All right...I've got a 1989 F-250 4x4...4.9 I-6, 5 speed tranny. I am having a heck of a time trying to figure out what is up with my speedo...

It's slow...way slow...when you step on the gas, it's probably 10-20 miles under what it should be....let up on the gas and it seems to go back up to what it should be at....at lower speeds anyhow....

I replaced the entire instrument panel tonight...still the same problems I had before except all my gauges work great now...

Everything is stock...I replaced the speed sensor already also....Sticky speedo cable?

Lemme know what you think....

Thanks!
Phil

 

Check the plastic gear in the transfer case. The one that is on the output shaft. Mine did the same thing, then it just quit altogether. It turned out to be that that gear was worn out.
It's not hard to replace. Unhook rear drive shaft from xfer case, unbolt nut (1 1/4 socket needed) on the output yoke and remove yoke (be sure to mark it's position). You will need to remove the seal, if you're carefull it can be reused. Slide out the metal sleeve that the gear sits on and then replace gear.
Installation is reverse of removal. Tourqe the ouput yoke nut to 100 to 120 ft/lbs.
As you can tell, I did this recently, so the memory is still fresh.

Roger Lane
Test Analyst
Sr. Automated Test Engineer
IBP, Inc.

 

Yep, that's exactly what it was...I got a new gear for the speed sensor this morning...it improved, but still wasn't working quite right...

I asked the guys at the dealership if it was a plastic gear in the transfer...sure enough....wore out right in the middle...

Hopefully I can have a replacement within a day or so...no one stocks 'em....

Thanks
Phil