Bench Bleeding M/c In Car????

[TodFitch]

For what it is worth, my '33 came with 1/4" lines for the brakes.

 

Are the lines on this car original? Could there be a rust pinhole in them somewhere?

 

A soft pedal is basically something giving while under pressure. The most likely thing in a hydraulic brake system is compressible air in the lines. But it could be a rubber hose slightly expanding under pressure because it has broken down and is not as strong as it should be. It could be the brake shoes are have a different arc than the drums and are bending slightly to conform to the drum when under pressure. It could be the drums have been turned too far and are weak enough to expand slightly under pressure.

 

My money is still on air in the lines though. Darned tough to get it all out sometimes, especially if you are using DOT5 (silicone) brake fluid and aren't really careful not to entrain air in it as you pour it into the master cylinder.

[JIPJOBXX]

Have you ever run into a problem like this??? I address this to my buddy with the 42 Dodge and just cut and pasted it here.

 

I decided to take oft the front drivers brake drum and remove the brake shoes to test if something is adrift in that cylinder. Well when I did block it oft with a "C" clamp I did notice that the spongy brakes went away or maybe it just in my head. I also notice that where the shoe go into the aluminum expansion plug that that the end of the shoe was not rounded oft but kind of just retangular in shape with curved ends. Kind of a non finished thing. Anyway I ground that end down and made it curve like the original one. So here is where I stand I'm going to put the front brake hubs and shoes back in place and do a little test to see if the original problem comes back. The cylinder itself is not leaking but the end that I trouble getting it out in the first place is very hard to shove in under pressure.

 

Ok but I suspect something like you said is going on and it acts something in wheel cylinder. I put the brakes back together and they did the same thing again. But when I just put a "C" clamp with a backing plate over the ends of the wheel cyclinder and apply the brakes the pedal stops like its suppose to. I know I can figure this out and its only a matter of time. Or someone else who has experience this problem. I know its not the shoe adjustments as you had them on dead nuts.

 

Adams seems to think its the size of tubing? But why when I disassemble the brakes and only have a backing plate with a "C" clamp over the expansion plugs does this problem disapear? And pedal works just fine!

[Plymouthy Adams]

NLA

Edited June 18, 2013 by Plymouthy Adams

[JIPJOBXX]

I understand what your saying and I'm trying to do it right.  I took the hub over and had it measured and it's 11.029"-that ok. The arc is ok also! The shoes are dialed into within .012".   If I do change out the lines from the original size what will I gain? I know you have explained it to me befor but why on green earth could these lines not work today when in 1942 they did!  They are steel lines but two lenght have been replaced with new material.   Finite;The act of trying to something within specs and not to deviate.

[Plymouthy Adams]

NLA

Edited June 18, 2013 by Plymouthy Adams

[JIPJOBXX]

Just want to say thanks to all who have helped me through this problem.  I really do appreciate all the comments and oft line help people have given me on this subject matter.  Adams yes I mention that in the past my brakes did not work correctly but I thought they were simply out of adjustment and needed new springs and shoes.   So with the help of a friend and his special tool we dialed in the new shoes and installed the new springs.  But apparently this was just part of the problem but just added to the situation.  But I do notice that all four brakes are working better even if i have mushy brakes.  Today I will take oft the back drum just to make sure that its within the stated Torrance for usage and then reinstall them.  As you guys know this requires a special tool just to take the hubs oft but luckily I have a friend who will loan me his snap on hub remover.  I will recheck the soft goods on those brakes for leaks and then reinstall.  After that one more bleed and then if that doesn't get it then I will take it to a automobile repair shop.  This goes against my grain but maybe my old car just needs another eye to check it out.  Jon

[Don Coatney]

Did you replace the wheel cylinders and if so was the bore size the same as your originals?

[Plymouthy Adams]

^{it is almost becoming a soap opera...}  

Edited June 18, 2013 by Plymouthy Adams

[wayfarerstranger]

Thats it, there is soap in the lines ! "COL TIM BO AUTOMOTIVE DETECTIVE" u have solved another mystery !

