Kendog 170
Let the boy go !
Just get the dual reservoir style that's been posted. Post 33 or 42.
Don't forget about the pushrod.
Don't forget about the pushrod.
1965 Valiant brake woes
- Thread starter scott_s
- Start date
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AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
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Cobbled together or not, if the parts themselves are working correctly, and properly fitted; then anything works with anything. Brakes are not rocket science. How well they work together as a team, only depends on the "tune", which is the sizing of the various parts
Assuming the drum system is staying;
#1) ignore the rear brakes for now at best they are usually sized to not do more than 15% of the stopping
#2 Start by replacing the Booster Cuz clearly it is NOT working correctly. IMO the control valve inside it is busted, and there's only one way that happens, someone mashed the pedal with an improperly adjusted pushrod, and/or with excessive pedal-travel, for whatever reason; be-it hydraulic or mechanical.
It's a drum/drum system, this is as simple as it gets. Like I said, it ain't rocket science.
#3) Address the contact patch mismatch that is causing your pull.
The "pull" is caused by an imbalance in the L/R system. It could be Hydraulic, but more likely is mechanical. Drum brakes are self energizing, so the friction materials are the first suspects. With New linings, that have not been ground to match the drums, there is no controlling the contact patch, and if one side has more than the other, it will pull to that side, and there is nothing you can do about it. So fix this.
Furthermore; As long as the shoes are rubbing on their high points, the brake-drums are gonna flex with heavy application, causing a spongy feel, and lack of confidence, not to mention very poor ability to slow the car, at speed.
#4) with the shoes now working, revisit the pedal for being hard and high. If it it is not so, here is what I would do;
What I would do is remove ALL four drums and ALL the brake hardware, and ALL the rubber boots on ALL the w/c's. Then I would C-clamp across ALL the w/c pistons to keep them from coming out.
Then, I would again visit the pedal for high and hard. This is the only way, in your system, that you can ever know whether you have a hydraulic problem, or a mechanical problem, or some combination.
IF, your pedal is not high and hard now;
Most likely there is air in the System, but this is not a sure thing; You could still have a mechanical issue between the pedal and the M/C. With a new booster in there, this pretty much points to the connecting links.
Solution is by process of elimination. First:
If you suspect air in the system, start by bench bleeding the master; yes, take it off and take it back to the bench-vise. Observe how it is designed, and where air can collect. Install the bleeder hoses, ends lowered into the fluid, and Full Stroke that beotch. If the fluid enters the transparent hoses from the lines, but returns back the way it came, this is NOT bleeding. The fluid has to go around the circle. from line out, up the line, and drop back into the reservoir. Sometimes you have to pinch the line, to prevent back-flow. When you think yur done, change the angle of the reservoir to nose up, cuz little bubble likes to remain in the nose, and between the two pistons inside the Power-chamber. Then reposition nose down, to get the last of it out the C-ports.
After you think you got it all, keep pumping, cuz micro-bubbles like to stick to things inside the chambers. If you don't get them out at this stage, eventually they are gonna make trouble.
After the M/C is re-installed, it is almost guaranteed that a small bubble will remain at the junction of the lines to the M/C. Purge it by cracking the connection, while a helper is gently pushing on the pedal. If that air goes back up into the master, it's gonna be trapped in the bore somewhere and with the M/C nose up, it's likely to stay in there forever.
Next, I gotta tell ya; If there is air in the system anywhere, it will act like an air spring. When you step on the pedal hard, you can easily generate 800 psi or more in the line. When you step off the pedal, that air will try to instantly go back to zero. In doing so, it will supercharge the fluid back to the M/C, and if the lid is off, you will see a geyser in the reservoir(s). Which could spurt two or three feet up towards the hood. and when it comes down, it will make a mess. and most non-silicone brake-fluids attack paint. You have been warned.
Wipe up spills with paper towels ASAP and wipe the area with a Brakleened paper-wipe.
You can mitigate this by coming off the pedal very slowly, and having a helper observe the geyser..
