75 K5 Speedo not working

[jeremywrags]

Hi All,

I have a 75 K5 4WD and the speedo is not working...

What can cause this?

I notice that the cable goes into my transfer case via a small gray box looking thing, not sure what this is?

Can I use a drill to spin the cable, this should at least verify that the Gauge is working or that the cable itself is not broken?

Any thoughts?

Thanks

 

[chalet2506]

I believe you can spin it with a drill. Which transfer case do you have? Mine quit working when I had a 203. Put a new cable on it, worked for a while then quit again. Swapped in a 205, and speedo still wouldn't work so I tossed the little gear box and hooked it direct into the t-case. Works like a champ now.

So basically three things can break. Little gear box, cable, or guage.

 

[4X4HIGH]

Does you blazer have cruise control?

 

[jeremywrags]

No cruise control...

I did verify that the speedo cable is working and in turn also verified that the gauge works which leaves me with the little box attached to the transfer case, what is it, do I need it...

 

[4X4HIGH]

No cruise control...

I did verify that the speedo cable is working and in turn also verified that the gauge works which leaves me with the little box attached to the transfer case, what is it, do I need it...

That little box is to correct the speedo.

 

[jeremywrags]

where can I get a new one?

 

[4X4HIGH]

where can I get a new one?

First off, did your speedo read the correct speed when it was working? If not then just remove the adapter box and hook your speedo cable direct to the t-case and don't worry about it unless you want your speedo to read correctly. Those boxes have 4 gears in it and they are all different depending on how far off your speedo is. Thare are 1000 cable turns per measured mile so adding one of those boxes with the correct gears in it is how the speedo gets corrected. There are also two different styles of boxes, one is riveted together and the other is bolted together. The latter style comes apart and can be repaired/corrected. I have a box here but i'd have to check which style it is.

 

[jeremywrags]

Turns out it was the adapter box between T-Case and speedo cable. The Cable going into the box was OK up to the speedo but the little shaft out of the adapter had snapped off inside the T-Case. Ditched the adapter for now as as far as I can tell the only affect is that the speedo is approx. 10Mph behind, so at 35 I am actually doing 45, better keep an eye on that.

Thanks for the replies

 

[K85 Octane]

same subject

how come there is a box and not just a different gear inside the Tcase? I have a 208, so maybe it depends on the Tcase?