Tilton Adjustable Brake Proportioning Valve

When I began regularly autocrossing my 128 Rally in late 2000, I had to change my rear disc brakes back to the original drum brakes to be legal for SCCA's Street Prepared class. After I put the drums back on, I discovered that they locked up easily under heavy braking. Apparently the stock rear brake compensator wasn't functioning. Instead of installing a new one, I opted to install an adjustable proportioning valve, so I could tune the rear brake pressure, and change it easily if conditions required a different pressure.

I looked at several different valves, and decided to go with the Tilton 7-position lever-type unit. It was the only unit I could find that used AN fittings. All of the others used NPT fittings, and I did not like the idea of using tapered fittings on the braking system. I chose the lever-type unit over a knob-type since the seven distinct positions would be easier to adjust and remember than trying to remember how many quarter turns of the knob equalled what change in pressure. The Tilton unit was more expensive than all the others, but it was worth the piece of mind, and Tilton makes excellent products.

I purchased my proportioning valve from Performance Bodies. They sold it for less than anyone else I could find.
www.performancebodies.com
Tilton Prop Valve PN#901000
$69.95
1-800-722-4641

Other parts required were two 3AN tube nuts (steel) and two 3AN tube sleeves (steel). I bought these from American Street Rod, who specialize in Earl's plumbing.
www.amstreetrod.com
Tube Nut, 3AN Steel (qty.2)
Tube Sleeve, 3AN Steel (qty. 2)

Here is the procedure I used to install the proportioning valve in my Rally:

1. Peel back carpet to expose brake hard lines. On my Rally, the rear brake lines ran through the passenger compartment, next to the driver's seat - a good place to mount the proportioning valve. That put it in easy reach while driving, and eliminated the need for any excess brake lines running to and from the valve and the hard lines. I propped the carpet out of the way to make access to the hard lines easier.

2. Cut hard line. After identifying which line went back to the rear brakes (on my '78 the line going to the 4-way "T" before the compensator was the bottom line of the two), I cut the line with a small pipe cutter. This was easier to do after I popped the line out of the plastic retaining clips. Careful not to kink the line!

3. Drain the brake fluid. There will be a lot of brake fluid in the brake fluid reservoir that will want to spill out into your interior. A drop or two might come out of the rear segment of the line, while the front segment will be emptying the contents of the brake fluid reservoir. Quickly attach a rubber hose and drain the fluid into a suitable container. A few paper towels or rags will help save your paint and interior from any stray drops of fluid.

4. Flare lines. Cut out about 3.25" of the steel line before flaring the lines. REMEMBER: put the sleeves and nuts on BEFORE you flare the lines. They won't fit on afterward! I almost forgot that myself... The lines were painted, so I had to strip off about a 2" section so I could slip the sleeve and nut on, while leaving enough room for the flare tool to operate. Instructions for the proper flaring procedure should accompany the tool. The tool I used was made by RIGID and was a breeze to use. Sorry, forgot to take a pic of this step.

5. Install AN fittings into proportioning valve. No need to use teflon tape or anything. Install them dry and tight and they won't leak.

6. Install proportioning valve mount. It is a good idea to have something rigid to mount the proportioning valve to. The valve can be either "frame mounted" or "bulkhead mounted." I chose to make a small block that would mount the valve to the inner rocker panel. I would have simply mounted the valve directly to the rocker, but the lever would end up hitting the door, so it had to be mounted vertically (it looks better mounted veritcally anyway). I machined a small block that would get bolted to the rocker; the valve would then get bolted to the block. I used Nutserts to mount the block to the rocker. They are like pop rivets with threads in them - very cool! A pair of button-head 1/4-20 cap screws screwed through the block into the Nutserts (used button-heads due to clearance issues). Then a pair of 1/4-20 cap screws secured the valve to the block.

7. Install proportioning valve. The hard lines may require a little tweaking to make them fit properly, but if you are gentle and are careful not to kink the lines, you should have no problems.

8. Refit carpet. I cut a small slit in the carpet around the neck of the valve. Looks like a factory install!

This page last updated: January 3, 2007
This page created: December 24, 2000

Courtney Waters courtney@mirafiori.com

Back to Court's Main Page

1. Peel back carpet to expose brake hard lines. On my Rally, the rear brake lines ran through the passenger compartment, next to the driver's seat - a good place to mount the proportioning valve. That put it in easy reach while driving, and eliminated the need for any excess brake lines running to and from the valve and the hard lines. I propped the carpet out of the way to make access to the hard lines easier.
2. Cut hard line. After identifying which line went back to the rear brakes (on my '78 the line going to the 4-way "T" before the compensator was the bottom line of the two), I cut the line with a small pipe cutter. This was easier to do after I popped the line out of the plastic retaining clips. Careful not to kink the line!
3. Drain the brake fluid. There will be a lot of brake fluid in the brake fluid reservoir that will want to spill out into your interior. A drop or two might come out of the rear segment of the line, while the front segment will be emptying the contents of the brake fluid reservoir. Quickly attach a rubber hose and drain the fluid into a suitable container. A few paper towels or rags will help save your paint and interior from any stray drops of fluid.
4. Flare lines. Cut out about 3.25" of the steel line before flaring the lines. REMEMBER: put the sleeves and nuts on BEFORE you flare the lines. They won't fit on afterward! I almost forgot that myself... The lines were painted, so I had to strip off about a 2" section so I could slip the sleeve and nut on, while leaving enough room for the flare tool to operate. Instructions for the proper flaring procedure should accompany the tool. The tool I used was made by RIGID and was a breeze to use.	Sorry, forgot to take a pic of this step.
5. Install AN fittings into proportioning valve. No need to use teflon tape or anything. Install them dry and tight and they won't leak.
6. Install proportioning valve mount. It is a good idea to have something rigid to mount the proportioning valve to. The valve can be either "frame mounted" or "bulkhead mounted." I chose to make a small block that would mount the valve to the inner rocker panel. I would have simply mounted the valve directly to the rocker, but the lever would end up hitting the door, so it had to be mounted vertically (it looks better mounted veritcally anyway). I machined a small block that would get bolted to the rocker; the valve would then get bolted to the block. I used Nutserts to mount the block to the rocker. They are like pop rivets with threads in them - very cool! A pair of button-head 1/4-20 cap screws screwed through the block into the Nutserts (used button-heads due to clearance issues). Then a pair of 1/4-20 cap screws secured the valve to the block.
7. Install proportioning valve. The hard lines may require a little tweaking to make them fit properly, but if you are gentle and are careful not to kink the lines, you should have no problems.
8. Refit carpet. I cut a small slit in the carpet around the neck of the valve. Looks like a factory install!