Trying to Set Up CRG KT2 for Briggs on a Slick, Tight and Technical Track

Chassis Setup, Tires & Handling Forum
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Hey all.

First, Good evening! New member here!

This is my first kart, and I am completely new to the scene around here (Houston TX)

I spent a number of months reading forums, finding PDFs, watching youtube to try and amass some fundamental knowledge here.

I’ve run 3 race weekends, each of them was a disaster, especially the most recent one. I am going to summarize my most recent setup, experience, and changes - i’m not asking if it’s correct, rather, for the folks who have raced briggs, and perhaps have done so on a bigger chassis (like a X30/rotax) and perhaps find some common ground? Youtube has been difficult - the variables are just too many. most of these people are talking about a single track that ends up being irrelevant because I’ve never driven it.

This track I’m racing at could be described as “green”; its very slick. it’s asphalt, it gets a lot of use with rental karters, the track is very active… but we go out on Saturday morning and its like ice.

Ok so here’s where i’m at:

I had reconfigured the kart to be “Baseline” spec according to CRG. Rear axle UP, front “middle”; I then took the kart to a rather popular regional track for a test day and it handled great. I was continuing to improve times and I never really felt like I was fighting the kart too much - that is to say, the balance was right.

Afterwards, my tires looked like hamburger. I take that to mean they got a good working over and there was nothing really standing out (like one sided wear, etc)

I cleaned them up, and prepped for the race I would be running a week later expecting a similar performance… I was 2 seconds slower than everyone else. I was being left in the dust on the slow corners, the kart was slipping and sliding coming out of every turn…it was Sketchy As Frig!

  • Nervous and twitchy on brakes
  • neutral to tight coming into the corner
  • LOOOOOSE to drifting coming out of corners

I let some air out, ran my race at 12 psi but to no avail. Afterwards, my tires looked like they weren’t even used. such fine graining if anything.

So after yet more forum research:

  • Ride height was possibly too low and the kart wasn’t putting enough side force into the tires?
  • Started with too much PSI (17, ended up racing at 12 and it was still loosey-goosey)
  • Seat struts are evidently mandatory for short drivers in briggs series because the karts are so slow they need help keeping the inside rear lifted?
  • Briggs karts are slow and need help keeping the rear end free

Here’s what I noticed a about the other racers:

  • Each all run a briggs or 4S chassis, including CRG, Birel, Intrepid, Praga, and Tillotson
  • Each all run relatively close together
  • Each have only 2 rear bearings
  • Not everyone has maxed out rear track width
  • Ride height was “middle” from what i could see.
  • they have short wheelbase! 1030mm?

So IDK…hoping to address the issues. I probably made too many changes but we’ll find out. Either way - one thing for sure, is that most of the time i find “Briggs” or “lo206” kart info online, it’s dirt tracks/flat karts… Finding sprint kart info has been a chore, but I have found some good posts here, and that is why i decided to register at KartPulse.

Here’s the current config - and my thinking for it. Am I going in the right direction? (zomg pun)

  • I set rear ride height to the middle and forward position - so that means the wheel base is 5mm shorter.
  • I removed the third bearing entirely. I read about the zip ties, and frankly, nobody else runs 3, and i figure i need to make my chassis think its a FS4!
  • The front height is set with 6mm spacer on bottom, 9mm on top (it’s got 3 3-mm and 1 6-mm per side)
  • The front spindles are configured with 20mm spacers (2 8mm and 1 4mm)
  • I have both short and long wheels, both 6" and 7.10" tires to run, but im sticking with 6"

I am probably going to buy seat struts, because i AM short and i have a lot of weight bolted to the seat - that seems like it would help coming out of the corners?

Thanks for reading that ridiculously long first post, and i hope it wasnt too disjointed.

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There are a lot of thoughts and theories at play here, possibly too much. It’s easy to overthink this stuff especially when you’re new.

First off, what tire compound are you running? A leap from 17psi to 12 is a huge change.

Let’s simplify this. The kart handles well on the baseline setup on a normal track but is too loose on your low-grip track. Okay, so we start from baseline and need to make adjustments to compensate for the green track.

Honestly the first thing I would be doing would be slapping 7.10 rears on for the green track and leaving the baseline setup to see if that bigger tire gives you the rear grip you need.

Also keep in mind that with only three weekends under your belt, there is a LOT to find in your driving before taking huge swings on chassis setup.

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You don’t need to chase setup so much as just get laps in and work on driving.

New guys will chase setup changes without knowing what they are really feeling.

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We it be useful here to define “baseline” as a wet setup? Run the default wet settings as a baseline and then don’t touch anything until your driving improves.

I find it very hard to fight the urge to tinker, but then I just think to myself “could a better driver go faster in my kart?” The answer is a resounding “yes”, so I don’t tinker. There are sometimes though that I fix obvious issues like replacing old tires that are doing me no good, but even that was debatable, because I am still very much the loose nut. Still, it is hard to get comfortable with a kart when you are second-guessing the setup, so that’s why I propose the wet setup and then forget about it.

