Speedometer drive gear replacement?

[ammocj]

Hi,
I have an 83 4x4 with the 13-50 transfer case.
The speedometer was fluctuating but now it quit completely.
Cable, etc is good.
When I pull the speedometer cable out I can easily spin the worm gear that drives the speedo cable.

Is there an easy way to fix or replace this or do I have to pull the transfer case, again?

Al

 

[4x4junkie]

Is the gear chewed up? It might be possible the gear on the t-case output shaft is bad too.

If not, then it's only a 5 minute job to replace the speedo gear itself.

 

[MAKG]

If the gear isn't chewed up, I don't see how it could be the cause of a fluctuating speedometer. The usual reason is a binding cable core, but I could see a few other problems causing it. Mainly, that one end or the other isn't fully mated.

If the gear is ALL the way (flush) in the transfer case, reach under the dash and yank at the cable on the back of the instrument cluster. If it comes off, push it back on. If it doesn't, perhaps remove the instrument cluster and get a look at it.

Frankly, your description suggests the cable core bound in the past, and has broken. I'd suggest a junkyard replacment. Just turn the drivegear and make sure the instrument cluster end rotates nicely. You can try this same test on your truck to confirm it is the actual fault. Use your drivegear, not the donor's, when you install, or your speedometer may be wrong.

While you can replace just the cable core, it's possible the sheath has been chewed up.

Some cables from that vintage have an electrical speed sensor on them, and some don't. If yours has it, your donor needs it as well; otherwise, you don't care.

 

[AllanD]

He's saying that the WORM gear on the output shaft turns freely.

Frankly I'd suspect that the speedometer worm gear on the T-case
output shaft is missing it's "key" (actually a steel ball)
and it's possible someone tried to "glue" the worm gear to the shaft
and it finally busted loose.

AD

 

[ammocj]

AllanD, Thanks.
How hard is it to replace that key.
I imagine I need to disassemble the transfer case?

Al

 

[AllanD]

Disassembling the T-case would be a start.

I need to go look at my manual to remind myself how it's done.

AD

 

[AllanD]

Ok, on the T-case I looked at the gear is moulded to a steel sleeve and tightening the rear output nut traps it between the output flange and whatever is on the shaft forward of it.

SO if your worm gear is not driving the cable gear either the plastic part of the gear is brolken and slipping freely on it's sleeve OR the output flange nut is loose.

AD

 

[PetesPonies]

Do you guys have a pic of the transfer case exploded? I may have a drive gear problem also . . as my cable is not spinning.

 

[feellnfroggy]

tech library on the home page has pics of the 1350 simple and exploded views.