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Got a question for the group, since I changed from front drum to power discs I am changing the proportioning valve as well. The new valve has the light switch connector with only 1 pin, my original and the harness have 2 pin connector. Can I just swap the switch from the old to the new or buy just the 2 pin switch and change them out or do I need to send this one back and get a new valve with the 2 pin connector? Thanks.

 

Tom

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If it just has one pin it may be a brake light switch, not a system failure switch.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Thanks for the responses. Yes, it is an aftermarket valve. The switch is removable, can I just swap it out with a 2 pin switch that fits my stock harness? Thanks again.

Tom

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You need to do some research and find out what the purpose of the switch is. In the stock proportion valve it is a pressure differential switch that turns the warning light on in the dash when there is a pressure difference in the dual (front and rear) brake system. In some aftermarket valves it is just a pressure switch that turns the brake lights on when the brake pedal is pushed. On our cars the brake light switch is on the brake pedal arm.

The instructions that came with the valve should tell you what the function is. The ones that have a pressure differential valve are also called a combination valve, meaning they are a proportioning valve and a dual brake warning switch.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Thanks Don. Unfortunately there were no instructions in the box. The description calls it a "Combination Valve" Here is a link to it.  

https://www.cjponyparts.com/cj-classics-combination-valve-disc-drum-brake-aluminum-chrome/p/BCV12/

Any further thoughts on this would be appreciated. Thanks.

 

Tom

 

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43 minutes ago, vintageman said:

Thanks Don. Unfortunately there were no instructions in the box. The description calls it a "Combination Valve" Here is a link to it.  

https://www.cjponyparts.com/cj-classics-combination-valve-disc-drum-brake-aluminum-chrome/p/BCV12/

Any further thoughts on this would be appreciated. Thanks.

 

Tom

 

The description states "Includes a brake light switch that uses a GM style plug" which tells me this is not a pressure differential switch. When I was looking at proportioning valves I found that all the non-stocks unfortunately only offer a light switch. I have a Wilwood that I left the switch disconnected and kept the stock pedal switch. In any case, the pressure differential switch only works when you press on the pedal so it is too late then anyways to know that your brakes don't work.

Edited by tony-muscle

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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The warning switch is activated only when one side fails. It will most likely be the rear brakes that fail due to rust-out of the line running to the rear. So, when the warning light is on you should still have either the front or rear. If they both fail the warning light will remain off. 

One of these would probably work better, unless you want an adjustable valve.

COMBINATION VALVE, BRASS - #2B091-20BB - National Parts Depot (npdlink.com)

Edited by Don C

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Thanks everyone for the replies. This one will probably be going back and I will continue with my search to find a better solution. I appreciate the responses and learned something new.

 

Tom

 

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I'm not sure if this is a help or not with your system, but when I did my conversion using the SSBC 4 piston calipers, the kit came with an adjustable rear control valve and plugs to block off the rear circuit in the distribution block. It now only works as a junction for the two front brake lines. In this case, the idiot light "emergency" switch became redundant and is no longer connected. As Tony mentioned, by the time you see the light, it's too late anyway and I can certainly attest to that fact.

I never bothered to look for an alternative distribution block that would work with the adjustable valve for the rear. But, if you feel better with that connected, don't let me stop you. Just make sure you have the correct functioning one for your needs.

Geoff.

 I learn something new every day!

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The ideal situation would be to have a low brake fluid level light. So if there is a break in the circuit and the fluid empties out you could figure it out before you drive. I have pondered the idea of modifying my Wilwood MC lid to add a float switch to connect to the original "idiot" light. I even bought the float switch but not on top of my to do list at this time.

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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30 minutes ago, tony-muscle said:

The ideal situation would be to have a low brake fluid level light. So if there is a break in the circuit and the fluid empties out you could figure it out before you drive. I have pondered the idea of modifying my Wilwood MC lid to add a float switch to connect to the original "idiot" light. I even bought the float switch but not on top of my to do list at this time.

 Now THAT would be a good idea so you know if there is a leak in the system. Unfortunately, it would still not be a benefit should a line actually burst, as happened to me in my red 72 Mach back in around 1981.

Geoff.

 I learn something new every day!

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35 minutes ago, Stanglover said:

 Now THAT would be a good idea so you know if there is a leak in the system. Unfortunately, it would still not be a benefit should a line actually burst, as happened to me in my red 72 Mach back in around 1981.

You would need a fortune teller for that :biggrin:. Since these rust from the inside, it is hard to tell without replacing them and then replacing the brake fluid often. Unfortunately, brake fluid is like a sponge for water. Eventually, the water over time will rot the inside of the tubing.

Edited by tony-muscle

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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1 hour ago, tony-muscle said:

The ideal situation would be to have a low brake fluid level light. So if there is a break in the circuit and the fluid empties out you could figure it out before you drive. I have pondered the idea of modifying my Wilwood MC lid to add a float switch to connect to the original "idiot" light. I even bought the float switch but not on top of my to do list at this time.

