1949 Master Cylinder

Discussions related to braking systems.
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breezy
Posts: 43
Joined: Thu Jan 27, 2011 9:44 am

1949 Master Cylinder

Post by breezy » Tue Feb 08, 2011 11:11 am

My newly acquired 49' Packard brakes had no pedal pressure when I got it. The master cylinder resreve was empty but after being filled it still had no pressure (bleeding did no good). I bought a master cylinder kit from Kanter and installed it. There is still no resistance,the brake pedal goes to the floor. The brake lines have been checked, no leaks, no air. Anyone had this problem or have an idea what could be going on? Thanks in advance. Breezy

Adam
Posts: 1083
Joined: Fri Sep 04, 2009 4:15 am
Location: lincolnshire, uk

Re: 1949 Master Cylinder

Post by Adam » Wed Feb 09, 2011 4:03 am

Hello Breezy

There are a number of possible causes for your problem. Apologies if you have already eliminated any of these, but here goes.

The master cylinder is the heart of the brake system, so it is vital that it is in good condition. You mention that you have rebuilt the cylinder already, have you checked that, there is a clearance between the linkage from the brake pedal and the M/cyl piston. If the piston cannot return fully, it will not be refilled from the reservoir. Also, have you checked that the small holes (usually two) drilled between the reservoir and the cylinder bore are clear. They can become clogged with old seal rubber and muck. This will prevent the cylinder refilling.

Is the cylinder bore in good condition, without excess pitting that would prevent the seals from holding pressure? There is a ring seal at the end of the piston assembly that seals against the end of the cylinder. It is important that this is sealing properly as it holds some "line pressure" in the brake pipes to give a firm pedal.

If you have a soft pedal, the likelihood is that there are no blocked pipes as these would give a solid pedal. However, do you have a flexible hose that is weak and is "ballooning" under pressure?

I assume that you have bled the brakes well from each corner? It is vital that there is no air left in the system. Also brake shoes that are a long way out of adjustment will give you a long pedal travel. For the peace of mind it brings, I would remove all the drums and check the shoes and wheel cylinders and adjust them. It is possible that the adjustable brake anchor pins have been wrongly set, which will cause a long pedal. It is worth checking this.

Finally, if you still cannot get a good pedal, try clamping off one corner at a time using clamps on the flexible hoses to see if that helps you identify the area that is causing the problem.

I hope this helps

Let us know how you progress,

Adam..
"Do not underestimate the English cousin.....they are not as stupid as they look!" - Signor Altabani in The Italian Job.

breezy
Posts: 43
Joined: Thu Jan 27, 2011 9:44 am

Re: 1949 Master Cylinder

Post by breezy » Wed Feb 09, 2011 7:39 am

Hi Adam,
Thanks for the suggestions. I will get back to the brake probem and let you know what turns up.
Breezy

breezy
Posts: 43
Joined: Thu Jan 27, 2011 9:44 am

Re: 1949 Master Cylinder

Post by breezy » Fri Feb 18, 2011 10:48 am

Hello Adam,
The problem turned out to be the brake shoes were out of adjustment. Two of the shoe adjusters were completly locked up and one had to be soaked over night and heated before it would move. Apparently the brake shoes had not been adjusted in a very long, long time.
Breezy

Adam
Posts: 1083
Joined: Fri Sep 04, 2009 4:15 am
Location: lincolnshire, uk

Re: 1949 Master Cylinder

Post by Adam » Tue Feb 22, 2011 5:16 am

Hi Breezy

That`s great to know that you now have working brakes (!)

However, I would consider giving the brakes a full overhaul of master cylinder and wheel cylinders before you drive it very much. If the brakes have received no attention in so long that they were that far out of adjustment, you really owe it to yourself and everyone else on the road to bring them up to scratch.

Indeed, if the adjusters had seized solid, some of the wheel cylinder pistons probably have too.

Not intended as a lecture, just good advice. :)

Kind regards
Adam..
"Do not underestimate the English cousin.....they are not as stupid as they look!" - Signor Altabani in The Italian Job.

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