Andrew Schauer

My 1980 had an intermittently working speedometer and odometer, so last time I had the pod out, I finally found the problem.

There are nearly 10 connection points in the speedometer signal path from the sensor in the transmission to the speedometer itself. One in the spare tire well, at the central electrical panel, the plug which connects to the cluster foil, the cluster foil to a small brass rivet, the rivet to a hard circuit board, the circuit board to a small pin, the small pin to the speedometer unit, and yet another inside the speedometer unit! I had cleaned all these points in the past, which worked for a while, but never solved the problem.

Backside of the cluster, upside down on the bench:



The flexible circuit film is connected to a hard circuit board by half dozen small brass rivets:



Eventually the rivets seem to come loose, probably due to vibration. This results in a poor connection between the foil circuit and the hard circuit board which holds the pin connections. Carefully solder a solid connection between the rivet and foil circuit, and another on the opposite side to the hard circuit board. The foil is pretty delicate, so I would not attempt this as your first soldering job. Overheat and melt the foil circuit, and you'll be ordering a replacement. I also checked the factory pin soldering, but it appeared to be fine.

Foil side of rivets:


Hard circuit board side of rivets:



I also reflowed all the soldered connections on the speedometer unit it self, as some appeared to be cracked:



However, in the process, I managed to de-solder the green wire:



This resulted in a non-functioning odometer, until the next time I pulled the pod and found the problem. Soldered back in the correct place, and the speedometer and odometer have been fine for over two years.

Hopefully this will help anyone else with the same symptoms.

Bill Ball

Very nice job! You have been added to my short list of electrical whizzes for future reference.

j.kenzie@sbcglobal.net

Nice job. There are some circuit boards such as mine which are NLA. I did something like this to mine. It's the kind of work which may keep these cars running in years to come.

Andrew Schauer

Thanks Bill, but you must be an electrical whiz yourself to keep that Norton running and charging the battery.

Dave-
I feel the same way, replacing parts may not always be an option in the future.

John Struthers

Another spot in the path...
There is a small phoenilic (sp) block off the lower drivers side of the tranny where the wire jumps to the connector in the spare tire well. The wire has a cheapie looking small stove nut and washer which anchor there. Oil covered and loose on mine...cured my speedo maxing (170) and zeroing.

6mil928

Amen Brother Great job

WICruiser

I wonder - my speedo and tach do not like to operate when the car starts from cold until things warm up. I did have the speedo out to replace the odometer gears and I was pretty sure I got things back together tight but maybe I loosened the board just enough.

Another project for the winter season - I was hoping I was done taking the pod out for a while.

6mil928

I'll be pulling my pod soon also. Seems like it will be a fairly regular exercise.

Fabio421

This is a great thread. I have been dealing with this problem and now I have a good idea where to go to fix it. Thanks alot.

Sean79 5spd

My speedo and gas gauge problem was cured by cleaning contacts of connector on top of gas tank. Access is by lifting carpet up in back.

Sean

6mil928

Is that the connector in the spair tire area? Jason

Sean79 5spd

There are two connectors; one in the spare tire area and one in the access to the level sender on top of the gas tank. The one on top of the gas tank was heavily corroded.

pmooradian

Another fix that works well is to use a liquid copper repair kit for fixing rear window heater elements. I've used it on a couple of cars where my speedometer was operating intermittently or had quit working entirely. The liquid copper solution conducts electricity just fine once it dries and there's no need to solder on the plastic film and risk melting anything. The only thing you need to do is clean away some of the oxidation or material covering the copper on the circuit board and rivets to ensure you get a good connection. Been working for years in several of my cars where I couldn't get replacement printed circuit boards.