I’ve never driven an OTK, but the problems you are describing are similar to those I encountered on my Birel when the seat was mounted too far forward. Are you sure your seat position is correct?
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Probably not the answer you are looking for but… put the kart back to baseline and work on the driving - provided seat and weight distribution are done properly.
Seat should be flush with the bottom of the rail and for a typical S-ML Tillett T11 106cm from the centerline of the kingpin to leading edge of the top center of the seat and 108cm on the right. There should be 5mm of twist measuring from the front bar clamps to the leading edge of the seat. All that said… if you look straight down at the front of the seat in the crotch, the leading edge of the seat should be very close to the trailing edge of the center bar. There are dozens of ways to tackle seat position but this will land you in a nice neutral spot with the proper twist and offset.
Sounds like you probably are used to flicking the kart on entry to induce rotation.
In an OTK set your braking point so your brake release coincides with your point of turn in.
Then feed wheel in very deliberately but not fast/flicking while pushing on the wheel with the palm of the outside hand. The inside hand does very little. You determine the inside wheel lift point with where you start to feed wheel and you determine the duration of lift by using your outside hand, outside heel and outside torso to control when the wheel sets back down.
Yeah that’s a bit simplified and overly optimistic. But once you start to drive an OTK the right way, and get it to work properly, you’ll be doing very little unusual tuning.
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Unfortunatelly going from birel to otk is the direct way to go opposite. I drove some chassis and otk and birel are the both end of the scale. While otk is super aggressive at the front and birel is very rear driven. All other chassis are somewhere in between. You have to adapt to the style or go back. Changing the setup to make it driveable like birel will just slow you down because otk isnt meant to do this.
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Okay, so I need to try and drive it smoothly, not braking too aggressively and turn in while braking? Is it better to do all the braking while going straight and not turn until releasing the brake? Because I like to brake late and make the kart rotate with the brake. Is trail braking used more or less with OTK?
The seat was placed 65cm and 65,5cm each side of the seat from the front chassis bar. It was impossible to place it further back. The seat is an OTK size 3. The seat is positioned 1 cm further forward than what the last OTK table states, but many in this forum say that those measures are impossible and most use somewhat in between the latest measures and the previous ones which OTK used. The seat is further back than the middle bar of the chassis, people usually align the middle part of the seat with the start of the chassis bar, so it is even further back than what I read around here. In terms of height, it is about 0.5 cm above the bottom of the chassis.
The kart is more or less baseline now, one big spacer on the front, height standard front and back, neutral caster, camber two holes negative, toe out 2mm, back track 139,7cm.
I find it ultra responsive, impossible to make it to the apex or I eat the apex or lose it. This behavior can just be what you guys explain about OTK, and I need to get used to. What worries me is that it also loses the back in the middle of the turn, it gives a ton of grip on the front but in the entry of the turn the back also is responsive, but suddenly in the middle of the turn, without feeling like I’m going too fast the back part is lost without feeling it is going to happen, so I drown the engine’s exit.. That is what makes me think I may have some other problem. But again, maybe it is all just about the OTK behavior.
So now Im trying to understand how to drive the OTK. With Birel I was braking late, rotating the kart before the apex and accelerating also before the apex. I don’t know if with OTK it is maybe more like braking on the outside straight line, not turning until the speed is down to enter the corner.
Maybe I should just do laps and more laps and let my instinct slowly find how to cope with it… Not thinking too much about it.
You still want to trailbrake and drive deep into the corner, as you did with the other kart. But you need to be smoother with all inputs.
If you slow things down and try straight line braking, it might help you adapt to the feeling of the kart but the goal should be to still brake late and deep.
Over rotation at mid corner - if it isn’t just a case of overdriving the entry - can be helped by narrowing the front. If you still have input in and the front bites enough to rotate the rear at mid corner narrowing the front track width will settle that down. If you narrow it and get no relief, back up your brake application and release points but leave your duration alone.
Like TJ said - you can move those points back to get the kart settled for now and then once you have a rhythm, you can work on driving deeper again.
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How many practice days have you had in it
Loosing a second to your old kart is a big drop off
If you have had a few days in it might be time to go back to what you know how to drive
Same brand as before
But if you have only been out once that’s fair enough keep trying to get your driving style right
Hey Pablo,
I came from car racing to karts and purchased an OTK which was my only experience in a kart at the time. I’ve since driven a few Ital Karts, but I have also worked as a coach for the better part of a decade in racing with about 20+ years experience in cars.
If you think about the top of your steering wheel as the 12 o’clock position on a clock, I have found that the most I have ever needed to turn the steering wheel was to the 1 o’clock position in a right hand corner or the 11 o’clock position in a left hand corner.
Hopefully that gives an idea of how little steering is required in these things. In really tight turns I can recall going to the 2 / 10 o’clock position, but only for switch back hair pins.
It was challenging to get used to at first, however, I would say that some of the advice you’ve had to return back to neutral settings and adjust driving is what my advice would be.
