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ivanogburn 11-19-2007 05:40 AM

Man I need some help
Here is a damn stupid question but I can't find an answer!
(I posted this orignally in the "engine section" but thought I should epost here!)
I have this '77 Ford truck I just bought to rod and it has a GM TH400 tranny.
Currently the speedometer is not hooked up!
My question is will I need a special cable to connect the Ford speedometer to the GM trany? Or is there a better way to hook this up?

It would be really cool if there were a newer electronic speedometer that would fit in the space for the rectangular Ford speedometer.

Man I need some help!

79C10 11-19-2007 06:09 AM

I don't think that you'll have a problem using the speedo cable , as they sell replacements that aren't brand specific. You'll need the proper little gear that goes on the end of the cable in the trans , though.
Have you looked for a square chebbie speedo at your local junkyard? They sell digi speedos , which you can mount where you want , then put pictures of your loved ones in the old speedo hole!
good luck with it !! :thumbup:

Deuce 11-19-2007 06:14 AM

Never having owned a Ford newer than 1956 ... I cannot say for certain ... but on the numerous 56 Ford F-100's I have ovned ... the speedometer hooked to the GM transmissions ... just like a factory Ford ... bolt on.

Even if their is a problem ... most good speedometer shops can make a speedometer cable up that will work.

I would just check to see if it just screwed on. :D
There is a strong possibility that the reason it is not hooked up is because the speedometer is way off ... with the speedometer gears in the Turbo 400

(Shown above is a 700R4 ) but a Turbo 400 uses the same type set up. Changing them to the correct ones for your application is not a big deal.

speedydeedy 11-19-2007 06:58 AM

Like the others I can't say for your year model but I have seen alot of ford cables hook directly to chevy. Try it first and if it fits see if there is another problem that would have caused them to disconnect it. Then go from there.

poncho62 11-19-2007 08:17 AM

I had Chevy stuff in my 77 Ford...............(Sorry Centerline, it's just who I am)............If I remember correctly, the speedo cable fit.

496CHEVY3100 04-23-2013 12:26 PM

If the speedometer is of to much you will have to change gears shown above .a large change requires removing tail shaft and changing the plastic gear also. , hook up cable and drine truck see how much the speedometer is off,then go to any truck parts dealer Peterbuilt freightliner etc. you can buy an adapter that screws into transmission ,then cable screws into adapter ,they come in many ratios ,to speed up or slow down speedometer they are marked in percentages in underdrive or overdrive tried to find one in my shop to post a picture but could not locate one .hope this helps.

RWENUTS 04-23-2013 03:31 PM

496 it's called a ratio adaptor.
Look here.
Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4

poncho62 04-23-2013 04:20 PM

Its also a 5 1/2 year old thread.....problem is probably solved long ago

496CHEVY3100 04-23-2013 08:17 PM


Originally Posted by poncho62 (Post 1669673)
Its also a 5 1/2 year old thread.....problem is probably solved long ago

If it is not fixed by now he had a big problem LOL

496CHEVY3100 10-29-2013 07:00 PM

Or possible help some one else.

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