Below are some pictures of a disassembled master cylinder from a wrecked 2004 ford crown victoria police interceptor without traction control.

The cup seals inside the master cylinder are constructed of EPDM (Ethylene Propylene Diene Monomer) rubber. This material works good with glycol based brake fluids, but make sure not to expose the seals to petroleum oils.

Here is a closeup of the primary and secondary pistons from inside the master cylinder.

Here's one of the bendix branded cup seals removed from the piston. The spring on this piston came off without any special tools.

However, the other piston had the spring retained to the piston using a retainer plate and long phillips head screw.

The master cylinder housing from the top where the reservoir would normally be installed. Take note of the inlet and compensating ports.

Here's where brake tubing would normally connect

This is the end of the master cylinder that would normally be connected to the brake booster. The snap ring and pistons have been removed.

Do note that this is an anodized aluminum bore and you won't get a good service life out of the master cylinder after overhaul if you attempt to hone out the bore. Commercial remanufacturers of late model aluminum master cylinders install stainless steel sleeves instead of honing. Honing works good on older cast iron master cylinders, but not the recent aluminum ones.

A couple closeup pictures of the inlet and compensating ports.

On the side of this master cylinder is a bleeder valve like you'd find on the brake calipers. This part is only present on master cylinders for crownvics without traction control. Crown victorias with traction control use a different master cylinder that doesn't have this part.

Also shown in this picture are the two seals that are normally installed in between the aluminum master cylinder and the nylon reservoir. One of the seals got a portion torn off when a long prybar was used to remove the reservoir. Large amounts of force were required to remove the reservoir which is a good thing because you don't want this part accidentally falling off while you're driving your car.

Here's the reservoir from the top. The yellow part is a float that will bottom out and magnetically enage the brake warning light on your dashboard when the brake fluid is really low.

This blurry picture is the reservoir from the side.

Here are the two pistons from inside the master cylinder next to the pistons from crownvic brake calipers for size comparison. The size ratio between the master cylinder pistons and the slave cylinder pistons (brake caliper pistons) is very important in determining how much force is applied to the brake pads when you depress the brake pedal inside the car.

Here is part of my solution to get the pistons out of the master cylinder. At first, I tried using my fingers to cover the reservoir ports while compressed air was inserted via the brake tubing ports. But this didn't work well. So I covered the reservoir ports with some duct tape, and the pistons popped right out after blowing some compressed air in.

Here are the brake line tubing nuts and a small portion of brake line which would normally connect to the master cylinder.

These are metric iso bubble flares rather than sae double flares like you'll find on many older vehicles.

Starting in the 1998 model year, ford introduced black plastic coated brake lines to slow brake tubimg corrosion. This polyvinyl fluoride coating works well and many crownvics make it over 10 years without any corrosion related brake line ruptures. But as you can see, this coating can be removed from abrasion which exposes the raw metal tubing underneath.

All 2003-2010 crown victorias have M10x1 and M12x1 tubing nut ports on the master cylinder. There have been scattered reports of some aftermarket master cylinders manufactured with improper diameter or improper thread pitch ports which could really complicate a master cylinder replacement project.

Some people may notice that there is no proportioning valve present here. This is because in the 2001+ crownvics with antilock brakes, front/rear proportioning is controlled by the antilock brake controller electrically pulsing the rear brake valves to reduce pressure as needed. Ford calls this technology EBD (Electronic Brake Distribution). The 1996-2000 crownvics still had a mechanical proportioning valve inserted into one of the master cylinder ports though.

Ford Service Part Numbers:

Part Number
6W1Z-2140-AA Master Cylinder for 2003-2010 Crown Victorias WITH Traction Control
Also used in 2001-2002 Crown Victorias With Antilock Brakes AND With Traction Control
1" Piston Bore Diameter
M10 x 1 Brake Pipe Port
M12 x 1 Brake Pipe Port
Replaces: 1W1Z-2140-AA
6W1Z-2140-BA Master Cylinder for 2003-2010 Crown Victorias WITHOUT Traction Control
Also used in 2001-2002 Crown Victorias With Antilock Brakes AND Without Traction Control
1" Piston Bore Diameter
M10 x 1 Brake Pipe Port
M12 x 1 Brake Pipe Port
Replaces: 1W1Z-2140-BA
Master Cylinder for 1997-2002 Crown Victorias WITHOUT ABS Anti-Lock Brakes
11/16" Piston Bore Diameter
M10 x 1 Brake Pipe Port
M18 x 1 Proportioning Valve Port
Proportioning valve has M12 x 1 Port where Brake Pipe Connects

Master Cylinder Reservoir for 1997-2010 Crown Victorias WITH Traction Control
F7AZ-2K478-BA Master Cylinder Reservoir for 1997-2010 Crown Victorias WITHOUT Traction Control

Master Cylinder Aluminum Body->Reservoir Seals

Master Cylinder Reservoir Cap for 1995-2010 Crown Victorias WITH Antilock Brakes