Before I ever adjust something on a car I want to make sure the driver is able to clock very consistent lap times. Usually within 0.500 of a second. Once I see that over 10-15 laps I know I have the driver doing the same thing every time. If we change the driving input and after practicing it there are still issues then maybe look into setup.
I would also advise having someone who has experience on an OTK drive your kart if possible. But mostly make sure you are doing as minimum of input as possible into the steering and you’re being very sensitive to how you are using the brake and throttle.
Driver input is very import to a car / kart! Be sensitive!
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Thank you guys for your help! I have not been able to find how to answer each of your messages in one post, so I’ll just answer all of you.
I have only done 5-6 stints with the 2025 OTK, so there is still room for improvement getting used to it. As you all say it may be the most important part I can work on, rather than moving all the setup around. I’ll try to be smoother, being very gentle with the steering. If im not being consistent I will try to break slightly earlier, maybe trailbreak a little more looking to get right to the appex, and work on from there.
Being said that, do you find it acceptable to try with a small spacer on the front, 2 dots camber out? Neutral pill on the bottom and top pill looking backwards for less caster?Trying to make it just slightly more easy for me. Or it would be too much change from the standard setup?
Looking at OTK pictures i have seen they are using some kind of extensión to change the ackerman, I think they are also trying in the ofificial team to reduce the responsiveness.
And just today, one of the most known OTK dealers in Europe, Kartshop, has announced a new stub axle with different ackerman settings. It seems they are working in the same direction:
Link: Stub axle, HST4 / SA2 / BSD, D25
What do you think?
These are almost always used on Junior drivers that have a hard time physically dealing with rubbered circuits, with the steering becoming increasingly heavier as you add caster to allow the kart to rotate.
They are almost never used in Senior.
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Ah Ok! But the new stub axle from the shop is intended for senior OTK`s
That’s weird, always heard that the Birel is even more front aggressive than the OTK. Maybe that’s why they are as successful as Sodi in KZ
No they are way less aggressive. The benefit, they have alot of traction in the rear and that benefits the shifter class.
Hi Pablo, I’ve got 401RR KZ and what you’re describing feels the same for me. I tried to reduce as much I could sensivity by playing on column steering rods, reduce caster & camber, lowering front/back ride height but that was not enough. At this moment, the surprising best thing I found to reduce rear slides was to… tighten rear bumper and side pods, even if everybody will tell you the contrary, just try. As you said, we can’t set the seat as on the table chart, Birel chassis have the same issue by the way, the engine-side mounting bracket blocks the seat from moving backward.
The OTK chassis suits very well small drivers (check the performer in national/international races), and I’ve seen your height (same for me with 1.81m), we don’t need additionnal front with our size and the position of our legs/foot we naturally put a lot of pressure there. So we’ve to go in opposite direction of setup to feel confortable that’s why I am convinced this chassis isn’t done for us unfortunately.
Hi Max!
Thank you for your answer, i will go step by step trying things. Will also try your recomendations. In my case, the seat can not be placed further back because the chassis fixed supports touch on the edge of the seat. This happens with an OTK size 3.
Have you seen the new stubaxles i posted a few messages above? They should help making the steering less direct. Anyone knows on which hole the tie rods should be screwd to in order to have a less agressive steering?
KZ is a different beast where rear drive is much more important. Tight bars is a valid tuning solution - you might even want to try a rear torsion bar.
It seems something quite official from OTK with the reference : 0092.00KIT
The description I found on a website is : “This bolt on kit extends the steering arm out to increase leverage and makes the front end easier to steer for high grip tracks and smaller drivers” ; I’m from the same opinion of Simone that commented, I don’t believe this is the real fix.
On my side, I’ve got a Ardigo steering columns and of course I use the higher position, maybe to use the standard OTK steering column with the higher position (even if they advice the lower) could help a bit but I’m not so sure that the loss of lateral grip in high curve is only due to the input from the steering wheel, this is an overall and the physic of the driver matter.
I’m having all the same problems you’re describing with my 2024 Tony Kart. My weight distribution is 40/60 for a KA100. Which is heavy on the rear and it STILL is super loose. What @tjkoyen said was true though. I’ve found it’s really about being smooth. There’s one turn for me in particular that’s high speed and I noticed sometimes the backend is fine, sometimes it snaps out. The times it snaps out my steering input is just slightly less smooth.
I’ve also tried removing the front bar, lowering and raising the rear ride height. Different hubs. Several seat changes. Nothing made a difference to the snap oversteer. Running very low tire pressure made it come out a lot slower so I could keep it more in like, but also added a half a second to my lap times.
Sounds like you just need to slow your hands down. You can try the optional steering column. It has a setting between the two standard holes. I found the top standard hole too slow and too much of an effect on handling. About the only option since OTK doesn’t have options on the spindles to help slow down steering rate.
Once you get comfortable with that you can go back to the standard bottom hole.
That is exactly how it will act with that much weight back there. Move your seat forward. I ran similar, worse actually, for way too long because I couldn’t be bothered to scale my kart. I’m around 58/42 now. Night and day better.
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