69 charger power drum issue (no pedal travel)

[Brightyellow69rtse]

Hey guys my car still dosent stop worth anything. I haven't driven the car in a while as it's been a long work in progress. I have almost no pedal travel. The booster, master, proportioning valve, distribution block, rubber lines, wheel cylinders, shoes, literally everything has been replaced. This was done because I had this issue and I figured it needed to be replaced anyway as most of it was probably original.

We bled the. Brakes today and got good flow from each wheel. Sad to say there was no difference in braking. I went back and tried different adjustments on the push rod in the master and it made no difference.

I have 12" if vacuum at idle but at speed I have 18+. The car stops really bad even at speed so the extra vacuum makes no difference.

I'm at a loss here and it's getting disheartening really. Any ideas?

On a side note the car ran and drove great even though it's been sitting two years.

[birdsandbees]

Why do you have a proportioning valve on a drum brake car?

[Bronzedodge]

I'll bet you (he) meant the distribution block.   Quick booster test - check the pedal "feel" while idling.  Shut off the engine.  Booster should hold enough vacuum for 1.5-2 applications of the pedal.  After 3 presses w the engine off, it should feel noticeably harder.  If not, time for Booster Dewey.

[Brightyellow69rtse]

The brass block under the hood kinda near the battery tray Is what I meant.  Upon further inspection I noticed the return spring on the brake was in the wrong spot. My dad put it together and where it was made no sense. I think I know where it goes but I'll be dammed if I could get it on. I used a bungee cord for test purposes and between that and messing with the length of the rod going into the master it got alot better.

It had to be revisited but it was definitely positive results today. It's really hard to measure the length of that rod where it is on the car so I was kinda winging it.

[green69rt]

Here is a thought.  There is a piston nose in the power booster.  It sticks out and engages the master cylinder piston.  That needs to be adjusted correctly.  If it sticks out too far and the master cylinder is always trying to energize the brakes.  Not enough and you have too much travel on the foot peddle before the brakes engage.  You need to check the service manual or ask the guys on here how to get it right.

[green69rt]

Sorry, didn't read the whole thread.  Is this the spring you are talking about?

[birdsandbees]

I'll bet you (he) meant the distribution block.   Quick booster test - check the pedal "feel" while idling.  Shut off the engine.  Booster should hold enough vacuum for 1.5-2 applications of the pedal.  After 3 presses w the engine off, it should feel noticeably harder.  If not, time for Booster Dewey.

He said he replaced the proportioning valve AND the distribution block....   Why I asked...

[John_Kunkel]

I went back and tried different adjustments on the push rod in the master and it made no difference.

You tried different adjustments but did you verify that there is a gap between the pushrod and the MC piston?

[Brightyellow69rtse]

Sorry, didn't read the whole thread.  Is this the spring you are talking about?


Yes thats the spring. I store the car at my dads so I can't run out and look at it but it wasn't set up like that. I'm guessing he had a senior moment when he hooked it up.

[Brightyellow69rtse]

I'll bet you (he) meant the distribution block.   Quick booster test - check the pedal "feel" while idling.  Shut off the engine.  Booster should hold enough vacuum for 1.5-2 applications of the pedal.  After 3 presses w the engine off, it should feel noticeably harder.  If not, time for Booster Dewey.

He said he replaced the proportioning valve AND the distribution block....   Why I asked...

I had this issue and We thought it would be a good idea to just replace everything as most of it was original. I've owned the car since 2000 and I never even had to do a brake job on it so it didn't hurt to freshen everything up.

[Brightyellow69rtse]

Ok here's where we left it for the night. I put the return spring in the proper place but noticed it wasn't actually returning the pedal all the way up. So for bleeding purposes we used and additional bungee cord and it bled perfectly. The car stops ok. I can lock the wheels up but I really gotta stand on it. I still wanna get A different spring it add an additional one. I'm wondering if fine tuning the rod length will make a noticeable difference?

Tonight was encouraging anyway.

[John_Kunkel]

The spring in green69rt's pic is an anti-rattle spring, not a return spring. The return spring is inside the booster.

[Bad B-rad]

Here is a thought.  There is a piston nose in the power booster.  It sticks out and engages the master cylinder piston.  That needs to be adjusted correctly.  If it sticks out too far and the master cylinder is always trying to energize the brakes.  Not enough and you have too much travel on the foot peddle before the brakes engage.  You need to check the service manual or ask the guys on here how to get it right.

