:mad::mad::mad::mad::mad:
I spent all afternoon working on the f***ing thing and have gotten nowhere!

This is the '82 C20- the speedo quit working the second day I had it. I finally decided to get around to fixing it (I NEED to use the truck saturday, and would really like to have it work)

I figured it was the cable- WRONG, old cable is perfectly fine.
It had one of those little adapter things on the transmission, I took that out and discovered the shaft that drives it was snapped off.
I pulled the collar off that holds on the driven speedo gear and pulled it out.

By holding it upside down and tapping lightly with a hammer, the broken piece fell out. Once upon a time I had a truck that had one of these adapters on it and we took it off and it worked fine ever since.
I made sure the cable for the speedo meshed with the square hole on the gear. It did. I put it all back together and still have NOTHING!

I double checked that the driven speedo gear was meshed, and it is.
The cable is slid all the way in, I don't see why it won't work.

Any ideas?

Could the cable be snapped on the inside? Or did you verify that the ends both turn in conjunction?

Both ends turn. The only issue I can see is that it isn't meshed with the square drive gear. But from up above, I slid the inside cable in as far as it would go, and it looks about right.
I'm really lost on this thing.

I pulled the speedo cable out of the trans and reinstalled it (I was a bit more careful about it) .. and it works!
I got the dash put back together, and one front turn signal wired up and working.

When I got it both front turn signal lenses and sockets were missing.
I had the other socket I was going to put on but was walking around with it and set it down and now I can't find it, LOL.

When I got it both front turn signal lenses and sockets were missing.
I had the other socket I was going to put on but was walking around with it and set it down and now I can't find it, LOL.

its in my garage lol

good job on cable. a lot of times the square edge wears down and it doesn't want to engage properly or just spins

I haven't even put 10 miles on it, front marker light is working intermittently(apparently the light socket I used is shot), turn signal fuse blew, and then I looked down and the speedo was at 0!:mad::mad::mad:
WTF. I ran the living s*** out of it on the way home, was kinda hoping it would blow up and I could forget about it. I hit the governor at least 5 times:mad:.
I sure hope the brand new speedo cable isn't shot. I might take a look at it after the exhaust cools down, I think my pipes are glowing red, LOL

Little issues like this tick me off more than ANYTHING

Maybe beatin on it cured your lifter knock? ):h

Actually I got stuck a few weeks ago and had it revved up pretty high... ever since then it doesn't knock when first started.. takes about 20 seconds.

I pulled speedo cable out of trans and the cable was caught between the square hole it's supposed to be in and the housing.
I verified it wasn't broke by pulling on it, if it was broke the inner cable would slide out because there is a nut on the speedo end that keeps it from sliding too far.
Anyway, I assumed (like a dumba**) that I found the problem. Put it all back together and... NOTHING.
Maybe the cable came out of the speedo, it didn't clip in quite right (It has a nut on speedo end which isn't used for this setup)
I might try putting the old cable back on tomorrow (or yet tonight, if I get a wild hair) but I'm sick of taking this dash apart.

I'm hoping this thing will be road-worthy...eventually.

That's what mine does as well. It'll tick after it's started. I think i've just got a bad lifter somewheres. Replaced injectors, tick still present. Needed injectors anyways so no big deal. Pulled all GPs, all intact so no gp tip imbedded in piston. All that's left is an exhaust leak or a bad lifter.

I 'm not totally sure if the cable was clipped in the speedo head.. I don't think it was. It didn't seem to fit quite right.

I thought I'd try the old cable since it wasn't broke. I put it on, took off down the road and the needle was very jumpy and would show 20-30 at about 50 MPH.

Then I decided to file off the burrs on the new cable that keep the not needed nut on the speedo end of the cable.
http://i120.photobucket.com/albums/o174/dingoix/IMG_1118.jpg

Then I realized my problem.. I have the wrong cable!
The one on the right is the old one
http://i120.photobucket.com/albums/o174/dingoix/IMG_1119.jpg

Also here is the adapter that was on my tranny. The shaft that drives this is what snapped off inside the driven gear in the trans. Without this, I read about 10 MPH slow (45 on speedo is actually 55)
http://i120.photobucket.com/albums/o174/dingoix/IMG_1114.jpg
Anybody know where I can get one of these new?

Also, I got my cable at o'reillys, they said that is the only one they can get for that truck. I'm going to try and take it back. There is a small parts store around here I usually get stuff from but they don't carry speedo cables:confused:

BTW, if you're wondering what the green thing in the 2nd pic is, it's a blanket covering up one of dads classic cars in the garage (a '69 roadrunner, I might add:cool::cool:)

You shouldn't need to get a new adapter, just a new driven gear.

http://www.novaresource.org/speedo.htm

Best source I could find for ratios.

Interesting. I didn't know you could change the driven gear but not the drive gear.

Might have to look into it. I'm still debating the trucks fate- get it up to par and run the wheels off it or just save my money and part it out / sell it.

I'm trying to get things lined up where I can get a fairly nice '87 GMC K2500 6.2 4spd
I have too many vehicles but I don't want to get rid of any of them... LOL

I was also looking at a '90 K2500 6.2 that has a bad engine.