Now, if the C-clamped system is free of air;
the returning fluid will only roil in the bottom of the reservoir, and you may barely see it. The only amount of fluid that can return is the few or couple or maybe just one CC that went out, and it is returning thru the tiny Compensating port. If you see NO ROILING at all, chances are that your pushrod is too long, and the C-port is not passable. Shine a light into the reservoir looking for a shiney reflection coming at you from the port. If you see it, the pushrod is too long.
If the pushrod is too short, it will take a lot of pedal travel for the pushrod to actually reach the power piston, AND if your booster does not have the distance capacity, you might break the control valve trying to get there. So DO NOT power thru the long-travel. With a C-clamped system, engine not running, the pedal should be high and hard within one inch or less. This pushrod length is almost critical within too short or too long, so always adjust too long , to protect the booster, and work towards opening the C-port.
Ok so
once the geyser(s) are eliminated, the pedal should be hard.
Now you can prove the C-port is open by;
stab the pedal two or three times in rapid succession. This will prevent fluid backflow and the pedal should climb ever higher. Now release the pedal and wait a couple of seconds, for the fluid to return. Then step on the pedal, which should have normalized to as it was before the test.
If your pedal does not get higher, or does not normalize, most likely the fluid is not retuning and the usual suspect is a closed or restricted C-port. Shorten the rod not more than one turn atta time, and shine a light into the C-port. If you have a helper, slowly pumping the pedal back and forth, it will be easy to see the shiny reflection, which, you should NOT be seeing with the pedal parked!. As soon as the pedal works properly, it is short enough. It can be further shortened at a later time as a tuning trick; But all you need right now, is for it not to be too long.
#4A) This is a good time to check your booster (with the wc's still clamped. With your foot pressing moderately and holding, start the engine. As the booster charges, the pedal will drop. How far it drops will depend on how hard you are pressing. One inch or more is common with C-clamped w/c's. Later, with the brakes reassembled and adjusted with bedded-in shoes, you can expect pedal-drop of more than two inches, maybe closer to three, but still several inches off the floor. IF you do not have reserve room, then then if you ever have a failure and your foot drops on the brake-pedal during the event, it better not hit the floor!
#5) With the pedal now being high and hard, the C-port exhausting normally, and no geysers, the hydraulics are finally trustworthy. So now you can remove the C-clamps, reinstall the mechanical system, adjust it, and roadtest it.
#6) as for the mechanical system. By now, you should be intimately familiar with the mechanical system, so I'll only mention these three things;
1) If you have a parking brake, make sure the strut inside the drum, that interconnects the two shoes, is not preventing any shoe from parking on it's anchor. If it interferes then you may have a spongy pedal and lousy stopping
2) each drum should have one long friction shoe, and one short one. The long one goes to the rear of the car, so that they both wear at about the same rate.
3) the bane of any mechanical brake system, is flex. Look for it and try to eliminate it. Besides old hoses, unbedded shoes, and the aforementioned parking strut, about the only other source that I can think of is front wheel-bearing adjustment, and/or worn-out rear wheel-bearings. If the drums cannot stay centered, you will have issues.
I know it's a lotta work, but when you get it done, step by step, it will work, and the phrase "cobbled-up" will no longer be in your vocabulary. Brakes is just brakes. Once you go thru this, you can find shortcuts. Soon you be here telling fellow FABO-ers the same story, but with a happy ending.
Happy HotRodding
Assuming the drum system is staying;
#1) ignore the rear brakes for now at best they are usually sized to not do more than 15% of the stopping
#2 Start by replacing the Booster Cuz clearly it is NOT working correctly. IMO the control valve inside it is busted, and there's only one way that happens, someone mashed the pedal with an improperly adjusted pushrod, and/or with excessive pedal-travel, for whatever reason; be-it hydraulic or mechanical.
It's a drum/drum system, this is as simple as it gets. Like I said, it ain't rocket science.
#3) Address the contact patch mismatch that is causing your pull.
The "pull" is caused by an imbalance in the L/R system. It could be Hydraulic, but more likely is mechanical. Drum brakes are self energizing, so the friction materials are the first suspects. With New linings, that have not been ground to match the drums, there is no controlling the contact patch, and if one side has more than the other, it will pull to that side, and there is nothing you can do about it. So fix this.
