The brake light switch shown does not work, brake lights on all the time. I am thinking of using a mechanical switch instead. I know a lot of guys have trouble with short life span of pressure switches. I have a 10lb RPV in that line. I don't think that is enough pressure to keep the switch on but could it? That RPV is fairly common so I think that problem would come up. If I go mechanical would it be worthwhile removing that switch and replumbing the brake lines. I guess my question is do you think those 90 degree fittings might cause a problem with air bubbles? If I replumb the line from the master cylinder it would be flatter, no drop, with a smoother bend to connect with the line on the frame. Another option, I think a normal 3 hole T fitting would go there with a conventional pressure switch, I heard real Harley switches work well. If the 90s won't cause a problem. Thanks.
Harley switches work well, and last. Hydraulic switch should be upstream of the rpv, ie nearer the master cylinder. I'd say 10lbs should be enough to trigger the switch. Chris
You could open a bleeder on that line and relieve any pressure to see if that was the issue but I am leaning towards a defective switch as from what I could find a "low pressure Ford brake light switch" triggers at around 45 lbs rather than 55/90. Agreed that it should be upstream of the residual valve.
I did a mechanical switch on a 40 Ford. super easy. Wood screwed it to the floorboard, bent lever to ride on the brake pedal. Never have to worry about a pressure switch failing, which they often do.
I'm going to open the bleeder to relieve pressure ti check if it's that. But I'll probably go mechanical.
I must be lucky. I have never had brake light switch problems except when I ran silicon brake fluid not knowing I need a special switch. I went to the switche that Ron Francis Wireworks ((800) 292-1940) sells to use with silicon fluid and never had another problem. Charlie Stephens
Go with mechanical! 95 percent of the pressure switches are junk. The diagram starts leaking & they direct short. Personally I like the early 70's g.m. plunger switch, it's super simple to mount with brake pedal movement & it will last forever since it's inside the vehicle. It's also adjustable. Good luck
Is that actually a pressure switch? Never saw one that wasn't 1/8" NPT. Looks like that may be a mechanical "ball" switch (like a OEM back-up or Gennie/ Lokar neutral switch) activated by a piston inside that aluminum housing. If so the piston could be hung up.
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