Brake pedal went to the floor- rebuild time after 30 years

[desoto1939]

When to start my 39 Desoto the other day toget it up to temp since it was sat for a couple of weeks.  Engine came up without any issues.

Then I hit the brake pedal to test my brakes and the pedal went to the floor board.  The pedal did return becsue of the brake pedal spring so i know the spring is not broken.

Did a quick check at the backing plate of each wheel and did not see any wetness or indication of any blown out wheel cylinders.

I have a feeling that it might be a rebuild time on the master cylinder note there was not any fluid inthe MC when i took the capoff today.  The system was build with silicone brake fluid approx in 1987 and this is the first issue that i have had in 30 years.

It is to cold in the unheated garage to pull the wheels so it is going to wait until it warms up.  I do have an extra master cylinder rebuild kit and the other cups and other rubber parts for the wheel cylinders So it will be a fund time inthe next couple of weeks.

 

I do have a mighty-mite vacuum pump and this will be my first time to use this tool any suggestions and has anyone used one of these to bleed their brakes.  I will also have to take the floor boards and carpet out of the front of the car since the MC is bolted to the frame rail. I am alot older now and not as nimble but will get the MC out and pull it apart and rebuild. Does anyone know of a MC automatic fluid filler that i can get to get brake fluid to keep filling the MC when bleeding the brakes?

 

Rich HArtung

Desoto1939@aol.com

[bob westphal]

High Rich,

 

First to answer about an easy brake fluid filler. Summit carries the a Wilwood  Master Cylinder Remote Reservoir Kit part # wil-260-11098 ($19.38) that you fasten to the firewall with a hose going to a fitting you install in the master cylinder cap. You can do this when you rebuild your master cylinder. Make sure there is no taper or pitting. On the Cascade Pacific Plymouth Club site, I wrote an article on an easy way to bleed brakes. Check it out on http://www.cascadepacificplymouth.org/ tech section. I have used the vacuum pump but it is a pain compared to my article

[Branded]

Could very well be a line or a hose that let loose on the system.

[keithb7]

I use my Mity-Vac. It works well. Crack the bleeder and suck the fluid through. Close bleeder valve first while still under vacuum. Then remove Mity-Vac hose after. I fill the Mity-Vac canister, dump it and repeat. This ensures all old fluid is flushed out of each line and wheel cylinder. I check my master cyl fluid often and keep topping it up as I travel around 4 corners of the car. 

 

I have used my Mity-Vac to flush brake fluid on all the vehicles in the family. No complaints. There’s probably a better faster  way but I’m just a home hack tinkerer mechanic. 

[vintage6t]

1 hour ago, Branded said:

Could very well be a line or a hose that let loose on the system.

Even if not, with a single res system you might as well replace the rubber hoses while you're at it.

[dpollo]

Brake systems retain a slight pressure when at rest.  When this subsides, the master and wheel cylinder cups may leak.

This is why it is a good idea to stroke the pedal every few months.   Before you tear into it, refill the master cylinder.  Chances are good your brakes will return

after the air at the MC end is released through the relief port.   This does not mean the rest of the system should not be checked out.

 

[Niel Hoback]

  Two things; when you use a vacuum pump on the bleeder screw, it tends to pull air in around the screw threads. This doesn't enter the cylinders, but it makes it hard to tell if and when you get all of the air out of the cylinder. 

  Old timers told me that when I park the car for long periods, disconnect the battery and put a stick between the seat edge and the brake pedal to repressive on the system.  

   More free advice, use at your own risk.

[Tom Skinner]

I agree with DPollo. My brake pedal went way down after the cold drop and I refilled the MC. and Bled it several times. Its seem some trash in the M.C. may have also caused it. I took all wheel Drums off and inspected them - no leaks, finally after third bleed brakes have worked like new with no issues or leaks since.

[Dodgeb4ya]

As said above... to try to temporarily get your pedal back and high...

Just fill the M/C up and while slowly pushing the pedal down and letting back up slowly..... watch for bubbles coming up through the DOT 5 fluid.... you will see them come up and out of the larger hole in the bottom of the M/cyl reservoir.

Keep doing it till your pedal is back to normal firm and high..

Find out where your leak is.probably a wheel cylinder or M/cylinder or both.

 All new hydraulics probably required. I'd try to find OE asbestos shoes if needed too... off ebay. That's all I'll use anymore.

[Andydodge]

Dodgeb4ya........interesting that you comment about using asbestos shoes if possible.............thats no longer able to be used in any Oz car and Oz customs now will pull the car apart if theres a possibility of asbestos in the car when its imported..........has been some very expensive disassemblies done here on the wharf side.........I thought that modern linings/pads were the equal or better now............andyd  

[Dodgeb4ya]

I want safety.

Modern brake shoes on my and many others 1946-60 MoPar cars are not safe IMO.

Stopping is erratic with the modern constantly changing safe brake lining materials being supplied/sold for old MoPar/Lockheed brakes.

The old factory material  type shoes sure work well compared to modern materials.

JMO.

[Andydodge]

Well I stand corrected.........lol...........andyd

[desoto1939]

Thanks for all of your input to my situation.  I am going to try to put fluid in the MC and try to build up pressure. The odd part is about a week ago I started the car and pushed the brake pedal and had a good pedal and it moved the correct amount of distacne and did not go to the floor.  Then this week it went to the floor so I will have to pullthe front wheels first becasue they are easy to do then the back drums.

Just to cold to work inthe garage when it is high 20's.

I will keep everyone update as I make progress.

 

I do have relined brake shoes with the old asbestos lining. I have found the samethinh that the newer lining seem to get hardened and or glazed and then the brakes pull. We can stilluse the asbestos linings here inthe states.

 

Thanks,

Rich Hartung

Valley forge PA

desoto1939@aol.com

Edited January 26, 2018 by desoto1939