Brake pushrod length.... and other brake woes

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rustyswinger

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HI All,
Once again I am back to prove that I have just enough knowledge to be dangerous. 1974 dodge dart swinger. Brake pedal goes down a good 3 inches before it becomes "pretty good" which I know is definitely not good!

I have..... MANUAL BRAKES NO BOOSTER
1) REUSED the pushrod from old Drum/Drum MC for new Disc/Drum MC
2) Replaced New M/C from Rock Auto...Bench bled, probably poorly.....took a few attempts to get leaking lines corrected....may have sucked in Air at MC line hook ups
3) Replaced with new rubber hoses, and hard lines end to end. I detect no leaks ( finally)
4) Replaced new calipers, rotors, pads hoses lines in front.
5) Replaced everything new in the back......
6) New Prop Valve for disc/Drum set up
7) Taken OE Disc Spindles from my parts car
7) Passed mechanic inspection ( should not have passed! )
8) Bled and Bled and Bled......
9) Less than 200 miles on all this, haven't broken in brakes really, not real safe to drive as is.

Symptoms.....

A) Pedal goes down at least 2-3 inches before it really does anything
B) If I stomp it hard, it honks like a goose. I am not kidding. Honk is DEF at the MC
C) Upon removal of rear drums ( 10 inch) I notice the wear pattern indicates the shoe is contacting mainly in the center, less at the ends of the shoes
D) Pretty damn sure, I needed to adjust rear brakes outward. I thought I had drag....my rear end/Drive shaft/904 Transmission, seems pretty stiff to rotate in Neutral... how do I measure that?


QUESTIONS

1) Do I have the wrong pushrod?
2) Is it reasonable to "bench bleed" the MC on the car, with the pedal and lines routed into the pots?
3) My M/C Honks like a goose when I stomp on brakes. Is this Air in the M/C or JUNK M/C?
4) Should I simply take up gardening instead?

5)I have adjusted rear brake shoes to definitely drag, pedal seems better, but not good. must be fronts, or master?
6) The spanner bar that separates the rear shoes is the SAME on both sides..... it is merely reversed and upside down when you compare right and left. Everything else is new on the rear brakes except that part. Is that correct, or is there truly a right/left. I have checked the FSM but the picture I had was too grainy to 100% confirm. Everything else seems to be correct to the FSM pics.
 
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Double check the length of the pushrod between booster and MC.
If it's say 7/16" short then you might indeed have over 2-3" of play at the pedal.

The honking sound (not sure I should be answering this... ) is perhaps coming from the booster which forces the displaced air out somewhere. Most likely through its one-way valve.

Perhaps a bit late in the season but maybe tomatoes will still do allright this year.
 
BigBlockMopar said:
Double check the length of the pushrod between booster and MC.
If it's say 7/16" short then you might indeed have over 2-3" of play at the pedal.

The honking sound (not sure I should be answering this... ) is perhaps coming from the booster which forces the displaced air out somewhere. Most likely through its one-way valve.

Perhaps a bit late in the season but maybe tomatoes will still do allright this year.
Click to expand...
Thank you should have clarified
Manual Brakes, NO booster
 
Pushrod length is still important.
Even more with manual brakes where the pushrod should be locked in place into the MC or else it could fall out and leave you without brakes all together.

If you're real sure the MC has been bled properly (no more air appearing) I would open up the MC and have a look inside.
Not all new parts are put together properly and might as well be your problem.
 
BigBlockMopar said:
Pushrod length is still important.
Even more with manual brakes where the pushrod should be locked in place into the MC or else it could fall out and leave you without brakes all together.

If you're real sure the MC has been bled properly (no more air appearing) I would open up the MC and have a look inside.
Not all new parts are put together properly and might as well be your problem.
Click to expand...
Thank you. I understand Pushrod length is important.
My problem is I have nothing to compare to.

I need to know, if the pushrod I used off the Drum/Drum set up, is the correct one for my Disc/Drum set up.

New master cyl did not come with a pushrod, so I used what I had.
 
Yes the pushrods are the same.
Set the emergency, see if the pedal gets any higher , if so, the rears prob need more adjustment. If the pedal is still soft, prob needs more bleeding..
cheers.
 
