Making the best of a bad situation

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scott_s

scott_s

Well-Known Member
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Location
Rock Hill, SC
1965 Valiant.
I'd like some thoughts and advice on my brakes, please.
When I bought the car, it came to me with some issues and some "upgrades". I took it to a local shop that specializes in vintage cars. They fixed a leaky RF wheel cylinder, replaced a cracked drum (I believe it was the LF), some shoes, and bled/adjusted the brakes.
I was informed that because someone installed a power brake booster on a non-PB pedal, the throw is long and soft. He said there are different pedal assemblies for power and manual brakes. I am told the booster looks like a Chevy part.
The brakes work, but the throw is long and, as I said, somewhat soft. It seems like when I'm in town, they are more touchy. Something to do with the vacuum, I suppose?
But, recently I've been noticing that it pulls to the right when brakes are applied, and sometimes there's a "groan" on the RF that isn't normal. I plan on jacking it up and adjusting the brakes as soon as I can get some assistance in the garage. I guess it's possible that some of the new parts have "bedded in" and need adjustment again, even though it's only been a few hundred miles.
My questions are: Is there anything I can do about the pedal? The long throw? There's a bunch of dead travel before anything happens and the pedal goes down low, even though there's no air in the system. I can see a rod/nut on the master cylinder, under the dash... can that be adjusted to help? I know I have a mish-mash of parts here, but what can I do to make the best of what I have?


brake pedal upper.jpg


brake pedal.jpg


brake upper and mc.jpg


mc rod.jpg


power mc.jpg
 
Basically the master cylinder and booster don't know, nor care on what make of vehicle it's installed .
The very first thing to do is check/adjust the brakes, to eliminate the obvious.
The pedal return spring is interesting, and not supposed to be there.
I would be looking to see if it's there cuz the pedal is binding at the m/c pushrod, or pivot, if not, does it just pull the pedal back creating a clearance as you suspect.
If there's a gap created between the pushrod and booster, you need to correct that with the nut you mentioned, or as nec.
The other place for a gap is between the m/c and booster.
Just cuz it's an oddity, I'd gently separate the m/c from booster to check that gap, there is often an adjustment on the booster pushrod. Use something like plastercene, or mechanics dum-dum,
dead chewing gum?, to check .
If you take the spring off under the dash, and the pedal drops, find and repair that gap, - the pedal should seem awfully high at rest as it is now.
That's just what I would do, with what you got, - but as always, safety is the utmost concern, does the emergency work ?
Good luck
 
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It's been suggested that I ditch the power booster and go with a stock M/C. Any links or suggestions for the best one?

I know the booster doesn't know or care what vehicle it's on. I'm told ... right or wrong .. that the pedal assembly is wrong for a power brake system. Something about the length or leverage?
 
They're full of crap regarding different pedals for power and manual brakes. That's a big NO. They are the same. They probably told you that because they couldn't figure out how to get the pedal up on it. ........BUT remember, power brakes will have the pedal fall further down when the engine is running, because the booster is activated. How far down can you push the pedal without the engine running? That will give a good indication of whether the problem is hydraulic or not. That also looks like a A body booster "to me". But as inertia mentioned, as long as a booster fits, the application doesn't really matter. As for the shop you used, I'd find another one. Better yet, get a factory Chrysler service manual for your car and learn how to do it yourself. It's not difficult. At least that way, you'll know it's been DONE.
 
scott_s said:
It's been suggested that I ditch the power booster and go with a stock M/C. Any links or suggestions for the best one?

I know the booster doesn't know or care what vehicle it's on. I'm told ... right or wrong .. that the pedal assembly is wrong for a power brake system. Something about the length or leverage?
Click to expand...

No prob, was suggesting " best with what you had".
Some ppl freak at Chev etc, on Mopar, - was trying to ease any concern.
I often toss the booster, and use a 15/16 master to give best pedal and feel, normally a straight bolt on, - you may have to juggle plumbing a bit .
Adjustable pushrod from Mancini .
Cheers
 
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My 64 had a bungee attached to draw the pedal clear of the stop light switch.

I adjusted the mc pushrod (it was an adjustable style) and resolved that issue. I have a GM style booster and it worked fine ( currently in engine swap mode so it's out of the car)

Prior comments are spot on. Get a Tech Service Manual and walk through the maintenance checks.

Good luck
 
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RustyRatRod said:
They're full of crap regarding different pedals for power and manual brakes. That's a big NO. They are the same. They probably told you that because they couldn't figure out how to get the pedal up on it. ........BUT remember, power brakes will have the pedal fall further down when the engine is running, because the booster is activated. How far down can you push the pedal without the engine running? That will give a good indication of whether the problem is hydraulic or not. That also looks like a A body booster "to me". But as inertia mentioned, as long as a booster fits, the application doesn't really matter. As for the shop you used, I'd find another one. Better yet, get a factory Chrysler service manual for your car and learn how to do it yourself. It's not difficult. At least that way, you'll know it's been DONE.
Click to expand...

Does it look like I have some adjustment available in the pushrod? I know...pics are horrible, but it's really hard to get a good shot.

