Speedometer and Lowering front and rear

[jolobo64]

Quick questions

My speedometer is not working at all on 64 c10, my mechanic said something to the effect that I was missing something other than than speedometer cable, I'm not sure so my first question what are all the parts needed, or how can I troubleshoot what I need. I want to stay old school but not sure can I find all I need.

Another thing any suggestions on lowering the trucks, I don't want to drop it all the way to the ground but I don't like seeing that clear space above the front wheels. I just want to see tire only and not all the stuff under the fender etc. what's needed and is it something I can do myself?

[ray_mcavoy]

There is a gear on the transmission tailshaft that drives another gear that in turn drives the speedometer cable. Could be that one of those gears is missing. They come in various tooth counts that are used to calibrate the speedometer according to the axle ratio & tire size being used.

[jolobo64]

Originally Posted by ray_mcavoy

There is a gear on the transmission tailshaft that drives another gear that in turn drives the speedometer cable. Could be that one of those gears is missing. They come in various tooth counts that are used to calibrate the speedometer according to the axle ratio & tire size being used.

Okay I found the driven gear on the end of tranny side of speedometer cable size 23 and looks fine but the other drive gear can't seem to locate it.

[PGSigns]

Well you mechanic should be able to tell you whats missing. The simplest way to drop the truck would be a spring swap. You could go 2" in the front and 4" in the rear and be at a point where you could still go lower in the future with a set of spindles.
Jimmy

[jolobo64]

Thanks for the comments, you mentioned 4 " in the front and 2" in the back I don't know if you saw my truck under my profile but the fender gap is greater in the front and actually the back is close to where I want it but still could stand a little drop. Any updated suggestions since I explained it clearer?

[jolobo64]

Thanks for the comments so

[PGSigns]

You will never get the fender over the tire front and rear the same due to the shape. The front is much taller. The 2" in the front and 4" in the rear will get you close to level.
Jimmy

[forestb]

I would look at the static drop thread and find a truck you like and ask them how low it is. In order to get rid of the gap between the front tire and the wheel well to go away you will probably need a 3-4 inch drop but that will depend on your tire size which will also influence what gear you will need for you speedometer.

[luvbowties]

Originally Posted by forestb

I would look at the static drop thread and find a truck you like and ask them how low it is. In order to get rid of the gap between the front tire and the wheel well to go away you will probably need a 3-4 inch drop but that will depend on your tire size which will also influence what gear you will need for you speedometer.

Don't think front tire size would affect differential gear or speedometer gear needed at all.
Sam

[jolobo64]

Speedometer update:
I removed the dash totally and did the following :
1. Tested speedo cable from transmission end with cable in drill gun set to reverse and looked at other end at dash at it was spinning.
2. Tested speedo cable from transmission end with cable in drill gun set to reverse and had only the speedometer head without the "orange indictor needle" and speedo head also was spinning.
3. Upon reassemble of Dash and I Cleaned speedo head and all other related components, when I spin by hand the speedo head spins easily. When I spin by hand with speedo head and orange needle together, the needle is not moving. I'm assuming thats normal since I can't generate enough power to make it move.
So the head seems find but I'm not sure if the problem is the orange needle part (it has a small pin on the opposite side and it goes to a hole on the underside of speedo head and on the other side of the head is where the speedo cable goes. I do not know if that pin on orange needle is working because as mentioned earlier cable and head seems to be fine.

Only thing I have not checked is the second of the two gears in the transmission, one was easy to access and it seems ok but the other gear in the tail I have not checked as it seems like a task to remove the tail. Any ideas?

[ray_mcavoy]

That sounds like your problem is in the speedometer. Your test #2 should have produced needle movement (around 60 MPH with the drill spinning at 1000 RPM if I remember correctly). And your test #3 (spinning speedometer input by hand) should have at least made the needle jump up a little bit (maybe around 10 to 15 MPH).

Does the orange needle even move at all? Try (carefully) moving the needle by hand. It should move very easy.

[jolobo64]

Originally Posted by ray_mcavoy

That sounds like your problem is in the speedometer. Your test #2 should have produced needle movement (around 60 MPH with the drill spinning at 1000 RPM if I remember correctly). And your test #3 (spinning speedometer input by hand) should have at least made the needle jump up a little bit (maybe around 10 to 15 MPH).

Does the orange needle even move at all? Try (carefully) moving the needle by hand. It should move very easy.

Yes the orange needle moved very easy by hand, I can hit it lightly and goes up to whatever and then comes back by itself. My number 2 I didn't try with needle just speedo head only. On the back of the needle there is a little pin, should that pin go all the way through the hole of the underside of the speedo head? Mines seems a little short and I was thinking since it can't go all the way through the hole maybe the cable can't spin it, just a thought.

[jolobo64]

Originally Posted by ray_mcavoy

That sounds like your problem is in the speedometer. Your test #2 should have produced needle movement (around 60 MPH with the drill spinning at 1000 RPM if I remember correctly). And your test #3 (spinning speedometer input by hand) should have at least made the needle jump up a little bit (maybe around 10 to 15 MPH).

Does the orange needle even move at all? Try (carefully) moving the needle by hand. It should move very easy.

Ray ok with all components back in ( orange needle is the point) with drill gun did not move at all. Quick question in your original post you mentioned there is a gear in the tail shaft (found that one) that moves another gear that turns the speedometer cable, where is that one? I'm leaning to buying a new speedometer as you also agreed because on final test if there was a problem from the gear in tail shaft then when using the drill then it should have at least worked.

[ray_mcavoy]

Originally Posted by jolobo64

Ray ok with all components back in ( orange needle is the point) with drill gun did not move at all.

Yeah, that definitely sounds like a problem within the speedometer if you don't get any needle movement when spinning it with a drill.

Originally Posted by jolobo64

Quick question in your original post you mentioned there is a gear in the tail shaft (found that one) that moves another gear that turns the speedometer cable, where is that one?

The gear attached to the transmission output shaft is commonly called the drive gear. The other gear is the driven gear. It fits inside a bullet-shaped adapter that fits into the hole in the side of the transmission tail housing. The lower end of the speedometer cable housing attaches to the adapter. And the inner cable has a square end that goes into a corresponding square hole in the end of the driven gear.

Here's a cut-away view showing a typical set of speedometer gears in a transmission tail housing:


And here's an ebay listing showing the bullet-shaped adapter along with several driven gears (they're color coded according to tooth count) --> http://www.ebay.com/itm/NEW-GM-MUNCI...-/221620477330 Note: This listing is just an example and these may or may not be the exact gears that fit your transmission.

[PGSigns]

I have a bunch of speedometers and parts if you need help with yours.
Jimmy