My next adjustment was going to be removing the bar completely until I saw your reply but now I’m wondering why I shouldn’t remove it. Here’s my scenario: I’m 6’4" 190lbs with an OTK in LO206 and only ever had the flat bar in horizontally. I’m struggling with hopping from apex to exit even though I have the rear at max width, and minimum caster in the front. I’m scraping the bottom of my seat and the chassis in some places so I don’t know if i should drop it any lower (rear ride height is in the middle position so there is some room but I’ll have to raise my seat slightly to compensate). The other thing I haven’t tried is raising rear tire pressures but I thought that would be more of a fine tune. I still feel like I’m really far from the goal which is why I am considering removing the front bar completely. If there IS a wild or rare scenario where you would remove the bar, what would it be? Any advice would be much appreciated!
- If you need to cut weight.
- If you need to replace it with a new front bar
- If you have an altercation in the scale line and need a little more firepower
In all seriousness though, it can’t hurt to try it. I know someone that ran a 30mm OTK shifter chassis without a front bar, and it seemed manageable. Worst case scenario you go slower and have to put it back in. 
Hi Austin. I am of a similar build only 6’9" and 205. I have been running an OTK 30mm chassis as well, with a similar setup to what you are currently running. Low seat, less caster, max width and rear at middle height. I struggled with apex to exit hop for the longest time. Tried several changes, including moving seat forward and leaning back more. Nothing really helped much. After a few posts back and forth with TJ in an Axle thread, I pulled the trigger and went to the OTK H axle from the standard N. It was the single biggest improvement to eliminate the hopping. That and changing my line through the corner a bit. Essentially I was over lifting the inside rear and the outside rear could not maintain enough grip and would slide out causing the inside to drop, then grip up again and repeat the cycle. The H axle lessened the lift and I changed my line to be straighter toward corner exit through the apex. This took some of the side loading out of the tires and was more stable out of the corners. This also opened the tuning window for other adjustments to the kart.
This may not be your solution, but should have a better effect than adjusting/removing the front bar.
You can try it with the bar out. The kart isn’t designed to work with it out, but it won’t hurt anything. I know a few drivers who prefer to run without it in the rain which is baffling to me, and I’ve had a couple drivers insist on trying it as a last resort in the dry (didn’t work).
I agree with Greg here though and it sounds like you need to go to a stiffer axle. You’ve use up all your adjustments on this baseline, and now you need to go to the H axle and start from that baseline.
If I got in a fight in the scale line, I’d be looking for a good shield rather than a weapon - lift your kart up and have him try to wrestle 175 pounds of steel.
Thank you Greg/TJ for that input and Charles/Evan for the comedy! I will look into the H axle and look for that axle thread you mentioned. I think it’s just a big change requiring a lot of input for something I’ve heard mixed opinions about (referring to the Korsasport YouTube video on chassis tuning with axles being like “voodoo” lol). However, hearing that the stiffer axle worked for you Greg at 6’9” is encouraging.
OTK axles aren’t voodoo, I just said that because every kart brand uses axle tuning differently and I didn’t want to dive too deep on a video about the basics. The average club racer shouldn’t need to change axles much. But the average club racer isn’t 7 feet tall either.
Sounds like you need a big change and that’s what axles are for.
And if you like this axle change, but need more, there is the HH. I am 6’3" 220 lbs and running a class at 390. I needed the HH to get the kart freed up. OTKs are not made to work with low hp and large drivers, but it can be done.
13 posts were merged into an existing topic: Do different stiffness axles do anything?
I would go straight to the HH. I had the STV450 OTK kart and even though I’m only 5’9", I still had some hopping in a critical corner of the track. I switched to the H axle and it didn’t really help much to be honest. I actually went to the PKT soft axle and that was better.
I know some people do really well in LO206 with the HH axle. I think with 206 you either need to go soft, meaning a soft axle and no seat struts, or stiffen the hell out of it by going HH with 2 seat struts on the left and one on the right. Either way seems to free it up, just in a different way.
