[s-cars] Your TT posting

Bill Noland wenoland at pacbell.net
Tue Apr 24 09:00:00 EDT 2007


Colin -

I agree that 50 is too high for the track, even as a hot reading, but you're getting nowhere near the recommended 45psi starting with 28psi cold. A tire pyrometer would be a big help.  Here's a link to Roger Kraus Racing's listing of under/over-steer corrections. (Roger Kraus is THE Northern California tire shop.) You might try adding weight to the rear of the vehicle, as the chart suggests. Believe the great Speed Racer kept a chimpanzee in his trunk.   :-)

http://www.rogerkrausracing.com/TechSheets/overunder.shtml

Bill N
  ----- Original Message ----- 
  From: colin cohen 
  To: s car ; Bill Noland 
  Sent: Monday, April 23, 2007 11:36 AM
  Subject: Re: Your TT posting


  Many thanks.  The pressure suggested seems high but 45 is the recommended hot pressure for Hoosiers so I can use that as a place to start.  I have a test session next month and will try it then.  Seems that understeer would be promoted by high pressure though as it reduces the whee/ground aspect whereas you want to increase this to reduce understeer.  Now if one left the fronts at say 30 and put 50 in the rear that would make more sense to me in promoting rotation?

  Common question I know but the Quattro piece sometimes makes it work the other way.

  Colin
    ----- Original Message ----- 
    From: Bill Noland 
    To: colin cohen 
    Sent: Monday, April 23, 2007 7:41 AM
    Subject: Re: Your TT posting


    Colin -

    Instructor claimed they kept adding pressure -- up to 50 lbs. (at the front, one would assume), until the understeer went away. I would imagine that is about the limit for the P Zero tires they were running. Of course, this was for a few laps of autocross, with cool off time in between. Don't think I'd go near that high for club racing, but you may want to experiment with some higher pressures. Good luck.

    Bill
      ----- Original Message ----- 
      From: colin cohen 
      To: wenoland at pacbell.net 
      Sent: Sunday, April 22, 2007 12:56 PM
      Subject: Your TT posting


      Do you have any idea what the Audi Experience/Panoz guys did with the tire pressures that was son "radical".

      I am part of the Istook racing team and we are running 2 TTs in SCCA T3 class and battling this issue.  There are very few mods allowed and anything we could do to rotate these cars would be great.  Currently we run about 30F and 28 rear.  

      Anyone you could put me in contact with would also be helpful.

      Colin Cohen
      A4 (formerly the factory race car in 1997 Grand Am)
      TT (SCCA T3 Run Offs competitor)
      A6 V8
      SQ S/N 198


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