Racing a kart

[Juzh]

I have raced both 6 and 9HP karts - different tracks have different grip levels, and that's for sure, so you need to adapt.
Generally, I tend to brake very late and spool the throttle at the same time while turning in, so I get out of the corner on proper revs.

In S corners (a la Ascari on Monza) where I'm flat out others aren't so sure. I started doing karts when I was 65kg, now I'm almost 90, and the weight is an advantage. General fitness is also a plus, as on endurance races most give up - the karts that we drive are very nervous and require strong hands for prolonged amount of time.

What I'm not particularly happy about is the snap oversteer induced by low levels of grip on certain track - gives you very little confidence to "push like hell" and generally kills the fun.

Snap oversteer on a 9hp kart Those things are pretty much flat out everywhere from my experience. Must be some really twisty track you're racing on.
This is the layout of our local kart track and I can tell you, 9hp karts do not oversteer or understeer here at all.

[Nando]

The thing with karts is that instead of keeping your weight pushed into the corner you should roll some of the weight to the outside wheels.

relax your back some and let it slide out a little bit.

I hope you do kart more than once a year if you are handing out tips. I don't, so I only have questions. This with letting your weight go to the outside in the corners I have heard quite a bit, and it makes sense as it helps lift the inside wheels.
My question is, shouldn't one then do A LOT of it? Why not move your whole body 25cm to the outside?

well first of all I talk with people who race karts and when I'm at the track I always discuss the philosophy of going quick in a kart with the guys who run it,
then when I'm there I don't really just log laps, i am there to first understand the lines best for the kart to keep momentum then i also look at how the kart behaves,
you don't need many minutes to figure out how a kart behaves, problem is taking that knowledge and turning it into a fast lap time,
you can also watch pros go around the track and learn from that as well,

as far as leaning out too much, not good because you will most likely over power the grip and lose the rear (I have never really understeered in a rent kart.

[Nando]

You don't lean out to lift up inside wheel because that only equates to less grip (JT will kill me)
4 tires working is better then 3,

[JimClarkFan]

I have raced both 6 and 9HP karts - different tracks have different grip levels, and that's for sure, so you need to adapt.
Generally, I tend to brake very late and spool the throttle at the same time while turning in, so I get out of the corner on proper revs.

In S corners (a la Ascari on Monza) where I'm flat out others aren't so sure. I started doing karts when I was 65kg, now I'm almost 90, and the weight is an advantage. General fitness is also a plus, as on endurance races most give up - the karts that we drive are very nervous and require strong hands for prolonged amount of time.

What I'm not particularly happy about is the snap oversteer induced by low levels of grip on certain track - gives you very little confidence to "push like hell" and generally kills the fun.

Snap oversteer on a 9hp kart Those things are pretty much flat out everywhere from my experience. Must be some really twisty track you're racing on.
This is the layout of our local kart track and I can tell you, 9hp karts do not oversteer or understeer here at all.

That's one beautiful looking track.

[N12ck]

I raced Junior TKM, and I raced in BSKC and held a lap record, and what I found was any oversteer is bad, so anyone who says having oversteer is good is talking rubbish.

A good technique when going into corners is to unsettle the kart for a better turn in, ride kerbs, they help alot.

Now an argument people will have is 4 tyres when turning better than 3 (Rubbish) , the answer to that is, to lean to the outside, lift the inside rear wheel to get better turn in, if you have your back end flat all 4 wheels touching the ground when turning for tight corners then you are going to have your kart bouncing across the track compromising your exit.

[N12ck]

deleted

[beelsebob]

You don't lean out to lift up inside wheel because that only equates to less grip (JT will kill me)
4 tires working is better then 3,

Not quite actually. For tight tracks F1 cars are commonly set up to cock a leg over corners. The reason... Because all the car's mass on the outside wheel provides more grip than 75% on the outside wheel and 25% on the inside wheel doing --- all. I don't know if the same applies on a small scale when you have bugger all camber on the wheels, but I wouldn't be prepared to bet against it.

