Speedometer drive?!?

[scojack_2001]

This might seem like a stupid question, but what exactly drives the speedometer?I know it drives off the trans, but how exactly? And it the speedo doesn't work, neither does the odometer. Mine doesn't work any more. It quit Saturday night. I was told by my mechanic friend that there is a plastic gear and a bearing? I dont know for sure. All I know is that I need to get it fixed and I know it wont be cheap. Will I have to rebuild the trans to fix a out of round bearing? Or is it just the cable? I need help. Any will be appreciated.

Thanks

Scott

 

[Nordbert]

If you have a 200-4r, the output shaft drives a gear on the governor which not only turns the governor, but also turns the
gear which the speedometer cable is driven by. The governor is
inside the pan and above a cover which is held on by 4 bolts with
13MM heads. I'd check for a broken or melted speedometer cable housing. Sometimes the cable will twist off at the driven gear. Try to turn the cable and driven gear before looking
inside the transmission.

 

[HOTTOGO]

Like Nordbert said...

more often then not it's the cable. Pull the cable off were it goes into the trans with a pair of channel locks and stick it in a drill and spin it and have someone watch the speedo to see if it works. If not then that's it if it does work then pull the one bolt that holds the speedo drive in from where you just took the cable off and pull that out, it's just held in with an o-ring after you take the 10mm bolt out, it has a plastic gear that is prolly stripped.

 

[scojack_2001]

Thanks for the help. I'll see what I can do as soon as it stops raining.

 

[HOTTOGO]

Let us know?

 

[chris718]

run the car on a lift with the speedometer cable unplugged and see if you can see the gear rotating in the housing that it rides in.if it rotates ,this means that all is well in the transmission and the cable and speedometer head must be inspected .if it doesnt turn ,remove the 10 mm screw that holds the gear housing in on the rear of the trans and inspect the gear that rides in it for damage or stripped teeth.if the inner gear that rotates this gear in the housing is damaged or broken the transmission usually will not shift because this gear is also what generates rotation to create governor pressure.although highly unlikely,the gear teeth could be damaged causing no rotation of the driven gear even though the governor is spinning.