Vintage Mustang Forums banner

67 brake light switch

5486 Views 17 Replies 9 Participants Last post by  22GT
It's not broke so I'm not fixing it... This is just pure curiosity...

On my car, my brake switch is physically on the brake pedal. It's a switch mechanism that slips over the post that the brake booster shaft also rides on. This switch is physically identical to a few I've seen on '90's Fords.

But, I've also noticed that there's a switch in the distribution block right below my master/booster assembly off the firewall basically. Those wires are cut and not going anywhere.

Again, my brake lights work fine so I'm not fixing it... But which is actually correct out of curiosity? I'm assuming it's the one at the distribution block?

Thanks,
Khris
1 - 18 of 18 Posts

· Registered
Joined
·
1,112 Posts
The brake switch on the pedal arm is the rear brake indicating lamp switch. The brake switch on the distribution block is a low brake fluid warning lamp switch for the “brake” indicator on the dash panel.
 

· Registered
Joined
·
340 Posts
Discussion Starter · #3 ·
Oh... Wouldn't have guessed that! Thanks for the heads up... Definitely didn't realize that.

On a side note, interesting that ford never really changed that switch cause i had a mid 90's explorer that had that exact same switch on the pedal. I guess like I said in the initial post, not broke, don't fix it? LOL
 

· Registered
Joined
·
37,626 Posts
It's not broke so I'm not fixing it... This is just pure curiosity...
Actually, it is broke, and you should fix it. There's a shuttle pin inside the distribution block, and most likely it got off-center during brake repair or brake bleeding. I'd recenter it, and repair the wiring. Then if you should develop a leak in your brake system, the light will warn you.

There's even a special tool to hold the shuttle in place during brake work.

 

· Registered
Joined
·
247 Posts
It's not broke so I'm not fixing it... This is just pure curiosity...
Actually, it is broke, and you should fix it. There's a shuttle pin inside the distribution block, and most likely it got off-center during brake repair or brake bleeding. I'd recenter it, and repair the wiring. Then if you should develop a leak in your brake system, the light will warn you.

There's even a special tool to hold the shuttle in place during brake work.

I agree on fixing this. It is a fail safe, it lets you know you have lost your brakes.
 

· Registered
1967 Mustang GT fastback
Joined
·
3,992 Posts
It could possibly be a bigger job than merely centering the shuttle. Over the years many shuttles have seized in the bore on one side or the other, so the light stays on. For years the common fix was to leave it unplugged so there'd be no annoying BRAKE light on the dash. Not safe of course. There is a way to fix a seized up shuttle, but I haven't done mine yet.
 

· Registered
69 mustang convertible, 351W, 4bbl, 4 speed, mild cam
Joined
·
273 Posts
Would it be possible for someone to posts a few pics of the switch and area you are discussing. I would be interested in seeing what your talking about.

Thanks.
 

· Registered
Joined
·
6,440 Posts
It is on the master cylinder
For '67 & '68, stock setup the "switch" which monitors brake failure is NOT mounted on the master cylinder, but a single pin switch for 67 & dual pin switch for 68 is screwed onto center of the brake distribution block. (Not to be confused with the proportioning valve used only for disc brake cars).
This pic of my 67 with factory disc brakes, I used a '68 proportioning valve but 67 switch because had to match wire harness. Also the 68 prop valve, has end cap that comes off to push centering shuttle if stuck.
 

Attachments

· Registered
Joined
·
340 Posts
Discussion Starter · #11 ·
For '67 & '68, stock setup the "switch" which monitors brake failure is NOT mounted on the master cylinder, but a single pin switch for 67 & dual pin switch for 68 is screwed onto center of the brake distribution block. (Not to be confused with the proportioning valve used only for disc brake cars).
This pic of my 67 with factory disc brakes, I used a '68 proportioning valve but 67 switch because had to match wire harness. Also the 68 prop valve, has end cap that comes off to push centering shuttle if stuck.

I've got a factory disc brake car and I'm 99% sure I don't have a proportioning valve in my system. I'll have to double check but functionally, the rear definitely locks up too fast compared to the front. Is the cylinder just right'ish/below the distribution the proportioning valve? Is it adjustable somehow?