[JIPJOBXX]

Yep a soap opera and I'm the center focus of this evolution.  But with all my determination I have found one thing and that is I patient.   And with patient I will succeed!  Even if some people are trying to get under my skin it won't happen because its just a piece of metal and that is that! 

[JIPJOBXX]

And the soap opera continues but tomorrow its down to shop and money to be spent!!!

[JIPJOBXX]

Took the Dodge down to the repair shop but he could not work on it today as his lift was being used.  I took the car home and did a little adjusting to the M/C leakage and installed another return spring.  The car seems to stop great but still have the issue with air in the lines.  Well tomorrow tell the story as my mechanic will only haft to bleed the system and I have heard from so many people that these ofl Mopars have a real problem in that area.  I did clean all the areas where brake oil might leak out and then I placed some clean hand towels in those locations.  Did that just to make sure that there are no leaks.  Oh well what else is there to do in retirement? Just fooling around. And the soap opera continues!

[seabee1950]

I'm think there a people that get under there own skin.

 

But if you ask and don't like the fix then don't ask again if you don't follow there advice.

 

Then you don't have to hear it from people Right---Right 

 

I wish you God speed in your attempt to repair your brakes. 

[JIPJOBXX]

I have followed everyone advice here but changing out the brake lines and that will happen after I have tried all suggestions people have here.  So far I have tried to figure out what the problem is and have rebuilt or checked out probably everything on the old brake system.  Today I took off the front wheel cylinder caps and just made sure they were sliding freely.  Someone suggested that here and so I went ahead and check those items out.  You stated that I never take advice but you're so wrong! I have contacted people from brake specialist from Hagens autos and tried out there idea's and have learned a lot about these old brake systems.  Now tomorrow I will go to a guy who has been in the automotive bussiness probably for 40 years and knows his brakes.  I really think at this point it a matter of getting the air out of the lines and he has the equipment to do that and I do not.  So stand by and if you have some advice and its not going to cause a big problem than I will take whatever you have.

[JIPJOBXX]

Well I have tried everything else and now I will try the replacement of the 1/4 tubes.  I hope this works as its costing amost 75 dollars for the change out plus my time  Well we shall see:)

[_shel_ny]

 Now tomorrow I will go to a guy who has been in the automotive bussiness probably for 40 years and knows his brakes.  I really think at this point it a matter of getting the air out of the lines and he has the equipment to do that and I do not.

 

???

[Dodgeb4ya]

I hope your change in brake line sizing  goes well. Not a common or smart thing thing to do on a stock car if it is that.

Edited June 26, 2013 by Dodgeb4ya

[Merle Coggins]

I fail to understand how changing the size of the lines will change the pedal travel or feel. It doesn't make any difference what size they are. The displacement of the system, and necessary pedal travel, is determined by the size of the pistons in the master cylinder and wheel cylinders, plus the distance the wheel cylinder pistons have to travel to meet resistance. Once the lines are full of fluid they won't use any extra fluid if the line is bigger. The only thing a smaller line will do it cause more restriction in the system that will delay the operation at the wheels.  

 

I strongly believe that changing out your brake lines will be a giant waste of your time and money. You have another issue going on. Since you seem to have checked and rechecked the adjustments, and bled the system until the entire northwest is out of brake fluid, I'm thinking you may have a bad brake hose that is swelling under pressure. When a hose swells it act like an accumulator, absorbing extra fluid as it swells. It'll feel like you are stepping on a spring. Your test results state that when you disconnect the rear system the spongy pedal goes away. Have you replaced the hose at your rear axle with a good quality one?