Furthermore; As long as the shoes are rubbing on their high points, the brake-drums are gonna flex with heavy application, causing a spongy feel, and lack of confidence, not to mention very poor ability to slow the car, at speed.
#4) with the shoes now working, revisit the pedal for being hard and high. If it it is not so, here is what I would do;
What I would do is remove ALL four drums and ALL the brake hardware, and ALL the rubber boots on ALL the w/c's. Then I would C-clamp across ALL the w/c pistons to keep them from coming out.
Then, I would again visit the pedal for high and hard. This is the only way, in your system, that you can ever know whether you have a hydraulic problem, or a mechanical problem, or some combination.
IF, your pedal is not high and hard now;
Most likely there is air in the System, but this is not a sure thing; You could still have a mechanical issue between the pedal and the M/C. With a new booster in there, this pretty much points to the connecting links.
Solution is by process of elimination. First:
If you suspect air in the system, start by bench bleeding the master; yes, take it off and take it back to the bench-vise. Observe how it is designed, and where air can collect. Install the bleeder hoses, ends lowered into the fluid, and Full Stroke that beotch. If the fluid enters the transparent hoses from the lines, but returns back the way it came, this is NOT bleeding. The fluid has to go around the circle. from line out, up the line, and drop back into the reservoir. Sometimes you have to pinch the line, to prevent back-flow. When you think yur done, change the angle of the reservoir to nose up, cuz little bubble likes to remain in the nose, and between the two pistons inside the Power-chamber. Then reposition nose down, to get the last of it out the C-ports.
After you think you got it all, keep pumping, cuz micro-bubbles like to stick to things inside the chambers. If you don't get them out at this stage, eventually they are gonna make trouble.
After the M/C is re-installed, it is almost guaranteed that a small bubble will remain at the junction of the lines to the M/C. Purge it by cracking the connection, while a helper is gently pushing on the pedal. If that air goes back up into the master, it's gonna be trapped in the bore somewhere and with the M/C nose up, it's likely to stay in there forever.
Next, I gotta tell ya; If there is air in the system anywhere, it will act like an air spring. When you step on the pedal hard, you can easily generate 800 psi or more in the line. When you step off the pedal, that air will try to instantly go back to zero. In doing so, it will supercharge the fluid back to the M/C, and if the lid is off, you will see a geyser in the reservoir(s). Which could spurt two or three feet up towards the hood. and when it comes down, it will make a mess. and most non-silicone brake-fluids attack paint. You have been warned.
Wipe up spills with paper towels ASAP and wipe the area with a Brakleened paper-wipe.
You can mitigate this by coming off the pedal very slowly, and having a helper observe the geyser..
Now, if the C-clamped system is free of air;
the returning fluid will only roil in the bottom of the reservoir, and you may barely see it. The only amount of fluid that can return is the few or couple or maybe just one CC that went out, and it is returning thru the tiny Compensating port. If you see NO ROILING at all, chances are that your pushrod is too long, and the C-port is not passable. Shine a light into the reservoir looking for a shiney reflection coming at you from the port. If you see it, the pushrod is too long.
If the pushrod is too short, it will take a lot of pedal travel for the pushrod to actually reach the power piston, AND if your booster does not have the distance capacity, you might break the control valve trying to get there. So DO NOT power thru the long-travel. With a C-clamped system, engine not running, the pedal should be high and hard within one inch or less. This pushrod length is almost critical within too short or too long, so always adjust too long , to protect the booster, and work towards opening the C-port.
Ok so
once the geyser(s) are eliminated, the pedal should be hard.
Now you can prove the C-port is open by;
stab the pedal two or three times in rapid succession. This will prevent fluid backflow and the pedal should climb ever higher. Now release the pedal and wait a couple of seconds, for the fluid to return. Then step on the pedal, which should have normalized to as it was before the test.
