Speed control and speedometer cables

[Captainfury]

The speedo on my 1972 Fury gran sedan has not worked since I bought her, so I’ve purchased a new one. However, reading the FSM and taking the ancient rusted one off the trans, I believe that the speed control unit is going to be integral to this matter.
It appears that there is no direct cable from Speedo pinion to the speedometer housing in the dash. According to the FSM one cable comes from trans to speed control servo, then another goes from servo to speedometer. Is the implication here that unless one has a good functioning speed control servo, the speedometer will not work either?

 

[413]

No that's not right. The cruise can be inoperative and the speedo still work fine. It is mechanical in and out of the servo.

Take the cable off the servo that goes to the speedo, spin it up with a drill and see it the speedo is operating.

 

[Captainfury]

Thanks for the

No that's not right. The cruise can be inoperative and the speedo still work fine. It is mechanical in and out of the servo.

Take the cable off the servo that goes to the speedo, spin it up with a drill and see it the speedo is operating.

Thank you 413 for that great expeditious reply. I’ve just tried it with a drill and unfortunately nothing on the Speedo. I used the upper cable as per fsm. I suspected as much as PO said he’d been annoyed by it being noisy and so he disabled it. I removed the shield below the steering column, and began following the cable up to speedo, whereupon it disappeared behind and up above steering column. What a bastard of a job this is beginning to look like.

 

[CBODY67]

The PO's issue could in the housing of the lower cable? The one that goes to the cruise transducer. Check that the lower cable attachment at the transmission fitting does not spin in the housing, which would mean the two gears are not meshing due to wear. For things to work as designed, that lower output gear should not spin in the housing. Only moving when the transmission output shaft spins.

The coupling in the transducer will be mechanical, 1:1. The output to the speedometer cable goes directly to the speedo head itself.

Key would be where the sounds the PO didn't like were located. In the back of the speedo head or in one of the cable housing (normally speedo grease lube takes care of that one).

In the speedo head, where the cable attaches, there is a plastic bearing/bushing that can wear with time and miles. When it wears, it allows the rear speed cup to get off-center and physically rub the front speed cup, which is attached to the speedo needle. Such rubbing would be noisy and also make the needle move in unusual amounts.

All things considered, not knowing where the noise was and the age/mileage of the vehicle, might be better to find a good source for a complete replacement cable assemblies set, upper and lower. That would isolate the issue to the cruise transducer and/or the speedo head.

Just some thoughts,
CBODY67

 

[Big_John]

I’ve just tried it with a drill and unfortunately nothing on the Speedo.

I think you have to run the drill counterclockwise to make the speedo work. Did you do that?

 

[Captainfury]

Hi

I think you have to run the drill counterclockwise to make the speedo work. Did you do that?

Big John
I ran the drill clockwise. I’m going to try counter clockwise now. Thanks for the help.

 

[Captainfury]

The PO's issue could in the housing of the lower cable? The one that goes to the cruise transducer. Check that the lower cable attachment at the transmission fitting does not spin in the housing, which would mean the two gears are not meshing due to wear. For things to work as designed, that lower output gear should not spin in the housing. Only moving when the transmission output shaft spins.

The coupling in the transducer will be mechanical, 1:1. The output to the speedometer cable goes directly to the speedo head itself.

Key would be where the sounds the PO didn't like were located. In the back of the speedo head or in one of the cable housing (normally speedo grease lube takes care of that one).

In the speedo head, where the cable attaches, there is a plastic bearing/bushing that can wear with time and miles. When it wears, it allows the rear speed cup to get off-center and physically rub the front speed cup, which is attached to the speedo needle. Such rubbing would be noisy and also make the needle move in unusual amounts.

All things considered, not knowing where the noise was and the age/mileage of the vehicle, might be better to find a good source for a complete replacement cable assemblies set, upper and lower. That would isolate the issue to the cruise transducer and/or the speedo head.

Just some thoughts,
CBODY67

You know these cables, speed control devices and their overall operation very well cbody 67. Thank you so much for your in-depth advice. I’ve had my 72 Fury Gran Sedan for 12 months so am an amateur at best. She has the 400 ci, 2 bbl with 727 trans. Condition is ok, and I’m trying to get her to the stage where I can legally drive her on the road. I am looking forward to that day enormously .
Probably the only one in Sydney!! A working Speedo, and perfectly working lights/ indicators are the only two hurdles of any real significance remaining.
Best wishes
Kirk

 

[Captainfury]

You know these cables, speed control devices and their overall operation very well cbody 67. Thank you so much for your in-depth advice. I’ve had my 72 Fury Gran Sedan for 12 months so am an amateur at best. She has the 400 ci, 2 bbl with 727 trans. Condition is ok, and I’m trying to get her to the stage where I can legally drive her on the road. I am looking forward to that day enormously .
Probably the only one in Sydney!! A working Speedo, and perfectly working lights/ indicators are the only two hurdles of any real significance remaining.
Best wishes
Kirk

I forgot to mention that the vehicles odometer shows 432 miles. So it’s done 100432 I believe. Carpet everywhere except drivers floor is like new. Upholstery everywhere except drivers seat is like new. I suspect the car was used originally by either a businessman who drove around alone, or an owner without much family to speak of.

 

[Vinny]

Thanks for the

Thank you 413 for that great expeditious reply. I’ve just tried it with a drill and unfortunately nothing on the Speedo. I used the upper cable as per fsm. I suspected as much as PO said he’d been annoyed by it being noisy and so he disabled it. I removed the shield below the steering column, and began following the cable up to speedo, whereupon it disappeared behind and up above steering column. What a bastard of a job this is beginning to look like.

Did you try spinning the drill in both directions? You may have spun it in the wrong direction. Something to consider.