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1937 Cadillac fuel sending unit fix.

Started by rbrown7713, December 24, 2018, 08:11:15 PM

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rbrown7713

The 37 Cad. fuel sending unit was shot, so I got a 55 Chevy sending unit and removed the float mechanism and installed it on the 37's pickup and unit. The angle of the float portion was changed about 30 degrees and made it perfect for the empty-full position. I drilled a hole in the top seal portion and mounted the electrical pickup, should work well, here are some pictures. I am almost sure that the Caddy gauge is also bad and I will be replacing the gauge with a 0 to 30 ohm late gauge, hopefully to make the gauge look stock and will be doing that transition as soon as I get the gauge, I will let you know, Bob.
Robert Brown
1937 Cadillac model 60, on a 73 Buick frame
A&P mechanic
US Army helicopter pilot 25th Inf. 25 avn. bat.
I build 1:32 scale trains

Steve Passmore

I had one professionally converted in the USA just like that about 35 years ago but I'm sad to report it was a complete disaster. The gauge needle would only move a little in the middle.   I hope you have better results than I did at the gauge.   The company no longer exists and I was lucky to find a NOS unit (here in the UK can you believe?)
FYI The senders are identical to Buick and others of those years.
Steve

Present
1937 60 convertible coupe
1941 62 convertible coupe
1941 62 coupe

Previous
1936 70 Sport coupe
1937 85 series V12 sedan
1938 60 coupe
1938 50 coupe
1939 60S
1940 62 coupe
1941 62 convertible coupe x2
1941 61 coupe
1941 61 sedan x2
1941 62 sedan x2
1947 62 sedan
1959 62 coupe

rbrown7713

Thanks for your input, but since the gauge and the sending unit will be on the bench, I will assure that they work correctly before I install them.  I will also post the results of converting the gauge when I am done. Bob.
Robert Brown
1937 Cadillac model 60, on a 73 Buick frame
A&P mechanic
US Army helicopter pilot 25th Inf. 25 avn. bat.
I build 1:32 scale trains

yachtflame

I did a similar thing with my 1930 sending unit. I took a 0-30 ohm sending unit and made an adapter plate for it so it could easily screw to the tank. I hooked it up to a battery and spare gauge to try it out. With the float arm all the way up, it pegs to the 25 gallon mark. With the arm all the way down, it only goes down to 15 gallons. Not sure how to correct this. Any help would be appreciated!

Wayne
CLC member 17057
Wayne Elsworth
CLC #17075

rbrown7713

Here is what I found out yesterday.  Using a 0 to 30 ohm sending unit and a new 0 to 30 ohm  12 volt gauge, I applied 6 volts DC to the circuit and the gauge, at full movement of the float, only went to 1/2 full.  And then I read the directions.  It is a 12 volt gauge, so I applied 12 volts to the circuit and the gauge went to full.  So, the voltage of the gauge determines what the voltage applied will be.  Now I have an older gauge coming in the mail and if I use that gauge, I will only apply 6 volts, because it is a 6 volt gauge.  The ohms of the gauge and the sending unit have to match, and the voltage required by the gauge will determine what voltage to apply. I hope that helped you. Bob.
Robert Brown
1937 Cadillac model 60, on a 73 Buick frame
A&P mechanic
US Army helicopter pilot 25th Inf. 25 avn. bat.
I build 1:32 scale trains

yachtflame

Bob,
How do you determine the ohm rating of the gauge?

Wayne
Wayne Elsworth
CLC #17075

J. Gomez

The traditional fuel gauge has two coils one will have a higher resistance (voltage side) while the other will be about ½ or so, see attach drawing.

These are in series and the sender connects to both at the center. The sender and gauge would need to match depending on the vehicle application and specific voltage.

The 30 ohm sender were standard on 12V GM vehicles until about in the mid ’60 when these change to the 90 ohm.

The sender for the 6V may well be a bit higher possible in the 100 plus ohm range, someone with your vintage car may validate the correct range.

Good luck..!
J. Gomez
CLC #23082

rbrown7713

#7
Wayne, I put an ohm meter on the late gauge that they said was 0-30 ohms and when I tested it, it was 96 ohms, so what is going on there, I don't know, must have something to do with when the power is applied, all I know is that it worked.  I ohmed the sending unit and, in fact got 0-30 ohms.  Now, I received the 6 volt older gauge and when I hooked it up at first, it read1/2 full, when the float was at the low position and at the top, read full.  I played around by bending the needle, several times when trying different positions.  I also bent the lower metal magnetic emitter at the bottom to several positions and when it was all done, the gauge now reads correctly.  The distance that the, what I call the emitter, is from the needle will control how far the needle swings, and by bending the needle, either right or left, will also control what the center range is.  Like I said, before I started, the range was 1/2 to full and after the adjustments, the range, as you can see in the pictures is now, empty to full., Don't know exactly what I did, but it works correctly now.  I haven't received the late gauge that I want to use yet, so I haven't decided whether I will use the 6 volt gauge for the transformation or the 12 volt one, as it depends on which one will be the easiest to mount.  Here are some pictures, note how far that I bent the metal magnetic emitter down away from the needle. Oh, I forgot to mention this.  I also bent the needle stops so that the range of movement was increased, that helped. Bob.
Robert Brown
1937 Cadillac model 60, on a 73 Buick frame
A&P mechanic
US Army helicopter pilot 25th Inf. 25 avn. bat.
I build 1:32 scale trains

rbrown7713

#8
I decided to use the older 6 volt gauge and by drilling two holes and using two screws managed to attach the 37 face to the 6 volt gauge, I think it was a chevy.  I will attempt to load a video of the operation. Bob. Here is a YouTube link to the video.   https://youtu.be/Pwg8QMj-NVI
Robert Brown
1937 Cadillac model 60, on a 73 Buick frame
A&P mechanic
US Army helicopter pilot 25th Inf. 25 avn. bat.
I build 1:32 scale trains

rbrown7713

The fuel gauge fiasco is finished and works fine.  Here are some pictures. Since the gauge that I used was deeper than the stock one, I had to use stand off studs to mount it and still have to figure out how I will seal it. Bob.
Robert Brown
1937 Cadillac model 60, on a 73 Buick frame
A&P mechanic
US Army helicopter pilot 25th Inf. 25 avn. bat.
I build 1:32 scale trains