Mount the Master Cylinder
- Position the bolts through the body of the master cylinder and align it with the mounting bracket plate on the frame, placing spacers between the master cylinder body and the frame plate.
- Firmly secure M6 nylock nuts and tighten the master cylinder to the frame.
Step 1: Install Brake Line to Master Cylinder
- Take the connection bolt with washers on either side of the banjo fitting to secure the single end of the brake line to the master cylinder using a 13mm wrench. Pro Tip: Before installing, run the bolt through the master cylinder threads and remove it to clean them out, then install with fingers as far as possible before using the wrench to avoid cross-threading. Tighten by feel for a sealed connection with the crush washers (no technical torque spec).
- 1.1: Connect each side of the brake line to the rear caliper halves. Use a connection bolt and washers for each side, first running the bolt into the caliper threads and removing it to clear them, then installing with fingers most of the way before securing. Repeat for both sides.
- 1.2: Tighten both caliper connections completely with a 13mm wrench. Pro Tip: Use two washers on the backside of the banjo (between caliper and banjo) for proper spacing so the bolt doesn’t bottom out before crushing the washer. Use a small flathead screwdriver to keep washers centered while tightening for a sealed connection. Note: Unlike the video, thicker copper washers are provided, requiring only one washer per side of the banjo, not two on the caliper side.
- 1.3: Using a 6mm wrench, gently tighten the two bleeder screws on each side of the caliper. These threads are small and delicate—tighten by hand until snug, then use the wrench for a slight additional turn. Do not overtighten to avoid stripping the threads, as this cannot be undone or fixed.
Step 2: Prepare Gravity Bleeder Tool
- Unscrew the brake bleeder cap and pour DOT 4 brake fluid into the reservoir, filling it to about 80% to provide sufficient fluid weight to push through the system.
- 2.1: Crack open the valve to allow a steady stream of fluid to run through the bleeder, holding it over a trash can to catch the fluid.
Step 3: Install Gravity Bleeder Tool and Run Fluid Through Lines
- Use a 5mm Allen wrench to remove the master cylinder cap bolt, then screw the gravity bleeder tool into place, ensuring a solid connection (it should stop turning when secure) to prevent air entry. Remove the top cap of the gravity bleeder tool as well.
- 3.1: Open the valve of the gravity bleeder tool.
- 3.2: Standing behind the kart, loosen the rightmost upper bleeder screw with a 6mm wrench. Fully remove the screw and allow fluid to flow steadily out of the caliper for 5–10 seconds (it may take 10–20 seconds initially for fluid to appear).
- 3.3: Reinsert the bleeder screw and tighten lightly with a 6mm wrench, as in Step 1.3, to avoid stripping threads.
- 3.4: Repeat the process from sub-steps 3.2 and 3.3 on the left half of the caliper.
Step 4: Purge Remaining Air from Line and Master Cylinder
- After removing air from the caliper side, turn the bleeder valve shut.
- 4.1: Use a 2.5mm Allen wrench to remove the top plate screws of the master cylinder reservoir.
- 4.2: Lift the cover and rubber seal off the top and place them on the floor pan temporarily.
- 4.3: Slowly crack open the gravity bleeder valve until fluid fills the reservoir about halfway, then close the valve.
- 4.4: Slowly move the master cylinder lever back and forth 5–10 times to release any remaining air bubbles from the master cylinder or line. Once no bubbles appear, reinstall the rubber cover and top plate, then tighten.
- 4.5: Crack the valve open again and move the lever slowly 10–15 times to purge any remaining air into the gravity bleeder reservoir.
- 4.6: Shut the valve off, remove the bleeder tool from the master cylinder, then hover it over the hole and crack it open to fill the reservoir the rest of the way. Reinstall the cap and washer to secure.
Step 5: Check System and Confirm Brake Pressure
- Hook up the brake rod and pedal to the master cylinder lever and test the system to ensure it works. Pro Tip: After applying pressure, check all connections for leaks to prevent air entry, which would require repeating the process to remove air.
- 5.1: Once the system is complete and functioning, spray brake cleaner to remove fluid from the chassis frame. After cleaning, wipe WD-40 on the frame for protection.
