LO206 "Free" Talk (chassis)

At our local race series (~4 tracks ~200 racers), every LO206 driver (lights, heavy, masters), stretch the series mandated rear tire (6" MG RL2) onto +210mm wheels and run near max rear track width. The consensus is it “frees” up the kart so it doesn’t “bind” in the corners.

Can someone please explain how running a low rate of lift setup (wide rear and no sidewall) result in a more “free” kart? All the reading I’ve done would seem to indicate a narrower rear track width and 180mm wheels (more sidewall bight) would be the direction to take to eliminate binding? I may come down to nomenclature but please explain.

Stretching the tire onto a bigger wheel will stiffen the sidewall and reduce the ability for the tire to deform and dig into the track. It’s like running more tire pressure.

Track width can get tricky depending on tire and track condition. Widening the rear will help the rear squat and can induce flatslide in certain conditions. I would imagine that if you are stretching the tire onto a bigger wheel, there will be almost no way to get the sidebite you need with a high rate of lift. If you get the kart to lift the inside rear wheel a lot, with a stiff/stretched sidewall, it won’t hold that weight transfer and will cause handling issues.

Pretty common on harder tires and low hp to try and induce a little bit of rear slide to keep the kart free. There isn’t enough power or tire grip to really get the kart flexing and hiking the inside rear wheel consistently.

So it would seem with low power + low traction people have migrated to sliding the inside rear tire rather than lifting it as it’s more consistent and roughly accomplish the same thing (reduces binding). This seems to agree with how people tune at the track, and makes some sense. Although, it’s opposite of what is commonly exposed online about kart setup :>)

Continuing down this path, at some grip level a person couldn’t make it slide enough and they’d reach a cross over point where lifting the inside rear would be the way to go. It be like pulling a u-turn in setup which is probably why I’ve never seen anyone try during a race weekend. Could be the winning move on that late Sunday Final when its 107 deg and lots of rubber has been laid down.

That has not been exactly our experience in 206. We ran 20-25 club weekends over 2 years on a Rhino lined (very high grip) track where grip flips are not uncommon.

The standard setup approach for the 206 class on this surface was 7.1 rear rims, higher than expected tire pressure, full rear width, hard axles, cut down axles, reduced caster, increased front camber. That was running the old Evinco Blue on an OTK the last 2 years. Never saw an occasion where that changed from high temps and increased grip.
I did see the Rhino lined surface get extremely slick on cool or damp days, then you were throwing full wet setup at it to find some grip.

I don’t completely understand why the 206 like a stiff stretched sidewall with a cut down stiff axle. I just know it responded to the deflection on the end of the axle at the hub much differently than it did to a soft rear axle flexing along the entire length.
We were trying to lift the tire as little as possible to avoid setting up an oscillation/hop condition on the rear. Once it starts to hop, the 206 just doesnt have the power to drive through and bogs horribly.

That’s why this is mainly a club racing style of tuning because at bigger events where there is more grip on the track, you simply cannot slide the rear like that effectively.

We used to set our stuff up in that way for club racing and would find when we got into soft tires at regional and national racing, we were totally out to lunch on setup.

This is also why at club races you see some drivers who are pretty sloppy with their inputs do better, because there is no grip to penalize sloppy driving technique. Those same drivers become back markers at bigger races when they can’t flick the kart around anymore.

@tjkoyen, we surprisingly saw the opposite of this effect in LO206 racing. At the local club track my son struggled to run top 5, but at the larger regional races he podiumed and finished 7 on the season. A couple of the consistent podium winners that beat us on the regular at the local club would finish behind my son at the regional races. The local club track was hands down the highest grip surface we saw all year.

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I would imagine you’re a special case given how the track surface at your home track seems fairly unique.

The less you force the outside rear into the track, the better the kart accelerates off the corner. This is because engine power isn’t being used to deform the tire sidewall excessively

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I’m curious, where on the track (fast or slow turns) does the wider rim pick up time? If the time pickup is in a slower turn, where in the turn does time pick up with the wider rim?

Any time the tire is loaded in a way that will flex the sidewall significantly.

I have found in a 206 any flat slide and the kart falls on its face. I need it to roll every corner with minimum sliding to be fast all while picking up the inside tire through mechanical jacking or physical jacking.

I have never found a wide rear end setup that can get the turn in and keep the rear free enough on exit to be fast. I am usually wide in the front and narrow in the rear.

What tire are you typically running?