Do I have the correct master cylinder??

[insaneradio]

Good evening,

 

It has been quite a while since I last visited.  However I am back with the same soft brake pedal I have had for 20 years.  I am getting older and have decided to sell my car and wanted to get thing "right.  Twenty years ago I replaced the master cylinder, wheel cylinders, rubber hoses and bled everything thoroughly.  I have been VERY dissatisfied with the brakes the entire time I have owned the car.  To the point I only drive it approx. 50 miles annually.  I am too leary to drive it.

 

Fast forward to this week.  I rebuilt all wheel cylinders, purge all lines and check for leaks.  No leaks.  Bled everything thoroughly--to my dismay the petal is VERY soft.  Does not pump up.  I read about checking the small hole in the master cylinder.  I took a peek inside mine and it is configured differently internally.  It differs from the pictures of posts and the internals of my original that I still have.  The smaller hole is going forward.

 

 

 

Is it possible I was sold the incorrect master cylinder some 20 years ago??  I will check my receipts but I believe it was from Bernbaums. 

 

Thanks for any information!

 

Dave

Edited October 19, 2014 by insaneradio

[Reg Evans]

What year and make of vehicle ?

[insaneradio]

I am sorry.  1947 Plymouth Special Deluxe.

[desoto1939]

When you did the brake job 20+ years ago did you use the Ammco brake gage tool to set the correct arc for the shoes. If you did not then the real issue could be that the brake shoes are not properly set to your drums.

 

Rich Hartung

Desoto1939@aol.com

[plymouthcranbrook]

I had trouble with my 52 with the vent plugging up. After I got it opened I noticed that when I pushed the brake pedal and then released it there was a spurt of fluid out of the small hole. if you are getting that or maybe bubbles, then I expect the hole is open.  When I did my brake job I did not have access to the special tool and just spent a lot of time adjusting the wheels. Although my pedal is lower that I wish, the pedal is hard and doesn't sink to the floor. I did have a lot of trouble bleeding the left front wheel, especially the lower cylinder. Now the brakes work quite well except for the slightly lower pedal.

Edited October 19, 2014 by plymouthcranbrook

[insaneradio]

No I did not use the AMCO brake gauge.  I have been desperate to find one for years.  I used the "feel" approach.  I do realize this is NOT the preferred method however I had no other option.  I tore things apart again this evening.  Low and behold I found the left front upper cylinder leaking.  I will repair and retry.  However I am not optimistic being this has been a battle for a long time. 

 

I would be very interested in solutions other members have use to replicate the tool.  I do believe this is the only way to have the shoes seat perfectly within the drum.

 

Thanks!

 

I know it is a long shot but if someone has one they would be willing to rent out to a trustworthy person I would be greatly interested!!

Edited October 19, 2014 by insaneradio

[55 Fargo]

On my former 47 Chrysler Coupe, I rebuilt the entire braking system, but used the drums, had those machined on a brake drum lathe.

I adjusted the major adjusters to factory spec, witrh arrows pointing in the direction in the service manual.

Once I bled the brakes very well, I did use DOT 5 silicone brake fluid, I had a decent pedal.

The brakes at first were just so-so, after several hundred miles, I would do a minor adjustment, this I continued for another several hundred miles.

Once the brakes shoes wore into the drum radius, they were awesome, I could hit those brakes and put a passenger into the dash no problem.

Bob H aka Dodgeb4ya, gave me this recipe and it worked well.

When brake jobs were done years ago, brake shoes were shaped on the arcing machines to have maximum contact with the drum surfaces, so instant good brakes, the other way is to wear this in, and to do periodic brake adjustments.

Bob also mentioned that he owns the Ammco and/or Miller brake tool for thee Lockheed systems, but that he hardly used them.

What I am getting at, is you can still have good brakes, without those tools, but you must find a method to create maximum/total contact.

Some on this fourm have made brake adjusting tools, and have used those to get those shoes dialed in better.

Good Luck

[Don Coatney]

No I did not use the AMCO brake gauge.  I have been desperate to find one for years.  I used the "feel" approach.  I do realize this is NOT the preferred method however I had no other option.  I tore things apart again this evening.  Low and behold I found the left front upper cylinder leaking.  I will repair and retry.  However I am not optimistic being this has been a battle for a long time. 

 

I would be very interested in solutions other members have use to replicate the tool.  I do believe this is the only way to have the shoes seat perfectly within the drum.

 

Thanks!

 

I know it is a long shot but if someone has one they would be willing to rent out to a trustworthy person I would be greatly interested!!

Do a forum search for Ammco as this has been cussed and discussed many times

[deathbound]

Desoto1939 will loan you the AMMCO 1750 brake tool, send him a deposit & shipping one way, ship it back & he'll return your deposit when he receives the tool in the same condition as loaned. Also, post your location, maybe someone near you has one. If you're near So Cal, I do. Post pics of the car, shame you have to/want to sell it.

[Robert Horne]

"pedal is very soft, does not pump up", maybe your master cylinder does not have the correct internals.

 

You could disconnect the lines at the master cylinder, plug, and then see if you get full pedal.

 

If full pedal, the problem is in the lines, wheel cylinder, or adjustments.

 

If not full pedal, your master cylinder is the problem.

[insaneradio]

Thank you all. Very good information. I am in Northwest louisians. Not too many Plynouth/Dodge/Chrysler collectors out my way. I will be contacting Desoto1939 and discuss the loan option. Very kind of him.

Dave