Kart Brakes: How to Check and Replace the Pads
You are about to go out on track. Before getting into the kart, you push the brake pedal: a quick, almost automatic test. It is the check done by everyone who has already seen what happens when the brake does not respond as it should.
If the pedal is softer than usual, or gives too much before offering resistance, do not carry on. Kart brakes give no warning: they work until the pads are worn out, then they stop braking.
Checking the brakes is not advanced maintenance: it is the first thing to do before every session, even before tyre pressures or chain tension.
In short The kart brake is hydraulic, with the disc on the rear axle (on KZ and DD2 also at the front). The pads are checked before every session and changed when 2-3 mm of material is left; after every change the system must always be bled.
How the kart brake system works
The kart brake is a single-disc hydraulic system mounted on the rear axle. There are no front brakes (except in specific classes such as KZ or DD2).
The main components:
Brake master cylinder: operated by the pedal, it generates the hydraulic pressure.
Hydraulic line: transfers the pressure from the master cylinder to the caliper.
Brake caliper: squeezes the pads against the disc through one or more pistons driven by hydraulic pressure.
Brake pads: the friction material acting on the disc. They can be organic or sintered (copper/iron compound).
Brake disc: fixed to the axle, it brakes through the friction of the pads. On karts it is made of cast iron.
Brake fluid: the hydraulic fluid that transmits the pressure. There are two families incompatible with each other: glycol-based (DOT 4, DOT 5.1) and silicone-based. Never mix the two types: the seals get damaged and braking is compromised. Always check which type is specified by the manufacturer of your brake system.
When to check the pads
Pads wear with use. The check must be systematic, not only when you notice a drop in performance. Waiting to feel the problem on track means you have already lost control of the situation.
When to check: before every track session; after a race or a long session (over 40-50 laps); at the end of the season, before storage.
How to check: the brake caliper is directly accessible from the outside of the kart: nothing needs to be removed for a visual check. Look at the pads from the side of the disc: the friction material must have visible thickness. When it is down to 2-3 mm, it is time to replace them. Do not wait for the metal to touch the disc: you will ruin the disc, which is much more expensive than the pads.
How to replace the pads
The caliper is mounted on the bearing flange of the rear axle and is directly accessible: there is no need to remove the wheels. The procedure requires few tools: pliers, a flat screwdriver, a rigid flat tool to push back the pistons, a cloth for the fluid reservoir and a bleeding kit (strongly recommended after every pad change).
1. Put the kart on the stand
The wheels stay on. Work with the rear axle free.
2. Open the brake fluid reservoir
Open the cap and place a cloth around the opening. When you push back the pistons, the fluid will rise: if the reservoir was full, it could overflow.
3. Remove the screws and the retaining pin
The caliper is held closed by one or two screws and retaining pins. Pull them out by hand or with pliers.
4. Remove the worn pads
Slide them out of their seat. If they resist, the pistons are still extended: carry out step 5 first.
5. Push back the pistons
With a rigid flat tool, push the pistons back into the caliper body. This creates room for the new pads, which are thicker than the worn ones. Check the reservoir: if the level rises too much, draw off a little fluid with a syringe.
6. Insert the new pads
Slide them into their seat. The friction faces must face the disc. Check that they are correctly positioned.
7. Refit the screws and retaining pins
Put the pins back in their seat and make sure they are fully inserted and locked. Refit the reservoir cap.
8. Bleeding is mandatory
Pushing back the pistons can introduce air into the hydraulic circuit. For this reason bleeding is mandatory after every pad replacement, not optional. Bleed the system as described in the next section before going out on track.
9. Bedding in
After bleeding, make 2-3 progressive stops at moderate speed before using the brakes hard: this lets the new pads bed in on the disc.
Bleeding the brake circuit
Bleeding is needed in two situations: after every pad change, and when the pedal feels spongy while driving.
The reason is simple: over time brake fluid absorbs moisture (if glycol-based) or degrades, lowering its boiling point. Under hard braking the fluid can reach critical temperatures and form vapour bubbles. The pedal goes to the floor with no response: the so-called spongy brake.
