Joemac8

I am in the middle of the rebuild of my calipers and master cylinder for my 67 SB coupe. I rebuilt the master and re-installed it. I used a Motive Products power bleeder with alcohol to test the system. Since this was my first foray into any of this stuff, the alcohol just ran out several spots around the wheels. I removed the plate over the master and found a trace of alcohol in the bowls.

The northern winter in Wisconsin took over and the project went on hiatus until this weekend. I looked into the master and find bright red surface rust in both bowls. What is the best way to remove this rust so I don't contaminate the system?

Second question: When re-installing the master cylinder (No Power brakes) I pushed the "rod" from inside the firewall into the rubber sleeve and pushed the master on and bolted it. Was this correct? Should I have done something else to fit the rod????

Thanks again!!!!!! Joe

DSR

I think I would be going for a new master cylinder. I am not sure that you can get rid of the rust with out rebuilding the master cylinder.

gsholz

Before you decide on replacing the master cylinder give this a try. I found rust in my single master cylinder when I got the car home after purchase. I siphoned out the old brake fluid with a turkey baster and scrubbed the interior of the cylinder with a pad and used new brake fluid to extract the contaminated fluid. Did that about three times and refilled with DOT3. No more rust.

Joemac8

The rust is light surface rust that rubs off on a dry cloth. The master is otherwise in good shape and original to the car. I just rebuilt it so it is in good nick other than the rust.

I hooked up the bleeder pump with 15lbs of air pressure and it held for an hour.

DUB

I think you wrote you already rebuilt the master cylinder...and the reservoirs should have been thoroughly washed out....which as stated above...usually wipes out. But sometimes it is actually rust scale. And a more aggressive action might need to be taken.

Not knowing if you want to spend more time on the master cylinder and possibly another kit...BUT...with the master cylinder completely disassembled...you can wash it out very well and either media blast it in the reservoirs...which will require a VERY THOROUGH washing, blowing out and cleaning NUMEROUS times to make sure every speck of medal has been removed.

OR...soaking it in Evaporust or CLR or a de-rusting solution that may paint and body supply stores have on had to prep steel.

It may then require s light hone on the cylinder in the master cylinder when done to get it cleaned out.

AS for how you attached the master cylinder....I do it the same way. I leave the rod attached to the brake pedal and install the new master cylinder as you described.

DUB

MikeM

Tear down the MC and soak the MC in white vinegar for a half day or so. Rinse with water and re-assemble with a little brake fluid coating.

Roger Walling

Wash out with alcohol and disassemble the MC and soak it in a mixture of Molasses and water, (1 Molasses and 9 water) for a week.

Wash with hot water and blow dry with air pressure.

IT WILL COME OUT SPOTLESS!

Joemac8

This is what I will do. The water and molasses takes a week and I am not up in Wisconsin for that long.


Thanks to all who replied

John BX NY

I wouldn't do anything until I had time to change the system to DOT 5 silicon brake fluid which doesn't absorb moisture....

GTOguy

This was my first thought when I read the original post. Non-intrusive and easy to do. What I would personally do if it were mine.....

427/42566 coup

Ditto on DOT5. Every time I check Master cylinder fluid is clear

DUB

Thanks for the reply. I have never used white vinegar for this. I will the next time due to the acids I have can take 24 hours.....and the parts do come out spotless....but if I can use white vinegar....and it works like you wrote...TRUST ME...I will! Thanks again

DUB

GTOguy

I have used it, but usually it takes overnight or longer, depending on the degree of rust. In my engine block, I left it in for about 10 days, IIRC. Then neutralized with washing soda.