Brake Questions - Help

[dennisonwj]

New to the Forum, Hello All. I am working on a 1969 Barracuda that I recently purchased. I DO NOT have the build sheet and need some ideas on the direction I need to go on a brake repair. The vehicle is a 340 small block with front discs and rear drums. Here are the questions. Note : Please forgive me, I have done brake jobs but I am lacking information on the vehicle specifications here.

1) How would I know if the front disk brakes were factory installed or after-market? One of the pictures below shows the caliper and you can see "A71312" on the passenger side one.

2) Is the picture below a proportioning valve or a distribution block? I am concerned someone just threw on front disc brakes and did not install a proportioning valve nor install the correct master cylinder.

3) The master cylinder is manual and there is a "20872" stamped in the rubber seal gasket and made in "U.S.A." BUT both chambers are the same size/volume like it is for a 4 wheel drum car. Again, I am concerned someone bush-leagued the brakes and did not install a proportioning valve the correct MC.

4) The vehicle does not seem to lock up the rear wheels when braking and without a proportioning valve that would happen, right?

- Will

[jimynick]

First off. let's say hi and welcome to the site.    I'm not an expert, but I believe all the 340 cars got disc brakes and it looks like you have the 4 piston Kelsey-Hayes calipers (they're scarce). The picture is a proportioning valve AND a distribution block and may be bunged or stuck causing less fluid to reach the rear, but before I touched it, I would set up the rear shoes after checking to make sure you don't have a seized/leaking wheel cylinder. I don't know squat about MC #'s and others may help out there. Hope that helps even a little bit! 

[dennisonwj]

First off. let's say hi and welcome to the site.    I'm not an expert, but I believe all the 340 cars got disc brakes and it looks like you have the 4 piston Kelsey-Hayes calipers (they're scarce). The picture is a proportioning valve AND a distribution block and may be bunged or stuck causing less fluid to reach the rear, but before I touched it, I would set up the rear shoes after checking to make sure you don't have a seized/leaking wheel cylinder. I don't know squat about MC #'s and others may help out there. Hope that helps even a little bit! 

On another forum people told me that was JUST a distribution block NOT a proportioning valve and I would have to add one. This car was originally a 318 I am pretty sure of. It is a 4 speed convertible though, very low production numbers and was a HIGH value build so maybe those are factory front discs. Are you SURE that is a proportioning valve? All the ones I have seen of that shape are JUST distribution blocks.

[70chall440]

You will find this valve called both a distribution and proportioning valve. Mopar tended to "proportion" the break bias by using specific valves designed for the combination being run. It does serve as a distribution valve as well and goes to a "metering" valve again designed for the specific applications.

All this said, those valves (regardless of what you want to call it) can normally be cleaned up and made to work. Inline tubes as well as many others carry new ones.

[dennisonwj]

You will find this valve called both a distribution and proportioning valve. Mopar tended to "proportion" the break bias by using specific valves designed for the combination being run. It does serve as a distribution valve as well and goes to a "metering" valve again designed for the specific applications.

All this said, those valves (regardless of what you want to call it) can normally be cleaned up and made to work. Inline tubes as well as many others carry new ones.

A few folks have told that I need to install a "proportioning valve" after this device in the line that goes to the rear brakes because the fronts are K-H disks. Here is the part they mentioned https://www.inlinetube.com/_p/prd14/2359746521/product/1968-70-mopar-68-70-amc%2C-amx-javelin-pr104b.

[70chall440]

that is what Mopar called a "metering" valve. They are found on most 70 and up cars. You need to research how your car was made, if it is a factory front disc car then it might not have a metering valve. have you been over on the A bodies website and asked? You could install a proportioning valve if you want one (I have one on my 70 challenger and 73 Cuda), it isnt going to screw anything up.

[dennisonwj]

that is what Mopar called a "metering" valve. They are found on most 70 and up cars. You need to research how your car was made, if it is a factory front disc car then it might not have a metering valve. have you been over on the A bodies website and asked? You could install a proportioning valve if you want one (I have one on my 70 challenger and 73 Cuda), it isnt going to screw anything up.

So what about this http://www.doctordiff.com/1-piece-proportioning-valve.html. I could replace the distribution block with this and have a proportioning valve and d-block all in one. Done and Done. This type of thing is what is under my master cylinder in my Jeep.

I think someone put K-H brakes on after in left the showroom, left the stock MC and did not care to put a real PV or metering valve on it. I am trying to make it as right as possible, so a compliant MC and PV. The only correct MC I have found is here and it is ridiculous. https://www.moparmall.com/MoPar-2808-600-2225-411-2808600-2225411-Master-Cyl-p/862-040.htm

[70chall440]

Yes, that would work and to be honest is probably what you have on there now.

[jimynick]

That picture that you have of the MC from those thieves is exactly the same as the one for a re-built MC from Rock Auto, their # 101326 and since I'm Canadian, the price came up as $85.52 including the core charge. They also list a new one built by Raybestos for less than $40 CND which is about just over $30usd. I used the listing for a 68 Plymouth Barracuda. There's a couple of options for you. 

[dennisonwj]

That picture that you have of the MC from those thieves is exactly the same as the one for a re-built MC from Rock Auto, their # 101326 and since I'm Canadian, the price came up as $85.52 including the core charge. They also list a new one built by Raybestos for less than $40 CND which is about just over $30usd. I used the listing for a 68 Plymouth Barracuda. There's a couple of options for you. 

Yeah, I saw those as well, love RockAuto. I was going to use one from Autozone I picked up, but the ports may be wrong. https://www.autozone.com/brakes-and-traction-control/master-cylinder-brake-system/remanufactured-master-cylinder-brake-system/4143_0_2558_2867

In the AZ one, the ports are 1/2 inch 20 thread and 9/16 20 thread. I thought the right one was 1/2 20 and 9/16 18. Am I correct there???

[jimynick]

Sorry, I don't know the thread pitchs.