Well, my first question of the forum for my new XJ6 is about the Speedometer. It seems to read high and steady versus a GPS unit: it reads at about 78 MPH when the car is actually traveling 60 MPH.

My first guess is that someone changed the rear axle ratio, but I suppose it's possible that the speedometer itself was changed for another. Do all of the XJ6 speedos have the same TPM calibration, or did it vary by transmission type, axle ratio, or some other factor?

Can anyone say what the proper TPM and/or model number is for a '71 with an automatic?

Looks like I will spend some time tomorrow with one rear wheel in the air and the transmission in Neutral...

Many thanks,

Tom

Hmmm....I cannot seem to find the "edit post" button.

Anyhow, I looked at a photo I have, and my speedo appears to be 1020TPM.

Jaguars method was to put in a different speedo head for each rear end ratio/engine combo. Most of them are not available today and you might
have to resort to having yours recalibrated.

I have been successful using S2/early S3 parts and making them very close to perfect. The odometer is a separate portion and takes different parts and skills...