I need help with, rear end grip

Chassis Setup, Tires & Handling Forum
#1

Mac Minarelli

  • Need help with overall rear end grip, kart is always loose on exit compared to front runners. The kart is not so bad on fast sweeping corners.
    Most front runners are taller and heavier than me. My size front runners have their weight mounted on the top of their seat.
  • My total weight is 186kg, 16 kg on the left next to my seat and 12 kg at the front with 43% Front 57% rear
  • I’m 1.73 65kg
  • 4 stroke 24hp
  • Class weight 185kg
  • Tire MG Orange/rental line/ very hard side wall tire
  • Front 1 1/2 spacers
  • Front bar in
  • Rear 1380
  • No seat struts
  • Seat at 630 mm can’t find anything on the mac seat position, otk recommends 625 -630
    Top kart recommends 615-635
    Neutral Caster lap time 50.7
    Half Caster lap time 46.7

No adjustments change the situation.

  • Should I lift the seat and move it rearward?
  • Should I try seat struts?
  • Should I move the rest of the weight to the back top of my seat ?
#2

Your lap time varies 4 seconds with that adjustment? What are the leaders lap times?

#3

That’s a very wide swing in lap times, there has to be another factor at play?
Top kart’s seat recommendation is just a starting point and probably not ideal for the hard tire you are running.

#4

What kind of loose? Is it loose loose, snap loose, etc? You can be pushing until the fronts grab and kick your rear out. :grimacing:

1 Like
#5

It changed a lot with die caster change, the front runners are at 46.0 The only thing changed was the caster same tire pressure and temperature.

When I follow one of the front runners throughout a lap the back is loose corner exit. I can put the front wherever I like without understeer.

#6

Something else is happening then, as a small caster adjustment (no adjustment for that matter) is not worth 4 seconds. It may be a driving issue or something fundamentally wrong with the kart.

The difference between nailing the setup and being way off is 0.5-1 second at MOST. 4 seconds swing is a sign of a different problem.

Before diving too far into suggestions for chassis changes, it would be worth considering if your driving is consistent, as any chassis setup changes will be completely worthless without first nailing down driving consistency or ironing out whatever other issues the kart is having that’s causing that swing.

#7

I’d definitely try seat struts. Was a night and day difference for me.

#8

I struggled with a 180° right turn that immediately goes into a left, the caster made it much easier going through this section of the track.

#9

Seat struts stiffen up the frame allowing it to twist less. This had the effect of more positive jacking, better bite on tighter corners.

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I struggled like crazy through this section without struts (CRG KT2). I put struts on (1-1) and a bit of extra caster - made a HUGE difference.

Regarding the caster I found it a bit twitchy at neutral. A notch of extra caster took that away. Try it n see.