I replaced the inner cable with a repair kit all is well or so I thought, after replacing it, I took it out for a drive and it still didn't work. So I had to back track and find out what went wrong and make sure speedometer gauge worked.
I cut the end off of the old cable and inserted it into my cordless drill operating in reverse the gauge worked fine so I reconnected cable to speedo. Next I disconnected cable from trans and inserted cable end into drill running in reverse once again gauge worked fine so I pulled out gear in transmission checked it out inserted small piece of cable to make sure nothing was wrong all is well. So what can possibly be wrong? It turned out when I originally put cable into the gear in the trans I missed the hole now taking more time I inserted it properly and everything works fine.
So my question is; How do I make sure I have the correct gear in the transmission for correct reading on the speedometer? is there a certain formula for figuring this out? Tire size, rear end, tranny? A little help please
Thanks guys and gals
Staying low for now
Robert

 

my speedometer worked on my truck until one day i had the rear end jacked up and i started it while in 3 rd gear, now it registers everythign low.

what could be wrong? and how do i fix it?

 

Bob

Clock your truck with another new vehicle at a given speed.

Its sort of hit and miss due to not knowing the drive gear on the tail shafts count.
but you can go up or down a tooth on the driven gear based on how far you are off. Typically a tooth is good for ten MPH.

Young.. sonds like you stripped a few teeth. Pull the cable and inspect the driven plastic gear. if it has damage replace it with the same count gear.

Garbz

 

Take it on the interstate. run 60 and between mile markers should be 1 minute. Less than a min ur faster more ur slower

 

Thanks for the replys guys. speedometer is accurate at least that was what the cop issuing the ticket said "Boy do you know how fast you were going?" I said "No thats what I was checking so I how fast was I going?" so he documented it for me in the form of a ticket I was doing 70 in a 55 the speedometer said 70 but I didn't believe it. But I do now.

 

I got to say THAT SUCKS.....

Jon

 

Yeah it sucks but in a way it's worth it. Anytime you have an original 292 with a ford-o-matic trans running 70 and getting pulled over for speeding kinda makes you feel good that your slick can still get up and go. so not all is bad. And the speedometer works right so I feel ok about it.

Staying low for now
Robert

 

Well getting a ticket is not laying LOW!

I just got bagged for 50 in a 35... I have been running that section for the last 30 years at fifty and they go and change it.......

Garbz

 

Hey garbz2 every now and then you have to get on it, I'm still cruizing low just every now and then you want to blow the bugs out. My truck was going smooth being low, that it didn't seem like I was going fast 4500 lbs doing 70 is still an awsome feeling I wanted to peg it, only I got caught first so for awhile I'M going to stay low and cruise slow.

Staying low for now
Robert

 

Not sure what 'repair kit' consist of. If you are not sure # teeth you should have on the speedometer gear most of the Ford parts supplier's can provide the info. by providing them info on type tranny, rear axle, and size tires. Usually, fewer teeth make speedometer run faster, and slower w/ fewer teeth. Changing tires to lower profile you will need a gear w/ few teeth. If rear axle were changed say from 3.89 to 3.00 you will need fewer teeth. Don't know who to compute myself, oftain info from supplier. Viewing catalog, see where gears run from 16 to 21 teeth and appears gears interchangeable from 48 to 79. Have 2 F100's and each require different speedometer cables and gears.

dave