Pressure activated brake light switch question......

[cheapthrillz]

I have a Wilwood 7/8 tandem master cylinder and got rid of the ability to use the stock FoMoCo brake light switch. I'm wanting to use one of the unused ports on the master to work a pressure activated brake light switch. Unused port on master cylinder is 1/2-20 UNF. What should I do? What have others used that worked sucessfully?

Looking at something like this:
http://www.summitracing.com/parts/PRF-80174/


Any other better products out there?



Thanks!

[cheapthrillz]

Anybody? Looking to order this quickly before I lose interest again lol....

Also, what port on the master (front or rear) should it be installed on, or does it even matter?

[dontlifttoshift]

That switch is fine but i don't think you will adapt it to the master with one fitting. We usually tee them in at the proportioning valve, it's all 1/8" pipe already so a brass tee and your are in business.

[cheapthrillz]

I'm currently running all 3/16 line with 3/8-24 fittings. You're saying that the switch previously mentioned is 1/8 NPT? And that there are no 1/2-20 UNF to 1/8 NPT adapters?

Dammit.... that would be too easy. lol

[Apogee]

JC, how'd you plumb everything? Have you considered the Wilwood #260-11179 distribution block with built-in adjustable proportioning valve and pressure switch? Might be a good option for you.

Tobin
KORE3

[cheapthrillz]

Hey Tobin! I tried to stay consistent on my fittings. Since all but one of the flex-kore lines required 3/8-24 IF fittings, I used those for the most part. The proportioning valve is a wilwood #260-10922. It has a 3/8-24 inlet and outlet. For the front, I used the same fittings and a 3/8-24 3-way "T" fitting. On the master cylinder, I used the 1/2-20 to 3/8-24 reducers that came with the master.

At the time of doing all of this, I completely forgot about the brake light switch.....

[dontlifttoshift]

Wow, I didnt even know that prop valve existed. I have always used the ones with the pipe thread in them and then they were adaptable for inverted flare or AN style fittings.

I don't have an easy answer for you at this point.

[cheapthrillz]

Wow, I didnt even know that prop valve existed. I have always used the ones with the pipe thread in them and then they were adaptable for inverted flare or AN style fittings.

I don't have an easy answer for you at this point.

Nothing is ever easy in my world lol. Looks like I may have to break down and get a new prop valve with the port built in for the brake light switch....

I wish there was an easier way though....

[Hydratech®]

Pressure activated brake light switches were phased out many years ago due to the fact that they could (and did) blow out under hard braking pressure (causing an unexpected and dramatic loss of brakes). My advice is to convert your vehicle over to the modern design pedal mounted switch...

[cheapthrillz]

Pressure activated brake light switches were phased out many years ago due to the fact that they could (and did) blow out under hard braking pressure (causing an unexpected and dramatic loss of brakes). My advice is to convert your vehicle over to the modern design pedal mounted switch...

Hey Paul. Thank you for the insight. What about the ones built into a proportioning valve? Which pedal mounted switch would you recommend? I could probably remove the positive stop that I made with a well nut and replace it with the newer style switch.... it would have to be a fairly compact unit though.

[dontlifttoshift]

I too, prefer a mechanical switch.....so here's two options.

You can take one of the plugs supplied with the master and drill and tap for 1/8" pipe thread and install.

Or modify your pedal assembly to accept a mechanical switch. Standard Ignition SLS66 is the most common and easily adaptable. We use them all the time. Any DECENT parts store should have on on the shelf for about 6 bucks.

[cheapthrillz]

I too, prefer a mechanical switch.....so here's two options.

You can take one of the plugs supplied with the master and drill and tap for 1/8" pipe thread and install.

Or modify your pedal assembly to accept a mechanical switch. Standard Ignition SLS66 is the most common and easily adaptable. We use them all the time. Any DECENT parts store should have on on the shelf for about 6 bucks.

Ok thanks! I will check into the SLS66. A mechanical switch would be easier than drilling an tapping and having to worry about a blowout. I already have a mechanical switch with the wiring and all there, I would just need to fab it to the pedal.

