Hot Rods Brake Master Cylinder Leak

This seems pretty simple but I'm about to bust a gasket trying to stop this leak on a new Master Cylinder in my 36 Roadster. This started with upgrading the 48 Ford front brakes to the Boling Brothers 39-48 kit. While I was at it, I replaced the master cylinder and used the original outlet bolt, brass fitting and stop light switch. Leaked between the outlet fitting and new Master cylinder where pictured. Tried thread sealant on the outlet bolt and tightened with a BF Wrench. Leaked. Bought another new Master Cylinder, new outlet bolt, new outlet fitting and new stoplight switch. Used Permatex 54540 Hydraulic sealant and a couple of club members suggested I heat the copper washers so I did that too. Reinstalled. Leaks in the same spot. The bubble you see on the very bottom edge of the Master Cylinder is brake fluid.

Master Cylinder is located on a juice brake conversion bracket bolted to the X member and frame.

Suggestions?

 

did you install new copper washers?

Did you inspect all the surfaces that the washer seat against, for scratches, nicks, corrosion, etc?

 

Copper gaskets are one time use.

 

Been there.... I used a Stat-O-Seal. It works.

 

Installed new copper washers. The flat type from CW Moss.

 

Maybe it's just me, crush washer looks alittle dis formed. Maybe over tightening?

 

True the mating surfaces with a file.
Use new washers and do not over tighten.
I would not use a sealer on brake fittings.

I learned this a long time ago and it was one of the best lessons for me......
There’s tight and then there’s Hillbilly Tight. Hillbilly Tight breaks/warps/strips stuff.

 

See these rings in the brass bit?

I would install it with those rings facing the M/C, new crush washer.

 

I've run into some of those copper brake washers that seem to be a bit on the hard side.
I'd take them and use a piece of flat glass and a piece of fine sand paper to make sure the surfaces were smooth before putting it back together with that one side facing like Billy suggested.

 

You gotta anneal it, too.

 

I've never had to anneal a copper washer. Huh.

 

They make aluminum ones too. The brake kit I just install on the 51' came with both copper and aluminum

 

I've annealed and re-used copper washers for 50 years. If the washer is in decent shape to begin with and properly annealed it won't leak...

Given the hardness I've seen on some of the new washers available I think I'd anneal them before installation.

 

To anneal copper/ brass.....
Heat to red with a propane torch....drop in a cup of water.
It does not hurt to quench cool brass/copper as it’s a nonferrous metal
Brass and copper work harden a heat and quench softens it.

 

Here I thought annealing you let it cool naturally in ambient air temp?

 

Those "rings" should be on both sides of the brass fitting or you could make some in the copper washers. The rings are to bite/crush into washer for sealing. I used banjo fittings on a Alum MC and had a hell of a time to stop leak because of no "rings" IMO; I had thought about it, luckily the leak stopped before I could strip the MC threads. Yes that tight. You might try some washers with ID "O" ring built in but all surfaces must be smooth.

 

Thanks for all the suggestions. Got new copper washers, smoothed, annealed, didn't use sealant, tightened but not Hillbilly tight....leaked in the same place where the outlet bolt goes into the MC. Never leaks from the other side of the brass outlet fitting which also has a copper washer. Next up, double the washers and also order some Stat-O-Seals as Double Pumper suggested. What a PITA!

 

Sounds like a crack somewhere .

 

I would tighten and loosen and tighten and loosen and tighten and loosen about 4-6 times. The repeated process forces the surfaces to become “friends” with each other. Can’t hurt to try this method before you tear it apart again.

 

Put the old master back on with the old parts (new crush washers), if you want you can rebuild the old master.

 

Is the brass piece bottoming out before it gets to seal? Is it straight or tapered thread? You may want to sieve through some more fittings before going too crazy.

 

there is your problem. cheap chinese junk.
I have seen this on my parts, so has south main auto and the car wizard

 

I suspect the sealing surface on the MC isn't at a perfect 90deg angle to the threaded hole. Or maybe the brass piece faces aren't parallel. Checking with feeler gauges with things assembled loosely and no washers may locate the problem OR maybe some thicker washers and anneal, heat and quench in water.

 

I had a brake caliper that I could not get to seal, no matter what I did. I got a new one and it sealed up no problem. I think the threaded hole was not drill square with the flat sealing surface. If that is your issue you need a new master cylinder.