7.1 rear tire is what we run.
Here a picture of how I am sitting in the kart.
My seat was at 38 degree angle and I changed it to 33 degree.
The front height is set at medium height, the rear at high height.
Front width at 25mm spacers. camber +2 degree, toe each side 1mm out.
Silver freeline torsion bar, 1040mm Righetti Ridolfo soft axle.
The rear width I started at the above recommended 50.75inch and super short 50mm hubs, which worked well in the morning and at the first 3 laps. Afterwards the kart was hopping and binding up, the lap times got worse after 3-4 laps.
The next day I went back to my long 105mm hubs and set it to 1355mm (sorry for changing units). That day I set my personal best and was able to keep up with the others. I think the changes with the seat and rear right height are positive, the kart felt better at turn in.
Thanks for all the help and recommendations.
PS: Still, a Top Kart might be on my wish list with an Iame 100, after my driving improves.
I think the rear axle might be a problem. With the RR axle you never know what stiffness you get compared to the Freeline one. And i would also suggest to try a step harder one. 1355 is way to narrow. And as you say you put on longer hubs and went narrower and it got better, its defenitely that the soft axle is too soft. With this one you just dont get enough lift. With narrower rear and longer hub you help to lift the inner tyre. So i think a harder will help you
Hi Dimitry, I tried a medium RR axle and everything else the same (hubs, axle width, tires and so on) and that made the hopping worse. It was not just a little worse but quiet a bit. The soft Freeline and RR axle worked very similar. The advantage of the RR- axle is that I have 1040mm instead of 1000mm and that allows me to try shorter hubs with the wide >1350mm setup width.
When you state “1355mm is way too narrow” I have to state that I am willing to try to go wider but 1,400mm is the max allowed. In the past I tried about 1380mm but I could not find much or any lap time reduction compared to 1,350mm. But its worth a try again with my latest setup changes.
Thanks.
We normally never go under 1390cm. Maybe its for the LO the right width. But for higher hp engines its too low
I’m just going to chime in on a suggestion given to me this past weekend regarding the tires. The used kart I just bought came with 7.1” rears and I was told it’s not an ideal width for our 206’s due to the sidewall being squared off on a 180mm rim. I was told to try a 6” tire. I have a set of 210mm Freeline wheels that came with the package and I had a severe push when it tried those at the recommended 1395 chassis setup guide I put the 180mm wheels on this weekend and narrowed the track to 1330 and it helped, however I felt like it was binding up as the track gripped up. So I’m going to try the 6” tires on the narrower rims and take it back up to 1395 and go from there…perhaps that may help you as well. Take what I say with a grain of salt however, I’m just passing along info from a longtime karter that’s been really helpful so far. Here’s a picture of the tires on both wheels and what he says theoretically makes sense to me that the rounded profile will allow the kart to roll onto the edge and bite better in my case and help with jacking as well. I run at Orlando where it’s a tighter technical track so ymmv.
Just keep in mind that a 30mm adjustment on rear track width is a massive swing and it’s pretty easy to go the opposite way on your handling issues by making that big of an adjustment. For example this past weekend I changed the rear track from 1390 to 1380 and it completely changed the attitude of the rear of the kart. It went from slight oversteer at 1390 to completely overworking the rear tire and creating too much weight transfer at 1380.
Definitely don’t run 7.10s on 180s
7.10s on 212s are fine.
Agreed. So far what he’s been suggesting has helped me tremendously and has made a positive impact on where the kart is versus how I got it. It was set up very narrow with a small seat so I guess it was being driven by a junior.
Where I race, there are no options. It is 7.1 tires MG red, 212mm wheels on the rear (dry).
I am not seeing a chance to change the local reglement for the whole race series.
I think it is similar at many other tracks, there are not any choices unless you run outlaw.