The Stovebolt Site Forums The Shop Area General Truck Talk Speedometer Question

So I needed a speedometer. I bought one from a guy that rebuilds them and sells them on ebay. He doed ver good work.

Heres the problem.

My cable spins and works the odometer. When I put it on jackstands and run the motor I look at the drive gear and its spinning.

But the speedo does not work. When I take the cable off the drive gear and spin it with a drill or by hand the speedo works fine. The only time it does not work is when the two ends are connected. What is my problem? For the life of me this makes no sense at all.

Remember, the odometer work always just fine, so the cable is spinning and the speedo works when I run the tranny end of the cable by hand????

Sounds like the connection is somehow bad at the trans end. Is the inner cable perhaps too short or does it not engage the gear fully at the trans end? Have you tried taking the cable off at the speedo and making sure the cable is turning when it is engaged with the trans?

Yep!! It spins. I ordered a new cable anyway. I really have checked everything twice and then some. I even swapped out the drive gear with a different one. No change!!

I know with the 51 speedometer, there can be problems with the inside bearings such that pushing on the cable will stop the speedometer needle from moving even though the odometer continues to work.

I'm with Truckernix on this one - I had the same issue. In fact by unscrewing the the cable such that it wasn't tight on the end of the speedo fixed a similar issue I had.

Mark

I tried to loosen it but that didn't work. Hopefully the new bable will solve the issue.

Well I got a new cable and no difference!! Odometer works but no speedo. When I spin it fast by hand at the tranny end of the cable it goes up. Is this because I have a gmc? Is the speedo greared differently for a Chevy speedo??

I would love to fix this.

Thanks, Dan

I have a similar issue except my speedometer is buried above 100 MPH. Believe me, I was not going 100 MPH when it stuck.

I had issues before with the needle swinging wildly at times and merely touching the cable behind the dssh or unscrewing it slightly helped. However, once it stuck above 100, nothing I do will bring it back down. I unhooked the cable from the back and tried to 'manually' make the speedo drop with a small screwdriver. No luck. I put a small amount of oil into the speedo assembly and still nothing. Is this speedo now broken? Lastly, if it is, can I simply remove the speedo unit and have it replaced/rebuilt without disturbing the other perfectly functioning gauges? Thanks.

Short answer YES. The speedo is a seperate assembley and can be removed without harm to rest of gauge cluster. Remove the Needle carefully to prevent damage to needle before trying to detach the speedo unit from the back of the cluster. It is usually easier with the whole cluster removed to get at the speedo.

The odometer is gear driven off the cable, there for all the gears in the transmission are working, the cable is working, and the speedometer is getting the revolving cable. The problem lies in the speedometer head. The needle is magnetically driven from the cable rotating a magnet drive. The needle is mounted to a drum surrounding the magnet drive with a small spring to return it to zero. The clearance between the drum and magnet may be off. A quick twist may be enough to move the needle, but normal rotation is not. This is where you need to be looking.

Joe

x2

Time to contact the guy you bought it from and explain the problem to him and have the rebuit speedo rebuilt again.....