F1 Chassis

This topic has 5 replies, 4 voices, and was last updated 12 years, 9 months ago by mark crook.

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- November 25, 2013 at 1:46 am #16509
  
  Shaun Everard
  Participant
  
  I’m sure Ian Harrison would be able to help.
- November 26, 2013 at 7:35 am #16572
  
  mark crook
  Participant
  
  Ta,
  
  I seem to pester Mr Harrison every time something is up with my motor. Don’t want to be a nag.
  
  I have found that the 2004 chassis does understeer on first gear corners and I find myself trying very hard to get the back end around. Although on faster corners the rear is stuck to the ground which Is great but when I push hard it hops around like hell. Maybe a sign of too much rear grip??
  
  Quite new to karting so please bare with me if I sound like I’m talking rubbish
- November 27, 2013 at 5:29 pm #16683
  
  Ian Harrison
  Participant
  
  Hi Mark
  
  The excess of rear grip that manifests itself through the rear end hopping was a characteristic of the older F1 chassis, which was a bit soft for a 250 single. Virtually impossible to cure 100%
  
  As you have found you have to drive round it by just giving enough throttle to smoothly break rear traction, any more than that and you get the grip-release-grip-release situation that manifests itself as hopping. Either way it doesn’t make for good lap times and the hopping is tedious, tiring and destructive!
  
  I’m afraid that I don’t have hands-on experience of the newer chassis that Chris Purdie (CPR) produces, but I know that he has been addressing that issue.
  
  Best Regards
  
  Ian :-)
- November 28, 2013 at 6:57 am #16697
  
  Matthias Schümann
  Participant
  
  Hi Mark
  
  You could stiffen up the rear end a bit, by mounting bracket’s from the rear axle bearing mount to the seat, we used to have to do that when we raced in formula A 100cc in the late 80’ties early 90’ties, to prevent the rear end from hopping, sometimes we ran up to 4 of these brackets, 2 on each side. Moving from a 30 mm axle to a 40 mm one helped a bit.
  
  But with a soft chassis you should be fast in the rain :)
  
  Best regards Matthias
- November 28, 2013 at 2:56 pm #16723
  
  mark crook
  Participant
  
  Thanks for the replies,
  
  I have decided to sell the older chassis on and go with the more rigid 2012 frame. Need money to put towards building the new frame up and it seems silly to have two chassis on the go.
  
  I wonder if the older 32mm frame would have worked well with 125 gearbox on long circuit? (if you could keep the weight down)
  
  I like the idea of having extra support from the seat to the axle, may just try this in the future :) would this also transfer more weight onto the rear tires under load?
  
  An adjustable wishbone across the rear of the kart is what you need :D
  
  thanks,
  
  mark
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