 

Merle

[Plymouthy Adams]

actually the larger line will cause delay in the brakes not so the smaller line this was the end result and the why of the GM 1/4 lines to the rear when they went to disc brakes..Ford and Mopar used a proportioning valve..GM saved the money by going to a larger line...plenty of interesting reading on fluid dynamics in a braking system....it is not as most assume once full of fluid to be a so called solid steel rod effect...couple nice sites on the internet that are full of engineering data and not just the mindset and assumed principles as found on a variety of car forums..one must remember the word 'finite' when describing the operation of a working brake system on a car..

[Don Coatney]

Follow this link for some interesting reading.

 

http://www.chevytalk.org/fusionbb/showtopic.php?tid/286330/

[TodFitch]

actually the larger line will cause delay in the brakes not so the smaller line this was the end result and the why of the GM 1/4 lines to the rear when they went to disc brakes..Ford and Mopar used a proportioning valve..GM saved the money by going to a larger line...plenty of interesting reading on fluid dynamics in a braking system....it is not as most assume once full of fluid to be a so called solid steel rod effect...couple nice sites on the internet that are full of engineering data and not just the mindset and assumed principles as found on a variety of car forums..one must remember the word 'finite' when describing the operation of a working brake system on a car..

I am in Merle's camp on the size of the brake lines affecting this. But I sure would like to read some engineering based documents explaining why Merle and I are wrong, can you share some of the links you refer to?

[Plymouthy Adams]

Todd...last time you blew me off on this so why all of a sudden do you want the information...it is online..do a bit of research and reading for yourself...and yes brake fluid does compress..yes lines expand (even steel lines) they also expand in relationship to physical size, you have flow resistance...you have displacement and you also need to keep in mind that the system is finite...(approx. .934CC)

 

I am not saying 100% this is solely Jon's problem but based only and solely on his reported feedback of things checked, verified and components in his system being of correct value it is the only engineering fact left to attribute to his low spongy pedal..he has assure me that he will next test his rubber hose at the rear for ballooning..his words that it was replaced was not quite correct..it has been 10 years on that rear line and who knows if or if not it is ballooning...again..it is conditional only to the fact you are given to work with...

[Don Coatney]

You might or might not find this of interest.

 

http://www.jhf.com/catalog_v6/1362.pdf

 

http://www.insanehydraulics.com/library/hosesizing.html

[Dodgeb4ya]

I think that somethinghas been over looked. Incorrect wheel cylinder size type. Master cylinder not operating freely-piston not free to come back to its end cap stop or improper style cups/parts in it. Flexing hoses. Air still in the lines. Weak return springs. Shoes not arced to the drums correctly. Shoes not adjusted properly.

Someone who hasn't done these old lockheeds and does not know actually how they should work and feel will end up on the what do I do next merry-go-round.

 If it was my car I would have taken all the wheel cyls apart and and make sure they are the correct ones by the MoPar parts and shop manuals. Then  properly rebuild or replace with new. Same goes for the M/cyl  Replace old runbber flex hoses and carefully inspect the OE steel brake lines. Adjust all the major/ minor shoe adjustments with the miller or ammco tool-PROPERLY. Mount the drums and set final shoe to drum clearance. Pressure or vacuum bleed the system. Road test.

Bob

[TodFitch]

Todd...last time you blew me off on this so why all of a sudden do you want the information...it is online..do a bit of research and reading for yourself...and yes brake fluid does compress..yes lines expand (even steel lines) they also expand in relationship to physical size, you have flow resistance...you have displacement and you also need to keep in mind that the system is finite...(approx. .934CC)

 

I am not saying 100% this is solely Jon's problem but based only and solely on his reported feedback of things checked, verified and components in his system being of correct value it is the only engineering fact left to attribute to his low spongy pedal..he has assure me that he will next test his rubber hose at the rear for ballooning..his words that it was replaced was not quite correct..it has been 10 years on that rear line and who knows if or if not it is ballooning...again..it is conditional only to the fact you are given to work with...

I've done "a bit of research and reading" for myself. I haven't found links that I thought explained the situation to be as you describe, so I am now asking for links because I am obviously not finding the information you are basing your statements on.