gas gauge bail threads

J

JayJay

Well-known member
Good morning, folks. Question about 1930 CCPU.

The bail to my gas gauge has broken off at the back of the swinging body. I pulled the bail out of the tank with a pair of needle nose pliers and there are maybe 2-3 threads left. So I'm going to have to pull the gauge and likely drill out and rethread both the body and the bail. I'm wondering if anyone knows the proper thread.

Measuring the bail I get a wire diameter of 0.0962", which corresponds most closely to a #3 screw (0.0942"-0.0983"). Pretty hard to tell with just a couple of threads left (and my "mature" eyes) but it looks like it could be 48 tpi, which leads me to conclude that a 3-48 (NC) would be the appropriate pitch. That's not one I've run across before so I don't have that tap set and die in my collection, but before I ordered one I thought I'd see if this august body has any additional thoughts.

Yeah, I know I could just order a replacement gauge, but what's the fun in that?

BTW, when I pulled the bail out the float was just pushed on and soaked clear through with fuel. No end washer or retention. Looks like a champagne cork with the head cut off. So it's been replaced at least once before, and likely before the era of ethanol fuel. I've ordered a gauge rebuild kit with neoprene float.

Thanks all, and stay healthy.

JayJay
 
I would suspect that the thread on the bail is a rolled thread, so it would be slightly larger than the wire size. maybe #4? 4-48?
 
katy said:
I would suspect that the thread on the bail is a rolled thread, so it would be slightly larger than the wire size. maybe #4? 4-48?
Click to expand...


Katy - good thought, thanks. It looks like a cut thread to me, and when I mic'ed it over the threads it showed 0.092"-0.093". Major diameter of a #4 is 0.112". Regardless, since I've ordered a set of compatible #3-48 taps and dies, that's what I think I'll use and say to heck with it (although that is really an oddball thread - never run into it before).

Kind of reminds me of the time I needed a lock screw for an old Starrett caliper, turns out that was a #5-40. Another new one for me.

I'll use the neoprene float for now, and order a brass one. Where do you get those? Scavenge a carburettor?

JayJay
 

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JayJay said:
I've ordered a set of compatible #3-48 taps and dies, that's what I think I'll use and say to heck with it (although that is really an oddball thread - never run into it before).

Kind of reminds me of the time I needed a lock screw for an old Starrett caliper, turns out that was a #5-40. Another new one for me.

JayJay
Click to expand...

FWIW, 3-56, 3-48, 5-44, 5-40, and 5-36 and a whole bunch more are all obsolete "ASME" threads.
 
Instead of buying taps and dies (which you'll probably only use once) why not just buy a replacement assy??
Paul in CT
 
I have a few hundred original fuel gauges with good threads, all available very reasonably priced $20 for a complete original gauge, if that helps your cause..
 
1931 flamingo said:
Instead of buying taps and dies (which you'll probably only use once) why not just buy a replacement assy??
Paul in CT
Click to expand...


Paul - a very reasonable question. There are several answers.

  • From what I've been able to tell, the new replacement assemblies don't fit all that well.
  • I generally have no problem buying tools of almost any type. True, I'll never again likely rethread a Model A gas gauge bail, but who knows what other applications I might find?
  • Probably the most important, I find it a challenge to resurrect something that's broken into a usable state, as opposed to replacing. Kinda like being an old time mechanic as opposed to a parts-replacer.
Granted, not everyone feels like I do, and I don't pretend to say my way is the only way. But it works for me.

Thanks for the thoughts.

JayJay
 
SteveB31 said:
I have a few hundred original fuel gauges with good threads, all available very reasonably priced $20 for a complete original gauge, if that helps your cause..
Click to expand...


Thanks, Steve, I have the taps and die in hand. If I can't fix it I'll give you a shout. Nice to know (in this day of no swap meets) that there's a backup.

JayJay
 
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