Brake Questions - Help

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dennisonwj

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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

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Well, your bottom pictures shows a Kelsey Hayes, 4 piston, disc brake caliper, that was used on the 65-72 A body line of cars, so i would say it came down the assembly line with them.
 
'69 Fender tag may indicate if it was always disc brake car. Someone else here will know that off the top of their head.

I can tell you the pictures so far show a factory setup.
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.
Those pictured are the 4 piston fixed calipers made by kelsey Hayes and used with only a slight variation through the '72 model year.

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.
It is the correct distribution block for '69. The proportioning valve will be a little further back on the frame rail.

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.
Your concern is well placed. However the good? news is that most replacement master cylinders from the big rebuilders (like Cardone) use the master cylinder you have. They convert it to disk/drum use by removing the residual valve for the front brakes. It will work fine, but of course in an ideal world the disks should have a larger reservior. I finally bought a correct mc this past year from Kanter Auto.

) The vehicle does not seem to lock up the rear wheels when braking and without a proportioning valve that would happen, right?
The other way around. Proportioning valve reduces pressure to the rear to reduce lock up. Drums are self energizing and need less pressure compared to disks.
 
With 4 same sized tires on the car and front discs, yes the car needs to have the rear line pressure reduced to prevent pre-mature rear-wheel lock-up, and a possible resulting spin. As the rear tires gain footprint, the proportioning can be reduced. I run no proportioning at all with 295s on the back. and 15/16 wc's.

If you cannot find the stand-alone P-valve on your car, you can sub in the later style Combination valve. As it's name implies, it serves all three functions, namely distribution, proportion, and the brake failure warning light.
 
Well, your bottom pictures shows a Kelsey Hayes, 4 piston, disc brake caliper, that was used on the 65-72 A body line of cars, so i would say it came down the assembly line with them.

That would be awesome, I wish I could find the build sheet for the car. Went in the seats behind the glove compartment, everywhere, could not find one.
 
'69 Fender tag may indicate if it was always disc brake car. Someone else here will know that off the top of their head.

I can tell you the pictures so far show a factory setup.
Those pictured are the 4 piston fixed calipers made by kelsey Hayes and used with only a slight variation through the '72 model year.

It is the correct distribution block for '69. The proportioning valve will be a little further back on the frame rail.

Your concern is well placed. However the good? news is that most replacement master cylinders from the big rebuilders (like Cardone) use the master cylinder you have. They convert it to disk/drum use by removing the residual valve for the front brakes. It will work fine, but of course in an ideal world the disks should have a larger reservior. I finally bought a correct mc this past year from Kanter Auto.

The other way around. Proportioning valve reduces pressure to the rear to reduce lock up. Drums are self energizing and need less pressure compared to disks.

Attached is another picture of the block with labels.
On the car now there is no device rear of this one, there is only a device on the rear axle that the "TO rear drums" line goes to. It splits from there and goes to the rear drums. That COULD be a metering valve, but I am not sure. Today, I picked up a MC from AutoZone (https://www.autozone.com/brakes-and...master-cylinder-brake-system/4143_0_2558_2867). See pic. This was designed for front disc and the rear reservoir that goes to "FROM MC reservoir to front brakes" is larger than the one to the rear brakes by a little.

Is it possible this is a combination valve that does proportioning, distribution, and brake failure alert all in one? Note : there is no wire connected to it to throw the brake warning light on the dash, I have not gotten to fixing that yet. I mean, really, they light will go on to tell you that your brakes failed as you hit the pedal, you will feel the problem when you hit the pedal, is that light necessary?



20180513_140214_scaled_labeled.gif


download_mc.jpeg
 

So that small Texas shaped proportioning valve is no where to be found, it would be in the brake line that went to the rear, correct?
 
With 4 same sized tires on the car and front discs, yes the car needs to have the rear line pressure reduced to prevent pre-mature rear-wheel lock-up, and a possible resulting spin. As the rear tires gain footprint, the proportioning can be reduced. I run no proportioning at all with 295s on the back. and 15/16 wc's.

