I have a 79 Ford F-150 and the Speedometer is hosed. The thing works )I think) at lower speed but when you get to 45+ it starts bouncing when you get to 65 it is all the way to where 100+ mph would be. I pulled the cable from the transfer case and looks fine all the teeth are there and are not broken or smushed. Any idea's?

Thanks

Thomas

 

Replace the cable. Sometimes lubricating the cable will help for a while.

 

My speedometer has a weird thing, my tires are bigger than stock, so it of course reads too low of a speed. When it says 50 I am gong 60. But the odometer actually runs faster than it should. Checked it against the mileage markers on the highway, it clicks of just over 1.1 miles for every actual mile. Could someone have monkeyed with a gear in the speedo unit itself trying to get the thing reading right?

 

Never heard of that happening before but I suppose if someone were fiddling with the speedo it's possible. <!I've got a spare if you want to try it, you're welcome to have it for nothing.> You can also reset the odometer if you want and start from zero!

 

I had the same problem a couple of months back with my '75' F350. Before getting a new cable or speedo I pulled out the speedo and sprayed some penetrating oil on the gizmo behind the speedo dial that regulates the needle. Spun it by hand and sprayed some more. It appears to be some sort of clutch and weight set up to regulate the dial from the cable input. Hope that makes sense. The penetrating oil seemed to loosen it up a bit.

I put it back in and have had no more problems with it. It registers the same as before as the tachometer coincides with the speedo.

Give it a try. Good luck.

 

The odometer wheels are directly driven by the cable. The speedo needle is magnetically coupled. I've had some luck cleaning the bearings and the coupler. Use some lube on the bearings.

 

Ivan, it would be nice to zero if for the new motor, make it easier to remember when I swapped it <! I'll have to get them from you next time I see you>...thanks!

 

Yup, I zero'd mine out for no good reason, just thought it would be fun. <! I'll be home on the 9th so I'll get it to you sometime after that. Until then> no speeding!

 

The odometer is set up for 1000 revolutions per mile.

I have heard of someone bending the speedo spring in order to make it read different. It sounds like you may just need a new speedo head.

 

it could be the worn gear on the output shaft of the tranny. i've replaced everything but that in mine, and it does the same thing. i don't feel like droppin the tranny to fix it, so i calculated my gear ratios and drive by the tach.