Brake Proportioning Valve - The Butler Mod

The “Butler Mod” Installation Instructions

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The components of this device are basically a Galfer steel braided brake line attached to a Speedway Motors compact adjustable proportioning valve (APV). The technical name for this is a “flow control valve” and it will allow you to "fine tune" the rear brake system and thus prevent severe rear brake lockup under moderate-to-heavy braking. If you can replace your OEM rear brake line with a steel braided replacement brake line then you can easily install this line.

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So let’s start first by evacuating the brake fluid. Take the lid off of the reservoir and then either use a MityVac at the bleed valve on the caliper to suck out the fluid or attach a clear hose that will empty into a bottle or other container, and pump the brake pedal until the reservoir is empty. Now you can disconnect the brake line from the caliper and the master cylinder. At the caliper, remove the 12mm banjo bolt and use a rag to catch and brake fluid drips. Where the line goes toward the master cylinder, you will see one hose clamp on the side of the swing arm and then another on the underside of the frame next to the AIS valve. Use an 8mm socket to remove these clamps. The hose now goes forward toward the engine behind the horn on the right side of the engine. Remove the horn so you can get to the frame hose holders, where the one to the left is up under the frame swing arm housing. This spring-like holder is not removable where the rubber line grommet can be pushed out away from you. The second line holder is a heavy round rubber grommet that is held by a frame holder that looks like a large wire. You can grab the end of this wire holder with a set of vise grips or pliers and pull the end open to where this circular grommet will slip loose. Then when you put it back in with the new line you can take a flat blade screw driver and press the end closed to tighten up on the grommet.

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One quick note on assembly. When you take this line out you will find 3 flat rubber grommets and one thicker circular one (above), all of which can be taken off and used on the new line. Just slit one side and then just peel it off the rubber brake line. The replacement steel line is a smaller diameter, so just cut about ¼” off one end and then place it on the new line and wrap it with a couple of wraps of electrical tape.

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Now you are at the frame line cover just under the right foot board. This cover is taken off by removing the two 8mm bolts that attach this cover. You now are at the adapter going into the master cylinder. The short adapter that goes into the master cylinder is a spinning collar and when the line is held by a 14mm open end wrench, you can loosen this collar with another 14mm open end wrench and it’s off. Now when you put the cover back on when you are finished, it works better if you cut the front part of the cover back 1”. You can see from the picture below that you cut it down to about 3/8” from the bottom and then across from the front mounting hole. This cutout allows room for the line coming out of the valve so that there is no pressure on this connection.

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Now you are ready to install the new line. For now just work with the line off of the valve and start by threading the line back toward the rear from the horn area at the rear of the engine. Remember there are two flat rubber grommets that go on the swing arm with one flat one that will slip into the spring holder and the round one into the wire holder, where you can press it in to hold the grommet. Once you get the line threaded through to the caliper, attach the 30 degree end to the caliper and tighten the banjo bolt with new copper washers on both sides of the line banjo hole. On the rear line, I usually use the stock steel banjo bolt just because it’s stronger than the brass one that comes with the line. That way you can torque the bolt to 20ft/lbs (the manual says 22ft/lbs which I haven’t been comfortable with). Now attach the two line holders on the swing arm.

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Don’t put the line cover on until you are finished bleeding the line and making sure there are no leaks. Next attach the proportioning valve to the master cylinder by threading the spinning collar on the master cylinder to the front adapter with the knob turned down toward the ground. The adapters on the valve side with the copper washers are already tightened. The end that goes into the master cylinder is the adapter with the course 10mm X 1.25 pitch thread.

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Just snug this spinning collar to the point that if feels firm. Now thread the end of the line to the output side adapter on the valve and snug it up. Now with a 16mm open end wrench, hold the valve and with a 14mm open end wrench tighten the collar on the master cylinder until it feels tight. Do the same thing to the spinning collar on the line end. The threads on the line collar are a finer thread so do not over tighten.

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Now it’s time to bleed the line, but first open the knob on the valve all the way open by turning it counter clockwise (like a faucet). I usually use a MityVac at the caliper bleed valve to get the fluid started to the caliper. Then I use the conventional method of (1) closing the bleeder (2) pumping the pedal a few good times (3) hold the pedal down (4) release the bleeder to let fluid through and then (5) close it. Now go back to (1) and start over until all the air is out of the line and the pedal feels good and firm. Now check the spinning collars at the valve to see if any fluid is seeping at the connections. If so, snug them up just a bit more being careful not to strip a thread. Wipe the fluid that has seeped and then pump the pedal hard and let it sit for a few minutes to see if it is still seeping. Once you are assured there are no leaks, attach the line cover.

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Now turn the knob clockwise until it stops. At this point the valve acts like a shutoff valve, so turn the knob back out two turns. You can see the color rings under the knob, which indicate how many turns you have made. If you see 2 colored rings, then the knob is two turns out. This is only a starting point because from here you need to take the bike for a ride on a good concrete surfaced street to test the braking. It’s best to use a street with not much traffic on it Get up to say 40mph or more and gently apply the brakes pressing down more and more until (1) the bike comes close to stopping or (2) the rear wheel locks up. If it locks up, release it quickly. The latter condition means that you need to close the valve more by turning it clockwise. Adjust the valve to the point that you feel comfortable with the amount of braking resulting from how far you have to push down on the pedal. When it is right, you should be able to come to a complete controlled stop at 30-40mph with just the rear pedal. Of course remember that it’s very important to use both brakes when stopping, so in addition to the rear brake, be sure to apply an ample amount of front brake to help slow the bike down the most. But I have found that just as you are coming to a complete stop, release the front and use only the rear brake to come to that complete stop. Sometimes when you use the front brake at a complete stop, it may off balance the bike as you are putting your foot down. The rear brake now becomes more settling and comfortable at stops. Once you are comfortable with the feel, it’s time to lock the knob down. I first did this with a piece of safety wire which worked well but required a small hole be drilled through the knob. But since I started working with this valve, I have found the product information on this valve from the manufacturer (Deltrol Fluid Products) where it described a set screw in the side of the knob that could be used to lock the knob in place. This set screw can be turned in with either a 1.5mm or 1/16” hex allen wrench and will keep the knob from backing off. However, I still have drilled a small hole in the knob and have included a piece of safety wire as a secondary safety measure to make sure this knob stays where you have set it.

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If you have any questions concerning this installation, you can reach me by either e-mail or phone:

Rick_Butler@verizon.net

972-442-9840 Home

214-926-3905 Cell