Proportioning valve questions • The Dodge Challenger Message Board

by **Jon** » 30 Aug 2007 23:34

I'm replacing the brake lines in my factory front disk brake system and had a few questions about these valves. In the first picture on the bottom on the block their is a pin that is spring loaded and can be pulled out. Is this for bleeding the brakes or something? In the back gound is a sender of some sort which has a wire connected to it when in place. Thought it maybe a warning light but I don't think there is one on the dash...

The brass block in the second picture is located on the frame rail just below the driver foot well. The bottom of it has a threaded plug. What would that be for.

Thanks,

Jon

Edit: The pictures didn't load backwards as expected.

by **dave-r** » 31 Aug 2007 7:47

First of all. You do have a warning light in the dash. It is the same one that comes on when you apply the emergency brake. The wire connection on that block puts the light on if you loose pressure in one of the two brake circuits.

When bleeding the brakes it usually sets it off and you need to re-set it.

Second. Always fit an adjustable proportioning valve in the line to the rear brakes. Fitting discs to the front and/or fitting wider rear tyres always upsets the brake ballance.

by **Jon** » 31 Aug 2007 13:39

Thanks for the information Dave. I am confused about the location of the adjustable proportioning valve. Is it the top photo from the frame rail? Is that the factory valve?

What do the two attached blocks do besides distributing the fluid and the warning deal? How does one reset the warning light?. Although I have never seen the light come on thank goodness.

Sorry about all the????

by **dave-r** » 01 Sep 2007 9:44

I am not sure exactly what you have there to be honest. Is one a duplicate part? I am having trouble remembering how it all hooks together.

Anyway. An adjustable propprtioning valve is not a factory option. You need to buy one and splice it into the line running to the rear brakes. I have mine mounted on the inside edge of the frame rail with the knob down so I can reach under to adjust it.

by **dave-r** » 01 Sep 2007 9:56

I think I am getting mixed up with the proportioning valve and metering valve here.

You know. You really should get yourself a workshop manual. :roll:

But here are a few scans that might help.

by **Jon** » 01 Sep 2007 14:19

Thanks Dave, the information you have provided makes it clear that the proportioning valve on a 70 disk brake system is located on the frame rail.

If anyone out there orders new brake lines make sure you either ask for the one piece or two piece line that runs along the body to the rear axle.
Front disk vs. front drum determines this as the proportioning valve is only used in the disk system as far as I know.

BTW: I have an extra stainless one piece brake line if anyone's interested. :roll:

by **CraigRTSE** » 16 Sep 2007 0:43

Jon wrote:BTW: I have an extra stainless one piece brake line if anyone's interested.

Where did you buy it? Fine Lines gave me the single line by mistake also. It was months later until I realized it (when I finally got to install it), but they still exchanged it for the correct two-piece one.

by **Dale1035** » 13 Mar 2009 0:14

dave-r wrote:First of all. You do have a warning light in the dash. It is the same one that comes on when you apply the emergency brake. The wire connection on that block puts the light on if you loose pressure in one of the two brake circuits.

When bleeding the brakes it usually sets it off and you need to re-set it.

Second. Always fit an adjustable proportioning valve in the line to the rear brakes. Fitting discs to the front and/or fitting wider rear tyres always upsets the brake ballance.

Dave you have said that bleeding the brakes can set off the warning light and it would need to be reset. How do you reset the switch to make the light go off? My system may be just a little different for it is a 73 model.

by **Moparman1972** » 13 Mar 2009 2:06

Mine never went off! And my system was completely empty when I got it. The light works for the E-Brake. How does the sensor work? Perhaps mine is frozen from time?

Edit: I have now done what I should have done 5 minutes ago and read through all of Dave's helpful manual pictures. :hmmm:

I am still unsure why my light was never tripped. Would pressure have to be applied to the brakes with nothing in one half of the system to set it off?

by **dave-r** » 13 Mar 2009 8:26

Moparman1972 wrote:I am still unsure why my light was never tripped. Would pressure have to be applied to the brakes with nothing in one half of the system to set it off?

Yes. I think it is for when you completely loose pressure on one side of the system.

by **dave-r** » 13 Mar 2009 8:30

Dale1035 wrote:Dave you have said that bleeding the brakes can set off the warning light and it would need to be reset. How do you reset the switch to make the light go off? My system may be just a little different for it is a 73 model.

Giving it a quick look I think it re-sets itself when the pressure is equalised again by bleeding the brakes.

by **Moparman1972** » 13 Mar 2009 14:30

It says in your manual pages that if it is tripped it has to be replaced.

by **dave-r** » 13 Mar 2009 15:37

Moparman1972 wrote:It says in your manual pages that if it is tripped it has to be replaced.

Can't see that bit?

It says to replace it if it does not trip when tested.

It is just a spring mounted plunger. If forced one way it contacts a metal point that grounds the circuit for a light. There is nothing to stop it coming back to center again once pressure is released.

by **Alaskan_TA** » 14 Mar 2009 1:23

Just an FYI;

by **Jon** » 14 Mar 2009 3:16

On a pre 70 car here is the valves/splitter on the fender well as they are connected.

by **Dale1035** » 15 Mar 2009 2:48

Thanks for the tips. As soon as I can get a few minutes I will bleed all of the brakes and see what happens. I still have one wheel cylinder taht has not been replaced so I will change it while I am at it. I will let you know the outcome.