If you cannot find the stand-alone P-valve on your car, you can sub in the later style Combination valve. As it's name implies, it serves all three functions, namely distribution, proportion, and the brake failure warning light.

Do you have a link for the later combination valve? Is there any way to determine if the one I sent a picture of is actually a combination valve? I have seen pictures that may lead me to think this is an all in one.

The problem is that the brake lines are done and I am going to install an inline tube stainless pre-made set. I am wondering if there set will allow me to install the Texas shaped proportioning valve without cutting and having to re-flair the front to rear long line.
 
With 4 same sized tires on the car and front discs, yes the car needs to have the rear line pressure reduced to prevent pre-mature rear-wheel lock-up, and a possible resulting spin. As the rear tires gain footprint, the proportioning can be reduced. I run no proportioning at all with 295s on the back. and 15/16 wc's.

If you cannot find the stand-alone P-valve on your car, you can sub in the later style Combination valve. As it's name implies, it serves all three functions, namely distribution, proportion, and the brake failure warning light.


The tires on my car right now are P215/60R14/91S. My wife was driving it "gingerly" we have not had it very long, she has not attempted a panic stop to see what will happen with the rear wheels, BTW it is a 340HO motor with a 4 speed.
 
With that engine and a manual trans, things can go bad in a hurry with an inexperienced driver. This is because with high-compression, the engine generates a lot of compression braking, and it all goes into the rear wheels....... making it easier for the hydraulic brakes to attempt to lock them up. However, it cannot do that without stalling the engine.Experience tells us WHEN to push the clutch pedal down to prevent those things from happening. And the P valve tries to make the car safe for all concerned, by limiting the rear line pressure to IIRC 85% of the front, and the factory sized the rear brakes to limit their capacity to about 15% of the total. As you can see, there is a tremendous amount of braking potential to be had in the rear brakes......... for performance driving.

Your valve is NOT a combination valve.
Your valve is strictly a safety switch/distribution block.
In a C-valve, that Texas shaped part will be an integral part of it.
As for the block at the back; I have never seen it be anything but a splitter.

215/60-14s, 340HO, and manual trans,
Should never appear in the same thread.
In late summer of 1970, I purchase a slightly used 70 Swinger340. I drove her from then until fall of 71 on those skinny E70-14s, which math out to about the same 215. That car was, bar-none, the most dangerous car I have ever driven. I couldn't wait to get bigger tires on it! I drove that 4-speed SG equipped 4-wheel drifting death-trap on those pizza cutters until fall, and then put bigger studded winter tires on it. The following spring I got me some wider wheels and the biggest tires that would fit in there; G60-15s on adapters. I drove it until fall of 1974, having gone thru 14 tires, mostly rears. I fell on hard times and let her go for $1300. She was all but burned out; being on the second engine the second trans and now with 4.10s in her. The body was almost mint, except for all the wipe out dings. There was a lot of those.... lol. G's were a joke too :( You know what Gs math out to?, about 245s. IMO;a stout 340 stick-car built for the street,with a DP carb, will not be safe, until 295s go under there and 245s in the front. If you have a vacuum secondary carb, you could probably get away with 275s. I tried those. Both on 60s and in 50s. They had enough rubber in the forward direction. But the failed the left turn blast-off from a light, putting me facing backwards every time.... with the 750DP. I tried a 600 and a 750 vacuum secondary carb. The 600 choked my engine so bad I thought it turned into a 318. With the 750 , it felt like a soggy 340. I HAD to put that 750DP back on.
But I digress.
I hope you have bigger tires on the to-do list...... sooner than later.

Once 275s are on there, she won't need any rear proportioning, with 7/8" wc's, perhaps not even with 15/16".. Mine didn't.
 
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So that small Texas shaped proportioning valve is no where to be found, it would be in the brake line that went to the rear, correct?
yes. It may hard to see without getting underneath.

