I recently had my speedometer gauge restored - the speedometer worked fine, but the odometer and trip odometer never worked since I purchased the car in 2020. I installed the restored speedometer several months ago. Shortly after, I noticed the speedo not working one day. But after a few miles and it started working again.

This would continue on and off, here and there, but now it's to the point where the speedo doesn't work when I pull out of the garage, but it will start working after I've been driving it for 15-20 mins. It's like it needs to warm up before it will start working. Note: the odometer and trip odometer both work fine when the speed is not working. The odometer and trip odometer have zero issues.

Does that mean that the speedo cable is fine and that the issue is the speedo gauge itself? Or can the odometers work and the speedo not work and it can still be a cable issue?

Try disconnecting the cable at the gauge and pull it free so the end can be lubricated.
Line with Cable Lube, it goes down slowly; but keep adding.
If the rear is raised you can start the motor and put in gear. That will make the cable turn and distribute the Cable Lube.
Then reconnect and drive; it took me several drive before the lube took effect. I think I even went back a second time and re lubed.

I think the problem is with the speedo section itself if the odometer and trip meter are still workin fine. Maybe the needle of the speedo is loose on the operating shaft.

If the needle simply doesn't move, I suspect that lubing the speedometer cable won't cure the problem. A bouncing speedo needle, however, is a pretty sure sign that the speedo cable either needs to be lubed or has a kink or tight curve radius in the conduit which is causing the inner cable to bind up and release sporadically.

If the Odos are working that proves the cable is good.

Most speedos register the speed via spinning magnets and the needle is not mechanically connected to the drive cable.

The way they work is "sketchy" as hell and not very accurate.

If they are accurate at 60mph they won't be at 30 or 90...

Most show 60mph for a cable at 100rpm.

The gear drives for the two Odos make perfect sense and are "logical".
They ARE mechanically linked to the drive cable.

The spinning magnets are a little bit "magic" IMO...

Sticking mechanism/needle is what I would look to.

I hope a speedo restorer chimes in here.

I've fixed a bunch of Odos but have never been successful with the needle...

My PhD astrophysics son tells me that nobody understands magnetism.

You must be joking.

I just had a wonderful experience with a man named John Bell.
He restores gauges and rumor has it he is retired from one of the big names over priced shops.

He charges 150 for the Speedo and can refinish it also, paint and needles etc.

If you want, I can connect you

@DC_neun_vierzehn - interesting as I have what sounds to be the very same symptoms.

I have had mine recalibrated for my tire size by North Hollywood and it was fine. Until I pulled it to gain access to some other stuff behind the dash. Now, the needle is "sticky" but both odo's are fine and are accurate.

I'll be back to work on that issue in a couple of weeks but my first thing to try is to just pull it and re-install making sure the cable is doing the gentle curve before it heads to the tunnel as well as having the cable firmly and completely screwed on tight.

I have pulled and reinstalled a couple of times to ensure of proper fitment of cable into back of gauge and and curve of cable to tunnel. I have eliminated those items as a possible issues.

Mine recently started bouncing as well but not sticking. Recently replaced the angle drive and the gauge was rebuilt by NH Speedo <5k miles ago. Don't know about the cable so it certainly could be that and I'll try the lube procedure ASAP.

I found the Cable lube worked really well; however, it takes several applications because it doesn’t flow down the cable quickly- you’ll see what I mean. And, you may have to drive a few miles so the lube is evenly distributed; that’s what I experienced.
Now, the needle is solid with the exception of 0 to 10 mph

This doesn’t pertain to OPs situation.

However - be aware that you will never have a rock steady needle especially at low speeds with an eddy current speedometer like the 914 has.

It seems to me that as people get more used to electronic speedometers that have become the norm in modern cars, they expect the same needle smoothness and stability of a purely mechanical device which is never going to happen.

"yup" internal issue, I would send to Hartmut at Palo Alto speedometer, his people do excellent work

@DC_neun_vierzehn - My speedo was re-calibrated for my tire size by North Hollywood but after this issue started, they tested it and said it was ok. It's clearly not.

I just reached out to Hartmut via email - he said:

The odometer and trip odometer are gear driven, and the speed is driven by a rotating magnet. There is clearly an issue with the speed portion of the mechanism. If you were to send it to me, I can open it, and let you know what is going on. I’ve seen this before, and the repair will be approximately $395.00 + Shipping. The repair time is about a week.

North Hollywood is easiest for me as I can walk it in but i'm not wild about the service and after-sales support I've been getting. I'm also not wild about spending about 400 bucks on something I've already spent a pretty good chunk on but I need it to be right so I'll give Harmut a swing.

Only partly. I think his point is that some physics fundamentals remain unknown.

John Bell is great. John restored all of my gauges ; )

I’ve been in contact with him. He was kind enough to offer sending the speedo back to him so that he could open it up to determine the issue (since he was the person who restored it).

Before sending it back, I’m trying to eliminate all potential external issues. It’s odd bc on some days it works fine, but in other days it takes about 20-30 minutes to start working … like it needs to warm up or something. Very odd.

Note that the bouncing is not the same issue as the original one in this thread. Bouncing can be caused by problems with the cable, angle drive, etc. Having the speedo stop reading while the odometers are still counting up means there is a problem inside the gauge housing.

--DD

John Bell is our gauge guy. He’s done a ton of gauges for me and will continue to be my go-to guy.
He’s made some custom gauges for me in less time than it took the big gauge companies to give me a quote. Much better prices.