Also, what would need to be done if anything with the other electrical plug?
Sounds like it may be part of the kickdown?
67ss said
Sep 14, 2021
They typically can be converted to mechanical speedo. I have done it on a couple 700r4 transmissions. This should not be much different. The driveshaft will have to be pulled and the 5 or 6 bolts holding the tail housing on and pull the tail housing. The gear on the tail shaft will have to be pulled off there may be a clip holding it or it might be friction fit I can‘t remember. Then tap on the new drive gear which does have a clip that holds it in position. Reinstall the tail housing and driveshaft and then install the Speedo housing with the driven Gear. Sounds complicated but it is probably a 15 minute job.
67ss said
Sep 14, 2021
The other plug is for kick down function, there should be a switch on the gas pedal or the carb that would send Power to the solenoid in the transmission at wide open throttle.
BLyke said
Sep 14, 2021
Thanks Chris!
BLyke said
Sep 15, 2021
67ss wrote:
They typically can be converted to mechanical speedo. I have done it on a couple 700r4 transmissions. This should not be much different. The driveshaft will have to be pulled and the 5 or 6 bolts holding the tail housing on and pull the tail housing. The gear on the tail shaft will have to be pulled off there may be a clip holding it or it might be friction fit I can‘t remember. Then tap on the new drive gear which does have a clip that holds it in position. Reinstall the tail housing and driveshaft and then install the Speedo housing with the driven Gear. Sounds complicated but it is probably a 15 minute job.
Yes, the digital drive ring is not compatible with a driven gear and is what Chris is referring to replacing by removing the tail housing.
You will need to get a drive gear for the output shaft to take the place of the digital ring. Figure out your rear gear ratio and tire size and match the drive and driven gears for that combo.
-- Edited by Lost in the 60s on Wednesday 15th of September 2021 04:54:02 PM
67ss said
Sep 15, 2021
BLyke wrote:
67ss wrote:
They typically can be converted to mechanical speedo. I have done it on a couple 700r4 transmissions. This should not be much different. The driveshaft will have to be pulled and the 5 or 6 bolts holding the tail housing on and pull the tail housing. The gear on the tail shaft will have to be pulled off there may be a clip holding it or it might be friction fit I can‘t remember. Then tap on the new drive gear which does have a clip that holds it in position. Reinstall the tail housing and driveshaft and then install the Speedo housing with the driven Gear. Sounds complicated but it is probably a 15 minute job.
so all 3 of these will be removed and replaced?
The yellow gear is the governor I believe which stays along with the gear driving it. It is the ring behind those that has to be removed and then a gear installed in its place to drive the speedo housing.
BLyke said
Sep 16, 2021
Thanks Chris,
will the yellow gear come off when the rear housing is removed?
67ss said
Sep 16, 2021
No it won’t. If you search YouTube there are some videos of replacing the gears to give you some idea of what to do.
BLyke said
Sep 16, 2021
67ss wrote:
No it won’t. If you search YouTube there are some videos of replacing the gears to give you some idea of what to do.
Yep,
Found several and looks like it will be doable
Planning to go with a steel drive gear form LA Speedometer Gear. it is a press fit and Supposedly was part of a GM recall long ago
Working on the 51 Pontiac
Looks like the TH400 may have come from a GMC Truck?
Any way is has a electronic pickup for the speedometer, not too compatible with the 1951 speedometer.
Looks like with the yellow/white 19 tooth drive a older style speedometer
is it really that simple or must the digital drive ring be removed.
Hoping someone has actually done this and can confirm my suspicions
Thanks
-- Edited by BLyke on Tuesday 14th of September 2021 06:51:28 PM
Sounds like it may be part of the kickdown?
They typically can be converted to mechanical speedo. I have done it on a couple 700r4 transmissions. This should not be much different. The driveshaft will have to be pulled and the 5 or 6 bolts holding the tail housing on and pull the tail housing. The gear on the tail shaft will have to be pulled off there may be a clip holding it or it might be friction fit I can‘t remember. Then tap on the new drive gear which does have a clip that holds it in position. Reinstall the tail housing and driveshaft and then install the Speedo housing with the driven Gear. Sounds complicated but it is probably a 15 minute job.
The other plug is for kick down function, there should be a switch on the gas pedal or the carb that would send Power to the solenoid in the transmission at wide open throttle.
so all 3 of these will be removed and replaced?
Yes, the digital drive ring is not compatible with a driven gear and is what Chris is referring to replacing by removing the tail housing.
You will need to get a drive gear for the output shaft to take the place of the digital ring. Figure out your rear gear ratio and tire size and match the drive and driven gears for that combo.
-- Edited by Lost in the 60s on Wednesday 15th of September 2021 04:54:02 PM
The yellow gear is the governor I believe which stays along with the gear driving it. It is the ring behind those that has to be removed and then a gear installed in its place to drive the speedo housing.
will the yellow gear come off when the rear housing is removed?
No it won’t. If you search YouTube there are some videos of replacing the gears to give you some idea of what to do.
Yep,
Found several and looks like it will be doable
Planning to go with a steel drive gear form LA Speedometer Gear. it is a press fit and Supposedly was part of a GM recall long ago