Mine is a dual pin (2 wire)...
 

· Registered
Joined
·
6,440 Posts
If we're talking stock setups, best I know all of 67 (except for so called "very late" 67 had a prop valve mounted over rear axle area. Non-adjustable.
From reading NPD's catalog listing for brake lines, they listed a "very late 67" setup. This puts the whole setup (prop valve & distribution block all up front, just like in my picture. My 67 is a fairly late May 10, 1967. But I liked having whole setup up front, together so I used the "very late 67" brake line kit from NPD. As said I have the correct 67 single pin switch because of wiring. All works great.
https://www.npdlink.com/product/bra...2Blines&top_parent=200001&year=1967&year=1967
All lines:
https://www.npdlink.com/search/products?search_terms=brake+lines&top_parent=200001&year=1967


If you have a 2 pin switch then it's a '68 switch. Won't match a 67 stock harness.
 

· Registered
Joined
·
340 Posts
Discussion Starter · #13 ·
Thanks for the info... I've not looked up the build date info on mine but considering what I learned just a few weeks back about my steering column I'm guessing it's a earlier '67 because it doesn't have the rag joint style steering box/column. I'll take a peek under the rear and see if there's one in there somewhere. If not I'll just follow the lines up to the front and see if it has anything in line anywhere. Gives me a starting point.

Thanks
 

· Registered
Joined
·
191 Posts
Actually, it is broke, and you should fix it. There's a shuttle pin inside the distribution block, and most likely it got off-center during brake repair or brake bleeding. I'd recenter it, and repair the wiring. Then if you should develop a leak in your brake system, the light will warn you.

There's even a special tool to hold the shuttle in place during brake work.

Thanx for posting this! I had no idea this tool existed! Found one in the NPD catalog https://www.npdlink.com/product/mus...ms=shuttle%2Bcentered&top_parent=200001&year=

Harry Z
 

· Registered
Joined
·
1,112 Posts
Thanks for the info... I've not looked up the build date info on mine but considering what I learned just a few weeks back about my steering column I'm guessing it's a earlier '67 because it doesn't have the rag joint style steering box/column. I'll take a peek under the rear and see if there's one in there somewhere. If not I'll just follow the lines up to the front and see if it has anything in line anywhere. Gives me a starting point.

Thanks
If not located near the driver's side rear shock absorber, and near the vent hose for the rear axle, you might see evidence of it being replaced with a short piece of tubing. Anyway it should definitely be there.
 

· Registered
Joined
·
58 Posts
Oh... Wouldn't have guessed that! Thanks for the heads up... Definitely didn't realize that.

On a side note, interesting that ford never really changed that switch cause i had a mid 90's explorer that had that exact same switch on the pedal. I guess like I said in the initial post, not broke, don't fix it? LOL
I thought I would add that the brake switch that mounts on the brake pedal comes in several different versions, all appearing and installing the same. The difference in switches is the tension of the spring that is inside the switch housing. For example, power brakes take less pedal pressure so the spring is lighter tension as compared to manual brakes. This is important becasue if you install the incorrect switch, your brake lights may not be coming on timely which is dangerous. Springs are colored according to tension, but I don't recall what color is which tension. Just be sure to have someone check your rear brake lights as you apply pedal pressure. The lights should come on with little pedal travel or pressure.
 

· Registered
Joined
·
247 Posts
Yeah, I named the incorrect part.
My Proportioning valve in litteraly right on my master cylinder (minimal tubing between the two)... must be something the previous owner did. I also have a distrobution valve...drums where converted to disc in the front.

Maybe I should re-do my brakes...?
 

· Registered
Joined
·
37,626 Posts
I've got a factory disc brake car and I'm 99% sure I don't have a proportioning valve in my system. I'll have to double check but functionally, the rear definitely locks up too fast compared to the front. Is the cylinder just right'ish/below the distribution the proportioning valve? Is it adjustable somehow?

Mine is a dual pin (2 wire)...
Yes, this is the 67-69 proportioning valve. Mounted a bit lower on late 67, and by the rear axle hose on early 67. And no, it is not adjustable, but it is rebuildable.
 

Attachments

1 - 18 of 18 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top