Toploader wrote:

Rudi wrote:

.

I would really dread the thought of fitting that type of switch...

Just finished with the standing-on-my-head work of pedal mounted brake-light switches.
As 'the-guyz' suggested....removing the instrument panel FIRST... is the smart way/(less painful) to do it.
Everything is "right-there" and EZ to install. Only struggle
(skruggle if you live in Charleston) is the connecting/dis-connecting of the speedo cable.
6sal6 

If you can’t find wiring problem, try this.

In place of the pressure switch, start with a low amperage fuse in its place.

Then you can walk around and inspect lights and wire harness.
If fuse blows, definitely have additional troubleshooting to do.

Nos681 wrote:

If you can’t find wiring problem, try this.

In place of the pressure switch, start with a low amperage fuse in its place.

Then you can walk around and inspect lights and wire harness.
If fuse blows, definitely have additional troubleshooting to do.

I just did the electrical checks and there are no electrical faults or issues on the car. Definitely the switch is at fault...

Currently the plan is to take the failed switch back for a refund.
I've ordered another switch. It's the Hella brand and hopefully this one is of better quality and will last.
If this one fails, then maybe BB's theory is correct and then I will need to explore the option of retro fitting a brake pedal switch (which I really don't want to do).

Bullet Bob wrote:

Any possibility you got a little air bubble in there when you installed that switch.  And it worked it's way into the switch after a couple of uses?  Pretty strange for it fail in one day.
I've hated hydraulic brake lite switches for ever and won't have one.  But  I had pretty good luck with the pedal mounted stock switch on the 66....until I went to the current brake setup and ended up with a bit more free travel than I like.  That combined with the Fox V8 booster made for a very light pedal under normal slow speed braking which caused the brake lights to be a bit unreliable.  So
So, PIA as it was, I fashioned a bracket and installed a micro switch as a brake lite switch.  Works every time with about a half inch of pedal travel.

BB1
 

I've had my Mustang 20 years now and it seems that the brake switch failures only started happening after I converted to disc brakes. Prior to that, I had one switch on the original master cylinder for who knows how long, but it would have been years and years. I'm probably with you now in having the same opinion on hydraulic brake switches... Thumbs down.
Converting to an electric switch seems like a real pain though and it would be nice if I didn't have to.
My car was in the early production run, so the brake pedal most likely doesn't have the feature to mount a switch...

Last edited by Toploader (6/27/2023 9:27 PM)

I just checked my brake fluid and it is the non-silicone DOT 4 type, so that shouldn't be an issue?
I also wondered if I needed a low pressure switch? I have seen this discussed in some old internet threads.

 

Toploader wrote:

I keep reading up on this issue and saw someone talking about brake pressure switches blowing every month and put it down to the higher pressures in the brake system after converting to disc brakes.
Could this be something?

I was just getting ready to ask that question about the higher disc brake pressure requirement.  Also, you say the switch is mounted on the prop valve.  Zactly how did you do that?  With a "T" in one of the lines leaving or entering?

I am using the one MS sells for PB on my 65 with his PB kit. I also have LEDs and cruise. So the only add on was the relay for the leds to actvate witch also controls the crusie. Been working just fine for couple years now. My buddy has frame mounted brakes on his 57 chevy truck and we have replace the PS switch twice in one year, has 12v going through it and LEDS. 

 

Last edited by Cab4word67 (6/29/2023 11:05 PM)

BobE wrote:

You may be on to something regarding the higher pressure required for disc brakes.
If you decide to convert, below are links that contain some mechanical operated brake light switches you may want to consider.  These may be easier to install than the OEM pedal operated switch. 
https://watsons-streetworks.com/product/classic-button-style-brake-switch/
https://www.speedwaymotors.com/Search?query=brake%20light%20switch

 Thanks! Are there any websites showing examples of how to convert?

Here's an interesting read on hydraulic brake switches and their failures...

https://www.sw-em.com/hydraulic%20brake%20light%20switches%20notes.htm

Texas! wrote:

My 1958 F600 has what appears to be it's original factory installed hydraulic brake light switch and it works every time I step on the brake pedal. It's installed in the brake line underneath the cab.
The '64.5 Mustang had it installed in the forward end of the single pot master cylinder. The upper threaded hole in the photo.

Yep!!! I had the original single pot master cylinder on my car and as far as I can remember, it had the original brake switch. I wish I kept that switch and fitted it to the new disc brake set up 😔
So based on what you are saying, it shouldn't really matter where the switch is mounted?

Last edited by Toploader (6/29/2023 2:04 AM)

Well.... I just fitted the more expensive Hella brand of switch. The box says made in USA, but I couldn't see USA stamped anywhere on the switch.
I sure hope this part is USA made and will last like the original switches did.

Toploader wrote:

BobE wrote:

You may be on to something regarding the higher pressure required for disc brakes.
If you decide to convert, below are links that contain some mechanical operated brake light switches you may want to consider.  These may be easier to install than the OEM pedal operated switch. 
https://watsons-streetworks.com/product/classic-button-style-brake-switch/
https://www.speedwaymotors.com/Search?query=brake%20light%20switch

 Thanks! Are there any websites showing examples of how to convert?

ling this topic

I would try Googling this topic and see what comes up.  Or, try called Speedway, or Watsons, and see if they can offer any info.  Otherwise, I guess you'll have to figure out some kind mounting bracket.