If your pedal does not get higher, or does not normalize, most likely the fluid is not retuning and the usual suspect is a closed or restricted C-port. Shorten the rod not more than one turn atta time, and shine a light into the C-port. If you have a helper, slowly pumping the pedal back and forth, it will be easy to see the shiny reflection, which, you should NOT be seeing with the pedal parked!. As soon as the pedal works properly, it is short enough. It can be further shortened at a later time as a tuning trick; But all you need right now, is for it not to be too long.
#4A) This is a good time to check your booster (with the wc's still clamped. With your foot pressing moderately and holding, start the engine. As the booster charges, the pedal will drop. How far it drops will depend on how hard you are pressing. One inch or more is common with C-clamped w/c's. Later, with the brakes reassembled and adjusted with bedded-in shoes, you can expect pedal-drop of more than two inches, maybe closer to three, but still several inches off the floor. IF you do not have reserve room, then then if you ever have a failure and your foot drops on the brake-pedal during the event, it better not hit the floor!
#5) With the pedal now being high and hard, the C-port exhausting normally, and no geysers, the hydraulics are finally trustworthy. So now you can remove the C-clamps, reinstall the mechanical system, adjust it, and roadtest it.
#6) as for the mechanical system. By now, you should be intimately familiar with the mechanical system, so I'll only mention these three things;
1) If you have a parking brake, make sure the strut inside the drum, that interconnects the two shoes, is not preventing any shoe from parking on it's anchor. If it interferes then you may have a spongy pedal and lousy stopping
2) each drum should have one long friction shoe, and one short one. The long one goes to the rear of the car, so that they both wear at about the same rate.
3) the bane of any mechanical brake system, is flex. Look for it and try to eliminate it. Besides old hoses, unbedded shoes, and the aforementioned parking strut, about the only other source that I can think of is front wheel-bearing adjustment, and/or worn-out rear wheel-bearings. If the drums cannot stay centered, you will have issues.
I know it's a lotta work, but when you get it done, step by step, it will work, and the phrase "cobbled-up" will no longer be in your vocabulary. Brakes is just brakes. Once you go thru this, you can find shortcuts. Soon you be here telling fellow FABO-ers the same story, but with a happy ending.
Happy HotRodding
Last edited:
scott_s
Well-Known Member
Kendog 170
Let the boy go !
Yes. Same ones I posted on 33. Good luck!
Professor Fate
Push the button, Max...
I'm not gonna go out and get measurements, mostly because I don't have any GMs or Ferds handy to get the precise measurements; but "cobble" definitely applies.
I can't tell you what the pedal ratio is on a Ford, GM, Kia or whatever is, but I can pretty much guarantee it isn't the same as a Mopar. The pedal ratio is set up to give you the correct travel on a given master cylinder- a Mopar master requires just under an inch, about 7/8 IIRC.
Now let's say the master in question requires (random number) 1 1/4" of travel to pump the necessary amount of fluid to properly actuate the size braking system it was designed for.
Attaching it to the Mopar pedal that is designed to supply ~<1" of travel will NEVER allow the brakes to fully apply, giving weak braking and a spongy feel. No matter where you set an adjustable pushrod, you will not get a full stroke of the master cylinder. Unless you redrill the brake pedal arm to give you the appropriate amount of travel, the master will not supply adequate fluid to fully energize the braking system (wheel cylinders, caliper pistons)- and that is assuming that the systems were similarly sized (displaced hydraulic volume) to begin with. Too large of a difference there brings on it's own issues.
The opposite is also true- if the master supplies too much volume at a given stroke, it will result in a system that is overly touchy and locks the brakes the minute you touch the pedal, giving you no modulation or feel. It's simple geometry, and even I slept through most of that class.
OP, your decision to go with the parts that were designed to work together and be done with it is spot on.
True, those cobble systems don't care what make they're attached to; they can work equally poorly on almost anything. It's a rare occasion I've seen them work well (except maybe on a Chebby). Waaay too many threads on here already about trying to get those systems to work right.
I can't tell you what the pedal ratio is on a Ford, GM, Kia or whatever is, but I can pretty much guarantee it isn't the same as a Mopar. The pedal ratio is set up to give you the correct travel on a given master cylinder- a Mopar master requires just under an inch, about 7/8 IIRC.