How to bleed: connect the special column tool with its fluid reservoir, connect a small tube to the bleed screw on the caliper and put the other end into a syringe. With the syringe, draw the fluid while opening the bleed screw: the old fluid with the bubbles comes out. Close the bleed screw, top up the reservoir and repeat until the fluid is clean and free of bubbles. Alternatively you can work in pairs (one operates the pedal, the other handles the bleed screw), but on your own the syringe works just as well.
Top up the reservoir with new brake fluid of the same type already in the circuit. Never mix different families.
Checking the brake disc
Flatness: place a dial gauge on the braking surface and turn the disc. The run-out must be less than 0.1/0.3 mm.
Minimum thickness: the minimum thickness is often engraved directly on the disc. When the remaining thickness reaches it, the disc is replaced.
Cleaning: the disc can get dirty with oil, grease or rubber residue. Clean it regularly with a specific brake degreaser. Never use lubricants near the brake system.
Caliper: clean it with compressed air and degrease the areas where the pistons slide. If the pistons resist, the caliper needs overhauling.
We see it often: clean discs, new pads, but the brake is still spongy. The cause is almost always air left in the circuit after a pad change done without bleeding. It is the most repeated mistake, and it is only solved by a complete bleed.
Frequently asked questions
How do you check kart brake pads?
The caliper is directly accessible from the outside, without removing the wheels. Look from the side of the disc: the friction material must have visible thickness. When it is down to 2-3 mm it is time to replace them. In Arrive & Drive sessions TKS RaceLab checks the pads before every outing: it is one of the safety checks.
Is bleeding mandatory after changing the pads?
Yes, always. Pushing back the pistons to make room for the new pads can introduce air into the hydraulic circuit. Air in the circuit causes a spongy pedal and unpredictable braking. It is not optional: every pad change must be followed by bleeding before going out on track.
Which types of brake fluid are used on karts, and can they be mixed?
There are two incompatible families: glycol-based fluid (DOT 4, DOT 5.1) and silicone-based fluid. They must never be mixed: the seals get damaged and braking is compromised. Always check which type the manufacturer of your brake system specifies before adding fluid to the circuit. At tksracelab.com you will find compatible brake fluid for the main kart brake systems.
When should the kart brake disc be replaced?
When its thickness reaches the minimum value engraved on the disc itself. The disc must also be cleaned regularly with a specific brake degreaser: grease or oil on the disc compromises braking immediately. At tksracelab.com you will find brake discs and degreasers compatible with the main kart chassis.
Want to learn brake maintenance right at the track? With our Arrive & Drive you get the kart, the track and the technical support of the TKS RaceLab team, at Lonato, Franciacorta, Cremona and Ala.Discover Arrive & Drive →
🛒 Brake pads, brake fluid, discs and maintenance kits available in our shop: tksracelab.com
Conclusion
Brakes are safety even before performance. Replacing the pads is not complex (the caliper is directly accessible, without removing the wheels), but it must be done methodically: new pads, mandatory bleeding, progressive bedding in.
Questions about this topic?
Message us on WhatsApp: we answer personally, with the experience of people who live at the track. And if you want to drive a real racing kart, with Arrive & Drive you get into one of ours, ready on track. The right spare part? You will find it in the shop.
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Read also: Kart brake bleeding: the step-by-step guide → · Arrive & Drive: how to try a real racing kart without buying one → · Kart axles: complete guide to choice, setup and replacement → · Karting tyre pressure: grip and lap time → · How to change a kart axle → · Caster, camber and toe on a kart →
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Author: Sergio, TKS RaceLab | Published: 10 June 2026 | Updated: 4 October 2026
TKS RaceLab is the Italian online store dedicated to karting: spare parts, accessories and everything you need to get on track. With Arrive & Drive you arrive at South Garda Karting (Lonato), Franciacorta, Cremona or Ala and find your kart ready to go. No hassle, just driving.
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