Speedometer Recalibration

The transmission didn't change the speedo calibration, the diff gears did. I haven't got the link you asked for, but there is one - my guess is that Bill is sending it within the hour.

You will need to know the tire diameter and the diff ratio, and this will drive you to a specific gear size. The gear is easily replaced - find the speedo cable entering the tcase near the back on the driver's side, and take the single bolt out and remove the gear. Remove the E-clip that holds the gear on and replace the old gear with the new one. The shaft that the gear fits onto is on a round plate, but the shaft is off center. You have to turn the plate to align the gear with the gear inside the tcase. There are numbers and guide lines on the plate and the tcase, align the number that matches the gear count, and you should be good.

The speedo is WAY off, not just a little bit like gears would do. I am guessing that the "system" Jeep uses, and the "system" that the donor transmission came from were different. Here is the info that I forgot. T-18 transmission, D300 t-case (should not matter), 4.56 gears, 33" tires.

The trans won't matter at all, and the tcase is the factory fittment.

The difference you are having is the gear ratio in the diffs and the 33" tires. Having said that, I suppose the tall tires and the 4.56s would cancel each other out, and the error should be pretty small. The speedo itself can be dirty inside and this will cause it to be slow. (I didn't say if the error was + or -.)

There are actually 2 jeeps with this problem. both CJ's one a 7 one an 8. On the CJ7 it reads around 75 when you are going 65. On the CJ8 it reads around 40 when going 65 (using the khp chart it comes real close to the actual speed)

Very simple... this chart is the most accurate I've seen:

I don't think so, he's probably off by 10 mph. What are you thinking? (good description on installation though)