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This sounds like something easy to write - but how am I supposed to do that when i’m fighting the kart 100% of the time?

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In this case, a “wet” setup is increased (max) ride height and possibly increasing front height.

At once point I had the rear ride height at max already, but i had a frig ton of understeer… I tried a lot of spacers and not sure that helped much… but here’s two things i read about ride height:

  • Rear ride height will shift balance towards the front
  • Rear ride height will add rear grip and reduce front grip (push into corners)

Which of these is true? lol

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What tire are we working with here?

(Some) of the issues could be due to overdriving which I think is what Matt is getting at. A classic example of this being something called push\kick where the kart refuses to turn in at first, when it finally does it happens so abruptly that the rear then steps out near or after the apex.

In general I would say seat stays are something to have installed in 96% of situations. (96% is a stat made on the fly of course).

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GoPro video would be ideal here.

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Read my posts about unloading the inside rear wheel and how “grip” isn’t real.

Raising rear ride height increases weight transfer, allowing the inside rear wheel to unload more easily. This usually gives better lateral bite in the rear, but like any adjustment on the kart, go to far or get too far out of the tuning window and it can produce the opposite effect.

Again, need to know what tire and need to see some onboard video to get an idea of what’s happening.

Three races into your career, you should not be taking such huge swings on setup. Honestly everyone should just run the baseline factory setup for like their first year of driving.

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I’m with TJ on this one. That said, sometimes people buy used chassis that already have some foundational elements (seat type, seat placement, axle, etc) altered from factory baseline, and/or some items aren’t always clear as to whether they’re standard equipment or not, e.g. hub length.

What tire are you on?
What class are you running (senior, masters, junior)?
How tall are you?
What year is the chassis?
What axle is installed?
What length hubs do you have front and rear?
What brand and rigidity of seat do you have mounted?
Where is the seat mounted? (measure from leading edge of axle perpendicular to back of seat)

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I will add to Evan’s by asking if you have access to scales? Someone at the track maybe who would let you get on them?

Also, how old of tires are we talking? A lot of new folks try to tune to tires well past their useful life.

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This is a great point. I remember the first time I put on new tires during race weekend…it fixed all of my handling issues and I went 1.5 seconds faster lol.

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I agree with basically everything said. That said if base setup assumes more horsepower and stickier tires then things will probably trend toward wider front and narrow rear when going to harder tires. When sliding track is slick my experience is higher tire pressure, not lower. It feels a little backwards. Also 2 seconds slower is not unbelievable first time out. Work on consistency then speed.

Twitchy under braking - Make sure you are braking in straight line
Looooose out - Try to be back on gas just before turn in. It helps the corner be consistent. Back on gas mid corner is more likely to upset the kart

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yeah, push/kick sounds like what i described, exactly. The reason though is that the things i read about track width and setup all suggest that i should run as wide as possible in the rear, but thats clearly giving me way too much rear grip, isnt it?

Installed seat struts, one on each side - so i think that’s helped get the tire off the ground.

I had one practice since, i ran the 6" tires on the narrow wheels. I made an adjustment to bring the wheelbase in to like 54" and did about 40 laps.

Tires still look unworn.

My conclusion from that was that i can run a narrower rear track and bring the caster back down to the middle position. It was pushing a bit, and i feel like the caster was an over-correction in the wrong side of the kart, because at one point i really went for it and i knew i was almost on 2 wheels.

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Thats the thing everything i read seems based on either running ka100 or rotax/x30 - there seems to be very little reference material for briggs karts lol. this makes a lot more sense, and thats where my setup is going.

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For a standard engine package that makes actual power you usually want to be near max on rear track width. For a slower engine that can’t generate the same forces, you don’t want to be that wide.

Wider rear track width doesn’t necessarily mean more “grip”. Going wider in the rear will reduce the kart’s ability to unload the inside rear wheel. In some situations this will induce more understeer. In some situations this will induce more oversteer. It depends on what part of the tuning window the kart is currently occupying.

You can go too wide and make the kart soft and flexy in the rear which can induce a flat-slide oversteer. You can go too narrow and make the kart unstable and too aggressive in its weight jacking, overwhelming the outside rear tire and causing it to lose traction.

This is why viewing adjustments in terms of “grip” is the wrong perspective. Instead consider how each adjustment affects chassis flex and weight jacking.

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Flat-slide oversteer. Indeed.

I think i can consider this answered.

The track width was causing most of my issue - i couldn’t get any turn-in. I went to 52.75" and i was actually able to keep up with the rest of the field, and now i can finally focus on my actual driving!

I did make a late final adjustment and added a 4mm front spacer to each side, not sure if its placebo or what but MyChron said I was slower the whole session. So I think the sweet spot is somewhere between 16-20 mm front spacing and a 52.5-53" track width.

So anyhow, thank you for the explanations.

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