Repairing the Treadle Vac Master Cylinder and Brake Booster of my 58 Eldorado

26 | 09 | 13 | 14:02 | Filed in: 1958 Cadillac | Restoration

In June I bled the brakes of the 58 Seville because it needed some fresh fluid, and the fluid level was a little low in the reservoir of the Bendix Treadle Vac master cylinder.
Now as I wanted to drive it out of the garage, I found a puddle of brake fluid under the car.
So I went on to search where it was coming from.
I suspected a leaking wheel cylinder, but could not find any traces of fluid coming from the wheels. After some more searching, I eventually found out that fluid was dripping out under the brake booster along the push rod. When I checked the fluid level it was only half full.

So I knew that the Treadle Vac would need a full rebuild…
I ordered a rebuild kit at Cadillac Parts LTD. They offer a kit to rebuild everything from the booster to the master cylinder. As I found out, the gasket for the reservoir did not fit from their set and some other correct smaller rubber parts are also not included in the set. So remove everything carefully from your unit as you might have to reuse some parts for your rebuild. I contacted them about the wrong parts and they immediately sent me the correct parts by mail. Great customer services - I would order from them anytime again!

As I had never done a full rebuild I asked my Cadillac friend Lucky for help - knowing that he can repair almost everything, and that he had done this job during the full restoration of his awesome 58 Biarritz before.

He was so kind to offer his assistance and invited me to his fantastic work shop where he is restoring his cars.

So I carefully removed the whole unit from my car and visited Lucky´s workshop.

With his skills he managed to rebuild the whole unit within a couple of hours. As it turned out a bad O-ring caused fluid to leak into the booster.
Due to all the brake fluid the finish of the Bendix unit suffered a lot, and so I decided to strip everything on the outside down to bare metal to repaint it.
So I took everything apart once again to make sure to do it perfectly.
I ordered some great spray cans from Eastwood to get the perfect look to match its appearance to when it was new.
Originally the master cylinder was not painted at all - but left in bare cast metal. Of course it started to collect surface rust very quickly - even on new cars back in 1958.
The booster originally was painted in semi gloss black.

Eastwood has a product called "Brake Gray" which I used to emulate this look. It comes extremely close to bare metal, but of course the paint protects the metal from rust. This paint is also resistant against brake fluid. I first primered the master cylinder with self etching primer two times before two coats of brake gray were applied.

For the brake booster I ordered Eastwoods Chassis Black extreme primer and satin black paint - painting turned out really fine! See pictures below

To make bleeding brakes easier and a one person job I also ordered a set of speed bleeder screws. (SB3824-SS)

The unit still in the car - before removal

Removal has started

The unit out of the car - before rebuilding it.

Out of the car

In Lucky´s workshop with the rebuild kit I got from the USA

My friend Lucky at work

Lucky´s fantastic work shop

The Bendix master cylinder fully disassembled

Everything disassembled

This O-ring was leaking and caused the problem.

The new o-ring in place.

The vacuum cylinder

As you can see the paint suffered from the brake fluid - a repaint was necessary after the rebuild.

I started to wire brush the paint off - took it apart once again after this picture.

The master cylinder in primer.

After painting it with "Brake Gray" - great stuff.

The master cylinder with paint

The booster in bare metal before primer. I used Eastwood Extrem Chassis Black primer and paint.

In primer

Speed Bleeder screws

Speed Bleeder screws and bag

The new Speed Bleeder screw in place

The reassembled unit back in the car.