F355 Understeer vs Oversteer

Robb my guess is most have oversteer problems unless they have been changed. My only logic is both mine and henrys have oversteer characteristics. My bet is yours and your brothers will as well.

You can always test my logic just find a wide open parking lot you dont have to go that fast.

 

Sorry i didnt answer your question however i think to create an understeer characterist will not be simple because of the weight bias and the size of the stock tires. That being said some of the guys who race and understand the geometries better than me will need to chime in.

Once you get used to the oversteer its quite easy to control and much safer in my opinion than neutral or understeer.

 

I went 245/275 f/r tires and it's pretty much dead neutral. I can adjust for slight understeer/oversteer using tire pressure. At 35psi front and 33psi rear pressures I get slight understeer on entry and slight power on oversteer on exit. Lowering the front to 33 gives slight oversteer on entry and power on oversteer on exit (and results in me driving sideways too often),so I stick with 35/33 psi f/r. If I can keep the car in shape for a full lap at 33/33 it's probably a little faster but it's more difficult to do a clean lap as I'm fairly aggressive getting back on power and it requires judicious throttle application to keep the rear behind the front.

I honestly wouldn't worry about it too much,it's close enough to neutral that you can make it do different things just by changing your driving inputs. It's better (imo) and makes you a better driver to drive the car how it wants to be driven rather than try to make the car drive how you want it to.

 

Mine responds to tire pressure adjustments much more that I thought it would. I run my front tires 3-4 #'s less than the rears to get good balance.

 

cars sold to the general public are engineered for safety over balance and that is why they under steer. Understeer is easily corrected by what most people do when the car doesn't do what they want. Stab the brakes.

A car that oversteers takes steering inputs to counter a spin. A car spinning is an out of control event that usually results in the car stopping by hitting a fixed object or rolling over or both.

There really isn't an argument about what is safer for the street.

As far as how to change and adjust a cars dynamics
There are several ways.
Sway bar sizing, tire sizing and corner balancing.
Spring rates between front and rear. Even different types of differentials provide differing types of slip to keep tire scrub to a min on the drive wheels.

Like mentioned already. It's much more beneficial to be able to drive a car at the limit and be able to adjust the cars balance with technique.
Throttle on can change understeer to over steer.
Plenty of info out on the web about driving techniques, early apex, late apex, trail braking and discussions on corner speed, brake zones, driving line around a particular corner or track.
You can not drive your car at the limit on the street so don't worry yourself about any slight Bias either way. Or get out on a track for some driving school and you will quickly realize the limits on the driver are found long before the cars limits will be.

 

See publication "Introduction to the Vehicle Dynamics" for the Ferrari 355 Challenge. 55 pages. Thorough explanation to the 355s specific dynamics.

 

Not so much oversteer, but just less scrub while cornering.

Raise the rear by 2 turns on the spring perches, and you will increase the oversteer (should you desire it so.)

I leave my F355 in street configuration on road race courses. I find that I can drive the 70 MPH turns with oversteer/understeer controlled by the pressure of the right foot on the gas pedal. A little less and the nose drifts outward, a bit more and the nose drifts inward.

At the instant in time of the turn above, the tire pressures are 40 PSI all around, and tread temps are between 195dF and 205dF, with almost stock sizes of 225/40ZR18 and 275/40ZR18. Tire pressure and tire temperature can be used to control the oversteer/understeer relationship.

Tire temperature and pressure can tell you why the car is oversteering or understeering (front with too much traction, or rear with too little.) so you can adjust the car or suspension to deal with the end lacking grip rather than simply balancing the car to the end with little grip.

 

Rob Schermerhorn at Delta Vee published a good monograph on the subject a few years ago: Chassis Tuning Ferraris for the Racetrack

 

It's all in the tires. After a few laps adjust your tire pressure and you will see the difference

 

It's incorrect to say that on track drivers prefers oversteer, on the contrary, on RWD racing cars you want it to be slightly understeer.

When you read that the F355 has a set up for understeer, it means it will understeer on the limit under "no throttle" , not when putting the foot down, which will obviously cause oversteer.

Ideally, when someone talks about a car that oversteer or understeer, first question is: does it O or U on turn-in, on the apex or at the exit?

As as rule of thumb, RWD race cars have a slightly understeer setup on the turn-in so on the exit the power can be put down earlier, compensating for the "understeer" behavior and thus performing an ideally "neutral" trajectory.

If you have a RWD that oversteer under no throttle condition, you will lose speed by having to counter act on the steering wheel.

 

Not to mention the fact that biasing toward oversteer may result in permanent handprints on your dashboard from passengers

 

Here's a good summary...
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Side-note for beginners: check your tire pressures before and after EVERY session at the track. It's crazy how high they jump up after a few hot laps.

 

and lugnuts for tightness. That's all the car prep a newbie should have to worry about.

 

I have that book it's nothing more then a beginners manual that should have been 3 pages at most spread out in yadda ydda ydda to 55 pages

True Italian long winded explanation


My cliff notes version
Oversteer wheels go this way
Understeer wheels go the other way
Throttle induced over steer, hit gas wheels say hello to front wheels

 

Check your oil lines (and fluid levels in general), too.

I'd also flush the brake fluid and put fresh oil in, even if a newbie.

Also, check your oil lines.