Just my .02, but this makes a massive assumption that the movement direction is completely vertical. Considering the front wheels are in front of the bar, I’d imagine there’s some angle involved.
The GP14 chassis had a novel horizontal rod attached to the aft & front “waist” segment of the frame, intended to adjust lateral flex.
Though I haven’t seen anyone else adopt it, including CRG, who handles manufacturing duties for GP.
Just a general question… I have a Birel S6 and in need of a front torsion bar.
My question is, do I have to source a Birel / Freeline bar & clamps or will any 30mm front bar fit?
Some bars use funky sizes like 28mm tubes/clamps. You’ll want to confirm correct sizing, but other than that any old bar will do. I would try to match stiffness if you’re just going to buy one, and I believe the standard Freeline bar is 1.5mm. The Birel bar is shorter than some, so you can always cut one down to fit if needed.
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We ran our first practice at NCMP a few weeks ago. After a couple of sessions of knocking the rust off I changed bars for the heck of it. All tests done with a ‘21 Redspeed with a KA100 on used MG reds at fat guy weight (390lb).
I had started with the chrome front bar. I LOVED the way the front end felt and the responsiveness of the steering. However, from mid-corner and exit it felt on the verge of too bound up. I would get an oscillation in the chassis you could hear with changes of the motor almost on the verge of hopping. I will say on a spring day with a greener track it felt very hooked up.
I then changed to flat bar. It felt like I had really freed up the rear of the kart on corner exit being nice and smooth and felt like I should be rocketing out of the hairpins. However I lost front end feel and responsiveness on turn-in and I felt like I lost mid-corner grip. It ended up being about the same overall lap times compared with my brother and we had been running together all day.
What I want out of the kart seems like a unicorn in that I want the front end to behave like it has the chrome bar in, and want the rear end to behave like it has the flat bar. Is that at all possible? Or will I always have to fight that trade-off? TJ I need your wizardry here!
I had one session left so I tried going wider in the front with the flat bar to give more front end, and while it helped it wasn’t what I was looking for. Would adding caster and/or negative camber help the front end feel with flat bar?
Or should I look at other ways to free the rear with the chrome bar in like moving the seat forward 10mm? What about a softer seat?
maybe an adjustable torsion bar could be integrated, i’d need to check the rule book, but I think it could be legal.
Add a little caster. The caster makes the front end more responsive without the sacrifice of making the kart stiff/springy. The trade-off is potential for front scrub on exit, but that probably won’t be an issue if you just add a little caster. The caster will feel a little like widening the front end, but in a more effective way.
It sounds like you’re on the edge of it being good, so half-caster is where I would start. If you have less aggressive pills, I would try those even.
Knowing how NCMP can be when it’s green I would run a similar test when the track has more grip, as it may be more applicable to your racing conditions.
If you have similar results and caster doesn’t do the trick, then I would move the seat forward 10mm.
I agree with Evan. NCMP makes big changes from green to grippy. With the track gripped up, you will probably have enough front end and likely find you are back too much rear on exit. It’s even worse with less hp… 
Alternatively, you could try going with the chrome bar and removing a little caster. Tough to say which would be better. I’m usually of the mindset that the less caster the better.
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I’m in the opposite camp. As the old adage goes, “caster is faster”! 
That’s camber, not caster.
And regarding caster, it really depends on the class. Shifter/X30/KA even you can add caster and the power pushes through the caster on exit. Yamaha and 206 you’ll see more of a philosophy towards pulling as much caster out of the kart as possible all the time since they can’t overcome the extra resistance that caster brings.
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True that different classes have different approaches. Weight is a factor too!
Theoretically though, caster is not a good thing. Of course, we have to lift the inside rear, but thats the only reason the amount of caster that we have is in the kart. Caster adds resistance by putting that energy into twisting the frame, which the engine ultimately has to push through. With that in mind, you want the absolute minimum to lift the inside rear and keep it there. That applies elsewhere on the kart too. Ideally we would have a very narrow front width, very wide rear width, zero camber or toe, and as little caster as possible, but that’s never the case of what’s actually best because of many many other factors 
Good call, either one would possibly work.
As usual, there are many ways to skin a kart.
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Thank you all for the feedback it gives me some things to try.
This is so true. I had a look at the pointy end of the state title level field yesterday, there was a mix of flat bar in the horizontal position and the gold bar (and a few silver & chrome bars but no flat bars in the vertical or angled positions). Opposite ends of the spectrum, but getting similar results to each other. The obvious things were the same like 10mm spacers each side for front track, current model OTK chassis (although maybe a mix of 30 and 32mm versions). Obviously not easy to tell pill position.
Because I didn’t make it past the 3rd turn of the final (the perils of starting way back in the pack), I was able to watch the other guys during the final, it was amazing to see how much grip the front runners have, and with very little steering input.
Anthony i noticed the same thing as well.
Ironically i wasnt running a bar and had good pace but like yourself struggled with track position after qualifying 19th after doing no practice.
I ended up with a heap of positive camber to make up for it, but it allowed me to have excellent corner exit speed as the kart was so free which helped me with passes all day.
My next purchase is all 3 round bars and go do some testing.
You drove great Gary, making up places all day. Bad luck on that start in the final, it’s a case of what could have been. But at least you can use your chassis again, I think there are a few bent ones after that crash.
I was where I expected to be, given first visit to the track was a couple of sessions on Saturday. Def need practice & testing.
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great thread here, I will say the difference in my otk from flat bar flat vs flat bar vertical is immediately and obviously noticeable (in a 80 shifter on evinco blues) as sharper turn in but haven’t really noticed it on exit as described here, going to have to do some testing…