You'll only know if you measure it.
If you loosen the nuts of the MC a couple of turns, is the MC 'pushed' off it base a bit? (This would mean a too long pushrod, prob. not your case here).
If you can lengthen or adjust the pushrod, you should be able to lengthen it so it barely touches the MC when tightened down. Ideallly you want just a little play here or otherwise the brakes get applied and will start to drag after some driving because of pushrod metal expansion by heat.

Hard to tell, but when you push lightly on the brake pedal, do you feel just the brakepedal mechanics moving, or also some springy/mushyness of the MC?

Have a look at Dr.Diff's site and notice a manual brake pushrod should have the rubber locking washer:
Mopar '62 -'70 Adjustable Master Cylinder Push Rod

If you manually pull back up on the brake-pedal, does the pushrod pop out of the MC? (This would be very bad btw).
 
I'm going with a problem in the rear, and it's probably those new shoes that are only contacting at one place ; they are gonna have to break in . Or you can get them cut to match your drums.
Over-travel of the pedal is almost always due to a situation in the rear. And that is by design. In the past I have clamped the rear flexline on my car to prove it, but that is a bad idea with an old line, as occasionally it damages the line inside.
A better idea as offered by Inertia, is applying the parking brake. But the best test I have done is to clamp the wheel-cylinders pistons in such a way that they cannot advance out of their bores. This will prevent any fluid from leaving the M/C and the pedal will immediately get high and hard......... if there is no air in the hydraulics. PITA test but it tells the truth.
And BigBlock is bang on with the pushrod advice.
The clamped wheel cylinders will also point out a too-short pushrod. But you have to be careful to not make the pushrod too long. This will prevent the fluid from returning to the reservoirs thru the compensating ports. When this happens, the pedal gets lower and lower over time as the friction materials wear off. But worse is that in some situations with disc brakes, as the fluid heats up it expands and if it cannot get back into the reservoir it forces the pistons out,dragging your pads on the rotors,and eventually locking your front brakes on.
It is easy to see the compensating ports in action, but it is a bit tricky to not get brake-fluid all over the engine compartment. Here is the method I use. First as a newbe,cover everything within a 2ft radius of the M/C with cloth rags, lots and lots and lots of rags, and your entire fender, and down the firewall.
Then get a helper. Have him pump the pedal in rapid succession about 3 times and on the last pump, do not let the pedal return to the parked position. Just keep it about an inch from the top. Next, you go loosen the M/C lid, lift it up just enough to see the fluid,then have the helper slooooowly allow the pedal to return. As soon as the compensating port becomes exposed, you will see a little fountain in the reservoir. If there is air in the system, you could have a HUGE gusher of a fountain as the rear return springs ram the fluid back home.This is the reason for the rags, to prevent damage to your paint. Of course you should have a back-up plan for this, so you can signal your helper to stop lifting and instead start pushing. This will close the port and stop the gusher. Then you secure the lid. Then the helper can relax.
The gusher does not automatically indicate air in the system. The same will happen if the rear brakes are out of adjustment. The three pumps in rapid succession I mentioned will push the rear shoes out, and the fluid cannot return fast enough between pumps, so every pump pushes them out a little further.... stretching the return springs and creating a pressurized hydraulic cylinder. When the pedal is released, the return springs send all the fluid back, and Shazzam you see the gusher.
Air in the system does the same as it becomes an air spring.
This test proves the C-ports are open and the pushrod adjustment is not too long.
I like to make the pushrod as long as possible to initiate braking action right away....... with the above caveat; too long is bad.
Oh yeah, in a good working system, one pump will,upon release, either just roil the fluid, or at most you might have a little fountain about an inch high, probably less.
 
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inertia said:
Yes the pushrods are the same.
Set the emergency, see if the pedal gets any higher , if so, the rears prob need more adjustment. If the pedal is still soft, prob needs more bleeding..
cheers.
Click to expand...
Thank you!

I know I didn't have drag. I thought I did just because it took a fair bit of force just to rotate the drive train. That concerns me....

I had the cover off the 8 1/4, and it looked clean as a whistle, no apparent damage or burn marks anywhere including bearings. Fresh clean up, gear oil, and axle seals. It makes no noise that I can hear running at high or low speeds.

Transmission..... well it sat in a decaying car in a farmers field for almost 2 decades..... It pulls that car, and shifts like a dream... amazing. I dunno how stiff it should all be, but I thought I had brake drag. ( I could drop the drive shaft I suppose and compare with it on or off....)

