spastic speedometer

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Nov 25, 2007 | 04:30 PM

Mr. G

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spastic speedometer

Howdy all, I recently bought a 74 F250 390/C6 and the speedometer didn't work. I found out that the cable had been laying on the exhuast and had burt through. So I changed the cable. The speedometer works but the needle jumps up and down while excelerating or just cruzing. I pulled it out of the tranny and it seems to turn smoothly as far as I can tell but is this normal for thes trucks?

Nov 25, 2007 | 04:48 PM

Mil1ion

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Maybe be the speedo head is dirty and has old hard grease on it ?

Take it out an lube it up.

Nov 25, 2007 | 04:49 PM

Mr. G

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Good idea. I will try it today.

Nov 27, 2007 | 06:52 PM

Mr. G

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Well I took it back apart and oiled the speedo, but the thing is, it seems to move very smoothly. So I got to looking at the cable and where it coneects to the speedo and the cable looks like it is too small. It is hard to measure but the cable is about 3/32 and where it plugs in it is a hair over 1/8 so I'm thinking that it is skipping. I mean it acts like it is skipping. I guess all I can do is maybe buy another cable from a higher end parts store or shim it somehow. Anyone ever run into this?

Nov 27, 2007 | 07:20 PM

fasthauler

Fleet Mechanic

Joined: Mar 2004

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From: Hesperia, CA

Quote:

Originally Posted by Mr. G

Cables are usually universal in size, but you never know what can happen. The problem you are having is usually caused by the cable sticking and then releasing. this is usually caused by lack of lubrication or dried up grease as Dennis suggested. Occasionally the cable can be in a bind and this can cause the sticking and releasing. I would check the entire length of the cable for any binding. Also pull the cable completely out of it sheath and make sure its not fraying somewhere. The cable should slide freely in and out of the sheathing, if not then you definitely have a bind on the cable.

Nov 28, 2007 | 07:01 PM

rusty7983

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From: hohenwald, tn

my spedometer only works under 30 mph. and its off. i need to use my wifes gps and get it right. what do y'all think is wrong with my speedo? never seen one partially work.