Now let's say the master in question requires (random number) 1 1/4" of travel to pump the necessary amount of fluid to properly actuate the size braking system it was designed for.
Attaching it to the Mopar pedal that is designed to supply ~<1" of travel will NEVER allow the brakes to fully apply, giving weak braking and a spongy feel. No matter where you set an adjustable pushrod, you will not get a full stroke of the master cylinder. Unless you redrill the brake pedal arm to give you the appropriate amount of travel, the master will not supply adequate fluid to fully energize the braking system (wheel cylinders, caliper pistons)- and that is assuming that the systems were similarly sized (displaced hydraulic volume) to begin with. Too large of a difference there brings on it's own issues.
The opposite is also true- if the master supplies too much volume at a given stroke, it will result in a system that is overly touchy and locks the brakes the minute you touch the pedal, giving you no modulation or feel. It's simple geometry, and even I slept through most of that class.
OP, your decision to go with the parts that were designed to work together and be done with it is spot on.
True, those cobble systems don't care what make they're attached to; they can work equally poorly on almost anything. It's a rare occasion I've seen them work well (except maybe on a Chebby). Waaay too many threads on here already about trying to get those systems to work right.
Last edited:
scott_s
Well-Known Member
Thanks all for the suggestions, insights and links.
I've tried since day one to get the "stock" stuff working correctly.
I have sh*t brkes and leaky wheel cylinders, what should i do? Fix the bad parts .... OK, did that.
Still have bad brakes .... fix it with more stock parts, the 10" drums should be sufficient. OK, did that.
Brakes still ain't great, should i just swap to discs? Nah ... the drums should be all you need. OK, I'll optimize what I have. Did that.
This cobbled together mess still ain't optimal and is starting to fail. Again.
That's how I ended up here, with a second post.
I hope the Raybestos master cylinder and adjustable pushrod solve the issue. A buddy has a stock distribution block he's going to let me have.
I've tried since day one to get the "stock" stuff working correctly.
I have sh*t brkes and leaky wheel cylinders, what should i do? Fix the bad parts .... OK, did that.
Still have bad brakes .... fix it with more stock parts, the 10" drums should be sufficient. OK, did that.
Brakes still ain't great, should i just swap to discs? Nah ... the drums should be all you need. OK, I'll optimize what I have. Did that.
This cobbled together mess still ain't optimal and is starting to fail. Again.
That's how I ended up here, with a second post.
I hope the Raybestos master cylinder and adjustable pushrod solve the issue. A buddy has a stock distribution block he's going to let me have.
Professor Fate
Push the button, Max...
By "stock", do you mean a '66 and earlier distribution block, or a '67 and later factory block?
The early block will do you no good, since you are upgrading to a dual-circuit master- it will not have the correct number of ports for the new system, nor will it separate the two circuits. If a '67 and up drum/drum distribution block is not available, go with the "t" setup I described previously.
Best of luck!
Just a thought.
When I converted my 65 dart to dual master and Kelsey Hayes disc's, I replaced all of the lines and a new dual distribution block. Also found that 67 is different from 65 is different than 64 and 63 on the distribution blocks.
Inline tube sells all of them and stainless lines. Their dual conversion for the 65 is also available in pre-bent stainless, won't rust, corrode or give issues. I bought the whole kit, and replaced every line and hose on the car in the process. I only had to bend one line on the install. And straighten the long one as per instructions.
My three pump 10" drums went to a no-pump stock manual disc setup. They had been soft since the 80s. Found the crossover line to the passenger front was almost rusted through as well as the line to the back.
A pic of the correct 65 proportioning block for the conversion and the kit.
When I converted my 65 dart to dual master and Kelsey Hayes disc's, I replaced all of the lines and a new dual distribution block. Also found that 67 is different from 65 is different than 64 and 63 on the distribution blocks.
