Hello! Let’s see if you can help me. I finally have my new Tony Kart 2025 chassis; I used to have a Birel. We have set everything up more or less standard to start with. The thing is, the front end feels super sensitive; it’s impossible to be precise when turning. It reacts a lot, and even in full-throttle corners, it tends to oversteer a bit due to the amount of steering input I unintentionally give. This also makes it very easy to lose the rear if I don’t enter the corners perfectly. We started with everything neutral, the eccentrics facing forward, loose side pods, a flat and horizontal front bar, 1mm toe out on each side, and we began with neutral camber but added 1mm on each side to see if we could reduce some front grip. We changed the steering rods to the highest position where they meet the steering column, which is supposed to give the least sensitivity to the steering. The rear has the standard N axle, and the rear bumper is loose… I could try turning the top eccentric backward, but I assume that would help with rear grip in corners; I don’t think it would reduce sensitivity. I’ve been told to try turning the bottom eccentric completely to one side, but I understand that would create excessive camber, and I’ve always been advised that OTK is mostly neutral.
I would appreciate any kind of help, as Im very lost
You have it set up as it is supposed to, and the OTK kart is known to have a very sensitive front-end that requires very smooth hands to keep it from snapping on you and oversteering. To me it sounds like a matter of driving. If the tie rods are mounted high up on the steering shaft and you feel it is still too sensitive, you are probably moving your hands way too much and way too quickly.
One thing that may help from a driving perspective is to move your hands further up on the wheel. Holding the wheel higher reduces over-driving because you start using your shoulders more and it reduces your leverage you have on the wheel, meaning you make smaller inputs.
If the driver is making mistakes (unintentionally using too much steering input), the main things to focus on with the chassis would be to take steering sensitivity out, which you already have. If that isn’t enough, then I would avoid tuning the kart too much to counteract the driver’s bad habits. The kart is designed like this to achieve maximum weight-jacking on corner entry. Start to take those traits away and the kart will start to not work as it is supposed to and will be slower.
If you need to slow it down a bit more, you can narrow the front up to 10mm spacers as well. But this might just be something you need to get used to as a driver.
I drove Birels as recently as last year and I thought they were more sensitive than my OTK.
The seat is quite back, we tried to place it as the new OTK latest mesures. It is placed 65cm and 65,5cm from the front and slightly under 20cm from the axle. It was impossible to place it further back
The front width is one big spacer, so i can try with just one small spacer?
I thought about needing to get used to it mostly, but went out to the track again and found it impossible to be precise when driving. My times are 1 second worse than with my previous 2022 Birel. I’ll need to work on it, but will also like to find some change which can help me a bit.
An OTK mechanic told me to try placing the excentric facing to the side. Have you ever setup an otk with such camber? Always heard using 1-2mm between both sides. Only movíng camber one hole outwards the camber went over 2mm (one full box) on each side for a total of 4mm negative camber.
For Toe you all recommend 1-2mm toe out. 1mm would mean a quarter of a box on the snipper for each side? From what they tell me less toe out would make it less pointy on the front. But do not know if setting toe to 0mm is acceptable.
What about caster do you ever place a neutral pill on the bottom and the upper facing backwards? Or totally unload by placing the bottom facing forward and upper backwards?
You can run that much negative camber if you want, just be aware it may affect front tire wear or lead to front tire overheating. I would only ever run 1-2 dots on the eccentric of camber either way but you can go more or less.
Less toe out will make the kart more stable at the expense of straight line speed and front tire wear as well.
One small spacer is okay on the front. A bit narrower than normal but not bad.
You can go negative caster too (turning the top eccentric back) but again, will affect the kart’s ability to jack weight. With tall drivers we remove caster usually. I know some taller drivers who almost always run a bit of negative caster.
Seat position sounds normal.
Do you have any video to review to see if it is indeed a driving issue?
Two camber holes approximately how much negative camber should give? I was suprised that only one whole was giving a full box on the sniper (2mm on each side). So the mínimum camber we can set is 4mm?
About toe wouldn’t neutral toe give more straight speed as the wheels would be straight?
I don’t have yet an onboard
I will try first with just a small spacer on the front. Does narrowing the front always make the kart less pointy, results in less front grip?
If this is not enough maybe mínimum caster. Im 1,80m, but thin, only 71kg
I do not know the weight distribution as people and teams here do not usually check this. It suprised me how much you speak on this forum about it, as teams here never check. Engine is an X30.
I could try to get more grip on the back? As maybe I can get used to the front being so pointy. The problem is that i constantly lose the back. Not that Im near to spin, but revs go down or lose time sliding the back in fast corners.
I’m not sure I’d try any of the pills sideways, and I’d suggest just the centering pill in top for a negative caster adjustment to begin with. I tried more negative caster than the centering pill last year at a very gripped up track and the dynamics of the kart got really “weird” and inconsistent. The negative caster will slow down the steering more though but should take away even more side bite so it might make the rear worse not better.
Not to continue down the driver path instead of the setup path, but the video would really help understand if there’s brake overlap as well…meaning too much trail braking which will transfer even more unwanted weight to the front and make conditions even worse. That coule be another kart to kart adjustment you need to make for the OTK over the Birel.
When you say that narrowing the front will make the steering lighter what do you mean? I understand less front grip and less pointy, but lighter also sounds as easier to steer, which would be even more difficult to be precise.
Narrowing the back track would give more rear grip, it does the opposite as narrowing the front? As we are saying that it takes grip from the front when narrowing the front track.
When we say toe out 1mm that should be a 1/4 of a box on the snipper on each side?
With OTK then i understand that a softer axle gives more rear grip? But on the other hand a longer hub which i understand that stiffens the axle also gives more grip?
I have to record an onboard.
By the way, sorry for my English if i make too many mistakes.
The OTK tunes with the rear axle a little differently than other karts. On my BestKart the softer axle will make the rear more free. This comes down to the chassis design, material, geometry, and the axle materials used.
The flat chrome bar horizontal is the softest setting which will reduce the front the most, though some drivers prefer the feeling of the round bars.
The main thing with the OTK is just to be smooth and make sure the kart is stable at turn-in. You still want to brake as late as possible and apply throttle just before apex but you need to make sure every input is smooth.