KZ Braking Is Different: Front Brakes, the V Line and Engine Braking

If you want to feel what it really means to brake into a corner, you have to try a KZ. The KZ has front brakes, and every other single-speed kart on earth does not.

That one difference changes almost everything about how you approach a slow corner, and it catches out nearly everyone who moves up.

Why KZ is the only kart left with front brakes

It wasn't always like this. I drove with front brakes up until 2014, in a category called KF2, and it was really cool. You had a very light kart, around 150 kg minimum weight, and the brakes were genuinely effective because you had both fronts and rears.

But you didn't operate the fronts with your foot. You braked with a lever on the steering, on the right, almost like the clutch you have on a KZ except at the other end. You had to physically press it.

KF2 was the last single-speed class to use front brakes. So why did they go away? I'm not completely sure, but what I was told is that it came down to weight.

The whole front system, discs and calipers and everything, is about three kilos. For drivers already on the edge of the minimum weight, that was enough to make the category unusable for them.

So the brakes went. And now, if you want to experience karting with front brakes, the only kart you can get is a KZ.

The numbers, and why the brakes aren't optional

Let me give you my own figures. Last year I drove the CIK-FIA World Championship at Franciacorta, where I qualified P2 and ran P2 in the super heat. I was strong all week, though in the final I was involved in a crash at turn one on lap one. That's racing.

What I remember from the data is pulling 1.8 to 1.9G braking for turn five and turn thirteen, the last hairpin. That's high. When the track isn't grippy and the tires are gone, you probably won't see anything above 1.6 or 1.7G.

What moves that number, roughly in order:

• Track conditions on the day.
• The state of your tires.
• Your brake system above all: are the pads new or finished?
• Chassis grip. A low, well-supported rear end gives you the confidence to brake late and hard.
• You. You have to trust the brakes enough to stamp them and hold them.

Now consider the weight. KZ2 runs 175 kg. KZ, which used to be called KZ1, runs 170 kg. A junior kart is 145 kg and a senior is 150 kg, so you are carrying 25 to 30 kg more, arriving faster because you have gears.

High approach speed plus high mass means you need to actually stop the thing. If you try to do it on rears alone, or fronts alone, it simply will not stop. It feels like it isn't stopping, and that gets close to dangerous.

That double problem is, I suspect, the real reason front brakes exist in KZ at all. You can adjust the balance between front and rear, and that balance is a genuine setup tool, but you need both ends working.

One thing that surprises people coming from watching cars: you almost never truly lock a front tire in a kart. In Formula 1 you see the white smoke. In karting it's rare. What you get instead is vibration through the front, which is upsetting in its own way. Actual front lock-ups happen in the wet, or on a formation lap when you're braking hard to build temperature, but not in an average racing lap.

The V line: the part that catches everyone out

Here is the technique change that matters most. To use front brakes you have to be straight with the steering, and you cannot be straight if you are running the wide, rounded line that works in a single-speed kart.

So in slow corners you make a V. Not a V in the speed trace, a V in the line:

• Come in nice and wide at the beginning of the corner, same as always.
• Then point at the apex and travel toward it almost in a diagonal, rather than arcing round.
• That diagonal is what keeps the steering straight enough to trail the front brakes deep, without unsettling the kart.

And the exit works the same way. In hairpins you also come out on a diagonal, because you have to use that torque and traction. If you run the rounded single-speed exit line in a KZ, the sheer torque gives you push understeer and you simply cannot get the corner done quickly. You have to straighten the kart properly to put the power down.

Single-speed karting is about momentum and keeping the RPM up. KZ is a different animal. You attack the entries, rotate, and then get straight so you can use the power.

Two warnings, though. First, don't overdo it. There is a limit to everything, and an extreme V costs you more minimum speed than the braking gains you back. The goal is a sweet spot between the two, and every corner and every track wants a slightly different answer. Second, it's slow corners only.

