Ford 4-Speed Toploader

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Joe - 15 May 2005 13:28 GMT

I have a 1972 Ford Mustang, 351C-4V, 4-speed toploader, Hurst shifter.
The speedometer does not work (at all) so I replaced the speedometer
cable and reused the cable driven gear inserted into the extension
housing. Still doesn't work. I can feel the output shaft in the
extension housing with my finger through the speedo-gear hole. I can't
feel the drive gear on the output shaft. Is it possible that it broke
off and is in the bottom of the extension housing? Could such a gear
(plastic) just break off? If so, what's the best way to replace it
now? Does the whole transmission have to be removed or is it possible
to somehow remove the extension housing to expose the output shaft?

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Grover C. McCoury III - 15 May 2005 15:37 GMT

FYI: Some good information on Toploaders @

http://www.davidkeetoploaders.com/cutawayview.htm --> cutaway view of
speedometer cable/gear
http://www.gearzone.net/toploader.html
http://www.toploadertransmissions.com

Yet another $.02 worth from a proud owner of a 1970 Mach 1 351C with a close
ratio Toploader @ http://community.webshots.com/album/18644819fHAehGJAjt

>I have a 1972 Ford Mustang, 351C-4V, 4-speed toploader, Hurst shifter.
> The speedometer does not work (at all) so I replaced the speedometer
[quoted text clipped - 6 lines]
> now? Does the whole transmission have to be removed or is it possible
> to somehow remove the extension housing to expose the output shaft?

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351CJ - 15 May 2005 22:19 GMT

I don't think you have an internal speedometer drive gear problem. The
teeth on the internal speedometer drive gear run almost parallel with the
sides of the gear. Look at the gears in these pictures.
http://www.4speedtoploaders.com/shop/enter.html?lang=en-us&target=d9.html

Although I've only removed the tail shafts after I have removed the entire
transmission from the car, I suppose it could be removed while the
transmission is still bolted to the engine in the car.
Are you sure the speedometer cable is not turning? Are you certain it is
inserted all the way into the back of the speedometer? That can be a real
bitch sometimes. I would confirm these two items before I pulled the tail
shaft.

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Joe - 15 May 2005 23:17 GMT

Yep. The speedo cable is turning. I can actually spin the driven gear
on the transmission end and the speedometer moves (at least a little).
When I insert the cable into the transmission (which should mesh with
the gear), I can still spin the opposite end of the cable (at the
speedometer side). I don't think it is supposed to spin when inserted
into the transmission.

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Richard - 16 May 2005 03:29 GMT

> Yep. The speedo cable is turning. I can actually spin the driven gear
> on the transmission end and the speedometer moves (at least a little).
> When I insert the cable into the transmission (which should mesh with
> the gear), I can still spin the opposite end of the cable (at the
> speedometer side). I don't think it is supposed to spin when inserted
> into the transmission.

You are correct. You said you replaced the "driven gear" right. Not certain
but I thought that the drive gear is a steel worm gear. Points back to the
driven gear unless there is a shear pin that has broken.

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Richard

'94 GT 'vert
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351CJ - 18 May 2005 03:30 GMT

>> Yep. The speedo cable is turning. I can actually spin the driven gear
>> on the transmission end and the speedometer moves (at least a little).
[quoted text clipped - 7 lines]
> but I thought that the drive gear is a steel worm gear. Points back to the
> driven gear unless there is a shear pin that has broken.

They are both plastic, look at the picture in this link.
http://www.4speedtoploaders.com/shop/enter.html?lang=en-us&target=d9.html

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Richard - 18 May 2005 04:00 GMT

Plastic it is. Being plastic would seem to allow for it to break and/or
otherwise not be locked into position. Looks like there is a slot for a key.
Something has to lock into place. Can you reach in with your finger and
rotate the gear?

Signature

> >> Yep. The speedo cable is turning. I can actually spin the driven gear
> >> on the transmission end and the speedometer moves (at least a little).
[quoted text clipped - 10 lines]
> They are both plastic, look at the picture in this link.
> http://www.4speedtoploaders.com/shop/enter.html?lang=en-us&target=d9.html

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