I Will re-bench bleed the master, then the entire system again and see if I can make the honking noise go away, otherwise I toss it and start fresh.
 
BigBlockMopar said:
You'll only know if you measure it.
If you loosen the nuts of the MC a couple of turns, is the MC 'pushed' off it base a bit? (This would mean a too long pushrod, prob. not your case here).
If you can lengthen or adjust the pushrod, you should be able to lengthen it so it barely touches the MC when tightened down. Ideallly you want just a little play here or otherwise the brakes get applied and will start to drag after some driving because of pushrod metal expansion by heat.

Hard to tell, but when you push lightly on the brake pedal, do you feel just the brakepedal mechanics moving, or also some springy/mushyness of the MC?

Have a look at Dr.Diff's site and notice a manual brake pushrod should have the rubber locking washer:
Mopar '62 -'70 Adjustable Master Cylinder Push Rod

If you manually pull back up on the brake-pedal, does the pushrod pop out of the MC? (This would be very bad btw).
Click to expand...


Thank you, my pushrod snapped into the master, and locked in place
 
AJ/FormS said:
I'm going with a problem in the rear, and it's probably those new shoes that are only contacting at one place ; they are gonna have to break in . Or you can get them cut to match your drums.
Over-travel of the pedal is almost always due to a situation in the rear. And that is by design. In the past I have clamped the rear flexline on my car to prove it, but that is a bad idea with an old line, as occasionally it damages the line inside.
A better idea as offered by Inertia, is applying the parking brake. But the best test I have done is to clamp the wheel-cylinders pistons in such a way that they cannot advance out of their bores. This will prevent any fluid from leaving the M/C and the pedal will immediately get high and hard......... if there is no air in the hydraulics. PITA test but it tells the truth.
And BigBlock is bang on with the pushrod advice.
The clamped wheel cylinders will also point out a too-short pushrod. But you have to be careful to not make the pushrod too long. This will prevent the fluid from returning to the reservoirs thru the compensating ports. When this happens, the pedal gets lower and lower over time as the friction materials wear off. But worse is that in some situations with disc brakes, as the fluid heats up it expands and if it cannot get back into the reservoir it forces the pistons out,dragging your pads on the rotors,and eventually locking your front brakes on.
It is easy to see the compensating ports in action, but it is a bit tricky to not get brake-fluid all over the engine compartment. Here is the method I use. First as a newbe,cover everything within a 2ft radius of the M/C with cloth rags, lots and lots and lots of rags, and your entire fender, and down the firewall.
Then get a helper. Have him pump the pedal in rapid succession about 3 times and on the last pump, do not let the pedal return to the parked position. Just keep it about an inch from the top. Next, you go loosen the M/C lid, lift it up just enough to see the fluid,then have the helper slooooowly allow the pedal to return. As soon as the compensating port becomes exposed, you will see a little fountain in the reservoir. If there is air in the system, you could have a HUGE gusher of a fountain as the rear return springs ram the fluid back home.This is the reason for the rags, to prevent damage to your paint. Of course you should have a back-up plan for this, so you can signal your helper to stop lifting and instead start pushing. This will close the port and stop the gusher. Then you secure the lid. Then the helper can relax.
The gusher does not automatically indicate air in the system. The same will happen if the rear brakes are out of adjustment. The three pumps in rapid succession I mentioned will push the rear shoes out, and the fluid cannot return fast enough between pumps, so every pump pushes them out a little further.... stretching the return springs and creating a pressurized hydraulic cylinder. When the pedal is released, the return springs send all the fluid back, and Shazzam you see the gusher.
Air in the system does the same as it becomes an air spring.
This test proves the C-ports are open and the pushrod adjustment is not too long.
I like to make the pushrod as long as possible to initiate braking action right away....... with the above caveat; too long is bad.
Oh yeah, in a good working system, one pump will,upon release, either just roil the fluid, or at most you might have a little fountain about an inch high, probably less.
Click to expand...

Thank you AJ. I have read your posts about this type of issue in other threads. I appreciate your response.

My Pushrod is not adjustable, but it did snap and lock into the M/C that at least felt good. I assume I have air in my MC hence the honking noise I wrote about. I didn't want to continue troubleshooting until I can confirm 100% that the pushrod I used will work in this MC. I think I have that confirmed... but I guess not 100% sure yet.
 
