Speedo Diagnosis

[dwise]

The company you bought your parts from should be willing to assist in diagnossing what is wrong.
Rob Grady

John Hervey did indeed take the angle drive back and made an adjustment. We were able to install today, but there is still some tension in the speedo system. Check out this video to see what the speedo is doing now. (Jumping around and making a serious clicking sound) https://youtu.be/fmVBT5sGTyI

[David T]

Is the odometer moving? Does the noise stop if you disconnect the speedo head? I suspect a problem inside the speedometer.

[DMC-Ron]

John Hervey did indeed take the angle drive back and made an adjustment. We were able to install today, but there is still some tension in the speedo system. Check out this video to see what the speedo is doing now. (Jumping around and making a serious clicking sound) https://youtu.be/fmVBT5sGTyI

This video shows symptoms like a speedometer I had (not in the DeLorean, but another classic car). It turned out to be the speedometer cable was tight and sticking. At each rotation, the inner cable would stick at a certain spot then break loose with more twist pressure. This caused the input to the speedometer to "twitch" and the speedometer would jump just trying to follow along. I ended up pulling out the inner cable and lubing it. I Know this is a new cable but it's worth a checking to see if they lubricated it properly from the factory.

One way to check this is to disconnect the cable from the back of the speedometer and bring it down where you can observe it. Push a small piece of card stock on the cable to act as a pointer. Have someone rotate the left front wheel while you observe the pointer as it rotates. It should turn smoothly with the wheel.

Ron

[NightRider]

I've had a lot of problems with my speedometer/odometer recently. I just had my mechanic replace the original speedometer cables on my car, and less than 50 miles later, the speedometer has stopped working properly again. It seems to work ok from a cold start until I hit maybe 20 mph, and then the needle drops to 0 or fluctuates in the 0-5 mph range. The odometer stops working properly as well when this happens.

I'm thinking about getting the one piece cable, but I'm going to have everything checked first to make sure it isn't something else or simply a lubrication issue.

[Jonathan]

I've had a lot of problems with my speedometer/odometer recently. I just had my mechanic replace the original speedometer cables on my car, and less than 50 miles later, the speedometer has stopped working properly again. It seems to work ok from a cold start until I hit maybe 20 mph, and then the needle drops to 0 or fluctuates in the 0-5 mph range. The odometer stops working properly as well when this happens.

I'm thinking about getting the one piece cable, but I'm going to have everything checked first to make sure it isn't something else or simply a lubrication issue.

If yours is only working at low speeds, it might be that the dust cap is spinning inside the hub when it shouldn't be. Wrap a thin, single layer of electrical tape on the edge of the plastic dust cap and reinstall. You are trying to get it to sit in there snug and not rotate. The dust cap is meant to turn with the wheel so that the square hole on the inside of that dust cap that the angle drive cable end sticks into spins and that translates to your speedo needle moving. Try that and also make sure that square hole in the plastic isn't rounded out.

Oh, and yes, the speedo and odo work together. Or don't work together. If something isn't right from the dust cap to angle to lower or upper cable all the way into the backside of the speedo it will show-up on both the speedo needle and odo counters. If one works and the other doesn't (which would be rare) it's a problem inside the gauge.

I personally think that some speedo troubles are a result of small pieces broken off and being left inside in the gauge when someone breaks the trip reset shaft. Nothing to prove that though, just a theory.

[NightRider]

Thanks, I will check the dust cap before I take it back to the shop. Hopefully that is all that there is to it!

[Michael]

Thanks, I will check the dust cap before I take it back to the shop. Hopefully that is all that there is to it!

Agree with Jonathan. I noticed you are in NC, your weather is probably the same as ours. In cold weather my speedo also acts up and I am positive it's a worn dustcap, I even have a new one ready to replace but haven't done so yet.

[David T]

It can also be the square shaft spinning inside the square opening in the dust cap. Or the angle drive. You can test by using a drill to spin the inner cable and see what works and what doesn't. My theory is the posts break of inside the speedometer head and the metal clip gets stuck on the spinning magnet jamming the system leading to the dust cap getting damaged, the cables getting damaged, and the angle drive getting damaged.

[Michael]

It can also be the square shaft spinning inside the square opening in the dust cap. Or the angle drive. You can test by using a drill to spin the inner cable and see what works and what doesn't. My theory is the posts break of inside the speedometer head and the metal clip gets stuck on the spinning magnet jamming the system leading to the dust cap getting damaged, the cables getting damaged, and the angle drive getting damaged.

I think I see a pattern here

The dust cap is meant to turn with the wheel so that the square hole on the inside of that dust cap that the angle drive cable end sticks into spins and that translates to your speedo needle moving. Try that and also make sure that square hole in the plastic isn't rounded out.

I personally think that some speedo troubles are a result of small pieces broken off and being left inside in the gauge when someone breaks the trip reset shaft. Nothing to prove that though, just a theory.

[Grover]

I had this exact problem in the past. Long story short, I had to replace the speedometer because it acted exactly like your video. I tried everything to get it to work and the only way was to buy a replacement speedometer. I tried looking for a shop that could repair and recalibrate the speedo but couldn't find a place that I felt confident sending it to.