Inline tube sells all of them and stainless lines. Their dual conversion for the 65 is also available in pre-bent stainless, won't rust, corrode or give issues. I bought the whole kit, and replaced every line and hose on the car in the process. I only had to bend one line on the install. And straighten the long one as per instructions.
My three pump 10" drums went to a no-pump stock manual disc setup. They had been soft since the 80s. Found the crossover line to the passenger front was almost rusted through as well as the line to the back.
A pic of the correct 65 proportioning block for the conversion and the kit.
junkyardhero
Well-Known Member
one opinion is no more valid in a vacuum than any other, but please, if you go with a disc swap do yourself the favor and shop with doctor diff. the parts and customer service are head and shoulders above any other retailer.
www.doctordiff.com
Quality Body Shop Drivetrain
DoctorDiff specializes in classic Chrysler, Dodge, Plymouth rearends. Dr. Diff carries parts for Dana 60, Mopar 8 3/4", Ford 9" or 12 bolt Chevy.
www.doctordiff.com
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
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- 25,976
- Reaction score
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OMO
You should rename your Threads; Part 1 and Part 2
Or something, and for crying out loud, Don't start a third thread! Cuz I just posted this, in the other one;
Hang on a sec;
1) First your control valve inside the booster is broken, It no longer proportions the boost. It's either on or off; and in your case, mostly off.
Secondly their are TWO pushrods!
The First One goes from the pedal to the control valve. It is attached at both ends. and normally, on a mopar, is not adjustable; at least not that I remember. In your case, it appears that the original Chevy end was cut off and a Dodge end was adapted on. My guess is that adjustment was provided there, to adjust for the difference in the two system's installed depths. If this end is adjusted too long, it will break the control valve with excessive pedal travel. Then it will take a return spring to pull the rod and control valve back to a sortof "off" position.
Normally, we never need to talk about his pushrod, cuz MaMopar Scienced it out for us , and it's a bolt-on deal.
As to the Second;
the other pushrod goes from the backside of the diaphragm to the M/C.
This is the one we normally refer to when talking about adjusting a pushrod. This Firewall side pushrod has a small adjustment range that we normally use to make sure the Compensating Port stays open.
The booster-end of this pushrod is usually positively located in the control valve, and the other end, has the adjuster on it, and your job, during installation is to guide it into the socket, on the end of the M/C power-piston, to end up exactly the right length..
So since, IMO, your Chevy booster is ka-put, as is now becoming obvious by the hissing during pedal application; Yank it outta there, and get a Mopar one that is pre-engineered to fit your pedal. and get rid of the return spring. Mopar boosters have an internal spring that does the same job.
If the Chevy M/C does not bolt onto your Mopar booster, then get one that will.
The Mopar ones come in three sizes, namely 15/16th, 1 inch, and one and change ( I forget, maybe 1&1/32 or something). EACH smaller one will give a longer pedal travel, and be easier to apply.
The biggest one is harder to modulate, and takes more leg-power, and it takes a bit of getting used to.
I agree with @Garrett Ellison , the 15/16ths was my second choice over 20 years ago, and I liked it right from the start.
A New booster will NOT solve your pull to one side.
The pull could be:
a difference in the contact patches between the two sides, OR
a performance mismatch between the two w/c's, OR
a camber mismatch, OR
a strut problem.
You'll have to do a different diagnostic on that to find out which it is..
Here is a pic; notta Mopar, but you get the idea.
https://www.pinterest.com/pin/vacuum-brake-booster-construction--650770214894398633/
This pic shows the control valve, which I believe in yours is broken . The hissing you hear is vacuum from the engine side of the diaphragm finding it's way to the atmospheric side thru the broken valve. That's Not supposed to happen.
You should rename your Threads; Part 1 and Part 2
Or something, and for crying out loud, Don't start a third thread! Cuz I just posted this, in the other one;
Hang on a sec;
1) First your control valve inside the booster is broken, It no longer proportions the boost. It's either on or off; and in your case, mostly off.
Secondly their are TWO pushrods!
