I have to mash on my brake pedal to get any sort of stopping power. Do I need to bleed my brakes to get a firm pedal again?
If you're dealing with a poor or inconsistent feel on your brake pedal, you've stored your kart vertically, or you have a new race weekend coming up, we recommend bleeding your brakes. Also, your fluid could get dirty if you've experienced extremely hot conditions. At that point, it's a good idea to flush fresh fluid through the lines.
What you'll need
To begin the process, you'll need four tools (figure 1.1).
- Brake Bleeder
- 5mm Allen key
- 10mm wrench (possibly 8mm depending on your manufacturer)
- Recovery tank and hose
Of course, you'll also need brake fluid. We use DOT 4 in our video, but DOT 5 could also be used if recommended by your manufacturer, dealer, or mechanic.
You'll begin by identifying your master cylinder and your rear caliper; this is where we'll be doing all of our work. Remove the fill plug on your master cylinder with the 5mm Allen key and screw in your brake bleeder until it's a nice solid fit (figure 2.1). Some master cylinders could come with two fill plugs. In that event, you'll want to remove both of them.
Now you can open the check valve on the brake bleeder to begin releasing the fluid. You'll also want to vent the bleeder as well using the cap at the top. As the fluid releases, now you need to identify the bleed screws on your brake caliper. This is where you'll create the pressure in your brake lines. There may be one or two bleed screws, and they may be on the top of bottom of your caliper, so check carefully.
Your recovery tank and hose now come in to play. Put your wrench on your bleed screw, followed by the hose of the recovery tank. As you unscrew your bleed screw, the hose will now catch most of your fluid that comes out (figure 3.1). This helps keeps your pit space clean and the possibility of corrosion limited.
At first you'll see some air bubbles comes up with the fluid. You may have to wait a minute or two, but once those air bubbles are gone and the fluid is solid, tighten your bleed screw back up. If you have two bleed screws, do that to both.
The finishing touch...
After both bleed screws have been bled and tightened, now you can go ahead and shut off your valve on the brake bleeder. Unscrew it from the master cylinder and replace it with the fill plug. The fill plug should have a rubber o-ring that will give it the proper seal, so keep that o-ring maintained if it somehow gets damaged. Now you may check the brakes by pushing down on the brake pedal. You should have a solid feel.
If your chassis comes with a self adjusting brake system, you're going to have a recovery tank on the master cylinder. Most newer chassis have this and you'll want to check the level of fluid in that extra reservoir. To do so, unscrew the cap, washer, and rubber gasket, and look to see how much fluid you have. You don't want the fluid all the way to the top to compensate for the displacement of the gasket, washer and cap, but you should have some fluid in there. If it's empty or low, use your brake bleeder to fill it up a bit (figure 4.1).
- Screw your brake bleeder into your master cylinder fill hole; open the valve and vent the top to release fluid. (figure 2.1)
- Put your wrench and then the hose of your overflow bottle on the bleed screw on your brake caliper. Unscrew bleed screw.
- Bleed the brake fluid until air bubbles no longer present. Tighten screw and repeat for second bleed screw if applicable. (figure 3.1)
- Close valve on brake bleeder and replace with the fill plug.
- If applicable, fill the recovery reservoir on the master cylinder slightly using the fluid from the bleeder. (figure 4.1)