[N12ck]

You don't lean out to lift up inside wheel because that only equates to less grip (JT will kill me)
4 tires working is better then 3,

Not quite actually. For tight tracks F1 cars are commonly set up to cock a leg over corners. The reason... Because all the car's mass on the outside wheel provides more grip than 75% on the outside wheel and 25% on the inside wheel doing --- all. I don't know if the same applies on a small scale when you have bugger all camber on the wheels, but I wouldn't be prepared to bet against it.

2 words:
no differential, you need to have the inside wheel in the air, so by saying its not good to have the inside wheel of the ground in tight corners is rubbish

[beelsebob]

You don't lean out to lift up inside wheel because that only equates to less grip (JT will kill me)
4 tires working is better then 3,

Not quite actually. For tight tracks F1 cars are commonly set up to cock a leg over corners. The reason... Because all the car's mass on the outside wheel provides more grip than 75% on the outside wheel and 25% on the inside wheel doing --- all. I don't know if the same applies on a small scale when you have bugger all camber on the wheels, but I wouldn't be prepared to bet against it.

2 words:
no differential, you need to have the inside wheel in the air, so by saying its not good to have the inside wheel of the ground in tight corners is rubbish

Hah yes, no diff didn't even register in my brain, but yeh, that would make a serious difference. Next time I go karting I'll be making a serious effort to lift the inside rear.

[Scootin159]

I'll +1 the theory that you need to lift an inside rear wheel to get a kart to turn. I've driven all sorts of high-performance vehicles with solid rear axles (20hp to 135hp karts), and in all of them you need to set the kart up to take a good amount of the grip away from that inside rear wheel to reduce turn-in understeer. There's all sorts of technical ways you can do this, from raising the rear roll center (i.e., moving the driver) to weight jacking with front wheel caster to adjusting rear axle stiffness. Either way you need that wheel to lift to get the kart to rotate well.

If you can't play with setup at all (such as in a rental kart), things you can do is to brake later and harder to get the rear end to step out - but this can be tricky to get *right* as it's real easy to overstep here and get the rear end to step out too much and quickly kill any momentum that you have. Your goal is not to lock the rear tires, but to just overstress the inside (unloaded) rear wheel while keeping the outside (loaded) rear wheel within it's traction window. Given that they're on a solid axle you're obviously not locking that inside wheel, you're just causing it to turn at the rate of the outside rear wheel instead.

[JimClarkFan]

I raced Junior TKM, and I raced in BSKC and held a lap record, and what I found was any oversteer is bad, so anyone who says having oversteer is good is talking rubbish.

A good technique when going into corners is to unsettle the kart for a better turn in, ride kerbs, they help alot.

Now an argument people will have is 4 tyres when turning better than 3 (Rubbish) , the answer to that is, to lean to the outside, lift the inside rear wheel to get better turn in, if you have your back end flat all 4 wheels touching the ground when turning for tight corners then you are going to have your kart bouncing across the track compromising your exit.

Funny that you mention causing instablily on entry.

Watch this video from 1.30 to 3.00 as an example (particularly 1:50):
[youtube]http://www.youtube.com/watch?v=D0Sg8it4ZbY[/youtube]

Is this what you mean, it appears that the drivers are causing (dare I say) a bit of oversteer on entry? It seems almost as if they are drifting the rear into some corners.

What are peoples opinions on what exactly they are doing.



Also you lift the rear wheel? That is very counter-intuitive to me, I know it might be hard to explain but can anyone tell me why the inside rear?


Thanks guys btw, this is very informative =D>

[beelsebob]

Also you lift the rear wheel? That is very counter-intuitive to me, I know it might be hard to explain but can anyone tell me why the inside rear?

You need to lift a rear wheel because turning a corner requires the two wheels to go round different radius turns (because one is further out from the centre). That means that the outer one needs to move further, and hence turn faster, but the two are joined by an axle, and hence can't turn at different speeds. The only way to change this, is to lift one or other wheel. So then the question is, which wheel. To turn the corner you need an inward force, the kart will try to carry on in a straight line. Because of that, it'll lean somewhat out of the corner, and put more weight onto the outside wheel. Because of that, the outside wheel will have more friction with the ground, and provide more inward force to turn you. So, you clearly don't want to lift the outside wheel, because it's what's providing the grip allowing you to turn. Thus, the inside wheel is the one you want to lift.