67-KH.JPG
 
yes. It may hard to see without getting underneath.

View attachment 1715175595

I have a four post lift and the car is in the air, I can see the entire line front to back and I see no other device other than the distribution block "thingy" :) in the picture above. Is there a chance that is actually a combination valve? Is there any way to tell? I have no problem getting a proportioning valve like you sent me in the rear line (if the stainless new lines allow for it), but I do not want to put two proportioning valves in line with each other, that may be BAD.
 
With that engine and a manual trans, things can go bad in a hurry with an inexperienced driver. This is because with high-compression, the engine generates a lot of compression braking, and it all goes into the rear wheels....... making it easier for the hydraulic brakes to attempt to lock them up. However, it cannot do that without stalling the engine.Experience tells us WHEN to push the clutch pedal down to prevent those things from happening. And the P valve tries to make the car safe for all concerned, by limiting the rear line pressure to IIRC 85% of the front, and the factory sized the rear brakes to limit their capacity to about 15% of the total. As you can see, there is a tremendous amount of braking potential to be had in the rear brakes......... for performance driving.

Your valve is NOT a combination valve.
Your valve is strictly a safety switch/distribution block.
In a C-valve, that Texas shaped part will be an integral part of it.
As for the block at the back; I have never seen it be anything but a splitter.

215/60-14s, 340HO, and manual trans,
Should never appear in the same thread.

That is great information, not ONLY Is it a 340HO 4 speed, but has a large cam in it (still flat tappet lifters I think), a 750 Edelbrock 4 barrel, AND fender well headers (yeah I said it). So the car needs the brakes to work right. To round it out, it is 1 of 52 of these types of cars they made in 1969 (low production number) so I need it NOT smashed. And I need to custom bend the lines from the MC to the distribution block to got back to the firewall then down and forward to miss the headers. Kinda crazy. Finally, it is a factory power convertible.
 
Attached is another picture of the block with labels.
On the car now there is no device rear of this one, there is only a device on the rear axle that the "TO rear drums" line goes to. It splits from there and goes to the rear drums. That COULD be a metering valve, but I am not sure. Today, I picked up a MC from AutoZone (https://www.autozone.com/brakes-and...master-cylinder-brake-system/4143_0_2558_2867). See pic. This was designed for front disc and the rear reservoir that goes to "FROM MC reservoir to front brakes" is larger than the one to the rear brakes by a little.

Is it possible this is a combination valve that does proportioning, distribution, and brake failure alert all in one? Note : there is no wire connected to it to throw the brake warning light on the dash, I have not gotten to fixing that yet. I mean, really, they light will go on to tell you that your brakes failed as you hit the pedal, you will feel the problem when you hit the pedal, is that light necessary?



View attachment 1715175563

View attachment 1715175569
Well the prop valve should be on the that line. So it looks likethere is no proportioning valve on your car.
Correct - the rear brake line should go from the distribution block with the warning light switch, to the prop valve and then the hose with a Tee on the rear axle's vent. If you read the booklet, it explains the hydraulic pressure is not proportioned until something like 500 psi. So for light braking, whether it is present or not will not be noticed. At lower speed and dry pavement it will be harder to lock up than slick pavement and higher speed braking.

You can buy a texas shaped prop valve.
Yes, you can also buy a combo valve used on the later years. There are pictures of the same collection of Master Tech Bulletins. They are bigger and you'll not mistake them for the simple safety switch type.

That Master cylinder doesn't look correct. If it works, its only for the same reason the one you have works. They removed the residual valve.
All master cylinders for the a-body disk brakes used a bail retainer, not a bolt. There's a list on the last page of one of the master tech booklets.
All chrysler master cylinders use a different thread for the rear brake and front brake connections at the master cylinder.

Yea I know the brake light warning may be too late. LOL. But maybe in some cases it will help.
 