The First One goes from the pedal to the control valve. It is attached at both ends. and normally, on a mopar, is not adjustable; at least not that I remember. In your case, it appears that the original Chevy end was cut off and a Dodge end was adapted on. My guess is that adjustment was provided there, to adjust for the difference in the two system's installed depths. If this end is adjusted too long, it will break the control valve with excessive pedal travel. Then it will take a return spring to pull the rod and control valve back to a sortof "off" position.
Normally, we never need to talk about his pushrod, cuz MaMopar Scienced it out for us , and it's a bolt-on deal.
As to the Second;
the other pushrod goes from the backside of the diaphragm to the M/C.
This is the one we normally refer to when talking about adjusting a pushrod. This Firewall side pushrod has a small adjustment range that we normally use to make sure the Compensating Port stays open.
The booster-end of this pushrod is usually positively located in the control valve, and the other end, has the adjuster on it, and your job, during installation is to guide it into the socket, on the end of the M/C power-piston, to end up exactly the right length..
So since, IMO, your Chevy booster is ka-put, as is now becoming obvious by the hissing during pedal application; Yank it outta there, and get a Mopar one that is pre-engineered to fit your pedal. and get rid of the return spring. Mopar boosters have an internal spring that does the same job.
If the Chevy M/C does not bolt onto your Mopar booster, then get one that will.
The Mopar ones come in three sizes, namely 15/16th, 1 inch, and one and change ( I forget, maybe 1&1/32 or something). EACH smaller one will give a longer pedal travel, and be easier to apply.
The biggest one is harder to modulate, and takes more leg-power, and it takes a bit of getting used to.
I agree with @Garrett Ellison , the 15/16ths was my second choice over 20 years ago, and I liked it right from the start.
A New booster will NOT solve your pull to one side.
The pull could be:
a difference in the contact patches between the two sides, OR
a performance mismatch between the two w/c's, OR
a camber mismatch, OR
a strut problem.
You'll have to do a different diagnostic on that to find out which it is..
Here is a pic; notta Mopar, but you get the idea.
https://www.pinterest.com/pin/vacuum-brake-booster-construction--650770214894398633/
This pic shows the control valve, which I believe in yours is broken . The hissing you hear is vacuum from the engine side of the diaphragm finding it's way to the atmospheric side thru the broken valve. That's Not supposed to happen.
Last edited:
scott_s
Well-Known Member
Thanks guys. That's good to know about the distribution block.
If it's not suitable, I'll get a tee or the billet block shown above. I'll make sure I have the one I need before getting started.
If it's not suitable, I'll get a tee or the billet block shown above. I'll make sure I have the one I need before getting started.
Do you have a factory service manual for your car? If not, get one. And I mean factory Chrysler, not chiltons or haynes parts store garbage. Go over to mymopar.com and download one for free.
Wvbuzzmaster
Well-Known Member
I know this is not what you want to hear, but take out any brake part that does not match a single factory original brake system arrangement, and replace them with parts that do match. It sounds like what you are actually doing, but be sure to select a system that is dual 10” drums like you have, which arguably do not need a booster to work as drum brakes can lock up at 250 psi, where disc brakes should have a booster due to requiring 1500 psi or more to be effective. By making what you have match a factory designed system, and replacing any rubber parts in the process to make sure there is not a degraded collapsing brake hose or leaking wheel cylinder, you should have a brake system that works as good as the factory designed it to, provided that is good enough for you. For me I did power disc brake upgrade and picked 1973 Duster, no issues, excellent brakes. I know you are doing all drums, but it’s the same idea, factory put a lot of money into the design, why screw it up with non factory parts.
Have not read every post, but:
- nothing wrong with drum brakes
- if engine note changes with foot on the brake pedal, then the booster is leaking.
- long pedal could just be pushrod adjustment between booster & m/c
- proportioning valve is not usually used on drum/drum brakes. That is because the 'proportioning' was done with the wheel cyl piston diameters. Disc brakes require about 50% more line pressure than drums & with disc/drum brakes that was achieved by using a PV. No need for it with drum/drum & probably hurting braking performance
- brakes pulling; could be sticking wheel cyl, out of round drum, auto adjusters too tight, brake shoes not matched side to side, weak brake shoe return springs etc.
