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Tracking a stock 360

Discussion in 'Tracking & Driver Education' started by Gary(SF), Feb 11, 2004.

  1. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
    3,637
    Los Altos Hills, CA
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    Gary B.
    I intend to track my 360 perhaps 8 or 10 times a year. I plan to learn the handling dynamics with everything stock for the first few events, and would like advice from those that have been there. Can I expect neutral balance? Most magazine articles seem to love the balance, but I have heard some reports of high-speed oversteer. Tire pressure recommendations would be appreciated. After a few events I plan to fit Toyo RA-1s, which I have some experience with and are great for track days. The only available sizes for the stock rims, however, are 225/40 front and 275/35 rear. If there is a high speed oversteer problem, this won't help. I could go with Corsa or Pilot Sport Cups but their rears are 285/30, which may be a bit extreme on the profile.

    This is dragging on a bit, sorry about that. Any input greatly appreciated!

    Gary
     
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  3. thomasmurphy

    thomasmurphy Rookie

    Dec 14, 2003
    36
    I have tracked my stock 360 extensively, raced my 360 Challenge and recently tracked my 360 CS. You are right, there is considerable very high speed push with the stock 360. But it is at very high speed. Not surprising as it is a street car and it is very predictable and consistent, no real surprises. However one thing to watch for is the quickness of the rear end release. You must be ready to catch it if you go a little too far.
    As for tires , slicks are better. Call Bob Woodman tires for advice. Enjoy the car it is great fun on the track and wants to go!!
     
  4. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
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    Gary B.
    Just so I understand your terminology, when you say "high speed push" do you mean understeer or oversteer? I've always understood push to mean understeer.

    Gary
     
  5. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
    3,637
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    Gary B.
    I've done a lot of racing, including track days and SCCA stuff, and want to keep my life simple this time around. That means no second set of wheels, necessitating a support vehicle or trailer (ugh). I will only drive the car maybe 3k per year and plan on leaving the R-compound tires on the stock rims all year round.

    Gary
     
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  6. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,603
    Dallas, TX, USA
    Gary,

    I applaud you on your plans... here's my experience doing the same...

    Balance is neutral... which is ideal, but means its a bit more complex for you as driver. Under power, you'll experience a bit of push/understeer; under braking, you'll experience a bit of looseness/oversteer. So, if you trail brake, you may get the tail coming around, but if you gently release the brakes and apply the throttle gently, its easy to catch. Similarly, if you ease into the throttle coming out of turns, holding back a bit if you feel it start to push, you can ride that rail easily. This is a car that rewards gentle inputs!! But will punish abrupt ones... since the limits are sooo high.

    I found I needed higher tire pressures than I am used to avoid the extreme braking power from causing the tire sidewalls to buckle a bit, resulting in squirrelly behavior in heavy straight-line braking. That cost me some traction, but was much more pleasant than crab-walking left and right in heavy braking.

    I, like you, want ease of track experience AND max performance on the street. I ran R-compounds on the street. In my case, Kumho ECSTA V700s. Worked great except that the tire sizes available resulted in smaller diameter on the rear... which meant I had to leave ASR off. No big deal, except if I wanted to let someone else drive it.

    Before the Stradale purchase, my plan was to try Pilot Sport Cups next. I think that may be the best choice for the 360. The Toyo's are a bit lower performance than Kumho or (based on second-hand info) the Sport Cups, but are great street/track combo tires. The 275 vs. 285 probably won't be too big of an effect on balance, but as balanced as the 360 is, you'll have to try it on yours to know for sure.

    The biggest issue will be brakes. If you drive hard enough, you will evaporate stock pads. If you put racing pads on, and drive hard enough, you will boil stock fluid. When you step up to R-compound tires, I recommend Castrol SRF and Carbotech Panther Plus pads (or similar quality racing pad). Yes, that means that your 360 will be a bit noisy on the street.

    HTH, Brian
     
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  8. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
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    Gary B.
    Thanks Brian, that's very helpful. I figure as my confidence increases and my speed picks up, I will be shopping for racing pads and fluid. From my experience and others, I have to say the RA-1s will probably give any of the other R tires a good run over the life span of the entire tread. I hear the PSC is a little better early in their life and then gets gradually slower with each heat cycle, a syndrome the RA-1 is remarkably resistant to. And as a bonus they are about $250 a set cheaper than the PSCs.

    Thanks for your input,

    Gary
     
  9. thomasmurphy

    thomasmurphy Rookie

    Dec 14, 2003
    36
    Brian;
    You are correct. The brakes on the street car will disappear after a hard braking day at the track. However the Stradale brakes are amazing, very late braking points time after time. No fade at all. And at the end of the day no dust!
     
  10. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    20,575
    socal
    Be careful with the kumho's and one size of hoosier's (it is on their website). Tail heavy cars like Porshes and Ferraris can blow these tires. In my 348 I had a bead blow off a rear Kumho during my 3rd warmup lap breaking heavy then cranking a heavy turn uphill at about 50mph. The spin resulted in no damage. No one had ever heard of this until I asked about this on a Porshe list. They all new about it since it happened to some of them. Their recs are to skip the kumhos for tail heavy cars. In fact the PSC's are designed for Porsches with their tail heaviness in mind. After that insident I decided to stick to Pirelli slicks ran in by the challenge drivers.
     
  11. Brian C. Stradale

    Brian C. Stradale F1 Rookie
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    Mar 17, 2002
    3,603
    Dallas, TX, USA
    That's awesome to hear... in fact, those brakes are a HUGE part of why I jumped when they announced the Stradale. For us "ease of use" track & street guys, nothing could be better! I just hope they prove to be reasonably economical (bit longer wear to offset much bigger price tag).
     
