My speedometer is not working. I've been told it's probable the plastic sacrificial gear. Any tips on getting to it? I can't seem to get my fat hands on it. 65 Convertible with a 4 speed.

 

Pull the cluster and have it rebuilt/ restored/ calibrated and it will be good as new. You're not getting to it until you pull the cluster. So you might as well do the job right

 

Ray,
work easy to hard. Pull out the speedometer cable at the trans. It unscrews. Run the cable with a drill and have a helper eyeball the speedometer for movement.

If it spins the gear in the transmission which is plastic is suspect and needs inspection.

If it doesn’t spin the speedometer check for a broken cable. This would be the best senario .

If the cable and plastic drive gear at the transmission end are good then the instrument cluster will need to come out and the actual speedometer checked.
Mine was repaired in 1988 by the last owner as I have the receipt.
check that and report back so we can guide you through it.
Marshal

 

Ray - as Marshal suggested, there are some things you can check first before you pull the cluster, which is a bit involved.
Once you are under the car, remove the cable from the trans and spin the cable while someone inside the car tells you whether the needle is moving or not.
By the way, I'm pretty sure you have to spin it counterclockwise.
If that's good to go, then pull out what most of us refer to as the speedo-bullet. There's a small tab that holds these steel bullet to the tailshaft of the trans
that is secured by a single 1/4-20 short bolt. When you pull out the bullet, there is a plastic 'driven gear' inside and you want to look for wear on the teeth.
Typically that doesn't happen often but if by chance whoever was in there before did not perfectly align the steel 'driven gear' on the shaft, there is a
chance that the soft driven gear could lose some teeth and no more speedo. Happened to my 66 L79 Coupe after I had a few thousand miles on it after
having the trans done. Worked fine for quite some time but then...sheared off teeth.
One last word of caution, there is nothing but gravity holding that plastic gear inside the bullet so when you remove it to inspect the gear, try not to tip it forward
where the gear will drop into the trans.
Pic attached is what I found when my driven gear went away. They are cheap and color coded to correspond to the number of teeth.
Good luck.
Mike T - Prescott AZ