This is exactly what happened to my 69, I put in a new master and all new valving, and I also had no petal travel maybe 3/4 inch, and it would NOT return on its own.
I tried it all, then I got same advice as above, so I removed the master( just removed mounting bolts between master and booster, leaving lines attached) and slide it forward enough to back the booster nose off some, and now they work as they should.
It was a ten min fix,(once I knew where to look) worth a shot

[Brightyellow69rtse]

Here is a thought.  There is a piston nose in the power booster.  It sticks out and engages the master cylinder piston.  That needs to be adjusted correctly.  If it sticks out too far and the master cylinder is always trying to energize the brakes.  Not enough and you have too much travel on the foot peddle before the brakes engage.  You need to check the service manual or ask the guys on here how to get it right.

This is exactly what happened to my 69, I put in a new master and all new valving, and I also had no petal travel maybe 3/4 inch, and it would NOT return on its own.
I tried it all, then I got same advice as above, so I removed the master( just removed mounting bolts between master and booster, leaving lines attached) and slide it forward enough to back the booster nose off some, and now they work as they should.
It was a ten min fix,(once I knew where to look) worth a shot

So you just shortened the overall rod length and all was good?

[Bad B-rad]

Yes I just used the threaded hex on end of power booster, and adjusted it in.
I guess the difference between the old and new master cylinder, required  different adjustment.
I have the bendex booster, and I went from drum master to disc master.
I had swapped all brake components (before I knew to adjust booster piston) and I used a vacuum pump to bleed, so wasn't till after it was bled I found petal rock hard, no travel, and it would not return on its own.
I was at the point I was gonna buy a new bendex master/booster combo, and found an old Mopar mag, article describing my issue, and the recommended fix.(and it does make sense, if piston is out too far as you install the master on the booster it causes the master cylinder piston to depress some, or a lot, depending on how out it was/is lol)
Like I said it only took 10 mins from tools out till done, and saved me $350.
It may or may not be your issue, but for 10 mins worth a shot.

[Brightyellow69rtse]

Yes I just used the threaded hex on end of power booster, and adjusted it in.
I guess the difference between the old and new master cylinder, required  different adjustment.
I have the bendex booster, and I went from drum master to disc master.
I had swapped all brake components (before I knew to adjust booster piston) and I used a vacuum pump to bleed, so wasn't till after it was bled I found petal rock hard, no travel, and it would not return on its own.
I was at the point I was gonna buy a new bendex master/booster combo, and found an old Mopar mag, article describing my issue, and the recommended fix.(and it does make sense, if piston is out too far as you install the master on the booster it causes the master cylinder piston to depress some, or a lot, depending on how out it was/is lol)
Like I said it only took 10 mins from tools out till done, and saved me $350.
It may or may not be your issue, but for 10 mins worth a shot.

How far does your pedal actually travel?

I changed the length a few times earlier but not before we got it to bleed properly. I think I'm gonna put a electric vacuum pump on too. Idle is almost 12 inches of vacuum and if I rev it up it goes to almost 18. My thought is I let off the gas to use the brake so my vacuum would be on the low side.

[Bad B-rad]

I haven't measured the travel, I can, but it feels 100% better, and now returns on its own, lol!

Was your new master same as old one?
If you have changed the booster to master adjustment, with no change in pedal, could it be mismatched combo?
What I am trying to say is could: the booster aftermarket, and master stock, or vise versa?

[green69rt]

I can't figure out why adjusting the push rod length would cure the problem of no pedal return.  I can see why it could make for a hard pedal, just not the return problem.   

[b5blue]

You got the spacer between M/C and booster? 

[Bad B-rad]

I can't figure out why adjusting the push rod length would cure the problem of no pedal return.  I can see why it could make for a hard pedal, just not the return problem.  

I maybe wrong but I understand it like this:

If the booster rod sticks out to far, as you bolt the master on, the master cylinder piston CAN become compressed. and depending on how compressed you may have no more piston travel.


With the booster  pressing the brake in for you, it wont/CANT return, because the booster is keeping piston in forward (depressed)position, it mechanically cant return. Maybe even hydraulically


When I was removing the master off the booster to check why I had a brake issue, I noticed this was the case for me.
Some how I didn't notice this when I put it on.


I hope this helps.

[Bad B-rad]

Hey Brightyellow69rtse, I was wondering where you stand with your issue?

[green69rt]

You got the spacer between M/C and booster? 

What spacer?

[b5blue]

Bottom of this page: https://board.moparts.org/ubbthreads/ubbthreads.php/topics/1245845/re-70-master-cyl-spacer.html   

[Brightyellow69rtse]

Hey guys sorry for the delay. I haven't had the chance to work on it. Upon talking to my dad more I was saying I wanna pull the master off and bench bleed it again. Then he said I never bench bled it. Apparently he just put it on the car. It does bleed great but I assume since it wasn't bench bled that this may be my problem. What do you think? I'm hoping to go over possibly Friday to work on it again.

I thought I would start with a bench bleed and then bleed all 4 wheels and see what happens.

[b5blue]

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