Last year I had to replace my transmission; I found one at an auto wrecker in good shape, and had it installed at a tranny shop. The new transmission is fine, but now the speedo over-reports my speed by a whopping 30%, which also means that my truck is accumulating mileage on the odo much faster as well. I presume the transmission came from a truck with bigger tires or perhaps different differential gearing.

Is there some way to get my speedo to read accurately? Truck is a 94 ranger with 4.0 engine and 5 speed manual transmission.

 

For your 94 Ranger, you can change the speedometer gear at the transmission. To calculate which gear you need, all you have to know is the percent error and the tooth count of the gear that is in there now.

If your speedo is reading a known percentage high now, you will need that percentage more teeth on the speedometer gear to slow it down.

More info on the calculation and the gear part numbers in the Speedometer Correction section of the Tech Library at www.therangerstation.com

If you still have the old transmission, just pull the gear out where the speedometer cable entered and swap it into the replacement trans. If not, you should be able to order the gear. Be sure to specify that it is for a manual. Speedo gears for automatic transmission are different.