1996 - 1997 Ford F6SC-2B091-CA Proportioning Valve Rebuild

This document describes how to rebuild the 1996 - 1997 Ford Thunderbird and Mercury Cougar brake pressure control valve (marked F6SC2B091CA) using a new seal kit available from Muscle Car Research LLC.  Tools needed:

  • 7/8" socket or box wrench
  • Ball peen hammer
  • Dental pick
  • Long thin punch (or other tool to push with)
  • Clean brake fluid
  • Liquid ammonia or similar degreasing cleaning fluid
  • Fine steel wool
  • Thin brass bore brushes
  • Rubbing alcohol
  • Cotton swabs

The rebuild kit provided by Muscle Car Research LLC includes the following parts:

  • O-ring seals
  • Retaining rings
Arrange your valve, tools, and rebuild kit on a clean work surface. Let's get started! The first step is to inspect the valve and make sure that the exterior is undamaged. Check the port threads for damage. Make sure the body is securely attached to the mounting bracket. A loose mounting bracket can be tightened up by lightly tapping the mounting tab with a ball peen hammer. If any of the port threads are stripped or damaged you're better off finding another valve. If your valve passes the exterior inspection you're ready to disassemble it and inspect the internal parts.
Disassemble the valve as described in our 1996 - 1997 Ford F6SC-2B091-CA Proportioning Valve Autopsy article. Soak the metal parts for a few hours in a container of liquid ammonia or other cleaning fluid. Ammonia can damage plating, so be careful not to soak the parts for too long! Remove the parts, flush with water, and polish with steel wool. Clean the bores of the valve with the bore brush and make sure that the bores are perfectly clean - any dirty residue that lingers in here can cause a leak! Finish cleaning the parts using alcohol and cotton swabs.
Rust can be removed from the bracket with a wire wheel, bead blasting, or chelation, but note that abrasives will remove the original zinc dichromate plating. Rinse the cleaned parts with alcohol when finished. Lay out the clean parts and your rebuild kit. Please note that I'm only showing the rebuild of one of the two valve assemblies. They are identical except for two large o-rings that I'll describe later in the rebuild process.

Let's start with the red piston. It uses the smallest of the o-rings.

Lubricate the o-ring with brake fluid and install it onto the groove at the end of the piston.

The metal cup comes next. It requires two o-rings: the larger of the two small o-rings and an o-ring with a very thin cross-section.

Push the smaller o-ring into the indent inside of the cup. The other o-rings fits into the groove on the outside of the cup.

With the o-rings installed we can now start to put things back together. Note the relationship of the parts to each other.

Install the red piston with the o-ring end installed towards the small fluid port at the end of the valve body.

​Install the large spring.

Install the metal cup with the open end facing you. The red piston should just fit into the bottom of the cup. It might push the o-ring out a little. Push the o-ring back into place with your dental pick as needed.

Install the plastic spacer with the circular ridge facing you. That ridge helps keep the smaller spring in place.

Insert the smaller spring, small end down.

Install the retaining ring. You need to push it into place so that it bends slightly and locks against the inner wall of the valve. The open end of a small socket can be used as a driver, but you can also use your pin punch or the open end of a nut driver. Any circular tool should be just slightly smaller than the inside diameter of the valve.

Install the two large o-rings. Note that the rebuild kit includes 4 large o-rings of different sizes. The two valves have different diameters above the threads and over the weep hole. The largest o-ring will fit over the "large" valve's weep hole. The "large" valve uses the third largest o-ring to seal above the threads. The "small" valve uses the second largest o-ring to cover the weep hole and the fourth largest o-ring to seal above the threads.

Screw both valves into the valve body and the rebuild is complete! Sorry, I didn't take a picture of the finished assembly.

Now you can reinstall the valve in the car and reconnect the brake lines to the valve. Start each line by hand as best you can to ensure that the fittings are threading in straight and smooth. Be careful - it's easy to cross-thread the fittings. Tighten each fitting with a flare nut wrench. You may need to tighten, loosen, and retighten each fitting multiple times to obtain a leak-free seal. Add brake fluid, bleed the brakes, and check for leaks.