Briggs Cadet chassis setup - struggling a bit to find more exit speed

I’m wrenching for my 11-yr old daughter on her Charles Leclerc kart (from birelArt). She is coming in at around 242-244lbs with no added weight on the kart (class min is 235). We’ll be moving up to a full-sized kart next year when she goes into Junior Lite / Junior.

She has been driving in Cadet for about a year now and while her driving has improved immensely since moving from arrive & drive to club racing, we are still struggling to catch the fastest competitors. The biggest issue we seem to have is with exit speed. We’ve been working very hard on not overdriving entering hairpins and being smoother with steering inputs but still, even when she is on, it seems her competitors can pull out of the corners (hairpins or moderate sweepers) just that tiny bit faster.

I run an Osmo Action cam during all practices and races and lately have started noticing more and more that just before the apex, she begins to experience understeer and a lot of tire squealing, even on newer tires (Vega Blue). We have the last two races of the season this weekend and I’d really like to get the kart dialed in as best we can. Unfortunately, I think we’re struggling with the fact that her seat has been mounted quite far back due to her height. This has me wondering if her height/weight and seat position isn’t allowing the kart to be as free as it could be.

The challenge we have this weekend is that it is very likely to rain or at least be wet on Saturday, then dry on Sunday. She is doing well in the points (2nd or 3rd at the moment - depending on the drops) so I’d like to give her the best chance possible of placing well. I’m still new to the sport and kart chassis setup, though learning quickly.

For the dry, we currently run:


  • between 1 1/2 to 2 spacers front
  • -2deg toe total (-1deg each side)
  • iirc about -2deg camber
  • I’m not sure about the caster as I admittedly haven’t looked at it in awhile, so it is probably neutral as per factory recommendations
  • middle setting for chassis height
  • chrome front torsion bar


  • rear width is maxed to side pods (need to actually measure it); could go wider if necessary as it doesn’t exceed bumper
  • lowest setting for chassis height

Depending on the temps/track conditions I start at about 14-14.5 psi (Vega Blue) in the morning and decrease as the day wears on, settling at about 13.6-.8 for the fronts and 13.2-.4 for the rear. I run the rear right tire about .2-.3 psi lower.

We typically gear for about 5800-5900rpm (red slide) because of the RPM drop we see in some of the tighter corners. On a good day we can hit about 87-88km/h down the hill onto the straight with a 20/65 setup on the full track configuration.

For the wet, we currently run:


  • between 2 1/2 spacers front (maxed)
  • -2deg toe total (-1deg each side)
  • iirc about -2deg camber
  • caster probably neutral as per manufacturer’s recommendations
  • highest setting for chassis height
  • remove front torsion bar


  • rear width minimized
  • middle setting for chassis height
  • bumper loosened

For the particular track configuration we’ll be running Saturday (slightly shortened full track), I’ll probably be gearing the kart at 18/66 or 18/67. There are some good elevation changes at this track so will need the extra oomph…I think. We’ll have to see in practice. Tire pressures are usually between 15-18psi, depending on how wet it is.


For the wet, I think I want to try adding caster and removing some camber (0 or perhaps a bit of positive). I’m not entirely sure what to do with the front torsion bar. She was initially picking up the front inside wheel during practice, especially through the tight chicane, and this was obviously causing some issues. I’m not sure what causes that. Removing the torsion bar seemed to help.
I’m a bit worried about the additional caster making the steering too heavy for her, but I suspect the maxed front-end width will offset it a bit…is that correct?

For the dry, I’m at a bit of a loss. Since her seat is so far back - would adding a bit of positive caster upfront help the chassis flex a bit more and unload the inner rear better for the hairpins? This begs the question though - should I run 1 1/2 spacers upfront or 2? The caster will allow her to turn-in better and if we go 1 1/2 spacers, shouldn’t that also help give her a bit more mid-corner grip? The track surface is going to be colder than normal, so I’m also wondering if I should remove a bit of camber.

Adding a bit of caster sounds like the most positive thing to do (no pun intended :)), especially in the wet, but I’m not sure for the dry. I’ve heard some ppl do this and others recommend removing caster to free up the kart out of the corners. So I’m at a bit of a loss.

Any other suggestions would be greatly appreciated! Thank you.

Share a video of the problem for better feedback. My mind goes straight to over driving without seeing it, especially as a first year cadet driver.

Lots of details to consider here but my experience with cadets is none of them know how to use the brakes so they almost always coast into corners and end up overshooting the apex.

So we managed to make it to the track later in the day and talked to one of the National level racers there. He recommended some seemingly counter-intuitive changes - at least for my current level of understanding :slight_smile::

  • increase chassis height in the front (two spacers on top)
  • narrow front (1 1/2 spacers)
  • leave the rear bumper loose
  • front bar back in

I set the tires to 14.5psi and 14psi and sent her out. Ambient air temp was around ~19c. The changes made a HUGE difference…like to the point where it’s hard to believe. Where before she would start scrubbing at the apex or in general just understeer, the increased bite (I assume) of the higher ride height in the front seemed to fix pretty much everything. She was able to flow through the corners without scrubbing and she hit her apexes on the hairpins and absolutely no screeching from the tires. It was rather mind-blowing to be honest. She did so well that, for fun, we threw her on a gold slide (Cadet kart :metal:) and gave her some velocity training. :slight_smile: Again no screeching, no understeer/excessive oversteer, just hooked up and turned.

The one thing I want to confirm tomorrow is how raising the chassis in the front affects the alignment. Does it remove or add camber/caster, what about toe? Maybe those are unexpected changes that have helped things too.

Unfortunately, it is going to rain tomorrow but Sunday looks dry so really more optimistic about this weekend. I’ll see if I can dig up a video or two to show the differences.

Video: The hairpin that she usually has understeer on turn-in and after apex when getting on the gas. Sorry for the crappy zoomed in cell phone vid. This is after the changes we made (so shows how much better the kart is rotating). I’ll try and get up an onboard video later and see if there are any other suggestions for her.