[cheapthrillz]

I picked up the Standard SLS66 from Autozone for $6.99. I think I can adapt it to the positive stop location on the pedal. In the paperwork for the switch, it says that the switch should not be "bottomed out" and you should leave 1/16 inch of play at full compression since the whole switch is plastic.... so what I'm thinking is use a few nuts on the threaded part of the switch to create a bumpstop that keeps the switch from compressing all the way (ie. don't get full engagement on the nut at the end of the switch so that the plunger can't be fully compressed against the pedal support). I will take pictures of the setup and post them here. This is the least "intrusive" solution I can think of, so I will try it first....

Thanks for your help guys

[dontlifttoshift]

I think the thread on those is 1/2-20 so you could just shim a nut to work as your positive stop and still allow it to actuate the plunger in the switch.

I have pulled those switches apart in the past by overtightening the nuts so use common sense....snug is good enough.

Why do you have a pedal stop anyways? There should be a deep hole in that master and plenty of engagement on the pushrod that you would have to pull the pedal WAY up in order for it to fall out.

[cheapthrillz]

Ok, so here is what we've got.... I think I've got it figured out, but I'm posting this to possibly help other if they run into a similar situation.

Here is the removed pedal with the bumpstop I created with a well nut:



The old style Ford switch:



The new switch mounted at bumpstop location:




I still have to put a nut and some washers on the threaded part of the switch and install some new electrical connectors, but you guys get the idea.... I will take some finished pics tomorrow after I go to the hardware store to get some nuts and washers lol.

[dontlifttoshift]

That should work great! Glad you got it nailed down.

[cheapthrillz]

That should work great! Glad you got it nailed down.

Probably would have taken a lot longer to figure out if it weren't for you. I thank you sincerely! You got a name?

ALL HAIL (insert name)!!!!!! lol

[cheapthrillz]

Why do you have a pedal stop anyways? There should be a deep hole in that master and plenty of engagement on the pushrod that you would have to pull the pedal WAY up in order for it to fall out.

Was I referring to a positive stop when I should have been referring to a return stop? lol

The stop I have been referring to is the one on the pedal that keeps the MC pushrod from trying to pull out of the back of the MC when the pedal returns. It also keeps the pedal from making a loud metal on metal "ding" everytime I release the brake pedal....

Let me know if my nomenclature is wrong...

[dontlifttoshift]

Nope, you got it right. Just didn't understand why you needed a return stop. usually with manual brakes the pushrod is in so deep the pedal would hit the dash or something else before it could disengage the piston. However I have seen applications where it can come apart there and those would certainly require some sort of a stop on the return side. 55 chevys had a rubber bumper up there that did the job quietly.

My uncle bought a 65 LTD nearly new. It was special ordered for the dealer owners wife and she drove it very little for about a year and then my uncle bought it. The coolest part about the car is the factory 8track player. There are even FORD 8 tracks in the glovebox. The frame rotted away in the front (stupid midwest) and started to come apart so it got parked in the garage. That was about 35 years ago and there it sits with about 40,000 miles on the clock. Despite the frame rotting the sheetmetal is pretty damn decent. The point is, I have always thought those cars had cool lines and a great roof profile and everytime I see your rendering I want to go get it and give it a makeover......someday.

Anyways, glad it worked.

Donny

[Hydratech®]

There you go - no pressure switch to ever leak or blow out, saving you from the hassle of having to rework any of your brake plumbing, and providing a fully adjustable modern solution = true ProTouring ingenuity. I do suggest that you come up with some sort of positive pedal stop, as your foot slipping off the side of the pedal may cause the switch to get hammered - maybe a hard plastic or aluminum collar of just the right size to go over the remaining exposed plastic threads of the brake light switch? (dispersing possible pedal hammer effect to the steel brake lamp switch mounting nut / metal area of the pedal bracket instead of the plastic switch housing) or a dedicated fabbed up separate positive stop of alternate convenient mounting...

I remember a time MANY years ago when I had a manual brake pedal rod fall out of the back of the MC in a rigged up build I was rolling - not funny to find a free swinging pedal under your foot in rush hour traffic! Good thing I was in the outside lane and dodged off into the shoulder and popped the trans into reverse (DOH!)