Speedometer Cable Frustration

[krumpelsaurusrex]

My speedometer was bouncing around all over the place and sometimes didn't register. I pulled it off the speedometer and checked to see if it was worn. It seemed in good condition, but I noticed I could pull it out. I thought surely that if it the internal metal cable could be removed from inside the cab while still hooked up to the trans, that it was broke. So I finally found a local store that had it and I purchased it. I removed the old gear and replaced it on the new speedometer cable. I then realized that there is a small hole at the end of the gear that the metal cable goes into, and it does not actually fasten to the gear in a permanent fashion. It seems that the cable is only held into place at the gear by the pressure created by tightening the cable to the speedometer. Is this correct? if so, I think I just bought a speedometer cable that I didn't need, and only needed to tighten the old one. It's only $20, but It seems weird that the gear wouldn't fasten to the cable in a different manner.

[flyboy71]

Still trying to understand your question this early in the morning but here goes... If you are referring to the speedo attach, then yes its just a slip fit on the center of the cable. The square end of the cable core just slips into the socket on the speedo and can slide in and out freely; there is no locking faeture on that. Usually there is some grease on it also to allow it to be a slip fit. The outer shell screws on and thats all that keeps it attached. Its not a whole lot different than the antenna connector on the back of a CB in concept.

Hopefully that helps

[lee_ford]

My speedometer was bouncing around all over the place ...

I have found that after many years the lube on the inside dries out. When the inside part drags at the top it will windup like a spring and then unstick and spin fast, then bind up, then spin, bind, spin, bind, spin… This is why an older speedometer needle will jump around. On my 54 Ford, I unhooked both ends, pulled the inside cable out and used an oil can to pump oil down through it until some oil came out the other end. I continued to pump it for a little while to get as much dried up junk out as I could. I could have used some kind of paint thinner to clean it out good first, but I did not think of that until later.

As for the weight of oil to use, the thicker the oil the harder it will be to reinsert the inside cable. I used 30wt and it was a challenge. Since there is very little pressure needing to be lubed, I will use 3-in-1 oil next time or maybe some graphite.

[george worley]

I used grafhite oil I got at NAPA. It came in a small bottle with a small long tip that was easy to use . I oiled the cable housing and let it set till it stopped dripping. than clean the cable with mineral spirits and re oiled the housing and imediately put the cable in and hooked it up. That fixed the problem.

[krumpelsaurusrex]

I went ahead and installed my new cable. I screwed the cable onto the speedometer first and turned the gear to make sure the needle moved. I then ran the cable down to the transmission, it slid right into the trans and I bolted it in. Went for a drive, and nothing.. not even a bounce. I am assuming the cable came off the gear but really it's frustrating. I almost want to put some thread locker on the tip of the metal cable that inserts into the gear before I put it back together. The nice thing about the new cable is it's at least a foot longer then the one that was in the truck before, making it much easier to remove the instrument cluster if needed. Back to the drawing board on ho to get this thing to read. For now I'll use my GPS unit that I take hiking and Geocaching with me to watch my speed.

[SteveC]

there should be a keeper on the gear that keeps it held to the cable

[krumpelsaurusrex]

there is a keeper on the gear that snaps over it and into the grooves on the cable. but the square metal cable inside the housing that actually turns is what is giving me the issue. It won't (I think) stay put inside of the gear.

[SteveC]

hmm check the inside of the gear to be sure it isnt stripped and also make sure that the cable is tight on the back of the instrument panel...would be me starting point

[loglat]

I'm having the same issue. I think after however long of the gear sticking the plastic gear may just be worn down. It doesn't look awful, but when I turn the whole gear by hand, the needle moves fine. I'm ordering a new gear tonight. If that doesnt fix it, I'm out of ideas.

[loglat]

I'm having the same issue. I think after however long of the gear sticking the plastic gear may just be worn down. It doesn't look awful, but when I turn the whole gear by hand, the needle moves fine. I'm ordering a new gear tonight. If that doesnt fix it, I'm out of ideas.

[JMcTurnan]

What size gear do I need for a c4 trannY? because mines anywhere from 10mph to 30mph off.

[fordman]

the speedo meter gear size is determined by the size of the rear tires and the gear ratio in the rear end. there was a discussion a few months ago about the size of the drive gear in certain transmissions. i dont remember i started ignoring it after it just went on and on. one guy was saying the drive gears were the same size and the other said something about them being different inside fo different transmissions. they may have been talking about an np435 but i dotn remember. when you go to buy one what they will want to know is the number of teeth you want. and what transmission you have.

[JMcTurnan]

That does not help me whatsoever , because I don't have the right one that fits it, mine fits a 68 fairlane . So I believe theres quite a difference, I have 15inch rims, and not sure about gear ratio. But Its a '68 f100 rearend.

[fordman]

i figured soemone else would have chimed in by now.

[JMcTurnan]

=P