[Shotimes] Speedo/odometer problem

[krazgeo@comcast.net]

 -------------- Original message ----------------------
From: "Adam Phillips" <adambant@hotmail.com>
> i 
> barely brushed the speedo cable coming out of the tranny with my forearm, 
> and the plastic part kinda fell apart and disconnected. ... worked again fine....till tonite when it dropped to zero on my 
> way home. Took a peek with the flashlight in the driveway, grabbed the cable 
> and wiggled, hmm, nope, still all connected and snug like it shoud be. So im 
> worried if somehow it stripped out whatever is inside the transmission? If 
> this is the case, how crazy hard would that be to fix? Any ideas or 
> suggestoins please :) Thanx!

Been there...done all of that.  Here's the scoop.

The speedo drive gear is on a shaft that is inside the tranny case, and is not removable without taking the whole tranny apart.  Several bearings are lost as they must be destroyed to disassemble the case.  The replaceable driven gear is on the bottom of the speed sensor, which is what the lower short speedo cable plugs into.  The sensor's main purpose is to tell the PCM whether the car is moving or not, for throttle control, and it is also the source for the cruise control.   If there is binding in the speedo cable, the gears will take the brunt of the punishment, and the drive gear will wear rapidly.  The upper speedo cable tends to be overheated where it approaches the EGR tube at the corner of the intake manifold, and will disintegrate over time just above the joint between it and the lower cable.  This will initally cause bouncing of the speedo needle, and ultimately cause the cable to fail.   

If the speedo has suddenly quit, there either was binding somewhere in the cable assembly, or it has partially popped out of the speed sensor.  The way to test this is to remove the cable from the sensor by pulling it up, then disconnecting the two cables and reconnecting the lower one to the sensor.  This procedure takes the risk of further hurting the sensor and/or gears further out of the equation.   With the car jacked up on one side, preferably the right side for convenience, spin the front wheel either by hand with a helper or use the engine at idle (with jackstands) to see if the end of the cable is turning when the transmission is rotating.   If the gears are OK, the top of the cable as it sticks out of the housing will turn, and you will not be able to stop it with your fingers.  If it does not turn, or you can stop it, your drive/driven gears are gone.  That happened to me when I installed a Rock-Auto replacement speedo cable in my car a year and a half ago.  I killed the
 gears within 5 minutes of trying to drive it with the new cable.  With the cable disconnected, I could still use the cruise, as the speed sensor does not have enough drag to stop "my" gears from meshing.  But they do not have the capability to turn the speedo, even with new proper Ford cables.  I used the tach as a speedo until the car retired a few months later.

To everyone.....NEVER NEVER NEVER NEVER NEVER use a Rock Auto speedo cable.  They are totally wrong...too long, too rigid, misdesigned, and will not even connect to the speedo head...the plastic clip is the wrong dimension.  It's JUNK!!!!  I called them about it and the guy said "Send me pictures so we can improve it".....never heard from him again.

George