In a good working system with an adjustable pushrod, a person can set the amount of pedal travel, before brake activation occurs, with pushrod length. As long as your pedal gets hard before it hits the floor, your pushrod is not too short. It may not be ideal, but it's not too short.

If the pedal rises with multiple rapid pumps, the rear brakes need adjusting.
If the pedal never gets hard you most likely have a hydraulic issue. It could be mechanical, but more likely it's hydraulic. The clamped rear wheel cylinders will point to the right direction.
The pedal needs to park at the factory location. There is a stopper at the top that it is supposed to bang into. The spring in the M/C is the guy that does that, in conjunction with the pushrod length. Do not use the brake-switch as a stopper.

As to the honking
Hmmmmmm, I'm gonna go with a mechanical sound of rubbing parts, but that's just a guess. Perhaps the pushrod on the firewall. I can't see that, but....... IDK
 
AJ/FormS said:
In a good working system with an adjustable pushrod, a person can set the amount of pedal travel, before brake activation occurs, with pushrod length. As long as your pedal gets hard before it hits the floor, your pushrod is not too short. It may not be ideal, but it's not too short.

If the pedal rises with multiple rapid pumps, the rear brakes need adjusting.
If the pedal never gets hard you most likely have a hydraulic issue. It could be mechanical, but more likely it's hydraulic. The clamped rear wheel cylinders will point to the right direction.
The pedal needs to park at the factory location. There is a stopper at the top that it is supposed to bang into. The spring in the M/C is the guy that does that, in conjunction with the pushrod length. Do not use the brake-switch as a stopper.

As to the honking
Hmmmmmm, I'm gonna go with a mechanical sound of rubbing parts, but that's just a guess. Perhaps the pushrod on the firewall. I can't see that, but....... IDK
Click to expand...

I feel close to the answer....Both Air, and adjustment.
The honking is more inside the MC body I think than anywhere.....sounds like a big fart with no space to escape the cheeks... I moved the little boot on the pushrod next to the firewall, it made no diff. Pushrod isn't rubbing on the firewall, straight shot into the MC.

I will double check what is stopping the pedal on the trip up, it seems to get into the park position just fine. It gets high enough to kill the brake lights. (I have had a master cyl. go bad and leaked internally in my last A body.... decades ago. That brake pedal sagged and the brake lights stayed on)


When I pull the park brake, It made the pedal only a little bit better, I must have been way under adjusted, and have air. I will snap a shot of my assembly tonite.

Thanks again

I really appreciate the help. I am still learning lots and my 9 year old son is a great helper.
 
Well my little guy mistook "go slow" for " hard as you can" on the brake pedal when I had the MC lid.

huge geyser came out must be air. I saw some pedal improvement with rear adjust and pumping.

Mechanically things seem good and the pushrod is firmly attached at both ends, the brake pedal stop is working, and the pedal returns to the park position

Both rear pads on both sides move when the brakes are pressed and the drums off.
 
If you using a stock style proportioning valve/ combo valve, I have experienced the same issue. I have trained myself to pump the pedal and all is good. I don't have to pump it but it works. This drove me nuts cause I tried changing all brake components. Then I did the same disc brake swap to anther car same configuration, guess what same damn issue with the pedal. This is using all stock stuff, rebuilt and reproduction. I finally got fed up took it down to a mechanic buddy of mine and he bypassed the valve by sending the rear brake linefrom the MC directly to the rear brake line using a brass fitting. ( I have seen this trick before and wondered why people did this, now I know). Much better pedal pressure. My understanding is the prop valve is trying to regulate the brake fluid and a pedal drop on a disc brake car is normal as long as the car will stop. The push rod length should not make a difference. I have used the same push rod when converting from single to dual reservoir and from drum to disc , never noticed a difference. I would say the master cylinder was not bleed properly or is defective. Try to buy new master cylinders, not reman. You can "bench" bleed the master cylinder on the car just watch out for brake fluid spilling. A quick search online will show you how to do it. I have found this to be the easiest way to bleed them.

So in summary
Push rod length is not the problem, especially if you car already was dual circuit.
Try re bleeding the master cylinder
Try a new master cylinder


One more problem I have run into with the disc brake swap, I could not get the Proportioning valve to seal, even using 2 new prop valve from inline tube, Cant remember what I did to solve that problem though, but make sure you are not loosing fluid at the prop valve.
 
