brake problem

1157 Views 6 Replies 5 Participants Last post by xntrik, Feb 2, 2007

lawguy

Discussion Starter · Feb 1, 2007

Good morning all. I have a '40 Chevy street with a brake problem, one I have never before encountered.
The system is power Heidts front disc / GM 10 bolt rear drum. The components are new. It has a remote fill on the firewall with the master cylinder below the floor. The plumbing appears fine and is all new.
The problem is that every now and ( three times in as many months ) then the rear (drum) wheel cylinders will entirely bleed out. The cylinders were new when installed and have new end cups installed but still the bleed out. The front disc is not affected.
Thanks much for any help anyone can offer.

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pasadenahotrod

· #2 · Feb 1, 2007

So...are you saying the wheel cylinders themselves drain fluid out and down the backing plate and all over the inside of your tires?
Replace the wheel cylinders.
If not, then check around every joint in the system from the master cylinder to the rear wheels. You'll find the paint is gone where the brake fluid has been leaking. Tighten or replace the fittings. Bleed the system and go riding.

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poncho62

· #3 · Feb 1, 2007

This was happening to a friend with a 69 Dart with 4 piston front calipers....Took 3 calipers before the leaking quit. You have a improperly rebuilt wheel cylinder....replace it.

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pasadenahotrod

· #4 · Feb 1, 2007

Do not buy rebuilt anything for a brake system except relined shoes. New stuff is very reasonable and will give you the full service life and keep you safe.

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lawguy

Discussion Starter · #5 · Feb 1, 2007

lawguy

Thanks for the info. The initial rear wheel drum cylinders were brand new a couple of months ago. When they leaked the first time, I changed the cups. Worked for a while when they leaked again this week.
Will try new cylinders.

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KULTULZ

· #6 · Feb 1, 2007

Do you have a 2# and 10# residual valve installed in the rear drum circuit?

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xntrik

· #7 · Feb 2, 2007

lawguy said:
Thanks for the info. The initial rear wheel drum cylinders were brand new a couple of months ago. When they leaked the first time, I changed the cups. Worked for a while when they leaked again this week.
Will try new cylinders.

Drums should have a 10# residual valve in the line unless your master cylinder has one in the port. This amount of pressure will not cause brake drag but will keep the cups expanded.

Disks get a 2#.

I have always gotten the best service from Wagner parts, shoes and pads. Thermoquiet pads if they make them for the application.

Never use cheap parts even if they are life-time guaranteed. What if your lifetime ends at the scene of the crash? (not trying to be funny)

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