pumping brakes

[cerick305]

I have a P15 1947 Special deluxe.  I need to pump the brake pedal a few times to get pressure buildup.  I thought maybe I was losing fluid, but I am not.  Master cylinder was replaced few years ago and since then, I haven't had to add a drop of fluid.  Brakes work fine, but need to pump to get pressure in the pedal.  Not sure what a solution would be?

 

 

 

Edited September 20, 2019 by cerick305

[soth122003]

If you've had to pump them since the MC replacement, You've still got air in the system. If it is recent, check the brake shoe wear and the adjustments. Sounds like air in the system or worn shoes.

 

Joe Lee

[P15-D24]

Pressure bleed them.

[keithb7]

If your shoes are traveling too far to contact the drum, ya gotta pump twice. Or three times. Then they reach the drum. Then you get pedal feed back.

 

A proper concentric adjustment, makes all the difference in the world for these lockheed brakes. Gotta do so, with some type of mocked up tool. There are several examples on this site if you search. Here’s my mockery. 

 

[desoto1939]

Brakes are out of adjustment. Need to do a minor brake adjustment to each wheel.  Too much travel or space to the brake shoe to the drum.

 

Rich Hartung

[P15-D24]

Low pedal height is shoes out of adjustment. Multiple pumps to get full pedal is air in the line. 

[Merle Coggins]

I’ve had severely out of adjustment brakes take a pump to get a firm pedal. First pump gets the shoes out to the drum, residual pressure valve holds them close long enough to ‘get another bite’, second pump applies the brakes. 

[austinsailor]

I have no idea what state - or country - Palos Heights is in, but if you were close to me I’d say drive over and we’d use my factory brake adjustment tools to fix your problem - which is out of adjustment brakes.

[kencombs]

1 hour ago, Merle Coggins said:

I’ve had severely out of adjustment brakes take a pump to get a firm pedal. First pump gets the shoes out to the drum, residual pressure valve holds them close long enough to ‘get another bite’, second pump applies the brakes. 

Yep, quite common.  air can cause it too, but always accompanied with a spongy feel first.  If the first application is solid, but low pedal, it's adjustment.

 

The tools are nice, but one can get by with careful, repetitive, major and minor adjustments.  Instructions are on this site, under the technical tab, then select brakes.

[keithb7]

2 hours ago, Merle Coggins said:

I’ve had severely out of adjustment brakes take a pump to get a firm pedal. First pump gets the shoes out to the drum, residual pressure valve holds them close long enough to ‘get another bite’, second pump applies the brakes. 

 

Thats been my exact experience too. Bleeding completed, never fixed the need to double pump. A good adjustment got everything feeling right.