I'm trying to find out why my speedo does not work. I put in a new Pro-Built 700R4 to replace the old one and changed the rear from a 2.77 to a 3.42. Pro-Built gave me the new driven gear so I put that in. After installing the tranny I put the speedo cable where it is supposed to go on the tranny. It didn't work so I pulled the cable out and cleaned it and put it back in. It still doesn't work. Am I missing something? Are the drive and driven gears not meshing?

 

Theres a good chance your going to need an offset speeometer gear housing but usually if the gear will slip in the housing its the correct one. Sometimes its tricky getting the housing installed correctly, put the housing in and turn it counter clock wise as much as possible this should mesh the gears.

 

Ok, I did that, still doesn't work. Is there some kind of retainer or anything to keep the driven gear from moving laterally in the housing? Can it slid in and out (not completely out) of the housing when installed, and therefore not be meshing?

 

Nope.
The only thing that holds the driven gear in place is the housing. It should work, the offset housing I posted about earlier will allow a smaller driven gear to slide in but not the other way around and it will not mesh. Its possible you do have an offset housing and are trying to use a setup from a standard housing. What size driven gear are you working with here?? 38+ teeth use the offset and smalller gears use the standard housing.

 

Check the actual drive gear on the output shaft to see if it is cracked. That would cause it slide around back and forth and not mesh with the driven gear...it's happened to me before. Also there is a metal clip that holds the drive gear on the shaft...check to see if that's not broke either.

 

On the face of the adapter for the driven speedometer gear
is cast the gears which the adapter was made for, such as
38,39,40 and 41. Your gear should listed on the adapter. If not,
you will need to get an adapter with your tooth count on it.
I would put the blade of a pocket screwdriver into the square
hole for the cable and try to turn the gear. If the gear turns,
the gears are not meshing or are stripped. Turning the cable should make the speedo needle move. If it doesn't, check for
a broken cable or a melted cable housing .

 

I got it fixed. It was the housing or "sleeve", the black plastic thing I had to get a different one, one with a shorter sleeve for the driven gear. It works now. Thanks guys.