I'll see how far the pedal moves without the engine running when I get home.
 
scott_s said:
Does it look like I have some adjustment available in the pushrod? I know...pics are horrible, but it's really hard to get a good shot.

I'll see how far the pedal moves without the engine running when I get home.
Click to expand...

There isnt a good view of the rod or avail adjment.
That's a fabricated piece, so a mystery.
Gotta get in there and check it out, also make sure the pushrod can't fall out of the booster, - resulting in no brakes ! !
I often have to make a "guide" out of something to keep the pushrod where It's supposed to be, usually a washer welded to a rod, welded to pedal mounting bracket assembly.
 
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As mentioned, with the engine off, take up any free play by using your hand to feel for any. You only want 1/8" of free play movement in the pedal. If you still have a low pedal, but, it's hard and the shoes adjustment is correct, there's a mismatch there somewhere. I'd be tempted to get rid of the booster and run a stock '67-up drum type master and a stock push rod. If the pedal is soft/spongy, there's still some air in the system. Of course, you could just go with a disc brake system and really improve the situation! :) On a side note, the factory setup in the '66 and older models with a single stage master cylinder, do have a return spring. Not like the one you have, but, it's a weak wound spring and rubber boot that goes around the pushrod. It's just enough of a return spring to turn the brake light switch off.
 
Oh, there's a ton of free play. I guess the free play can be measured in inches, and the pedal will go almost to the floor with the engine off.

I'll start with readjusting the brakes and see what happens.
 
Free play is different than pedal travel. Free play is just the excess slop in the push rod to booster, and booster push rod to master cylinder piston. There are lots of things that affect the pedal travel. Adjustments, hydraulics, firewall flex, master cylinder and wheel cylinder piston diameter ,etc.
 
scott_s said:
Does it look like I have some adjustment available in the pushrod? I know...pics are horrible, but it's really hard to get a good shot.

I'll see how far the pedal moves without the engine running when I get home.
Click to expand...
Possibly. But it is a terrible angle. I know it's a beeotch to get under there.
 
scott_s said:
Oh, there's a ton of free play. I guess the free play can be measured in inches, and the pedal will go almost to the floor with the engine off.

I'll start with readjusting the brakes and see what happens.
Click to expand...
Read what @cudamark posted. Free travel is the amount the pedal will move before it ever starts to depress the pushrod. You'll likely have to pull up on the pedal to get a good feel for it. There can also be some between the booster and master cylinder if it has an adjustable rod "there". Some have adjustable rods there and some do not, they just have a solid rod. I would get the free travel out of the pedal side first. That's the adjustment you asked me about earlier.
 
Just a follow up, in case anyone is interested.
Took the car to a different shop and they found a ton of air in the RF wheel cylinder. He said that the proportioning valve was set all wrong and that's why the other shop couldn't get the brakes bled properly. He adjust the valve, all brakes and bled the crap out of all the wheel cylinders. I'm happy to report that I have MUCH better brakes right now, with a pedal that sits like it should, has a nice feel to it, and the brake booster actually works.
 
Well, back again.... sigh...

The car is still pulling to the right under braking. The shoes have been adjusted two or three times since the last post, and bled to death.
I'm now getting a hissing noise from around the pedal, which I'm told is a leaking vacuum booster. I'm so over this crap.

A front disc conversion will cost me at LEAST a grand, and would require new ball joints. I just had the ENTIRE front end rebuilt, so I'd be swapping out ball joints with maybe 500 miles on them, as well as needing another alignment.
At this point, I'm considering a stock drum/drum, dual circuit master cylinder. Pirate jack has them for $75. RockAuto has cheaper options, but I'd like confirmation on which one is correct.

MC1323 - 1960-1970 MOPAR A, B, E Body BENDIX 2660809 1" Bore Drum Brake Mopar Master Cylinder

More Information for QUALITY-BUILT M1516

Since I have no clue what pushrod is in there, I guess I should source the correct, stock rod? Can anyone show me what I need?

Also, there's a proportioning valve in the car (it was there when I got the car). I guess I could keep it and readjust for a manual drum/drum setup but, if I'm at this point, would you just put in a stock distribution block?
I've spent WAY too much time and money trying to get this bastardized combination working right.
 
i'd throw the power booster in the trash for starters...

leave the prop valve in there, source a drum/drum dual master from rock and then either hunt down a stock pushrod or grab an adjustable from dr. diff

the adjustable that you have in there looks sus AF and who knows what cobbled together BS that is. so adios to that.

for my own edification, i'd run back on the previous work and make darn sure everything was dress-right-dress with the parts: correct wheel cylinder, correct bearings/hubs (and adjusted properly!), correctly plumbed and routed, all hardware present and accounted for, installed properly, etc.

personally though? i'd just bite the bullet and go disc. yeah it's another chunk of change, and a whole *** bunch of work; but the net positive of great performing, easy to service and available parts would make the investment well worth it.
 
I’m using Speedway kits on my 39 ford currently. For what it’s worth, nothing has worked correctly or lined up (pedal assembly, booster, master) and their tech support has been at a loss as to why.
 
The OP has another thread about the same subject. Confusing!
 
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 systems. 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.

1726184952039.png

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 atmosphere thru the broken valve.
 
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