I dont confess to be an Auto box expert, so i could do with some help before proceeding.
My speedo according to the last 2 MOT tests, hasnt been working [mileage identical], i removed the non-functioning cruise control, and bought a one piece cable. Putting it into the back of the speedo head and giving it a twiddle caused some correct movement on the dial.
However after connecting to the gearbox end, nothing, taking it up the road [speedo disconnected] i can see the cable isnt turning at all.
The square drive in the gearbox is not rounded, its all a good fit.
Any ideas? And if theres a common fault here, how easy is it to fix?
Thanks.

 

A wild guess??

 

Wild guess?

The square drive in the gearbox will probably be moulded into a gear wheel or else how would it be driven? Perhaps the gear wheel or other part is broken, especially if it's plastic (like my old 2.8 Capri's speedo drive..)

EDIT:- See if you can somehow turn the square drive in the gearbox - if it was still connected then perhaps it would not turn unless the transmission is running, if you know what I mean.

Mark.

 

Yeh that did occur to me, my other point being , how hard is it to get that drive out if its faulty, theres a small bolt holding a forked braket, that appears to hold the gear in, but i dont fancy trying to dismantle it if you have to take the tail end of the box off\apart.

 

If you spin the cable itself, does the gauge register this? I lost my speedometer and found out the retaining clip came off the drive gear on the output shaft! Luckily the clip didnt migrate It allows the drive gear to go backwards not engaging the driven gear, so no reading That cover wherer the cable connects comes off easily enough, you will lose a minimal amount of fluid.

 

I believe to replace the gears the tailshaft has to come apart, check out the tech articles on the main page i believe theirs a segment there with pictures and all about doing speedo ears.