Front / Rear Track Width

Hi. I’m finding my kart wanting slide straight off track mid to late corner.
Does widening the front or narrowing rear track have the same effect?

Sort of.

Widening the front will increase front “grip” at turn-in, but will also unload the inside rear more harshly. Narrowing the rear will reduce the amount of weight jacking needed to unload the inside rear, and can help both lift the inside rear but also dig the outside rear into the track.

To really dial in what you need to do on the kart to fix your oversteer, we have to figure out what’s causing the oversteer to begin with.

Does the kart turn-in well or does it struggle to turn-in when you initially put input into the wheel?

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Thanks TJ. I’m a first year racer on Birel running 206 SR @380-ish.
I know it starts with me not braking well enough yet and setting up a better line. Kart enters hairpin turn fine. Around mid point it wants to drift to outside of track, and several times I’ve been off mowing grass.
Wondering if I can tweak kart to my style, while my style improves.

I think both have similar affect in different ways. I think the wider front lifts inside wheel more because of caster. I think narrow back holds up inside wheel more because of weight jacking. Often I widen the front because it is the easiest change to make. But lifting more by steering means more energy used to lift. I think next time I am narrowing the back.

It sounds like you could be overdriving and “charging the turn”, but it’s hard to say. Do you have any video?
Worn tires can cause issues too of course.

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I’m with James here. It’s unlikely that a Birel (assuming an AM29) at 380lbs is too free on apex off. Try backing the corner up a little. Get back to the throttle sooner and see if that tightens it up. Very likely you are over driving and over powering the outside rear.

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You’re under steering on exit if I understand correctly. I’d try to narrow the front end (but keep in mind you’ll induce some entry understeer - look to find a balance) or try a stiffer rear axle to keep the inside rear in the air longer

I would tend to agree that a 206 breaking free at 380 is likely a driving issue, especially if you’re a newbie.

In reality most handling issues have some root in driving from issues until you are a top-tier driver.

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Thanks all!
2019 AM-29
Briggs 206
-40x3x1000-F (hardest)
-Neutral setup
-Used set of Vega reds +which now have 5 more racedays from me)
-15 psi cold
-Running mostly at Nicholson and some at Sandy Hook, which are 1/4-mile sprint tracks.
-I’m 6’2" @215, so no lead on kart
-My best lap is about 1.3 secs behind leaders, with a 0.7 sec variance

Overdriving /charging sounds like me, but I’m reluctant to brake into corners for fear of more spin-outs. Then I feel like the understeer kicks in causing me to drift wide and lose momentum, and time.
I get the concept… On gas as long as possible, then hard brake just enough for appropriate momentum into corners, then back on gas to maintain or accel.

@fatboy1dh What is backing the corner up?

@KartingIsLife video from camera mounted on fairing where I started in P3.

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I knew you’d ask, it means sacrificing your entry speed to get on the gas earlier.

If that means, start corner wider, turn in later, apex later, but I’ll be running straight longer and back on gas sooner. Then that’s what I thought you meant.
Sounds like trying to run the ideal line for best qualifying time.

Have a read of this thread, it’s discussed in detail.

Looks like the exit of that tight left handed really creeps up, so I think you’re keeping that steering angle in a long time in order to make the turn, but also speeding up as if the exit was straight. One thing I like to do in practice is brake early and coast into a turn, that way I can go into the turn exactly whatever speed I want to so I can try different things. You seem to be getting on the gas late there so I think you need to back the turn up a little like others have said. Another thing it could be is if your steering inputs at the exit are harsh and not smooth than the karts balance would go off and the kart would handle poorly on exit.

Here’s your issue. And it’s a common one with newer drivers. Braking is a tough one to master. If you’re afraid to locking up and spinning and it’s causing you to coast into corners rather than using the brakes, you’re carrying too much entry speed and then the kart understeers. That delays your throttle application. You can see in the video you’re pretty late to the throttle most corners. In most cases you want to be applying throttle before you get to apex. If you aren’t able, you are carrying too much speed and need to either brake harder or earlier.

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Current set of tires on right vs a newer used set on left. Both are Vega reds.

Current FR shows greater wear on inside edge which I read on here somewhere is indicative of needing a wider front track for driving style. (can’t find that post though) Plus general wisdom indicates widening front is easiest and most minor adjustment.

While I believe there’s still life in current set for a new driver learning the craft, I plan to use the newer set tomorrow. It’ll be my first time driving in 90F weather. It’s only been 50-70F for me, and the colder the worse I drove.

The uneven wear on the fronts may just be a characteristic of the track. Mine wear unevenly at one particular track, purely because it has more corners that wear one side than it does the other.

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@tjkoyen Thanks TJ!

That’s the other conclusion I’ve been coming to. I’m a one man ‘team’ right now and have been seeking input from my peers which has been very general most of the time. Been doing a lot of formal reading specific to karting. Practice is hard to come by here in DE/MD area, but I’d like to pursue it and even pay a good coach for a couple hours time.

I don’t have a tach, so I time myself while watching my video. In another video, a lap that seemed like my slowest to my eye ironically turned out to be my smoothest and fastest of the day, reinforcing your point.

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@tjkoyen is a Demi god, we also call him Yoda.

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@Richard_Jacques Thanks!
I swap the tires to other side of kart every raceday to even out the wear. That FR has been concerning though.

Surely that’s because of my height? :sweat_smile:

A tach would certainly be helpful and would give you access to data that could be very beneficial. But yeah it’s often the laps that look slowest that are fastest.

The front tire wear is likely due to you using the front tires to scrub and slow the kart down rather than the brakes. You can see a little feathering there in the front which indicates the tire sliding on the track surface. The rears don’t really show feathering so that would confirm that the front is sliding. The uneven inner shoulder wear isn’t a huge concern. Because of the kart’s geometry the inner edge will always wear more.