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Massive understeer on a 328 -- suggestions?

Discussion in 'Other Racing' started by Tillman, Dec 7, 2003.

  1. Tillman

    Tillman Splenda Daddy
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    Nov 26, 2001
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    I went through my first driver training/performance course this weekend. One of the elements was a run through a road course about a mile long -- with no straightaways at all. All curves.

    The 328 was really pushing hard, as if it had no grip on the front end. I'm running Portenza PE730s. Those are mainly street tires, but it should have stuck better than that. Instead, it was if my steering input had no effect at all for a while, and then kicked in hard and whipped the car around.

    Pressure is 30 all around, no mods on the car. They are wearing normally and didn't show any signs of rolling under after the sessions.

    Suggestion to bring it back to a more neutral feel? More air, less air, 200 lbs of sand in the front trunk?
     
  2. STEEDA30

    STEEDA30 Karting

    Nov 1, 2003
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    Atlanta(Vinings),Ga.
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    Rick Charles
  3. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
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    Gary B.
    Actually, I disagree with Steeda30 on this. I would try 34f, 30r on the tire pressures. Most understeering cars respond to increased pressure in the front tires. Also concentrate on turn-in technique, be very smooth and deliberate with your initial steering wheel input, to allow the front tires to bite. It is very easy to crank the steering wheel too fast, and once traction is broken, it takes several seconds of plowing and slowing to get it back.

    Gary
     
  4. PSk

    PSk F1 World Champ

    Nov 20, 2002
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    Pete
    Have a look at your throttle control, if you are accelerating into a corner with all the weight on the driving (rear) wheels it will cause the car to push. Try going in a little faster a lifting and then getting on the throttle again to control it all. I had this trouble with my last (not non-Ferrari) club racing car, after racing a fwd car for a few seasons, I had to learn to lift otherwise the lsd would push the car.

    Most cars will understeer on a slalom course because you gain speed as you get in the grove, plus you are constant throttling. Personally I would not set my car up for a slalom course because it is not a natural or real race course ... and yes real race courses have chicanes but you go into them completely different than a slalom course.

    Just my 2 unknowledgeable cents worth ...

    Pete
     
  5. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    Phil Hughes
    Your tyres should have a couple more lbs in the rear than front. When cold, they should be around 32F and 34R. ...When HOT, ie after use, they'll be up around 36F 38R or more. Anything over 40lbs on a road tyre is excessive, but keep them close to it.

    Get a wheel alignment done, and ensure you've got the correct settings at least, after that you can improve things with more negative camber at the front, and more caster is good too.

    Spring changes can be done to improve things further, but a balance should be attainable with good driving practices and reasonable car set up.

    328's are inherently very chuckable...so if your's isnt there's some kind of problem somewhere.
     
  6. Tillman

    Tillman Splenda Daddy
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    Thanks for the suggestions. I think I have a combination of all the above -- poor throttle control, too quick input, and tire pressure problems. I'll work on all of them
     
  7. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
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    Rob Schermerhorn
    Yes, yes, yes!
    No. I couldn't disagree more.

    In general, reducing pressure aids tire compliance and improves adheasive and deformative grip. BUT, in this case, the mid-engine Ferrari with road-car tires needs higher front pressure to stabilize the sidewall and footprint of the tire. This improves not only grip, but also response. Meanwhile, runing less pressure in the rear relative to the front, increases grip via the aforesaid compliance grip. Plus, rear tires have more volume to support the tread.

    Read my article under "Parts & Service": Chassis Tuning Ferraris for the Racetrack.

    Best regards,

    Rob Schermerhorn
     
  8. BigTex

    BigTex Seven Time F1 World Champ
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    Dec 6, 2002
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    Bubba
    Rob, I noted the factory tire pressure chart showed the front/ rear imbalance (rears higher), but this was for identical tires all around on my 308GTB. 14" 70s.

    If you go with a later tire stagger with larger rear tires, does this cancel this requirement?
     
  9. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    6,334
    Also look at what you brake foot may or may not be doing! A sloppy transition from braking to turn initiation can result in understeer as the fron end rises after the release of the brakes and is not capable of taking steering at that moment in time. Suggestion, get braking done earlier and get off the brakes earlier and see what the steering does without the influence of braking on the chassis.

    Many cars and most Ferraris have more traction in turns while the POWER is ON. Geting the brakes done early allows you to squat the rear under power and takes weight off the front allowing faster turn initiation and reduced understeer. Don't dilly daddle with power; ON means above 70% WOT.

    Finally, many first timers are under the impression that late braking wins races and is therefore a good technique. Late braking wins races because it hurts your opponents time more than it hurts your time. It is almost NEVER the fast way around the track, and is NEVER seen in qualifying!
     
  10. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    Sorry Rob, but you're caught up in low profile technologies it seems to me.

    The 328 does not have particularly low profile tyres, and the same rules do not apply....348,355,512TR,360 etc, and I'd agree with the lower pressure in rear when cold theory...but 308,328,BB etc with high side walls.....The extra weight of the rear will overheat the tyre if not propped up with extra pressure, and the car will roll around on it's sidewall flex causing instability....and besides, Ferrari say to have higher pressure in the rear...i think they know what they're on about, and all the successful challenge teams of the 328 vintage know what they're up to too.

    So.....Disagree all you like....I'd love to race in a series against you, maybe one day.....
     
  11. NoTorq

    NoTorq Rookie

    Nov 3, 2003
    29
    If a lowly auto-xer may chime in here, I'd like to second this post. I was having a huge problem with understeer in my S2000 (a car more known for oversteer). During all my pit side chats with experienced S2000 auto-xers I kept hearing things like "WOT till you see God, then BRAKE!" I took that too literally and was braking too late and pushing through every turn. It wasn't until the last auto-x of the season that it finally clicked and I was able to get my braking under control. My understeer problem disappeared, now I'm shopping for a stiffer front sway bar for next season in anticipation of the S2000's more charateristic oversteer.

    I would suggest before you change anything (assuming there is nothing wrong with your 328!) that seat time is far and away the best way to improve lap times. I would also suggest that auto-xing is a cheap way to get seat time, it has helped me to improve my skills immensely. It's no substitute for the adrenalin of a real road course but it is a low risk, inexpensive training tool.
     

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