Speedometer Question

[TLBREWER]

So the last few days I've been trying to get some nitnoid stuff fixed on my daughter's truck before she takes off in it for college in three weeks. Had to replace the headlight dimmer switch which was causing the low beams to go out over bumps...a little un-nerving in the dark. Then I changed out the wiper control module since the truck has only had high speed wipers since we got it. It doesn't rain much here so it was never a priority. By-the-way, that's a Ford only part and it'll stick you for $129.

Now comes my question. I've asked about this before and taken the advise recommended. The speedometer quit working. At this point I'm assuming the cable is good since it's less that 4 years old and looks fine. I've pulled the drive gear end out of the tailshaft, checked the condition of the cable gear, stuck my finger in and looked with a mirror at the drive gear in the tailshaft. All looks good and it feels like the gears mesh when inserting it back into the tailshaft. This week I pulled the other end apart, cleaned tha cable, lubed the cable, and pushed it into the speedo as far as possible, making sure the tabs locked it in. The speedo makes no noise and sometimes around 50-55 MPH will jump around a bit then go back to zero. Nice thing is it's not racking up any miles. Am I missing something obvious? I'm leaning towards a speedo rebuild. Is that something I can do myself or does it have to go to a shop (special tools, parts, testing)? And how much does it cost to have one done? There's nothing about the speedo system in my Haynes manual. The only thing left I can think to do is drive it around with the cluster out to see if the cable is turning.

Tom

 

[SKimballC]

Have you tried swapping the cluster with the one from your wife's truck to see what it does?

 

[TLBREWER]

Have you tried swapping the cluster with the one from your wife's truck to see what it does?

Shane

No, but that's a good idea. What was I thinking?

Tom

 

[zigg]

Tom

Mine did a similar thing. It would work, then not for a while, then jump a bit, then...

Anyway, it turned out the gear in the 4x4 box was toast, that, and the cable kinda hangs where it goes in, so the 2 gears don't really mesh as well as they should. So, new gears, and then I suspended the cable just before where it went into the tranny, so that it didn't drop down and lift the driven gear up off the drive gear. Works perfect now.

You could also pull the cable, and put the tranny end into a drill, and spin it, and it'll make the speedo work. If not, then the speedo is pro'ly crapped. Best to do with a reversible and variable speed drill, so you go the right way, and not too fast. The tranny output shaft will be turning the same as the engine at highway speed.

Just a couple thoughts...

Zigg

 

[TLBREWER]

Yet another good idea! Thanks.

Tom

 

[SKimballC]

Actually that's what Gear Vendors told me to do when I was having problems with their unit. Chuck it up in a drill and run it on reverse, counter-clockwise. At full speed it should show around 60 mph so they say.