My '94 tranny is makeing the dreaded countershaft bearing noise and also grinding goining into 2nd (either up or down) so I'm thinking it is time for a rebuild. I've built lots of engines before but never any transmissions. I see rebuild kits on Ebay. My question is are there any clearances or tricks I need to know? Is there a detailed instruction manual available with clearances and steps etc?

 

Usually the only critical measurement when rebuilding the transmission is adjusting the end play of the countershaft and output shaft using shims. Its really as simple as taking the transmission apart, replacing wear parts and putting everything back together.

 

Thanks Bart. Can you or someone clue me in to these endplay clearances?

 

End play measures how much the respective shafts can be moved in and out compared to a fixed reference point.

To measure the end play, you'll need a dial indicator and suitable base. Counter shaft end play is measured when the counter shaft is installed, whereas measuring the output shaft end play is usually one of the last reassembly steps performed before re-installing the transmission. You make the initial measurement by installing the counter shaft or input shaft, turning the transmission tail end up, then installing the dial indicator so the end of the probe touches the end of the counter shaft or output shaft. Rotate the input shaft/counter shaft a few times, then zero the dial. Lift up on the counter shaft or input shaft (helps to use a block of wood on the input shaft since everything is assembled) and note the reading on the dial indicator. This shows the thickness shim needed to obtain proper end play. Remove the input bearing or counter shaft bearing retainers and install an appropriate sized shim or combination of shims, then repeat the measurement. Usually you want zero end play for both, but Ford considers up to .004" to be acceptable.

Using too thick of a shim will result in too much bearing preload and will probably result in shorter bearing life. If its just .001" thicker, you'll probably never notice the difference, but if the input shaft or counter shaft is difficult to turn by hand afterwards, then you definitely need to use a thinner shim. Too much end play results in the transmission popping out of gear and/or rough shifting. It is somewhat less critical on the counter shaft to obtain zero end play. If it is less than .004", leave it alone.

 

Thanks again Bart. I'm getting pretty good at double clutching and since I'm the only one that drives the truck I might wait until spring to rebuild. In the mean time I bought a CD Service and Repair Manual that has the process. thanks again.