[Scootin159]

That's exactly the amount of rear slide I was talking about - any more than that and you're going to be locking up the outside tire and causing all sorts of speed to be scrubbed off.

The reason for lifting a wheel is to take the weight off of it so that you can slide it. You don't really need to lift it in the air, but just get a good percentage of the weight to transfer across the chassis, but with as stiff a chassis as a kart is, that can mean actually lifting it up.

The reason for sliding the inside wheel is that with a solid rear axle both wheels must turn at the same rate, which makes it impossible to turn. Thus to get it to turn, something's gotta give - either one rear wheel slips, both rear wheels slip or the front washes out.

Here's an example from my 105hp "kart" in the rain:
[youtube]http://www.youtube.com/watch?v=r_Y9aWn2gNI[/youtube]
(disclaimer, yes it is a formula car, but it has a solid rear axle so the theory works)

If you cut to the 1:00 mark there's a great example of what happens when you DON'T get that inside rear wheel to slip - even though there's really quite a bit of grip in the front end, it just won't turn in at all because that inside rear wheel is gripping and preventing the two rear wheels from spinning at different rates, preventing the car from turning.

However when you get that weight transfer and can 'lift' that inside rear wheel, the two rear wheels are allowed to spin at different rates, allowing the car to turn:

[youtube]http://www.youtube.com/watch?v=ycQoZXFZBsQ[/youtube]

[N12ck]

I raced Junior TKM, and I raced in BSKC and held a lap record, and what I found was any oversteer is bad, so anyone who says having oversteer is good is talking rubbish.

A good technique when going into corners is to unsettle the kart for a better turn in, ride kerbs, they help alot.

Now an argument people will have is 4 tyres when turning better than 3 (Rubbish) , the answer to that is, to lean to the outside, lift the inside rear wheel to get better turn in, if you have your back end flat all 4 wheels touching the ground when turning for tight corners then you are going to have your kart bouncing across the track compromising your exit.

Funny that you mention causing instablily on entry.

Watch this video from 1.30 to 3.00 as an example (particularly 1:50):

Is this what you mean, it appears that the drivers are causing (dare I say) a bit of oversteer on entry? It seems almost as if they are drifting the rear into some corners.

What are peoples opinions on what exactly they are doing.



Also you lift the rear wheel? That is very counter-intuitive to me, I know it might be hard to explain but can anyone tell me why the inside rear?


Thanks guys btw, this is very informative =D>

What they are doing is this:

a tyre going sideways causes much more friction than a tyre going forward, so by jerking the steering wheel as they are, they are getting the back to turn slightly sideways then the other way, meanwhile braking,,, so what they are effectively doing is reducing the braking distance allowing for later braking, we have a nickname for it at my local track 'Snaking' it is used quite a lot, thats what I mean by unsettling the kart into slow corners after a fast straight and so on,

[Hail22]

I will say weight plays a role especially weight shifting in corners (taking a left corner you shift weight into the inner most right part of your seat and vice versa).

Been karting since I was a pup (currently own an FA Victory MA11 Kart with Iame X30 Shifter engine Rebuild after my second race meet).

What most people said above is true, in terms of competitive karting...however if anyone dares to do it, one of your first priorities is to buy a rib protector as you will take an absolute beating in corners (remember there are no muscle tissue or bones protecting your kidneys guys!).

This isn't my driving, but I found this fellows video to be quite good (FA Victory MA111 kart with Iame X30 engine -Non-Shifter).

[youtube]http://www.youtube.com/watch?v=fukQT2Em1C8[/youtube]

Also a side note...anyone who says driving a shifter kart is easy (when you're a rookie) is a straight up liar, I don't know how many times I've seen rookies stall without leaving the main garage/pit lane. Shifters are a beast that needs to be understood!

A bit of rear slide into corners can help by the way, also it depends how aggressive some corners/kerbs are, I try not to ride all the kerbs on the tracks I drive on (purely because two of those kerbs are replicas of the sausage kerbs used in the Indian GP) They're used as a deterrent as some racers have exploited said kerb (all 3 wheels off due to its width the 4th is the right rear wheel as its a left hand corner/turn, hence sausages are there to prevent said...bunny hoping).


P.S Apologies for grammatical errors, its very early in the morning.