So here is MY brake story....scratching my head.

[Bmartin]

A question on use of the AMCO brake tool.  I set the tool to the drum and then mount it on the hub. I set the shoes so that they drag a little on the tool indicator.   When I go to put the drum back on, it won't fit.  I then need to back off the minor adjusters to get the drum on.  But I can't turn the adjusters back to where they were after the drum goes on.  Should I be using some sort of feeler gauge to set the spacing from the adjuster indicator?  Am I trying to get the adjuster too close to the actual drum diameter when taking that measurement?  The original plymouth tool had the spacing built into it according to the manual, not sure if the Amco does

[TodFitch]

A question on use of the AMCO brake tool.  I set the tool to the drum and then mount it on the hub. I set the shoes so that they drag a little on the tool indicator.   When I go to put the drum back on, it won't fit.  I then need to back off the minor adjusters to get the drum on.  But I can't turn the adjusters back to where they were after the drum goes on.  Should I be using some sort of feeler gauge to set the spacing from the adjuster indicator?  Am I trying to get the adjuster too close to the actual drum diameter when taking that measurement?  The original plymouth tool had the spacing built into it according to the manual, not sure if the Amco does

There is supposed to be some clearance at the toe and the heel of the shoe.

 

For my car they are two different numbers. Looks like for the P15 through P-25 era it is a simple 0.006" for both. So you can set the Ammco tool for 0.006" under the drum size and then adjust the shoes. Since my car lists different clearances for heel and toe I set the Ammco to the drum diameter and then use two different feeler gauges to set the two different locations.

[Bmartin]

Ok, I have front brakes now with the rears capped off.  I redid the adjustment with a .007 feeler gauge and then used my friends vaccum bleeder.  Now its on to the rears, going to readjust and bleed with the vaccum bleeder and see where I am at.  Pedal has 1" free travel before hitting the piston and then its got about another 1/2" of movement before it gets firm. 

 

Now I have to wait till monday to rent the puller for the rears again. 

[DJ194950]

Just a question on your using the ammco tool.

After you measured the drum dia. with the tool say it was .040 over, did you adjust the micro. meter to .020 before you put it on the axle to adjust the shoes? The instructions tell to do this.

 

Good luck,

 

Doug

[soth122003]

Hey B,

 

Glad to see your MC is good now. Was it the rebuild kit that did it for you, or the washer trick? Anywho, your one step closer to road ready.

 

 

 

Remember, a bullet may have your name on it, but a grenade is addressed "To whom it may concern".

[Bmartin]

DJ194950, I did not notice those instructions.  Its in a little note in smaller type on the instructions.  That would have helped. 

 

I'm about 75% there.  First let me thank Suntennis for coming over and lending me a hand on Friday.  It was great to finally have a second opinion and to discuss how to set the shoes up.  So I went through and readjusted all the brakes using a .007 feeler gauge.  I set the shoes so that they were equal distance from the indicator on top and bottom and bottomed out on the center of the shoe.  On the rear, I had to back off the minors a tad to get the drum to be able to turn.

 

Then I went through and used the vaccum bleeder on all four corners.  I've got 1" of free play in the pedal and then about 1/2" to 1" more before I get a firm pedal.  I believe there is still air in the system and intend on hitting all four corners a couple more times.  Then its time to drive it and see how it actually stops. 

 

I actually did not rebuild the master, just put it back together with the washer in it. 

 

Almost there....

Edited March 17, 2014 by Bmartin

[Don Coatney]

 

[_shel_ny]

Dodge brake shoe heel vs. toe clearance was different, as it was for the Plymouth prewar vehicles. Your manual may have those specs..

[Bmartin]

Well tonight was a setback.  I was doing a final bleed and final adjustment of the minors.  I went and pumped the pedal and now the brakes do not release.  The pedal got stiffer after a few pumps.  I went back after a half hour and the drums were still locked, although the pedal could be pumped up again. 

 

The obvious thing to check is the master cylinder.  Are there any other not so obvious things to check?  I was thinking weak release springs, but on all 4?  Could my adjustment somehow be causing this?  I have already had the brake gauge too long and need to get it back to Rich.  So I want to try anything that may require that first.

 

I've got other things going on the next couple weeks, so I am going to have to step away from it soon.  And I probably need it at this point. 

