1954 Fleetwood brake issue

[RobertM]

I'm trying to track down a brake issue that just developed in my '54 Sixty Special.  I had noticed the past couple days that it took alot of effort and I had to push hard on the pedal to come to a complete stop.  Today the pedal went almost to the floor before I got a little resistance and still had to stomp with both feet to get it to stop completely.

There are no leaks anywhere, and the reservoir was still full.  All the pads, springs and wheel cylinders were replaced less than two years ago.  At the same time I had done a rebuild on the master cylinder.  Is there a way to test if the problem is the booster? 

The biggest clue I have to this problem is that yesterday the pedal only travelled an inch or two before engaging..today it travels all the way to the floor.

Thanks,

[Caddy Wizard]

From your description it could be one of several things (in order of likelihood, in my opinion):

1.  Master cylinder has failed

2.  Power booster has failed

3.  A wheel cylinder has developed a substantial leak (failed seal/rubber cup)

4.  One of the lines has developed a small hole in it (the metal lines rust from the inside out, so often the first indication that anything is amiss is when the brakes fail).

[RobertM]

Thanks Art,
I may have been a little premature to say the sky is falling.  An update...

When I felt the pedal go to the floor this morning, I was afraid to even go out of the driveway.  I decided to investigate a little further this afternoon:  After I let the car idle for a while, it was actually much better.  With the pedal feeling a little better after idling, I took it for a drive around the block and it does pump up to a better level.  Not great, but better. 

Makes me think there is a vacuum leak somewhere and I had taken off before it had built back up this morning.  I'm not sure.

[Julien Abrahams]

Wouldn't a vacuum leak cause the pedal to become firmer than usual due to the loss of power assistance from the booster? I think there is an (internal) leak somewhere. My guess is that there is something going wrong in the Master cylinder.

[RobertM]

It started with a really firm pedal...then the next morning the pedal had dropped almost to the floor, but it comes back when the car runs for a while (but still firm). It's a confusing set of symptoms.

[CEC #20099]

RobertM
If the car has a remote Hydrovac Booster, same as my 55, then Pressure bleed the 2 bleeders on the Hydrovac. This should restore pedal height & braking, temporarily. About 20 psi dry, compressed air works fine.
C Chleboun #20099

[RobertM]

CEC,
I'm not sure what you mean...into what would I be putting the compressed air?

[Walter Youshock]

This is a hydro vac booster with remote master mounted on the frame.   If you never had the booster rebuilt,  do it now.  Fluid is pushed from the master through the booster where the pressure is amplified an sent to the wheel cylinders.  These are a "wet" booster because the brake fluid triggers the vacuum side of the booster.  It's probably full of crud and the seals are bad. 

You can try bleeding it.  Look at the booster and you'll see 2 bleeder screws.   Bleed the upper one first, then the lower one.  The upper is the master cylinder feed in and the lower is the booster out.  Then bleed your wheel cylinders from right rear, left rear, right front and then left front.  If you don't notice a difference, send the booster out to ed strain for an overhaul.

The hydro vac was pretty neat because it could be easily added to any car without power brakes.  If it failed,  you still had non - power brakes which sounds like what you're experiencing.

Another thing:  the leather vacuum piston is supposed to be lubricated with neatsfoot oil once a year.  There's a plug on the back of the vacuum piston.  I use hydraulic jack oil.

Even properly working, they're not the best and you won't get that hard pedal feel like a modern car.  I think this is a reason why women from that time had such gorgeous legs.  It was from trying to stop 5000 pound cars!

[RobertM]

Thank you Walter.  This car had sat in a garage for almost 25 years before I picked it up 2 years ago.  One of the first things I did was the brake system (new wheel cylinders, pads, cut the drums, replaced most of the lines).  The only thing I didn't touch was the booster, mostly because I had no idea what to do with it.  So I guess now it's time to learn    

I have a lead on a rebuilt booster with no core charge, so I will be swapping it out shortly, then will look to rebuild this one and maybe get a good bit of my money back.  This looks like a pretty straightforward swap - or at least I hope so.

[joeceretti]

This era of car is far from what I know but I do know that neatsfoot oil is still available. I have seen it at the tractor supply store.

[RobertM]

Today the brakes completely disappeared.  Pedal right to the floorboard.   I drove the car last night with no issues, and when I started the car this morning, they were gone.  Thank goodness the parking brake is in really good order.

I searched again all the wheel cylinders and master cylinder for leaks.  Nothing at all.  The fluid in the reservoir hasn't gone down at all.  I'm going to bleed the system today and see if that helps.  If not, the master cylinder will come off so I can get a good look at it.

I rebuilt the master cylinder about 2 yrs/1000 miles ago.  What would I be looking for to see if there is a problem with it?