XJ Speedometer Calibration
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.
End of Speedometer page.
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