VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1939 stop light switch

The stop lights on my 1939 is not working any more. Bulbs and wirings are ok. When I short-circuit the two wires connected to the stop light switch on the main cylinder, the lights are working. So I have limited the problem to the switch.
I have removed the switch from the main cylinder, and reinstalled it properley.
I know the switch is hydraulic operated from the main cylinder. What can be the problem?

Did you use teflon tape on the threads?

No tape used. It is no leakage, as I can observe.

Those pressure switches are prone to failing by needing more and more pressure to activate as they age. Mine would eventually get to the point where I'd have to lock the brakes up to get the brake light to activate. I got tired of replacing the switch every year or two and converted to a later lever operated mechanical switch.

So you think it is the switch itself that has became bad, and it will help if I replace the swich with a new one?

Yep ! I think a new switch is what you need.

I thought he said he installed a nrew switch. I replaced the switch on my ''39 every ten years until conveerted it to a later ever type.

Like Tiny and Gene, I have added a lever style mechanical switch to my ”˜37. I did that to make the brake lights come on much sooner when I start pushing the brake pedal. I drive frequently in traffic so I want the extra margin of warning to anyone behind me.

I tried 3 or 4 different hydraulic switches and was never pleased with when the lights came on. My experience is that most of the new switches you buy today are rated to activate at 60 psi or even higher. The original switches had much lower activation pressure, 30 psi or less. If you can find a NOS one it probably will fail pretty quickly.

No, I have not installed a new switch. I removed the old switch and reinstalled it just to check if it helped. I am ordering a new switch now, NOS from ebay.. Lever system looks more complicated.

The only complicated thing about the lever switch is mounting it since there's no factory mounting provision. Other than that you simply run short wires from the lever switch to the wires that would normally connect to the pressure switch. FWIW I've read that the old Harley brake light switches were low pressure switches. They look identical to the stock Chevy switch. I have no clue if new repop HD switches would be any different from those sold for our cars or if the lower pressure claim is valid. I once had a 70 Harley with that type of switch and it worked great.

I do agree with y'all about the lever action switch but. I've owned my 39 for 19 years and
have only replaced the switch once about 5 years ago. If your happy with your switch as it is
I'd keep it , If not change it to a lever action switch
Just my opinion......

I ordered my lever switch from Rock Auto. It is the one they list for a 1949 Chevrolet pickup. It probably fits a lot of Chevy models over multiple years.

My experience with eBay sellers for “NOS” parts is that there are very few of them who really know the application.

The switch I bought from an eBay seller was “NOS” aftermarket. It probably was a 1960’s hydraulic switch for a Ford. It fit the Chevy Master cylinder and did work. When the brakes were at least halfway applied!

I did some more research and determined that it was a 90 psi switch. That is way too high for my preferences in these older lower pressure systems.

I bought a new switch from OReilly auto. It didn't last long and they replaced it. I think the original price was $18-$20. I panicked about the short life of the switch and did some eBay searching. I started finding old stock aftermarket switches pretty cheap, sometimes 2 or 3 at a time. I stocked up and that did the trick, no more problems with new switches.

Mike

I use the old original designed switch. Unlike Rusty, whose car doesn't draw the respect that a 41 does and thus has other motorists tailgating him, I find that those behind are sufficiently far back enough to allow my slower brake lights to be quite adequate warning.

(Go back up and read Rusty;s comment for yourself,)

I consider the add-on lever action switch a modification. I try to avoid modifications, even it I were to destroy tailgater's grilles now and then. I figure it's their own fault for trying to get too close a look at my 41. Who would want to get a closer look at the rear of a 37? Nobody.

Seriously. I find the pressure switches adequate. I seldom take the car out where there is heavy traffic and avoid having to slam on brakes when i do.

I do think the lever action switched may work a bit faster but how much faster I have no idea.

Best,

Charlie

Hi Charlie,

Great to hear from you. Hope you are doing well.

Your analysis is correct. When people see my ”˜37 that want to get a closer look. It reminds them of how much better looking a ”˜41 is!

I appreciate Charlie’s dedication and enthusiasm to keep things authentic. If I had a car as great looking and unique as his I would do the same.

The real differences are that my car is just a decent looking “as is” car and is my daily driver. While it attracts attention from a large percentage of the public, those of us who know these old Chevy’s recognize it for what it is.

Both Charlie’s approach and mine allow us to enjoy our cars in our own ways.

When I shall replace any part in my car, I always look for a NOS or NORS on Ebay.. Modern reproductions have almost always lower quality or other design than the original. Now I am waiting for my NOS hydraulic switch.

I will be interested in how your NOS switch works with respect to pedal travel.