I’ll definitely keep that in mind. If I still can’t stop hopping, I’ll try to get the HH. At an additional $200, gonna need to sell one of the other axles lol
One thing that can help with the hopping is jetting and driving habits. I was 100% convinced my hopping problem came from the kart setup, so I tried everything under the sun to free it up at the rear and nothing worked…turns out engine was too rich on the bottom, coupled with too much time off throttle before entering and during a turn. That flooded the engine, lowering the power mid-corner, with the chassis taking over and sticking too much. Not saying it’s your specific case, but before throwing $$$ at radical chassis setups, make sure it’s not a problem of low-end power/slow corner speed…it’s a cheaper fix
A lot of discussion on OTK karts. Any experience with adding the front bar to Merlin karts? My son drives KAjr in an LM30. Mostly at Badger which is a tight course.
Principle is the same; stiffer front end gives a quicker, more reactive turn-in and quicker inside rear-wheel lift and drop.
I’ve seen guys run with or without the front bar on the 29, but I think on the LM30 most people run with it in. We always did when I ran them.
Posting here, because this is the best and most complete thread on torsion bars I found. And because after a lot of confusion and thought, my adventures with my second OTK chassis has led me to…more confusion and thought:
To cut a long story short (ish), I always ran my first OTK chassis without the torsion bar because it always felt better and was always quicker for me. This always bothered me because I realized that it’s not commonly accepted that this is a ‘normal’ setup. None the less, it was always the fastest for me, so I ran it. Fast forward to the new chassis (also OTK), and I made sure to start off using manufacturer defaults for all my settings (meaning bar in) in order to reset my perceptions and make sure I wasn’t bring my biases into the picture from the beginning.
I drove it this way for one and half days of track time, then finally realized that I was feeling very beat up by the kart, braking was sketchy, and I was not happy with the lack of rotation I was getting out of the kart. After realizing this, I tried driving through it and figuring out how to work with the current setting, but eventually I decided it was time for a change. Knowing that the bar was probably my biggest divergence from ‘standard’, I started by just taking it out. And viola, immediately most of my complaints went away and I was faster.
Why? Well, from my perspective the rear end now felt looser letting me rotate the kart better and get off the corners better. I also felt like my feedback for the rear traction/sliding went way up. With the bar in it felt like the rear would stick, stick, go - whereas with the bar out the a slide might started creeping in earlier than with bar in, but you had a clear idea of it right away and knew where you stood. It ‘flips me out’ that my only real observations about the front bar have to do with the rear…
From here I guess I’ll play with caster, alternative materials for the front bar, and possibly weight distribution to try and fine tune things (because it’s still not perfect, the rear can get a little more slidey than I like from entrance to apex sometimes).
Caleb - Is this LO206 or KA100?
Rok GP (new kart - my old kart also had a 125cc TAG engine)
If it works for you, it works for you. Your feelings about the bar are opposite of 99% of people, but there could be a situation where the bar out is better for a certain driver in a certain condition. I have had a national-caliber driver beg to run without the bar a lot of the time and he somehow could make it work. Some combination of the track, tire, driving style, engine package etc all made it feasible for him. Put 99 other drivers in that seat and they would all hate how that kart felt.
Until you’re looking for those last few tenths, that setup may work for you even if it’s considered bizarre. Being able to squeeze 110% out of a poorly handling kart will still be faster than squeezing 90% out of a optimally tuned chassis.
Thanks for the feedback, TJ. I guess that’s where I’m at in my head, too. That said, I’m sure this won’t be my last go-around with the torsion bar.
I know a world-class racer who runs asymmetric set ups and goes to the Nth degree with his set up work, and I know a guy who won the Grand Finals who revealed to me he just asks for maximum caster and just deals with it. A lot of set up work is preference based. I watched a kid in a top British race have his rear wheel slowly push itself inwards because of hub movement to the point it was basically at the sprocket, and he was still setting purple laps. Also, the big teams with manufacturer support will be testing different chassis construction as there’s real big changes there that can be made beyond just set up.
They key is having the confidence to forge your own path and not be too distracted by what everyone else is doing. There’s safety in the herd from knowing you might not have gone down the ‘wrong’ path, but all the best guys I know tend to follow their own way.
I have lost count how many times I sh*t hot driver has won on a random chassis only to hear people say “yeah it’s coz he’s good though”.