With that engine and a manual trans, things can go bad in a hurry with an inexperienced driver. This is because with high-compression, the engine generates a lot of compression braking, and it all goes into the rear wheels....... making it easier for the hydraulic brakes to attempt to lock them up. However, it cannot do that without stalling the engine.Experience tells us WHEN to push the clutch pedal down to prevent those things from happening. And the P valve tries to make the car safe for all concerned, by limiting the rear line pressure to IIRC 85% of the front, and the factory sized the rear brakes to limit their capacity to about 15% of the total. As you can see, there is a tremendous amount of braking potential to be had in the rear brakes......... for performance driving.

Your valve is NOT a combination valve.
Your valve is strictly a safety switch/distribution block.
In a C-valve, that Texas shaped part will be an integral part of it.
As for the block at the back; I have never seen it be anything but a splitter.

215/60-14s, 340HO, and manual trans,
Should never appear in the same thread.

I will buy one of those Texas shaped proportioning valves and install it in the line from front to back, someone must have removed it or it was NEVER there. That would be bad if these front brakes were factory, right? Who knows what happens to these cars on their way to us, I just need to make it as right as I can.
 
I have a four post lift and the car is in the air, I can see the entire line front to back and I see no other device other than the distribution block "thingy" :) in the picture above. Is there a chance that is actually a combination valve? Is there any way to tell? I have no problem getting a proportioning valve like you sent me in the rear line (if the stainless new lines allow for it), but I do not want to put two proportioning valves in line with each other, that may be BAD.
for your car you can buy the new line in a two piece that allows for the rear prop valve from Inline tube
.PAB6804
https://docs.wixstatic.com/ugd/4d7af2_fec1d22057b34de19b02c89afb5a4d87.pdf
 
That is great information, not ONLY Is it a 340HO 4 speed, but has a large cam in it (still flat tappet lifters I think), a 750 Edelbrock 4 barrel, AND fender well headers (yeah I said it). So the car needs the brakes to work right. To round it out, it is 1 of 52 of these types of cars they made in 1969 (low production number) so I need it NOT smashed. And I need to custom bend the lines from the MC to the distribution block to got back to the firewall then down and forward to miss the headers. Kinda crazy. Finally, it is a factory power convertible.
Seems to me you might want to take a look at the fender tag and see how much info is on it. Shop manual will have some basic decoding. Some of the guys here will be helpful, especially if you are putting some effort in on your end. In addition to the imperial club, another great resource is The 1970 Hamtramck Registry Home Page

List of master tech bulletins and filmstrips:
Master Technician Service Conference - Chrysler's Training for Mechanics

here's direct to a picture of the combo valve:
1970 Chrysler Imperial Hydraulic Brake Service Guide from the Master Technicians Service Conference Session 274
1970 gets confusing with all the variations, even though the concepts remain the same. That's why I didn't want to post that earlier when it seemed likely the disks were a factory option.
 
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Well the prop valve should be on the that line. So it looks likethere is no proportioning valve on your car.
Correct - the rear brake line should go from the distribution block with the warning light switch, to the prop valve and then the hose with a Tee on the rear axle's vent. If you read the booklet, it explains the hydraulic pressure is not proportioned until something like 500 psi. So for light braking, whether it is present or not will not be noticed. At lower speed and dry pavement it will be harder to lock up than slick pavement and higher speed braking.

You can buy a texas shaped prop valve.
Yes, you can also buy a combo valve used on the later years. There are pictures of the same collection of Master Tech Bulletins. They are bigger and you'll not mistake them for the simple safety switch type.

That Master cylinder doesn't look correct. If it works, its only for the same reason the one you have works. They removed the residual valve.
All master cylinders for the a-body disk brakes used a bail retainer, not a bolt. There's a list on the last page of one of the master tech booklets.
All chrysler master cylinders use a different thread for the rear brake and front brake connections at the master cylinder.

Yea I know the brake light warning may be too late. LOL. But maybe in some cases it will help.


