What to do w/ brake light switch when converting a '66 from single to dual res. M/C

[bfoldy]

The '66 master cylinders have a pressure switch in a port on the top of the M/C that engages the brake lights, but I guess when Ford went to a dual res. M/C in '67 they moved from this style to a switch on the brake pedal that is activated as the pedal moves. How has someone who has converted their '66 single res. M/C to a dual res. M/C handled their brake light wiring? Did you keep the pressure switch or covert to a pedal switch?

I thought about adding a Tee off one of the ports on my new dual res. M/C to handle my old pressure switch + one of the brake lines, but I'm not sure this is the best solution. Has anyone else tried this, and if yes, what size will the inlets on the tee need to be?

 

[thegreatjustino]

I have not done this personally, but if I were to, I would ditch the pressure switch and install a switch on the pedal. They both utilize just two wires, so it should be a simple matter of running the wires that go to the pressure switch back through the firewall and hook them up to the pedal switch. I have a pressure switch on my '65 Mustang and have had to replace it three times over the last 12 years due to old brake fluid gumming them up. Switching to the pedal switch would eliminate that problem.

 

[bigjhoov]

Yes, you can convert to a pedal switch. It will take some doing though, because the pedal is different. You can either swap in a later pedal, or you can use some spacers and such to accept the pedal switch. The other route is to "t" in a pressure switch as you mentioned before. I chose to add a pedal switch.

 

[1957]

I converted my 66 to dual MC. It took a bit to get it to work. I have a 74eb and I used some parts from it. I used the pedal switch not the pressure switch and wired it to work. When I changed to the dual MC I split the front & rear brakes lines into a block that came off the 74. I installed and routed the brakes lines the same as the 74 and per the ford manual. I tried mounting the pressure switch to the block but couldn't get it to work. As far as putting a tee off of one of the MC I didin't think to try it. As far as the fitting size I would have to check the MC and get back to you. One problem I had with using the pedal switch I couldn't get the brakes lights to come off when I released the the pedal. But after a while I was able to adjust it properly.
Tony