Th350 not spinning the speedo cable

[82sbshortbed]

My speedometer worked but was reading about 10 mph fast or so. Swapped transmission now it doesn't work. So where would I start to look into this problem? Do I have to remove the tail end and have a look? What in the transmission drives the cable?Thanks for any help.

 

[edgephoto]

There is a gear on the output shaft called the drive gear. Then the speedo gear housing goes into the side and the gear in the housing connects to the cable. This gear is called the driven gear.

If you are sure the cable is not spinning. You have one of these issues.

1. Drive gear is damaged or missing. They are plastic
2. Driven gear teeth are worn and not meshing with drive gear.
3. The square in the driven gear is rounded out.

 

[brooksman9]

There is also a clip on the drive gear on the tail shaft that keeps it in place. If it’s missing it can slide back an not contact the driven gear. Pull the housing from the tranny and spin as a unit. If the needle moves check the gear on the shaft.

 

[Edelbrock]

A few alternate options:

Download a free speedometer app for your phone. Doesn't cost anything, and you can turn on speed alerts, so if you exceed the speed limit by a certain amount, it will alert you.

Or If you use Google Maps to see your speed, it will also alert you to speed traps that have been reported by others.

You just turn on an app and place the phone on your dash in front of the spedo.

A better option:

GPS speedometer. It sits on the dash, and projects the speed onto the windshield. They call it a "HUD" or Heads up display. You can see your speed without taking your eyes off the road, there is no need to look down at the dash. $10 on Amazon. I have one, and they are cool.

Amazon link for the GPS HUD:

https://www.amazon.com/dp/B0DS6F226K/

 

[justhorns]

Both ends of the cable can be -short- of what they are supposed to drive. Either the tranny isnt driving it, or the cable isn't driving the speedo. I had issues at the speedo end as the new junk cable was too short. Remember the inner cable can be too short although the outer may be correct. The cable fits into both ends with a squared shape that must engage at both ends. Take one end apart at a time and make sure it engages. test it, do the other end. Its OK to pull more cable to the speedo, but, some cables have limiters to place the cable at the speedo end. Just play with it. I have a old inner cable that I use to test speedometers, and I just drive it with a drill.
It will still be 10 mph fast. you can change the driven gear to more/less teeth to alter accuracy. There is about 5 gears available.

 

[82sbshortbed]

A few alternate options:

Download a free speedometer app for your phone. Doesn't cost anything, and you can turn on speed alerts, so if you exceed the speed limit by a certain amount, it will alert you.

Or If you use Google Maps to see your speed, it will also alert you to speed traps that have been reported by others.

You just turn on an app and place the phone on your dash in front of the spedo.

A better option:

GPS speedometer. It sits on the dash, and projects the speed onto the windshield. They call it a "HUD" or Heads up display. You can see your speed without taking your eyes off the road, there is no need to look down at the dash. $10 on Amazon. I have one, and they are cool.

Amazon link for the GPS HUD:

https://www.amazon.com/dp/B0DS6F226K/

That's pretty cool! I have a speedometer app that I was using. But I like the hud one.