CCHHAARRGGER! said:
If you using a stock style proportioning valve/ combo valve, I have experienced the same issue. I have trained myself to pump the pedal and all is good. I don't have to pump it but it works. This drove me nuts cause I tried changing all brake components. Then I did the same disc brake swap to anther car same configuration, guess what same damn issue with the pedal. This is using all stock stuff, rebuilt and reproduction. I finally got fed up took it down to a mechanic buddy of mine and he bypassed the valve by sending the rear brake linefrom the MC directly to the rear brake line using a brass fitting. ( I have seen this trick before and wondered why people did this, now I know). Much better pedal pressure. My understanding is the prop valve is trying to regulate the brake fluid and a pedal drop on a disc brake car is normal as long as the car will stop. The push rod length should not make a difference. I have used the same push rod when converting from single to dual reservoir and from drum to disc , never noticed a difference. I would say the master cylinder was not bleed properly or is defective. Try to buy new master cylinders, not reman. You can "bench" bleed the master cylinder on the car just watch out for brake fluid spilling. A quick search online will show you how to do it. I have found this to be the easiest way to bleed them.

So in summary
Push rod length is not the problem, especially if you car already was dual circuit.
Try re bleeding the master cylinder
Try a new master cylinder


One more problem I have run into with the disc brake swap, I could not get the Proportioning valve to seal, even using 2 new prop valve from inline tube, Cant remember what I did to solve that problem though, but make sure you are not loosing fluid at the prop valve.
Click to expand...


Thanks for the reality check. I wish my dad could help. He could always get a rock hard brake pedal

I feel better in the fact I have the right parts. I'm not afraid to throw another new master cylinder in it.

Prop valve wasnt easy to seal, none of the fittings were perfect first try. I'm convinced I have them all sealed up now.

as bad as my pedal is, when it does firm up, it will hold pressure against my heavy foot. no leaks at least
 
inertia said:
Yes the pushrods are the same.
Set the emergency, see if the pedal gets any higher , if so, the rears prob need more adjustment. If the pedal is still soft, prob needs more bleeding..
cheers.
Click to expand...
Can u tell me the length of the pushrod having similar problems only in conversion can’t find a manual pushrod need length for adjustable
 
Center of shoe wear is really common. The old days we arched the shoes on a ammaco arcing machine.
post-62228-143142698387_thumb.jpg
 
halifaxhops said:
Center of shoe wear is really common. The old days we arched the shoes on a ammaco arcing machine.
View attachment 1715573180
Click to expand...
New drums and shoes “SHOULD” fix this problem. In the town close to me there is an old garage Started in 40s that still actually fixes things like recurve brake shoes repair starters alt. Generaters rebuild carbs and the like. Look around maybe? Sign of the times parts cheaper than labour so R and R it is
 
I have had plenty of new shoes not press "centered" on new drums also. I usually put it together, drive a few miles and then sand them by hand so they make better contact. Eventually they will wear and contact right.
 
halifaxhops said:
I have had plenty of new shoes not press "centered" on new drums also. I usually put it together, drive a few miles and then sand them by hand so they make better contact. Eventually they will wear and contact right.
Click to expand...
Wear a dust mask that crap will kill ya.
 
of course and a face shield. I am lucky a friend has a brake lath I showed him how to use and can use it any timed needed. He owns a farm equipment salvage yard has alll the fun tools.
 
halifaxhops said:
of course and a face shield. I am lucky a friend has a brake lath I showed him how to use and can use it any timed needed. He owns a farm equipment salvage yard has alll the fun tools.
Click to expand...
you mean the kind you have to think and can actually repair something instead of r and r
 
Yup sad in many ways. I am his electrical guy since I have those tool (scopes and a bunch of working old sun machines). He has great old school equipment and he is only early 40's. Buisness was passed down, third generation now.
 
The geyser is proof of either
1) the rear shoes are way out of adjustment, and the return-springs rapidly retract the shoes which drives the pistons back, which drives the fluid back.
2) big time air in the system, which acts like an air-spring.
Those are the only two I have ever experienced .

You can lock the rear wheel cylinders by C-clamping them.
 
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