Just installed a jtype trans into my 63 544 after a tunnel expansion job. I've got a 4.10 rear but since I've installed the tranny my speedo is showing about 8mph slower than actual speed. Any suggestions? I assume it's the speedo gear?

Do you know which speedometer drive gear is in your overdrive?

Are you using a speedometer angle drive? The angle drive attaches to the overdrive and then the speedometer cable is then attached to the other end of the angle drive.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

It’s the green gear. No angle drive.

The traditional way of calibrating the speedometer with changeable drive gears is to use a gear with less teeth to increase the speed reading at the speedometer, but there are alternatives. You can get an inline gear box that requires your cable to be cut and then new ends crimped on and recently 1 of my customers found a shop that can make angle drives that can change the ratio. BTW, the stock angle drive Volvo used was 1 to 1 meaning it didn't change the ratio or affect the speedometer reading.

Volvo used 2 green colored speedometer gears in the J O/D, light green with 21 teeth and dark green with 22 teeth.

FYI, if your speedometer cable routing requires a sharp bend to be connected to the O/D, then that might affect the reading and an angle drive might be needed.

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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com