The idea is to Frankestein this:

330-12646-med.jpg.821d899a4db1b1d2ce50a19c231660d8.jpg

onto this:

wil-330-8573_lg_xl.jpg.7fb29aa33fd7fa61a4ca5ffb0e713e50.jpg

Edited by tony-muscle

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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1 hour ago, tony-muscle said:

You would need a fortune teller for that :biggrin:. Since these rust from the inside, it is hard to tell without replacing them and then replacing the brake fluid often. Unfortunately, brake fluid is like a sponge for water. Eventually, the water over time will rot the inside of the tubing.

Yes indeed Tony, that's exactly what happened, the line blew outward, but looked fine on the outside. Fortunately, I was slowed up enough that I was able to not hit anyone going through a red light which was literally 20 yards from my driveway and I was able to pull in. Scared the living heck out of me!

Ok and now back to the program! 

Geoff.

 I learn something new every day!

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With a  properly operating dual master cylinder if one end (front or back) fails the other end will still be operational. If it's the front brakes that fail, just using rear brakes can be exciting, but they will stop the vehicle.

Brake warning lights work fine is you have a slight leak, brake line or fitting, or a wheel cylinder. However, the only time I've had a failure was all at once when a rusty brake line failed, on a '64 F100 and it had only a single master cylinder, and a warning light would not have worked. It didn't take me long to find a suitable dual master cylinder and convert it to a dual system.

That said, I think Tony's idea of a float level switch is a good one. There may be a better way of installing floats in your Wilwood master cylinder, though.  You can source a float from a vehicle in a salvage yard, a lot of them use floats, some use sensors that would require additional electronics. I believe that Hondas is one that uses floats.

Or, get something like this, easier to install although not as slick looking, due to the wires coming straight up out of the top:

littelfuse_reed_sensors_59630_datasheet.pdf.pdf

You can get them for less than $7 each.

59630-1T02A - Littelfuse - 59630 1T02A FLOAT SENSOR ROHS COMPLIANT: YES (newark.com)

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“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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20 hours ago, Don C said:

With a  properly operating dual master cylinder if one end (front or back) fails the other end will still be operational. If it's the front brakes that fail, just using rear brakes can be exciting, but they will stop the vehicle.

Brake warning lights work fine is you have a slight leak, brake line or fitting, or a wheel cylinder. However, the only time I've had a failure was all at once when a rusty brake line failed, on a '64 F100 and it had only a single master cylinder, and a warning light would not have worked. It didn't take me long to find a suitable dual master cylinder and convert it to a dual system.

That said, I think Tony's idea of a float level switch is a good one. There may be a better way of installing floats in your Wilwood master cylinder, though.  You can source a float from a vehicle in a salvage yard, a lot of them use floats, some use sensors that would require additional electronics. I believe that Hondas is one that uses floats.

Or, get something like this, easier to install although not as slick looking, due to the wires coming straight up out of the top:

littelfuse_reed_sensors_59630_datasheet.pdf.pdf

You can get them for less than $7 each.

59630-1T02A - Littelfuse - 59630 1T02A FLOAT SENSOR ROHS COMPLIANT: YES (newark.com)

Those bulkhead ones are good since the hole will have to be smaller. Thank you. I still need to figure out the length of the float rod. I have one from the lower unit oil of my boat that would be cool except that it is designed to work from the bottom up instead than from the top cap down.

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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  • 2 weeks later...

Not to keep going off topic here, but after @Don C shared the link for the level switches.  I did some research and called one of the fluid level manufacturers. I was recommended to use the Madison M8000 switch (https://www.amazon.com/gp/product/B00909404Y/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1). Being so cheap, I got one right away. Last night after taking measurements and making sure it would work I decided to take the plunge and drilled the cover. The MC has a bladder gasket between the cap and tank that I needed to account for. I drilled, tapped, put a spacer and I think I am in business. I will connect it between the idiot light dual wires and ground. In this way, the light should turn on for a test before cranking. The way it is right now, if the level goes down by ~1/8" it will turn on. It may be an issue when cornering or hard breaking so I won't know until I test. I have it in the forward reservoir that feeds the front brakes. However, the Wilwood MC has a little hole interconnecting both tanks about half way up the tank so if the rears leak it will drain some fluid from the front. Something I would like to add is some type of sealer between the rod of the level switch and the bladder. Does anyone know of a sealer that would work with brake fluid?

20210222_235223.thumb.jpg.f2b311ec3657ed5c46a9d8c51dc60b66.jpg

20210222_235254.thumb.jpg.1c578e145861e409a97b3c3eb5a73f33.jpg

20210223_000015.thumb.jpg.a4da47922d97023739c0763ed15d0cb6.jpg

  • Like 1

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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