- nothing wrong with drum brakes
- if engine note changes with foot on the brake pedal, then the booster is leaking.
- long pedal could just be pushrod adjustment between booster & m/c
- proportioning valve is not usually used on drum/drum brakes. That is because the 'proportioning' was done with the wheel cyl piston diameters. Disc brakes require about 50% more line pressure than drums & with disc/drum brakes that was achieved by using a PV. No need for it with drum/drum & probably hurting braking performance
- brakes pulling; could be sticking wheel cyl, out of round drum, auto adjusters too tight, brake shoes not matched side to side, weak brake shoe return springs etc.
scott_s
Well-Known Member
I've asked my buddy what year his distribution block is from. He has a Barracuda, but I'm not sure what year.
If I'm basically going "stock" drum/drum but with a '68 style dual circuit master cylinder, are these the type I'm looking for? ( I was gonna post some OEM used ones from eBay, but they're either the same price as the new ones or in ROUGH condition!)
**EDITED**
I contacted Inline and here's what they suggest:
1965-66 Mopar A B C-Body Dual-Reservoir Master Cylinder Distribution Block for Disc or Drum Brakes
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Did you switch up to DOT-5?
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I did not.
Didn't see a need. Everything else I have is either 3 or 4. I did use the lucas synthetic, though.
The brakes wont be getting hot enough to boil the fluid and I don't forsee a lot of water getting into the lines.
Exactly the one I used.
scott_s
Well-Known Member
So, if I've replaced two bad front drums and some bad wheels cylinders, I should have everything at the wheels ready to go.
My plan now is the Raybestos dual circuit master cylinder, as used on '68- drum/drum cars, and adjustable pushrod, and the distribution block. This should get me back as close as possible to factory 10" drum/drum brakes, like on later model Darts, etc.
Sound like a solid approach?
My plan now is the Raybestos dual circuit master cylinder, as used on '68- drum/drum cars, and adjustable pushrod, and the distribution block. This should get me back as close as possible to factory 10" drum/drum brakes, like on later model Darts, etc.
Sound like a solid approach?
scott_s
Well-Known Member
Will I need anything to mount the '68 m/c to my '65 firewall? Am I missing any brackets or anything?
MadScientistMat
Well-Known Member
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It lines up directly with the bolts on the firewall. No brackets or adapters needed. You only need them if you start looking at later aluminum body, two bolt MCs.
Be careful with the studs coming out of the firewall if they have had a lot of exposure to brake fluid over the decades. With the booster system installed, they are probably fine... DOT 3 can do some damage.
scott_s
Well-Known Member
I can see them on the inside firewall, under the dash. They look to be in good shape.
I've seen pics where the distribution block is mounted low, on a frame rail. I've seen some on the inner fender. The prop valve is on the inner fender, near the m/c.
If I may have to fab a couple of new lines, does it matter where I put the distribution block? Is on the inner fender OK, keeping the lines going FROM the prop valve to the wheels and maybe just replacing the lines from the m/c to the block?
I've seen pics where the distribution block is mounted low, on a frame rail. I've seen some on the inner fender. The prop valve is on the inner fender, near the m/c.
If I may have to fab a couple of new lines, does it matter where I put the distribution block? Is on the inner fender OK, keeping the lines going FROM the prop valve to the wheels and maybe just replacing the lines from the m/c to the block?
TheBlueNinja
New Member
There should be a plate with a dust boot that attaches to the back of the master cyclinder. Some masters have a c clip holding the pistons in. You are are probably dont have one since your "original" sutff is missing because of the aftermarket master along with the added booster. That tab shown is more a shipping bracket that holding the pistons inside the master. My original bracket was bent and boot was torn from previous attemps at removing the pushrod. I just made a plate with three holes (both tapped holes and the piston). Also, make sure your push rod has a rubber o ring like gromet which will retain the rod in the master (there is an undercut in the the piston) other wise the rod may fall out if the brake pedal get pulled up accidentally (foot under the pedal when getting in and out of the car, shoe laces caught, etc.).
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