Chassis stiffnes

Hi there! As many of you know i drive for swedish IPK factory team… i got to test another chassis (Praga fighter) its mixed 28, 30 and 32mm tubes… i did todays race with it. In heats i was p1 and started p4 in final (touched someone +5sec) i was really strugglibg in the final and overall with rear wheel lifts. On my dragon all 30mm frame its really easy. So i coulden’t work my way up to p1 again? Why is this?
Me with my mechanics:

Me having no stress bc im in my natural habitate P1

It was lifting too much or too little?

Lifting close to nothing😭

Well it’s a different kart so it works differently. Hard to say the exact reasoning why, but some combination of tuning thickness and chassis geometry means it flexes differently. Your mechanics couldn’t find a solution? Why did you switch karts?

We wanted to try diffrent models. We tried everything. Switching axles. Traxkwiths, rideheight, seats, seat positions, front geometry. Weight placement. Etc. Can it be beacuse its thicker?

Depends on where the tubing is thicker. It could just be the design of the frame too. I’m not sure what tubes are what thickness on that chassis.

It HAS to unload the inside rear wheel in some way. If you narrow the rear track and raise the seat and add full caster, it WILL lift. Unless the kart is broken. But it wouldn’t make for a very good product to sell if it didn’t lift the inside rear wheel at all… Maybe you just didn’t find the sweet spot on the setup? Different chassis might take a different driving style as well.

It can’t have been too bad if you were up front.

What felt different in the final vs. the heats? How did you times compare between heats and final, and how does the progression compare to a “normal” race weekend? Did you slow down throughout the day, or did your competition speed up?

If you and the team are serious about having this chassis as an option then you may want to find a test day to do a back-to-back comparison vs. your regular chassis.

I second what everybody else here is saying, if you ended up P1 in heats, chassis can’t be that bad. Probably something was off with the setup later on, conditions changed or the changes you usually make on the other chassis didn’t work out on this one, lots of variables.

I own both, I have a Dragon Evo 30mm and a Fighter 30/32, both in shifter setup. One is paired with a Rotax (Dragon) the other with a KZ. They are both great chassis, but the fighter is much, much stiffer than the Dragon. By a mile, which affects the way you drive it and setup…if the kart was not sliding (spilling over) but simply staying too flat, my bet is that you didn’t have enough weight transfer to make it twist. So check what TJ was saying setup-wise, all else equal you probably need to go in that direction (seat up, narrow rear, add caster etc) compared to the baselines you run with a Dragon.

Begining od session i had no pace at all. Mid session i got more pace and got back my p1 place. The track was colder in finals by 3 degrees. But i wan’t getting rear wheel lifts at all (even with high grip rims)

Being that it’s 32mm on all the crossbars you may not have the upper body weight to load and flex the kart to jack it very well.

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32mm cross bars are made for heavy guys with lots of power. This chassis will work its almost identical to my SKM prototype (IPK before 2013ish) You have to widen the front to max and narrow the rear to like 1000mm axle length and short hubs.

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im 160cm short and weight 59kg

The stiffer the chassis the less likely to lift the inside rear wheel.

But if it showed that much potential it’s definitely worth trying to keep working at it and finding a bigger setup window.

You might need to try a different stiffness seat, and caster should help this.

I have a tillett t11 vg in it (my fav seats) and a greyhound habdmade seat ( softest on thir line) its softer then t11 vg

Im going to italty next week so i have some more chassis to test ready