Bendix Brake Master Cylinder

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Caution, whenever you work with brake fluid keep in mind that it will do a great job of taking paint off any surface it contacts.

In 1997, the previous owner of my Pantera installed a Pantera Performance Center aluminum brake master cylinder system. In 1997, the system cost was $210.00.

View of the Pantera Performance system. Note the aluminum Pantera Performance Center adapter between the brake booster and brake master. The master is a Bendix 1" bore for four-wheel disk brakes (no residual pressure valve). With this system it is important to make sure that the spare tire cannot contact the brake lines.

The system has worked very well, but a few years ago, I had a brake problem and wanted to replace the master as part of the trouble shooting process. I contacted Pantera Performance Center and discovered that they no longer sold the aluminum Bendix master cylinder.

I spent a lot of time trying to locate a source for the aluminum master without success and ended up using a new castiron Bendix that had the same specifications. It turned out that the problem was not caused by the master so I just left the castiron unit in place and stored the original aluminum Bendix.

Recently, the castiron unit started weeping brake fluid from the back seal. Not wanting to get brake fluid in the brake booster, I pulled off the master cylinder right away. I disassembled, flushed out, and inspected the original aluminum Bendix master that I had stored away. The bore and everything looked really good so I reinstalled it.

The original Bendix works great but I decided it would be nice to have a spare aluminum Bendix on the shelf. After my last hunt for an aluminum Bendix I knew it would take a lot of research to find the one I wanted.

After a lot of searching and emails to manufacturers, I discovered that the remanufactured A1 Cardone 10-1518 met my specifications and often were aluminum, but not always. Apparently an aluminum 10-1518 is dependent on cores being remanufactured at any given time by A1 Cardone. I located one at O'Rielly Auto Parts by phone, and had them check the box. It was aluminum and on sale for the absurd low price of $14.99, plus a $2.00 core charge.

View of the A1 Cardone 10-1518. If you buy the A1 Cardone 10-1518 you will need to check the box to verify the casting material because there is nothing in the part number that denotes aluminum.

View with the adapters installed and I replaced the top and retainer wire with the nice shiny one that was on my castiron Bendix.

What is most amazing about this particular A1 Cardone remanufactured unit is the casting is a Bendix casting with the same 3560 number stamped on the front end as my original! I'm not sure if, or when, I will need the unit but it has a limited lifetime warranty through O'Rielly Auto Parts.

Pantera Performance Center recommends adjusting the brake booster push rod so that the master has .015 to .030 pre-load. Too much pre-load and the bakes will not release or drag (sometime this does not happen until the brakes are hot) because the fluid cannot return to the master reservoir after the brakes are applied and no preload or free play creates lost movement in the brake pedal action. Best to be on the safe side and use the smallest preload. Preload means that the piston in the master is pushed forward slightly when the master is bolted tightly to the adapter.

The Pantera Performance recommended pre-load is for this master cylinder, other master cylinders may have different clearance space between the intake ports and the front edge of the piston seals, so be very careful pre-loading the master. Most master cylinder manufacturers recommend NO pre-load, but in a Pantera that adds unwanted extra brake pedal movement. The adjustable push rod connects between the adapter mechanism and the brake booster and is accessible behind the adapter.

To test the preload, put the backend of the master into the adapter and lightly push the master backward toward the adapter front face. When the piston in the adapter contacts the master piston there will be resistance as the master piston is pushed forward. The gap between the front face of the adapter and the back face of the master mounting flange as the two pistons come in contact is the preload amount.

I find that it is easer to feel piston contact and measure the preload gap with no brake lines attached to the master. There is a rubber donut shaped seal behind the adapter that is part of the brake booster. When removing the pushrod to adjust the preload be carful that the seal is not damaged.

View of where the gap will be between the master mounting flange and the adapter front face when checking the preload distance. To make absolutely sure that the piston seals are not blocking the intake ports I use a piece 30lb plastic fishline that fits nicely in the intake ports as a feeler to make sure the ports are not being blocked or partially blocked by the piston seals with the brake pedal released.

Caution, whenever you work with brake fluid keep in mind that it will do a great job of taking paint off any surface it contacts.

When a brake master cylinder is installed it is critical that the master cylinder be pre-filled with brake fluid and all the air be be purged from the cylinder before it is connected to the brake lines. This process if often referred to as "bench bleeding". If this process is not done, there is a good possibility that air will be trapped in the brake system, and no matter how much bleeding is done at the calipers, air will be trapped in the system.

My preference is to "bench bleed" the master with it installed in the car. First, get the preload adjusted, then bolt the master to the adapter and with the brake lines disconnected perform the "bench bleeding".

There are a number of ways to perform the bleeding. My preference is to use bleeder plugs. Master cylinders are often supplied with plastic bleeder plugs that fit directly into the master, but because the Pantera uses brake line adapters, I have some 3/8-24 metal plugs that fit the adapters. After the bleeding is completed you will want to be able to quickly attach the brake lines and not mess with installing the adapters.

With the plugs in place, fill the front and back reservoir about 1/2 way with new brake fluid and place the cap on the cylinder to keep any fluid from splashing out of the cylinder. I also put some paper towels around the bleeding plugs just in case they might leak any brake fluid. Then with the engine off, press the brake pedal down about 2" and repeat the process slowly until the pedal resistance is firm. It takes quite a few cycles to purge all the air but eventually the pedal will not be able to move the master piston and will feel hard.

The next step is filling the reservoirs and connecting the brake lines. Remove one bleeder plug at a time, connect the brake lines and bleed the system at the calipers. If only the master was changed, the system may not need bleeding at the calipers.