Thanks TJ.
As simple as it is, I’d not thought to try a different line to prevent hopping. Helps me realise I’ve gotten ‘locked in’ on my concept of the racing line. The optimum line will vary with the conditions, whereas I’ve been driving habitually to the geometrically obvious one. That’s an important revelation.
As to using lean to unload the inside rear: would I ever want anything other than as-close-to-zero force on it as I can get?
Great answers as always. Thanks buddy.
Lee
The only time you want the inside rear down is for traction purposes. So for example, a rain race, hard tires or very high horsepower, you want to get it unloaded but then you may want it setting back down early to provide extra traction earlier in the corner.
Thanks TJ. Appreciate.
@tjkoyen
Got it, so basically you’ll almost always want seat struts (I think), but you’ll just have to position them differently depending on the exhaust setup and seat position.
@Marin_Vujcich
Based on your description, I think “bucking” is a VERY accurate way to describe it. If you watch my onboard video (below) you’ll notice especially towards the END of the run (as my tires presumably heat up and grip more) that my helmet camera shakes around more and more. This is most noticeable at OVRP in the box turn (double-left hander in front of the pits) because I feel like that turn requires a bit of maintenance power in the middle (to maintain speed) and then smoothly rolling back onto the gas for a quick exit. Only problem is, I can’t seem to give it enough gas through the exit, because the bucking jostles me around really hard. By the end of this run, I was really worked/tired, but I feel like it shouldn’t have to be that way with a proper setup, since I am plenty fit enough.
The hop is in the low speed turns most noticeably. It seems like the frame is resonating.
Wow that’s severe and everywhere as soon as you turn the wheel. I think your initial turn-in steering might be a little harsh, but that doesn’t explain it.
My first question is… are you sure the chassis isn’t cracked anywhere?
That was my thought as well.
@KartingIsLife
Not 100% sure, but now that you mention it a cracked or worn out frame would make a lot of sense…Plus this is a rental kart which, by this day, had seen almost a full season of use.
I’ve seen lots of drivers post “used” karts for sale that only have a few races on them, and I’ve always wondered why. Do you think frames wear out and become uncompetitive that quickly?
My first kart ever was a Fullerton that I actually ran for about 3 full seasons (after buying it slightly used). Season #1 it almost won OVRP’s Junior Yamaha championship, but by Season #4 I had somehow cracked one of the seat posts where it connects to the bottom of the frame (perhaps from just hard cornering over and over). I eventually sold it to my college’s FSAE program, where one of my classmates figured he’d weld the piece back together and then use the kart for training purposes.
No, but if they’ve been raced hard and beaten around, there’s a good chance they’ve been bent, bent back to straight, maybe scraped on the ground etc., so that would wear a kart out quicker. But generally a kart frame does not wear out that quickly.
Video shows pretty aggressive hop. I would:
Any of those should fix it.
I second to everything that @tjkoyen said, I had a similar hop in the chassis when I ran x30 senior. It took me months to figure out that the seat was in the wrong spot. If the smaller changes don’t work then the seat will probably need to be lowered to get your COG down.
That thing is hopping everywhere, severely. Assuming the frame isn’t bent/cracked, that looks like an incorrectly mounted seat to me.
Would it be worthwhile to try a stiffer grade of seat? Standard T11 perhaps?