I gave up on the factory motion switch in my 69 and installed a pressure switch. Works great.

I have the pedal motion switch on my 66. Still the original switch, even with power brakes added.

MS wrote:

I gave up on the factory motion switch in my 69 and installed a pressure switch. Works great.

I have the pedal motion switch on my 66. Still the original switch, even with power brakes added.

I'm not keen on switching to the under dash brake pedal switch, but I seem to be going through these pressure switches.
Is there a better brand or something?

Standard Motor Products sells a good one:
https://www.summitracing.com/parts/smp-sls27

and a chinese one:
https://www.summitracing.com/parts/smp-sls27t

Notice that the good one is cheaper than the chinese one!
Any SMP part number that ends in T is their cheap chinese part competitor.

 

Kinda funny topic, I was visiting my buddy with a 64 Thunderbird tonight.
He recently replaced his original pressure switch.

I think it's the ethanol they put in the modern brake fluid.   

I don't have the wiring harness handy, does the switch complete a ground side circuit or a 12v side circuit? Hopefully ground... You mentioned you have LED's and I do think that is part of your problem, don't know exactly why just yet, but I think it is

Toploader wrote:

Nos681 wrote:

Kinda funny topic, I was visiting my buddy with a 64 Thunderbird tonight.
He recently replaced his original pressure switch.

Far out... I seem to be going through the switches like every year or so at the moment.
Let's put it this way... I put my foot on the brake pedal each time I go out, to make sure I see the reflection of the brake lights on the garage door before driving off.
The part stores mostly stock the Fuelmiser brand, which I thought was US made and good, but I don't know any more.
It can't be too high a current going through the switch as I have LED tail lights and I think the Max current at the switch measured something like .3 of an amp.
An NOS brake switch was my next thought, but where do I find these?

 
I was able to get information about the switch he purchased.

Car Quest (Advance Auto) brand
Part number:  YQPSAA1149

1964 Thunderbird, 390ci, 4 wheel power drums, jar type master cylinder

They actually had it in stock and purchased first week of June 2023.
I tried his brakes with engine off, it worked with a light amount of pressure applied.
The old switch required a lot more pressure, most likely due to the ethanol in the brake fluid…I mean age.

Raymond_B wrote:

I don't have the wiring harness handy, does the switch complete a ground side circuit or a 12v side circuit? Hopefully ground... You mentioned you have LED's and I do think that is part of your problem, don't know exactly why just yet, but I think it is

I'm guessing that the switch must complete the ground side of the circuit. I think it's what Ford did on some of the Thunderbirds and the very first run of Mustangs, before the under dash switch came along.
Before I went to LED for the taillights, I wired in a set of three bulbs each side to make the lights brighter (bad idea) and it would cook the brake switch with around 20amps or so. Before that, I had the standard taillight set up and the brake switch would last for years and years and years.
Now, I'm thinking I need to replace the switch every year or so?
This latest switch (Fuelmiser) seems to activate the brake lights with minimal pedal pressure. The last switch I was noticing that I needed to really push the brake pedal, or even start the engine to create the vacuum assistance with the booster.
I have the new switch in and all seems to be good for now, but I'm paranoid about these switches just failing randomly.

Last edited by Toploader (6/17/2023 8:07 PM)

6sally6 wrote:

Hand signals are still legal.....last time I checked.

Problem is...all these simple-minded, cell phone tote'n,brain damaged, my face zombies
who got their licenses through 'social-promotions' have NO CLUE why 'you're sticking your arm outta the window of that old car'.
(IF they even see ya between glances of the road while texting).
Besides......what's da big deal if ya get rear-ended?!   Ya got in-shore-uns...right?!
(-oh no I used a word I shouldn't have--uming they even have insurance ...OR even stop after they smash into ya !)
J/K of course.
6s6

I've been rear ended in another old car (twice actually) and it was definitely not fun.

Toploader wrote:

Raymond_B wrote:

I don't have the wiring harness handy, does the switch complete a ground side circuit or a 12v side circuit? Hopefully ground... You mentioned you have LED's and I do think that is part of your problem, don't know exactly why just yet, but I think it is

I'm guessing that the switch must complete the ground side of the circuit. I think it's what Ford did on some of the Thunderbirds and the very first run of Mustangs, before the under dash switch came along.
Before I went to LED for the taillights, I wired in a set of three bulbs each side to make the lights brighter (bad idea) and it would cook the brake switch with around 20amps or so. Before that, I had the standard taillight set up and the brake switch would last for years and years and years.
Now, I'm thinking I need to replace the switch every year or so?
This latest switch (Fuelmiser) seems to activate the brake lights with minimal pedal pressure. The last switch I was noticing that I needed to really push the brake pedal, or even start the engine to create the vacuum assistance with the booster.
I have the new switch in and all seems to be good for now, but I'm paranoid about these switches just failing randomly.

Yeah inherently better idea low side switch. Might be worth putting a multimeter on the switch and then pushing the brakes to see the reading. Then multimeter on one side of the circuit then ground the other side and get a resistance reading. Then compare. If your meter can measure amperage it'd be a good idea to measure that.

Do you have any of the failed switches? I'd measure those too.

My personal feeling is that even those LED bulbs need low voltage, they have much different resistance than your incandescent bulbs which is leading to the switch failures. That's why measuring current is important too.

Hopefully someone who's better versed in electricity can phrase it better.
 

The 64 Thunderbird’s brake switch operates a relay (in engine compartment) for brake lights.

My friend has been using an old GM electromechanical relay with short pigtail jumpers (type “F” connectors…male and female….aka slide on) due to Ford’s infinite wisdom to make an unusual blade arrangement for the brake relay (3 vertical on one side).  You can’t even use the 3 blade relay that were used for factory sequential lights.

About 8 years ago, the Scott Drake electronic flasher and sequential boxes with old school 1157 bulbs (x3 per side) were installed with same setup.  My friend tows his vintage 60’s boat every summer with this car as well.  He mentioned that he upgraded the boat trailer lights to sealed LED’s to get better turn indication on the trailer and visibility for idiots behind him.  No problems with car lights.

Last edited by Nos681 (6/17/2023 9:55 PM)

Willward sells a stop/brake light pressure switch, #300-11181, available at Speedway and Jegs, maybe it is a better quality (?)