1968 Mustang Pb Conversion

Paxton.5oh · Jun 13, 2017

Recently I assisted my cousin with the swap of his old master cylinder to a master cylinder that is paired with a power booster. I purchased the booster from eBay and I am having issues with the brake light switch for it. I contacted the seller for more information and I have yet to receive any assistance. Below are the links to the pedal, brake booster, and the brake light switch that I tried yesterday. I am at a loss here and do not know what to do. Any and all help is appreciated.

Links:

Brake Booster: http://www.ebay.com/itm/New-1967-68...ash=item3d3232c222:g:BpwAAOSw2xRYk89C&vxp=mtr (Not The Same Listing)
Brake Pedal: https://www.npdlink.com/store/products/pedal_assy_power_brake_repro-144759-1.html
Brake Ligh Switch: https://www.npdlink.com/store/products/switch_brake_light_replacement-176414-1.html

Vehicle Info:

1968 Mustang Coupe
Inline 6 Engine
C4 Transmission
Mostly original

horse sence · Jun 13, 2017

What is the problem with the brake light switch? If the pin in the proportioning valve is tripped the light will be on all the time .The pin or bar slides in the valve if the brakes have failed or the pedal was pushed with the drums or calipers off it will have to be reset through bleeding the brakes .If you used the old switch it may be stuck on ,push through the hole in the top with the end of a paper clip and it will release

Paxton.5oh · Jun 13, 2017

We bleed the breaks in the beginning before installing the brake light switch. The problem is the switch gets bound up and compresses the spring when the pedal is in the up position.The lights remain on and the switch itself functions. I removed the switch and pressed the plate on it to activate the lights and it was functional. I believe the issue is the oddly shaped pushrod by I may be mistaken.

Paxton.5oh · Jun 13, 2017

If all else fails I could always go to an inline pressure brake light switch right? Something similar to this just for the appropriate line size? Speedway Motors

horse sence · Jun 13, 2017

So you are talking about the pedal switch not working ,yes it works off of the pedal rod .Do you have the bushings in the correct positions?

Paxton.5oh · Jun 13, 2017

I have all bushings except for one. Would the bushing cause that issue?

Paxton.5oh · Jun 13, 2017

My cousin dug out the last bushing. I will go try that now.

Paxton.5oh · Jun 13, 2017

With the 1 washer against the pedal and the bushing on the pushrod, the brake light switch will not go onto the pedal.

zookeeper · Jun 16, 2017

I'm having a little wrapping my head around the problem. Are you having trouble mounting the switch itself or is the problem the brake lights won't come on or go off?

Paxton.5oh · Jun 16, 2017

The on pedal brake light switch is causing the brake lights to remain on. The issue is the push rod is too thick on the back side. When trying to up the pushrod bushing it is physically impossible to put the switch on the pedal. We are going to add a bracket to the pedal just like the one shown in the NPD link. We will then use the newer style switches that are activated when pressure is relieved from the button.

zookeeper · Jun 19, 2017

While that's one way to go, you do realize those switches and/or pushrods are meant to be adjusted right? By either bending the tabs on the switch, or filing the pushrod contact point you can make the lights come on earlier, later or whatever you feel is "just right".

EDIT: This is an older post, but is kinda relevant to your situation. Unless your switch, pushrod and/or pedal is much different than stock, this should work for you.

https://www.stangnet.com/mustang-forums/threads/brake-light-switch.757121/

Paxton.5oh · Jun 19, 2017

We considered filing down the pushrod but wanted a solution that did not require us to remove the master cylinder and power booster for the 3rd time. The last thing we wanted was for the brakes to get messed up or have to be re-bleed.

zookeeper · Jun 19, 2017

Please don't take this the wrong way, but that's how things are sometimes when working on cars. Parts don't always fall into place, sometimes brand new parts fail immediately or require tuning in order to get what you want. I've learned to approach every job on my car with knowing full well it may have to come out several times before it's right. If removing 4 bolts and bleeding the brakes is too daunting a task, then maybe working on the single most life-threatening system in the car should be left to a professional. That's not a knock on you or your experience, but if it takes removing the master cylinder 10 times to get it right, then that's what needs to be done. Don't compromise doing the right thing just because it's too hard or inconvenient. You'll only be sorry later.

Paxton.5oh · Jun 19, 2017

I completely agree with you. When it comes to my car I do this. However, with this project, I was essentially in the back seat and didn't have too much say. I would have much rather pulled the master out and taken the grinder to the pushrod to get it just right. The people I was helping just wanted functionality so they decided to go a different route with the brake lights. I understand where you are coming from and agree that things must always be done the right way. If I was in charge of the project I would have done things so differently and honestly redone a lot of the car. I wouldn't have let them do anything that would mess it up. The brakes stop perfectly fine and there aren't any issues when it comes to the stopping power. The brake lights were fixed by using a newer style switch on a bracket which is generally more reliable than the older style that these cars generally have. When it comes to safety things do have to be taken seriously and you can't do stuff half ass.

zookeeper · Jun 19, 2017

Sounds like you have a good head on your shoulders. I agree that sometimes people who you're either helping or doing the work for are content with "close enough" and there's not much you can do or say. A friend of my Dad's built a really nice hot rod a few years ago and used reproduction '39 Ford taillights. My first time behind him in town was an eye-opener since in daylight, the brake lights were so dim you could barely see them. When I mentioned it, he just shrugged his shoulders and said, "well they work so there's not much I can do". In this day of LED lights there's no excuse for that, but it's not my car. You do what you can sometimes...

Paxton.5oh · Jun 19, 2017

The way I look at it is as long as the vehicle operates safely and the things he does to it do not affect the safety of the vehicle I will let them do it how they want. If it is going to get somebody hurt then I will say something. As long as he is contempt with it and safe it does not bother me because it is his car and that is his choice. Also, I am glad there are members on here who try to make sure people always are safe when working on their rides.

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