Fast corners: no change. Driving a KZ and driving a senior kart through a fast corner is pretty much identical, because you aren't using the brakes much and the torque advantage doesn't count for as much at high revs. Medium corners: no change either. You open the entry like a single-speed kart. It's specifically the slow corners that need the V. Sorting out which is which is what corner types are for.

Engine braking is part of your braking

The other thing that separates KZ is that the gearbox helps you stop. Downshifting aggressively gives you real deceleration on top of the pedal.

This is a bit of a taboo subject. Some teams and engine tuners don't want you downshifting hard; others don't mind at all. I'm not talking about how many gears you take, but how aggressive the engine braking is. Personally I like to be on the high end of it.

You can brake one or two meters later just by using your downshifts properly. And it sounds fantastic, the engine roaring behind you while you do it.

It's especially useful in the wet, where you can downshift fast, over-rev slightly and pull a lot of speed out of the kart when there's no grip to brake against. Going from second to first is where you really feel it, almost as though the engine is doing the last phase of braking for you.

But be careful, because there are two costs. It's harder on the engine, the gearbox and the crankcase. And every aggressive downshift partially locks the rear tires, which overheats them. Early in a run, when you want temperature, that might be a bonus. Later on it's too much locking, and it costs you stability and lap time.

The rule of thumb that tells you something is broken

Here's a diagnostic I use constantly, and it's worth stealing.

If I find myself relying too much on the engine braking, something is usually wrong somewhere else.

Work down the list: the brakes aren't biting, which usually means the pads are finished or there's air in the system that needs bleeding. Or the kart's grip level isn't enough to let me stop. Or it's simply the track that has no grip.

The wet is the honest exception. There, you genuinely do lean on engine braking, because there is barely any grip and gluing yourself to it is one of the only ways to slow down. But on a dry day, creeping engine-brake dependence is a symptom, not a technique.

What about DD2 and the other shifters?

Rotax DD2 has front brakes too, and two gears. I've never driven one, but from what I hear it sits between a single-speed kart and a KZ: more powerful than a senior, and fun. My guess is you wouldn't need to V the corners nearly as much, and you'd drive it smooth with open entries and exits like a single-speed kart, but with the ability to brake really deep because the fronts are there. X30 and Rotax both have shifter versions as well.

Moving up: how to actually learn it

The question I always get from drivers coming out of an X30 or Rotax senior is what they should do first. Honestly, the answer is that you go out and experience it, the same as anything worth learning.

Focus on the V-shaped line on the brakes, because that's the genuinely new skill. Watch onboard videos and race footage on YouTube to get a sense of where the lines go. Then record your own onboards and your telemetry, and go looking for the specific things:

• Am I actually braking late?
• How hard, in G, and how does that compare to my own best laps?
• Am I holding the brakes, or releasing the moment I turn? That's the coasting habit and it's expensive here.
• How much of my deceleration is the pedal and how much is the gearbox?

You can see all of it in PURPL if you connect your MyChron directly. The braking section gives you peak G, braking distance and braking-point repeatability, and the trail braking channel shows the overlap between brake input and lateral G, which is exactly what the V line is supposed to produce. If the fear of stamping them is the thing holding you back, that's a fixable problem, and the underlying braking fundamentals are the same in every class. For the class landscape itself, see karting classes explained, and the shifter kart driving tips on Senndit cover the wider picture.

Then go out and smash it. Push yourself, downshift aggressively, get to the point where you lock the rears properly. Make sure there's no air in the braking system, the pads are healthy and the tires are decent. You'll have a ton of fun, and the amount of grip you can find on a KZ entry is genuinely addictive.

I'll be honest, I preferred single-speed karts back in the day, but now I prefer shifters. It feels a bit like driving a formula car. The braking, the torque, the gears: it feels like a beast, more alive.

Sign up to PURPL, let me know how it goes, message me on Instagram if you want to get in touch, and remember to keep sending it. Ciao.