TR2/3/3A Fuel Gauge again....

[karls59tr]

Looking at the back of the gauge there are two studs. One for the green power wire and one for the green and black wire to the sender. Should these two studs have fiber washers between the nuts to isolate the wire connections from the case? My gauge dosn't! Seems to me if not they would ground against the case? Maybe this is the source of my problem?

 

[Sarastro]

There should be some kind of insulation between the studs and the metal case. Obviously, you can't have the connections making electrical contact to the case. My TR4A gauge may be a little different from the TR3, so I can only generalize--typically, in this kind of application, there will be an insulating shoulder washer that protrudes into the case, so the stud does not short to the edges of the hole.

 

[karls59tr]

Well that was the problem. The DPO had installed a metal washer that was similar to a fibre washer under the post:grief:

 

[karls59tr]

There should be some kind of insulation between the studs and the metal case. Obviously, you can't have the connections making electrical contact to the case. My TR4A gauge may be a little different from the TR3, so I can only generalize--typically, in this kind of application, there will be an insulating shoulder washer that protrudes into the case, so the stud does not short to the edges of the hole.

I just reassembled everything using round fibre washers but they do not have a shoulder on them. You make a good point about how the stud could ground to the case. Anyone know if the TR3 fuel gauge originally came with "shoulder" washers at the stud?

 

[TR3driver]

Seems to me the shouldered pieces were inside the case, with only flat fiber washers on the outside. But that was an early gauge, the post-60K gauges with the Lucar connectors might be different.

 

[Sarastro]

Something here might fit:

https://www.mcmaster.com/shoulder-washers

Of course, you can cut them down to reduce the shoulder height as needed.

 

[DavidApp]

Here is a photo of the back of my fuel gauge.

There is a fiber washer, a flat washer, a spring washer then a nut. On top of that is a piece of insulation which I presume keeps the spade connectors in line. Then a washer and nut.
The bolts are in clearance holes in the case and do not touch the case.

David

 

[karls59tr]

Is that a TR3A fuel gauge? I've never seen that upper piece of insulation before? Apparently I'm missing those spade connectors as well!

 

[TR3driver]

That is a post-60K gauge, which as I said, are different than the earlier ones. Pre-60K does not have the fiber strip, nor the Lucar terminals. Instead, the connections to the gauge are made with ring terminals and nuts.

The two are interchangeable AFAIK, but early cars just had the nuts and washers.

 

[DavidApp]

I think it is a TR3 gauge but can not be sure as I ended up with a couple of extras trying to get a good working gauge. Found out the hard way that the case has to be grounded. The one I ended up using has spade connectors and the remnants of that insulation piece.

David

 

[karls59tr]

That is a post-60K gauge, which as I said, are different than the earlier ones. Pre-60K does not have the fiber strip, nor the Lucar terminals. Instead, the connections to the gauge are made with ring terminals and nuts.

The two are interchangeable AFAIK, but early cars just had the nuts and washers.

Do you know if a TR4A gauge would work or would it need a Resistor??

 

[TR3driver]

No, tr4 and 4A gauges are different electrically. They read full for a low sender resistance, instead of empty as the Tr2-3 versions do. To make one of them work, you'll need to change the sender unit in the tank, and add a voltage stabilizer.

The adjustment slots visible in the above photo mark it as a later TR3A/B gauge (or possibly from another non-TR). The TR4-TR6 versions have round holes for adjustment, instead if slots.