratio:
Engine RPM:	Gear Ratio:	MPH:

Here is a quick and dirty RTI calculator. I say quick and dirty as it does not take into account tire pressure or how wide your tires sit. This will give you an estimation of your RTI score on a 20, 23 and 30 degree ramp. Enter your wheelbase and how high you can lift one tire in inches.

Crawl Ratio Calculator. This will tell you what your final crawl ratio will be. If you are running an automatic, a good rule of thumb is to double the final number to take into account slippage in the transmission and the torque converter at slow speeds.

Going up to a larger tires size will throw off the reading on your speedometer. This calculator will let you know how far you are off. Enter in the original tire size for your vehicle and the new tire size that you are running. Then put in what your speedometer says and your actuall speed will be calculated.

Below are some ratio's for some of the common Transmission and T-cases that are out there. If you don't see yours and you know what the ratio's are, PM the information to Sandman here on the board and I'll get it entered in!

Some Common Transfer Case Low Range Ratio's
Dana 300	2.62	NP 203	2.00
DANA/Spicer 18	2.46	NP 207/208	2.61
DANA/Spicer 20	2.00	NP 231	2.72
Borg Warner 1356	2.69	NP 205	1.98
Toyota (67-74 3 speed)	2.31

Some Common Manual Transmission Ratio's
Transmission	1st	2nd	3rd	4th	Transmission	1st	2nd	3rd	4th	5th	6th
Borg-Warner	4.07	2.39	1.49	1.00	T-178	3.00	2.08	1.46	1.00	-	-
SM 420	7.00	3.60	1.70	1.00	Mazda 5-spd	3.40	2.20	1.50	1.00	.79	-
SM 465	6.55	3.58	1.57	1.00	NV3500	4.02	2.32	1.40	1.00	.73	-
T-176	3.52	2.27	1.46	1.00	NV4500	5.61	3.04	1.67	1.00	.73	-
T-177	3.82	2.29	1.46	1.00	ZF S6-650	5.79	3.31	2.10	1.31	1.00	.76

Some Common Automatic Transmission Ratio's
Transmission	1st	2nd	3rd	Transmission	1st	2nd	3rd	4th	5th
TH350	2.52	1.52	1.00	700R4	3.06	1.62	1.00	.70	-
TH 400	2.48	1.48	1.00	4L80-E	3.10	1.48	1.00	.75	-
C4/C5/C/6	2.46	1.46	1.00	Ford AOD	2.40	1.47	1.00	.67	-
Torqueflite 727	2.45	1.45	1.00	Allison 1000	3.10	1.81	1.41	1.00	.71

All of the above calculators were programmed 100% in PHP.

Planet 4x4

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