Tek Info
HOW THE KEWLTEK BRAKE SYSTEM WORKS
It is possible to add a right hand master cylinder and run hoses from it down to the front calipers and just stack the banjo connections at the calipers. Both master cylinders will drive the calipers but the problem with that system is that if you only actuate one master cylinder at a time you will just push the brake fluid from one master cylinder into the other one because the feed port in the other master cylinder will still be open to the reservoir. So that configuration simply does not work!
The Kewltek brake system uses a special control valve that has two inputs and one output. This valve keeps the fluid from each master cylinder completely separate so that it is not possible to pump brake fluid from one master cylinder to the other. It allows each hand master cylinder to be operated completely independently from the other or it allows them to be used together and the pressure, but not the fluid, from each will add together giving maximum braking power.
HOW HYDRAULIC BRAKE SYSTEMS WORK
Hydraulic brake systems are really quite simple. They consist of master cylinders, hoses, brake calipers and brake discs.
A hydraulic ATV master cylinder cross section is shown in the picture below. The piston moves when the brake lever is pulled. The piston pushes fluid out of the master cylinder and through the hoses into the calipers. When the master cylinder piston first moves about .04” the seal covers the feed port and closes the hydraulic circuit. As the lever pushes the piston further the fluid pushes the pistons in the calipers and they push the pads against the discs. When all of the play is removed from the system the pressure will build as more force is applied to the lever.
HAND MASTER CYLINDER SECTION
FLOATING CALIPER SECTION
FLOATING CALIPER FORCES
Brake calipers are a housing with a piston and slide pins. The fluid pushes the piston and presses the brake pads against the disc. There are two basic types of calipers, floating and fixed. Floating calipers are used on almost all ATVs. They have slide pins so that the body of the caliper can “float” side to side so that when the piston pushes on one pad the caliper floats and pushes on the other pad. This allows both pads to push on the disc equally using only one piston.
The seals in the caliper roll with the piston when the fluid pushes on it. When the pressure is released the seals roll back and pull the piston in slightly so that the pads do not continue to rub on the disc when the brakes are not applied.
There are different types of hoses on ATV’s. Originally they all used rubber hoses. Now many use Teflon tubing with a stainless steel braid over it and usually a vinyl cover over that. The advantage of the Teflon/stainless steel braid is that it expands much less than rubber and gives a better feel on the brake lever on most systems. They are also extremely durable. Kewltek Performance uses domestic Teflon/braided stainless hoses that have DOT approval.
BRAKE SYSTEM BLEEDING:
PURPOSE: The purpose of "bleeding" a brake system is to remove all of the air. Air is easily compressible but brake fluid is not. If there is air in the brake system the brake lever will feel “spongy” or soft and will travel more than it should when it is actuated. This can limit the ability of the brake system to function because very little pressure can be built up inside the system and so very little force will be applied to the brake pads in the calipers.
METHOD: To fill and bleed an ATV brake system manually do the following:
1) Ensure that hoses are installed correctly and that banjo bolts and tube nuts are torqued correctly.
2) Remove covers from hand master cylinder reservoirs.
3) Fill reservoirs with clean fluid from a sealed container.
4) Open the bleed screw on the control valve.
5) Tap on the right hand master cylinder and the hose with the plastic handle of a screwdriver and pull repeatedly on the lever. Bubbles will rise through the brake fluid as the air comes out of the system. Keep the reservoir nearly full. Continue until bubbles stop coming out of reservoir and only fluid comes out bleed screw in control valve.
6) Close the bleed screw in the control valve.
7) Pump the right hand lever several times and hold it. Then open and close the bleed screw in the control valve quickly to let out air bubbles. Repeat until bubbles stop and only fluid comes out. The lever will still feel soft because of air in the calipers.
8) Remove one mounting screw in each front caliper and loosen the other bolts to allow caliper to rotate so that bleed screw is at the very top.
9) Open bleed screws in front calipers and rear master cylinder.
10) Let fluid flow down from the left hand master cylinder until bubbles stop coming out of the bleed screws. Add fluid to the reservoir as necessary.
11) Close the bleed screws when bubbles stop.
12) Pump the left hand lever several times and hold it. Then quickly open and close the bleed screw in one caliper to let out air bubbles. Repeat for the other caliper and the rear master cylinder until bubbles stop and the levers are both firm. Repeat on right hand master cylinder if necessary.
SAFETY:
Use caution when working with brake fluid and follow safety instructions on container.
