Need assist with transmission identification and driven gear removal

[HIGHWAY BY THE SEA]

The speedometer in my 67 3500 has not worked in at least 20 years (title confirms). I checked both the original one and newer replacement by spinning the cable with my fingers, and they both work. But neither works with the speedometer cable hooked to the transmission. The cable will not turn at all (tested it by driving the truck with my finger on the cable tip). So I tried to take the driven gear out of the transmission, but could not quite figure out how. Below are pictures of the transmission and driven gear attachment. What kind of transmission is this? (I think that it is a three speed on the floor with an "L" gear listed on the shifter knob). And how do I remove the driven gear?

[jocko]

Normally the speedo gear housing is just pushed in and retained by a tang that holds it there - the tang usually secured by a separate bolt. See pic below (a T5 trans speedo bullet, just for illustration purposes) - you can see that the only threads are for the speedo cable itself and the tang slot is visible on the left side. A little piece of metal fits in there and is normally bolted to the trans - so recommend clean up around the speedo bullet housing and look for a bolt and retainer. If there is one, then you just remove the bolt and then pull the whole thing out. If not, then I'm stumped. But that would be the first place to look. Oh, and don't forget to replace the o-ring while it's out! Also check inner seals (pic 2). Common trans leak culprits.

As for trans ID, I'm going to assume that if it has a 3-sped pattern and an L, then it's a granny low 4-speed. Is that what you're describing? The Chev Granny 4 was standard on C30, with the only optional manual trans being the M28 (NP close ratio). If nothing outlined on your SPID, then you likely just have the standard granny 4. Your picture looks like the Chevrolet model to me. Info in pic 3 may help you ID your trans by its shift pattern, etc. In other words, if your reverse is low to the left, it's a Chevrolet trans, if low and right, it's a New Process. If neither, well, then it's probably not an original trans to the truck. Hope that helps

[HIGHWAY BY THE SEA]

Thanks for the quick response! I see no way to remove the threaded bullet assembly. Maybe the grease and dirt is hiding something...? It appears to have a nut at the base of it.

[jocko]

yeah, I can see that now that you mention it - can only assume it's threaded into the case and that the hex is part of the housing - assume you'd just need to wrench it out

[HO455]

That looks identical to the speedo connection on a SM420. Clean it up, put some penetrating oil on it and a 6 point socket. Don't get too carried away torquing on it. There isn't much material in the hex and it can become round rather quickly. If you need a picture I'm sure I've got one out in the garage somewhere.

[HIGHWAY BY THE SEA]

The gears on my truck shifter knob are like this:

L - 2
- N
1 - 3. R

I may have to buy that socket to remove this because my largest one will not fit it. So this one is not that bullet-shaped thing?

[HO455]

Here is a photo I harvested off the interweb that may help. Probably not exactly what you are going to find when you get it out but it give you the basic idea.

[HIGHWAY BY THE SEA]

Originally Posted by HO455

Here is a photo I harvested off the interweb that may help. Probably not exactly what you are going to find when you get it out but it give you the basic idea.

Huh.
I was expecting a plastic gear of a specific color. Now I wonder if I can fix the speedometer problem myself.

[AussieinNC]

Your shift pattern shows me the trans is a New Process 4 speed...granny Low to some folks...

I would jack up the rear end and turn the tail shaft with the trans in Neutral....check to see if the end of the speedo drive sticking out of the trans is turning ....if it is, there is no need to try and remove the gear unit...these gears are steel on steel and almost never fail...except when a rear support race fails totally.

If the speedo drive end unit turns the drive square ok...the problem is a broken speedo cable...very common, especially where the able comes close to the exhaust pipe...where it gets hot and dries out.

Attached is an image of the retainer nut unit...and driven gear.

[HIGHWAY BY THE SEA]

Thanks for the pictures gentlemen. So it is possible for the speedo cable have a small piece broken off at the bottom and still spin the speedometer when moved with my fingers, but not seat correctly in the driven gear? It just so happens that my speedo cable has an extender on it. Maybe a new extender cable is in order. Hmmmm...

[jocko]

I'm re-reading your original post. It sounds to me like the trans end of the speedo cable is not engaged. In other words, the square cable is not seated in the square receptacle in the driven gear. An extension can sometimes cause this as the extra bends induce some amount of slack, just enough to allow you to screw the cable onto the housing while the cable backs off just enough to not engage the square hole.

If your main speedo cable is long enough to reach the driven gear without any drastic bends, toss the extension and connect directly. If not, then just buy a new correct-length cable and be done with it. Someone may have had the extension in there for any number of reasons. I've found the little Stewart Warner reduction/correction gears in line on a couple speedo cables on trucks I've bought over the years. They often get yanked and ebayed and folks leave the extension cable if they used one.

To check for this issue - connect your cable to the trans and disconnect it from the speedo, then see if you can spin the cable at the speedo end with your fingers? If it's properly seated in the trans, you should not be able to spin it. If you can, it's not engaged at the trans. Btw, it DOES sound like the connection between the original cable and the extension is good - since you were able to spin the trans connection end with your fingers and see a response on the speedo. This is why I suspect the square cable is just not connected at the trans. If it is, then the issue is likely related to the speedo gears (driven or output shaft gear). So the next step would be to remove the driven gear and check it out.

[HIGHWAY BY THE SEA]

Well, hats off to jocko!
I went outside, lay on my crawler, slid under the truck, reattached the speedo cable, double checked that the cable was engaged, and tightened it in place. Then I realized something. The cable attachment seemed to be not quite tight enough and there was in fact some slack in it like jocko said that there might be.
I grabbed my channel locks and tightened that thing HARD. As I was really tightening it, I could feel it threading through decades of old oil and dirt, as if it had been this loose for a long time. I then detached the cable from the back of the speedometer and tried to spin it with my fingers. It would not budge.
So then started the truck, and drove it back and forth in my driveway (still not street legal!) with my finger on the cable and it was spinning! So I reattached the cable to the speedometer, drove it back and forth, and it now works!!!!
So it appears that at some point over 20 years ago the speedo cable slackened up, or was not tightened correctly I guess. This is a LONG time for someone to neglect a non-functional speedometer. But the fuel gauge was not working either, so there you go.
Thanks again to all who assisted, with a special nod to jocko.