Speedometer Info

At the bottom of the speedometer face, look for the numbers 940, 960, 1000, or 1020. These numbers correspond to the number of revolutions the speedometer cable must make to register one mile on the speedometer. Tire size modifications will also require adjustment to your speedometer gearing. In the electronic transducer systems, the speedo transducer will put out 2000 pulses per mile traveled.

To calibrate the speedometer, the appropriate Drive Gear and Driven Gears must be installed in the transmission to provide the speedometer with the proper RPM.

The Drive Gear is a worm gear on the output shaft of the transmission inside the tailpiece. The tailpiece must be removed to replace this gear. But, on most transmissions, it can be viewed by removing the Driven Gear Sleeve. You can count the number of teeth by rotating the output shaft while viewing through the Gear Sleeve hole.

The Driven Gear is easily replaced on most transmissions, even with the transmission in the car. Simply remove the sleeve and slide in a new gear. It is necessary to open up the square output hole in the Driven Gear if Jaguar speedometer cables or connections are used. This can be accomplished with a small square file, or by heating a square rod of the proper size and carefully melting the plastic.

This chart will help you select the proper gears for your transmission. If a certain application shows more than one combination and a Driven Gear is in red print, use that combination for best accuracy. The Jaguar gear ratio for your car can be found on a tag, or stamped into, the differential inspection cover. It will either be the gear ratio, or the number of teeth on the gears inside (obtain the ratio by simple division of the 2 numbers).

On TH-400's, 700-R4's, and "large sleeved" TH-350's there are 3 gear sleeves that hold the "driven" gear. One supports 30-35 teeth, one supports 36-39 teeth, and the last one is for 40-45 teeth. "Caution" gear colors may vary. Use the part number when getting the gear.

Rear-End Gear Ratio	GM TH-350		GM TH-400 or 700-R4
	Drive Gear	Driven Gear	Drive Gear	Driven Gear
3.54	9 Green GM #6261782	24 Tan GM #3860347	17 Blue GM #8640518	45 Lt. Blue GM #9775187
	8 Black GM #6261783	21 Red GM #398792		44 Dk. Gray GM #9780470
	7	19 Natural GM #3987919	15 Gray GM #8642620	40 Black GM #1362048
		18 Brown GM #3987918		39 Brown GM #1359273

3.31	10 Blue GM #6261785	24 Tan GM #3860347	17 Blue GM #8640518	43 Purple GM #1362196
				42 Green GM #1362049
	9 Green GM #6261782	22 Green(Corvette) GM #3860345 Silver GM #3987922		41 Yellow GM #1362195
	8 Black GM #6261783	20 Blue GM #3987920	15 Gray GM #8642620	38 Blue GM #1359272
				37 Red GM #1359271
				36 White GM #1359270

3.07	10 Blue GM #6261785	23 Black GM #3860346	17 Blue GM #8640518	40 Black GM #1362048
				39 Brown GM #1359273
	9 Green GM #6261782	21 Red GM #3987921		38 Blue GM #1359272
	8 Black GM #6261783	18 Brown GM #3987918	15 Gray GM #8642620	35 Orange GM #9780628
				34 Light Green GM #9774413

2.88	10 Blue GM #6261785	22 Green(Corvette) GM #3860345 Silver GM #3987922	17 Blue GM #8640518	37 Red GM #1359271
		21 Red GM #3987921		36 White GM #1359270
	9 Green GM #6261782	19 Natural GM #3987919	15 Gray GM #8642620	33
	8 Black GM #6261783	17 Purple GM #3987917		32

Note: This table assumes a tire size of 215/70-15 and a speedometer requiring 1000 RPM’s per mile.
Based on data computed by Bruce Bowling, and compiled by Mark Chiampi 9/24/97.

Be advised that this table is a work in progress and while we are making every attempt to check each part number and spec for accuracy, we are only human and do make mistakes. Lump's Admin.

Calculations Table built by Thomas A. Harrison

with Java help from Frank Chu and Louis Reed)

TIRE SIZE DIMENSIONAL DATA, AND

SPEEDOMETER GEAR CALCULATIONS

User Input: Speedometer Revolutions Per Mile: Rear Tire Overall Diameter: Differential Gear Ratio: Want to find: Gear Drive or Driven Gear teeth (opposite to selected above) Click to calculate the gear needed: Gear needed To reset the form input:	Size	Overall Dia.
	P205/70R15	26.2
	P215/70R15	26.8
	P205/65R15	25.5
	P215/65R15	26.0
	P205/60R15	24.6
	P215/60R15	25.2
	P225/60R15	25.6
	P205/55R15	23.8
	P215/60R16	26.2
	P225/60R16	26.6
	P205/55R16	24.9
	P225/55R16	25.7

Links below, if referring to photo album, Are ** NOT **, for the Lumps Photos
it is for the "Traditional Jaguar Photos"

TIRE SIZE DIMENSIONAL DATA, AND

SPEEDOMETER GEAR CALCULATIONS

User Input: