Let's talk Torsion bars

Hey all. Quick question: front torsion bar pictured above. Currently vertical.

What does bar do, and how would one expect changing it to horizontal or removing entirely would affect the kart?

I am guessing if you soften it up, you get less wheel lift.

Right now, my kart feels pretty tight under braking and very knife edged, hoppy.

I am wondering if moving it to flat would make the front end less skittery under braking and turn in.

Softening the bar will lessen mechanical weight jacking on turn in. It also may let you carry the inside longer and if you’re getting hop from overloading your outside rear, it could calm that down. :man_shrugging:t2:

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Thank you! Twenty Chars

I have tested running without a bar, with a blade horizontal /vertical, with a steel tube and with a nylon bar. The moment I fitted any of these the lap times improved - I could load the front tyres more. But the blade made front skid over bumps, tube even worse - way too rigid over any imperfections. Tube or blade propably work on a smooth track :man_shrugging: Nylon felt like the best compromise where I drive

crg road rebel

In my 206, I have found just adding more front width to be the faster way to get more front grip.

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Funny you should mention that. Since I did not have tools for torsion bar, we narrowed the front. The margay has an simple system that uses washers and sort of pins to hold it all in place. Easy peasy.

Narrowing the front went from 49.9 to 48.7 so right direction. I found the kart to still have the same front end grip and the narrowing seemed to help with the skittishness at braking and turn in.

I moved seat forwards about 3cm as a first step. Then lowered front as second step. Narrowing was 3rd.

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This is very relevant to me here at ovrp. The braking zones are quite bumpy in some places and the hoppiness of the kart makes it extra-fun.

Not sure how much flex the Margay chassis has but in addition to what has already been mentioned I think you will get more flex out of the chassis which could help on a bumpy track. However, I have discovered the Comkart we have has so much flex that running no bar is not recommended. If the chassis is a spring there is only so much deflection before the steel flexes too far.

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I couldn’t stand my 4R with no bar.

It seems a mixed bag. A bunch of folks are no bar. Does not appear to be a consensus.

It’s depends on about everything you can imagine. Especially when you consider the position of the front bar can vary by chassis brand too.

I can imagine. In this case its a spec series where everyone is on a specific margay with spec tires etc. Sorta interesting that you see empty, round, and blade setups and all are different.

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This. Every chassis is different. It’s also the easiest and quickest chassis change at your disposal. Do five laps, pull in and rotate the bar to 45*, do another five laps, rotate to flat, do another five, remove bar, etc.

@Bimodal_Rocket - regarding the instability under braking, be sure to double check your front alignment. Toe measurement being out of whack can cause the kart to be twitchy/darty. You could also try widening the rear, loosening the 3rd bearing, or tilting the seat rearwards to put more weight over the axle.

Ah, I spaced on the spec part.

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Evan, Thx for thought. Its not the rear that twitches so much. It’s the front end. It sort of feels like it wants to go darting off in different grip vectors as it gets load and pulls in multiple directions briefly. Its controllable but feels odd. If you look at that video of me running off the track at end of straight above. Watch how my front wheels twitch in multiple directions as I decelerate.

Maybe I missed it, but could you link to the video again?

I realize we’re talking about a front end issue, but if you run out of options with front tuning then you should also consider adjustments at the rear of the kart that help with the overall balance. After all, the front and rear ARE connected to one another.

Is everything tight, and are all components straight (not bent)? Does the kart respond equally to inputs in each direction, or does it turn one direction differently than it does the other?

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Sort of a crappy example in that tires are cold and I had a brain fart as I was approaching my braking point. Anyways, you can still see the behavior played out, less so on the initial bite but as it bleeds out and I am trying to keep the kart inline while not skidding. So, braking pressure somewhat constrained by surface and drama.

I am not sure on the bent but I think we are OK in that regard. No major bonks (that I know of). I hear you on the two being connected and was just trying to clarify that it felt more from the front.

The steering does not seem dominant on either side. It feels balanced normally.

Lol, that wasn’t at all what I expected to see. Do your brakes even work? Looks like a hella long throw, and it doesn’t seem like there’s much stopping power?

Oh they work fine. Like I said a brain fart so I had to manage sorta missing the initial punch. Basically my heelstops dont really make my life any easier. This was a practice lap or something so its ok to derp here. But the weird oscillation in the steering (faster when I actually brake hard) is what Im talking about. Here’s the footage of a race. I’ll timestamp a quick lap:

@olivier.p comment about me maybe giving too big inputs makes sense. But, if you look at the wheel, it does seem that I do have to crank it to get any action.

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Hmmm…I would do a thorough front-end alignment and go from there.

Visually, that kart does seem to push like a dump truck. Could be combination of setup/tires, but the rear seems pinned down for sure, and the front seems non-responsive. Having to use that much wheel throughout the duration of nearly every corner seems like a red flag to me.

Have you tried setting the kart at the manufacturer’s suggested baseline (complete setup, and seat placement) for your size and weight class?