New wheel cylinder fail

[bill41ford]

The 41 coupe rebuild is proceeding and I am getting the details done for it to move around on its own. I have been working on this car for a while and have done a body off rebuild. I completely replaced and rebuild all suspension and brake parts - stainless brake lines, new master and wheel cylinders and brake parts. This all took place a couple years ago and I left the brakes dry since then. I have progressed through the rest of the rebuild to the point of putting brake fluid in. I am using dot5 silicone brake fluid. I filled master cylinder and slowly pumped brake pedal, then added brake fluid and pumped pedal just to get some fluid into the lines. Got to the point of bleeding and pumped the pedal a couple times and lost the pedal - the one front brake cylinder failed and leaked brake fluid out.
Any ideas on why a brand new cylinder would fail - the wheel cylinders were listed as made in USA when I bought them. I have not dissasembled the failed cylinder yet. I will do that today. Any ideas or suggestions would be appreciated, thanks.

[KiWinUS]

I’m guessing you will find the cup inside slightly creased by fluid port being drilled in wrong location and not deburred so when adjusters are backed all way off the tension of spring pulling shoes together has piston pushing cup hard into fluid port. The seals I have seen in the new wheel cylinders are also slightly different than originals.

[alchemy]

I experienced that. You need to make sure you don’t press the cups in when you are assembling. Then adjust the shoes out to the drums before you give them fluid. If you are lucky the new cylinders have an internal spring.

[wga]

My 'made in USA' had metric mounting threads. Found some old Wagner WC's in my parts attic, and had those rebuilt. New does guarantee quality, a new MC leaked at installation.
Very frustrating.

[Bruce_MO]

My brand new master cylinder on my ‘46 Mercury started leaking several months after I installed it along with all new lines, hoses and wheel cylinders. I bled the brakes and all was good until I got ready to take it on its first drive several months later. All of a sudden, it was leaking badly when I depressed the brake pedal. Replaced it with another new one and I’m finally on the road. The leaking one showed a bit of discoloration on the inner bore (not real pitting) and a small funky discolored area on the piston cup. No obvious issues. All my brake parts (except lines), including the second master cylinder came from Thirdgen.

[bill41ford]

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Thanks for thoughts on this issue - I will be working on this soon and will see if I see why it happened.

[wickcopland]

I have experienced the same thing. I bought the wheel cylinders and master cylinder 1.5 years ago. Got distracted and did not get bake to the brakes. put everything on with all new lines. The left front started leaking right away. I went back to where I got them and called but was told that it was past the warranty. Bought another elsewhere and installed it. Then the right front went to leaking. Bought another and replaced it. So far the others are good. Looked at the front ones and found the seals to be poor quality and were slightly smaller. Learned another lesson.

[J Franklin]

Those cylinders are good candidates for rebuilding.

[tcom]

Yeah, a set of pair of cups, quick hone and clean up. Renistall, and bleed. Done.

[tubman]

About thirty years ago, I bought all of the old Ford wheel cylinders that my local NAPA had that were made in the USA or Israel. They are all in their original boxes, still wrapped in the dark wax paper they used back then. Does anyone know the shelf life of stuff like this? I rebuilt all of the original cylinders on my '51 when I restored it in '88 and nothing has gone wrong since. I drain and flush the system every 10 or so years, replacing the fluid with fresh DOT-4. It must work.

[slowforty]

tubman Probably better storage in your shop than at the NAPA store

[paetsgone]

The is a epidemic of new parts failing right our of the box.

[Flathead Fever]

Originally Posted by KiWinUS

IÂ’m guessing you will find the cup inside slightly creased by fluid port being drilled in wrong location and not deburred so when adjusters are backed all way off the tension of spring pulling shoes together has piston pushing cup hard into fluid port. The seals I have seen in the new wheel cylinders are also slightly different than originals.

]I


I am thinking the same thing. A few years ago, friend went through this on his AV8, the cylinders were drilled wrong, and it didn't seem to matter where you bought them from. He had a heck of a time finding new cylinder that wouldn't puke on the floor. They might have fixed them by now but who knows. I used to buy NOS stuff and put them on the shelf, even if I have to replace the rubber cups at least I knew the bore and holes were drilled properly.

There is nothing wrong with rebuilding original cylinders if they are not pitted to bad, they can be lightly honed. Pits in the center where the pistons don't slide that far don't matter. Pits are caused from moisture that accumulates in the system. You are supposed to change your brake fluid every two-years. At work we did it every time we changed the brake shoes. I did it at work for 30-years and never killed anybody. I had about 20 of the ASE licenses, including small car and large air brake trucks. I let them all expire when I retired.

[Mart]

I bought rear wheel cylinders recently that were still drilled wrong. One also had an incorrectly manufactured seal. I did some mods to make them work and used another seal. I have found front cylinders to be drilled ok and any problems must be from bad seals or contamination.
I always dismantle, inspect and reassemble wheel cylinders.
Master cylinders are also a problem. It is important to dismantle and clean thoroughly flushing with brake cleaner. I got lots of grit out of the ones I bought recently.

I cover the subject in this video: https://youtu.be/4QhP2xwqxjA?si=irspjKnztvdHmg4t

Mart.

[bill41ford]

Took the failed cylinder apart and cleaned everything and put it back together - added fluid and bled brakes - so far so good - did not drive yet but at least got through bleeding and all that pumping - had a few fittings to tighten - will let go over night and see where we are at -
On a positive note and off subject, put gas in the new gas tank for the first time instead of running from a temp tank. I have stock fuel pump. Took a little bit to start but ran good once it was started and after sitting overnight it started right up - also the gas guage moved the correct direction -
It is amazing to me going from positive stuff happening and then a challenge - I have been working on projects my whole life but this 41 was the first one I've done taking it completely down and now getting closer to being drivable again. I have taken my time and done everything as correctly as I know and worked through everything that has come my way - sure is an experience! Great to have a forum like this to bounce things off of.

[Flathead Fever]

I was talking today with a friend, and he said he had trouble with the wheel cylinders leaking because the new lining was 1/4" thick, thicker than the original lining. The thicker lining pushed the pistons in further and the cups leaked. I have one of those vintage Bendix brake shoes grinding machines. I guess you could grind the new shoes down to the original thickness.

[1956 ford]

In Orange Calif is a company ABS Brake they sleeved mine stainless never go bad again
the most would be new cups

[corvette8n]

Bill post some pictures of your ‘41 when you get a chance.