Fading manual brake pedal..........1948 Fleetwood 60S

[Richardonly]

Gentlemen,

The car is a 1948 Cadillac Fleetwood 60S.

This past Saturday while driving to a show, the brake pedal went down to 1/2 way from the level of the gas pedal to the floor.  About 1 inch from the floor.

It's normal position is slightly ABOVE the level of the gas pedal.

Knowing I wouldn't enjoy the show being worried about the brakes, I returned the car home.  The pedal was about 1 inch from the floor.  There are no visible leaks, the pedal did NOT get any lower, but did feel as if the stopping power was lowered.

A few hours latter, I checked it and it appeared (it was) to be almost returned to normal.

I drove the car to the shop for some minor jobs I cannot do, AND one of them was now the level of the brake pedal.

Except it was now back where it has always been and had full stopping power.  (NOT power brakes.)

It the car "Christine"  from the movie of the same title which fixes itself???

Confused, Richard

[Dave Shepherd]

I would suggest a complete brake check, pull the wheels confirm that none of the wheel cylinders are frozen, look for contaminated brake fluid, all the hardware is in good shape and so on, I am in the middle of repairing a 51 Chev. p/u in my shop. It had a very high pedal but stopped poorly, both rear w/c's were frozen and did not move, this causes a high pedal but no rear brakes.

[76eldo]

Sounds like possibly a bad master cylinder.

In the older cars with a single circuit brake system, loss of pedal can be catastrophic.  On dual reservoir master cylinders, you can have complete front or rear failure and still have sufficient stopping power.  I have been through this before with loss of pedal on both types, and it's not fun.

Take the car to a pro.  You can get new master cylinders from Kanter and other sources, and any decent mechanic can work on the car.

Brian

[curly]

X2 on Brians post.  The M/C is most likely bypassing the piston seals, causing an internal leak, but no out side fluid leaks.  I've had it happen a time or two.   Replace or sleeve the M/C.

T Lewis

[Glen]

My first reaction would be to change the brake fluid.  If it has absorbed moisture from the air and the fluid gets hot the moisture would flash to steam which is compressible.  After the fluid cools off the steam condenses back and the brake system seems normal.  This happens most frequently in disk brakes but I don’t see why it would not happen in drum brakes under the right conditions.   

[Jay Friedman]

If you have your current m/c rebuilt or buy another, I recommend you have it sleeved with brass or some other non-ferrous metal to avoid future problems.  I had my '49 m/c rebuilt and sleeved by Hagen's in Pullayup, Washington several years ago and it has been problem free ever since.

[Richardonly]

Gentlemen,

Once again, thank you for your information.

As it turns out, the brake light switch is "IN" the master cylinder and was leaking.  It also caused the brake lights to remain on randomly.  The switch was replaced, the master cylinder bleed and both work fine so far.

Hears hoping that they remain that way.  When I stop thinking about it, then the problem is truly solved.

Richard