On page 13 of the booklet for the drum brakes it says that 2808600 is for Kelsey-Hayes Disc types and it does have a bail retainer. Does this one look right (NOS master cylinder for 1967-69 Plymouth and Dodge A-Body with power disc brakes). Presently this type is on the car looks like this 1967-1970 Plymouth Barracuda Brake Master Cylinder - Brake - Centric 67-70 Barracuda Brake Master Cylinder - 16637-05025203 - PartsGeek.

The one on there both reservoirs are the same size and I think it is for drum/drum configurations. Maybe a person after this cars sale put K-H brakes on it but left the MC and did not use a proportioning valve and they just dealt with the brake weirdness.
 
Seems to me you might want to take a look at the fender tag and see how much info is on it. Shop manual will have some basic decoding. Some of the guys here will be helpful, especially if you are putting some effort in on your end. In addition to the imperial club, another great resource is The 1970 Hamtramck Registry Home Page

List of master tech bulletins and filmstrips:
Master Technician Service Conference - Chrysler's Training for Mechanics

here's direct to a picture of the combo valve:
1970 Chrysler Imperial Hydraulic Brake Service Guide from the Master Technicians Service Conference Session 274
1970 gets confusing with all the variations, even though the concepts remain the same. That's why I didn't want to post that earlier when it seemed likely the disks were a factory option.

I looked at the fender tag and it does not list the codes for the brakes. I could not find the build sheet to date in the car.

I see on the Brake Service guide that pre-1970, there is a distribution block, the Texas shaped proportioning valve, and something else, is that other thing the block at the rear axle? Or something else entirely. Thanks for the registry link.
 
On page 13 of the booklet for the drum brakes it says that 2808600 is for Kelsey-Hayes Disc types and it does have a bail retainer. Does this one look right (NOS master cylinder for 1967-69 Plymouth and Dodge A-Body with power disc brakes).
Yes thats correct. But ouch on the price! lemme see if the place I bought still has any.

Yup. That's exactly what all those companies are doing. That link happens to be all drum, but they sell the same one as disk/drum by removing that little valve and giving them a different part number. Its cheaper for them and it works fine. I used one for 25 years. Just got to keep an eye on the fluid level.
 
Yes thats correct. But ouch on the price! lemme see if the place I bought still has any.


Yup. That's exactly what all those companies are doing. That link happens to be all drum, but they sell the same one as disk/drum by removing that little valve and giving them a different part number. Its cheaper for them and it works fine. I used one for 25 years. Just got to keep an eye on the fluid level.

Someone dropped this list on another forum. I will try to get them MUCH cheaper than that one above.
Manual disc brake compatable cylinders are
101326 M Cardone
MC 36221 Raybestos
18M1019 AC Delco
UP 36221 Napa
SS4736221 Napa

Please educate me if you would, what is a residual valve and why would you remove it? I will of course RTFM on it, but am interested in your expertise on it. I am basically a newb on MCs.
 
is that other thing the block at the rear axle? Or something else entirely.
Entirely different. It's a metering valve. Not used on a-body's. If you flip to the next page, you'll see the check list of what goes with which brake system. I did say it could be confusing!

Metering valves were used to hold off brake pressure on the front lines when the pedal is first applied. This was reduce the chance of front lock up on very slick surfaces such as ice. As the car begins to slow the weight transfers foward and the tires will bite better as the front brakes get their full pressure.
 
Someone dropped this list on another forum. I will try to get them MUCH cheaper than that one above.
Manual disc brake compatable cylinders are
101326 M Cardone
MC 36221 Raybestos
18M1019 AC Delco
UP 36221 Napa
SS4736221 Napa

Please educate me if you would, what is a residual valve and why would you remove it? I will of course RTFM on it, but am interested in your expertise on it. I am basically a newb on MCs.
It's a low pressure one way valve. If it was in the line to the disk brakes, the pistons would have more trouble retracting. There would be 10 psi in the front lines to overcome. Drum brake shoes retract with the assistance of heavy springs. A little pressure in the lines helps keep air out and the pistons ready to go into action.

If your front disks aren't dragging, that much at least is probably fine.
 
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