[desoto1939]

This is rich Hartung.  I had an issue with my 39 desoto that still had the original mast4er cylinder inthe car.  After getting the car and driving it for a while I noticed that the brake pedal was getting harder and then not retracting. The brakes felt like they were fully engaged and the car would not move.  If I let it set for awhile then the pedalhad some free play.

 

I looked inthe body of the MC and there are two weep holes for letting the back pressure of the fluid to retunr to the reservior.  I was able to  put a tag wire to clean out the one hole bu then founf out that the other hole has partially tapped but was not tapped intirely. I then  ran a drill in to the hole and then the mc worked.

 

Clean all the holes that let the fluid and pressure come out of the MC body.

 

Rich HArtung

[Don Coatney]

Posting # 43 in this thread.

 

 

Another good suggestion. That would be the port that has the prick punch in it.

 

 

[Bmartin]

I cleaned all those out when I had the master out.  I'll open it up and try again. 

 

Just for clarification, this has all been done with the car up on jack stands and wheels off. 

Edited March 18, 2014 by Bmartin

[BobT-47P15]

My car is a 47 Plym, but due to it being in an accident years ago--it has a 1939 Dodge pickup rear end...or some similar vintage Mopar. Has only one brake cyl per wheel. I got those from Andy Bernbaum (now under new ownership). Cost of the last pair was about $50 each. Or...White Post Restoration (and some other.places) can sleeve the old cyl.

[BobT-47P15]

You said the brake hoses look new-ish. So did my rear one...but the inside was apparently collapsed. Fluid would go thru it to cyls, but could not return. ...locking rear brakes. So i would replace both those hoses asap. If that doesnt solve the problem, at least youll know they are new.

Edited March 19, 2014 by BobT-47P15

[Don Coatney]

Have you checked the length of the cylinder push rod for sufficient free play?

[Jim Yergin]

When I first got my '41 back on the road, the brakes locked up within the first 200 yards. Turned out (just as Don suggests) there was insufficient free play in the m/c brake rod to allow the piston to clear the relief port.

Jim Yergin

[Bmartin]

I currently have 1" of pedal travel before the rod touches the piston. 

 

Also, all soft lines have been replaced with brand new lines. 

 

 

Thanks for the suggestions.  I really hope its just a clog in the port.  I used .03" welding wire to check it when it was out.  It went through, but the hole was not smooth, the wire would hang up, I don't thinks its the cleanest casting.  Does the relief port need to be a certain diameter to release?

[Bmartin]

I pulled the floor and master cylinder cover.  The relief port is the same, drags but goes through with a .03" welding wire.  When I pump the brake pedal, fluid shoots out of the relief port on the compression stroke.  The inlet port is open as well.  My other master seems about the same as far as hole size.  The brakes still have not released from yesterday (all 4). 

[Dave72dt]

Crack the line at the back of the master. Brakes release, there's a problem in the master.

[Bmartin]

Dave72dt

 

That's a very succinct way of thinking of it.  I'll give it a try..

 

 

In a previous post plyroadking mentioned that the 1940 had a special length piston that is shorter than most that are included in rebuild kits.  This may carry over to newly manufactured master cylinders.  Does anyone have the correct length of the piston? 

[TodFitch]

Crack the line at the back of the master. Brakes release, there's a problem in the master.

Something wrong with the residual pressure valve in the master?

[Bmartin]

I did crack the line and the pressure was released.  I'll be rebuilding my old master with the kit I received from Bernbaum and then swapping it in.  We'll see what happens. 

[desoto1939]

I did crack the line and the pressure was released.  I'll be rebuilding my old master with the kit I received from Bernbaum and then swapping it in.  We'll see what happens. 

 

In the kit that you got from Bernbaum does it have the instructions included in the kit?  If not I have a kit with the rebuild instructions for you MC. I can scan it and then send it to you if needed.  Since the pedal came back after cracking the line it might be that you have the  relief value in backwards. check this when you redo the MC. Also take you time with the Ammco  gage that I sent you.  Get the brake correct. I am not in any hurry to get it back. I also have the Miller MT19 tool if i need to do a brake job. 

 

Rich HArtung  

[Dave72dt]

In post #81 you mentioned reassembly and putting the washer in.  An incorrect or installed washer may have put the piston in the wrong position to work correctly.  A careful inspection prior to and during the disassembly of the master should indicate what the problem was.  The results of that inspection may be helpful to others.

[ledfootslim]

I ran throught the whole system on my '48 Desoto S-11, and finally had to find a longer spring for the master cylinder. After that, I had a firm pedal and am stopping just fine!