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  13. PSk

    PSk F1 World Champ

    Nov 20, 2002
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    Pete
    Brian,

    Have you got your car yet?

    Pete
     
  14. Brian C. Stradale

    Brian C. Stradale F1 Rookie
    Lifetime Rossa

    Mar 17, 2002
    3,603
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    No, not yet... if I did, I wouldn't have to ask how the brakes held up... I'd be out discovering that experimentally!! ;) My car should be coming out of production any day now... I keep waiting for a call... but it never comes... :(
     
  15. PSk

    PSk F1 World Champ

    Nov 20, 2002
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    Pete
    Good, I hope to read soon that you have the beast ... ;)

    Pete
     
  16. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,677
    Go for 8 to 10 times per year, and if you catch the addiction, you can easily bump it to 18-20 times per year!

    Stick with street tires untill you have a couple hundred laps under your belt. Street tires have less grip to be sure, but they have gentle breakaway characteristics and those will help you learn what the car feel like neat/at the limits. Once you are fast on street tires you are finally ready for faster tires, the higher grip with more sudden breakaway tires will sneek up on you and toss you into the weeds.

    You should find a neutral balance that can be altered with tire pressures. The actual tire pressures that you and the car like will be different based on the tracks you drive, the raod surfaces, the tires, and your driving style. You can start with the factory pressures. Get a high quality pressure guage, take notes and figgure this one out for yourself. The pressures you like might not be the pressures you friend driving the exact same car on the exact same track likes.

    If/when you make the move to r-compound tires, look for tires with the same rolling radius especially at the read. Given a choice between 275/35 and 295/35 go with the 295s because they have the rolling radius closer to the stock RR. If you find yourself constantly driving on r-compounds, you can change the rear ride height to rebalance the oversteer/understeer relationship with almost any combination of front and rear tires (within reason) without having to throw springs, shocks, or roll bars at the suspension.

    It might take more than one track day, but sooner or later you will fade the stock brakes. At this point you should consider putting better pads in the calipers, using higher temp fluid and ducting afresh air to the rotors. You can stay with high performance streetable race pads unless you start running slicks and leave them in for street driving duties.
     
  17. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
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    Mitch -

    Thanks for all the good tips.

    Gary
     
  18. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
    1,572
    Kalamazoo, MI
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    Rob Schermerhorn
    Chassis Tuning Ferraris for the Racetrack

    Please note that the 360 is a true ground effects chassis. As one becomes familiar with on track handling and desires to go quicker, lap times will decrease with overall lowering and then chassis rake changes.

    Be aware that going too low in the rear will cause high speed porpoising (a.k.a. "pogomation") as downforce pushes the rear suspension to the bump stops and you either ride the stops, and/or kill some downforce which pops the chassis back up. This will continue to cycle up/down and is quite disconcerting. Not to worry, there is a good compromise ride height and rake that will increase grip and not porpoise.

    Sorry I haven't written a 360 chassis primer, but good info from this article will apply here too. Set-up F355 Challenge for Racing.

    Best regards,

    Rob Schermerhorn
     
  19. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
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    Thanks Rob, great stuff!

    Gary
     
  20. ferrarifixer

    ferrarifixer F1 Veteran
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    I cant remember the source of this, but it's not my work, OK


    Ferrari 360 Aerodynamic Development

    Since the late 1980s, development of Ferrari grand touring (GT) cars and Formula 1 racecars has been guided by aerodynamics in an effort to obtain high downforce, resulting in enhanced high-speed stability and cornering capability. The latest Ferrari GT car, the 360 Modena, follows this trend. Aerodynamics was one of the fundamental design criteria that drove the entire design process of the car.
    Figure 1: Pressure distribution along the car's longitudinal centerline.
    Although the use of wings and spoilers provides high downforce, it could present efficiency concerns due to high aerodynamic drag. Considering the great potential of the underbody for generating downforce with good efficiency, engineers decided to develop an aerodynamic design for the 360 Modena that did not require wings or spoilers.
    The company's Formula 1 experience provided solutions for the 360 Modena project. The car was designed having a flat underbody with large rear extractors. This design maximized the shape of the underbody's surface, and thus, the available downforce. More than 3000 h of wind-tunnel testing was performed during the development. Figure 1 illustrates the pressure distribution measured along the longitudinal centerline.
    Figure 2: Aerodynamic map of the 360 Modena showing the downforce coefficient CZ as a function of the front and rear ground clearances.
    Although this aerodynamic solution was beneficial to performance, it presented some drawbacks. The room available for the gearbox and the rear suspension was limited, requiring engineers to select a longitudinal gearbox and short suspension wishbones.
    In addition, the car's downforce was sensitive to the distance between the underbody and the ground. The aerodynamic map presented in Figure 2 shows that as speed increases, downforce increases, and the car's ground clearance is reduced. The process eventually stops when equilibrium exists between the aerodynamic downforce and the elastic reaction of the suspension's springs.
    Figure 3: Positive pitch angle at high speed (the angle is magnified for clarity.
    The usual solution to stabilize this process is by varying the suspension's spring stiffness using either special nonlinear springs, a nonlinear suspension geometry, or the addition of bump stops. These solutions were disregarded for the 360 Modena in favor of optimizing stiffness ratio between the front and rear suspension springs. Spring stiffness was tailored not only to the sprung mass, but also to the induction of a defined pitch variation of the car at high speed (Figure 3). As speed increases, ground clearance is reduced more in the rear than the front, which produces a positive pitch angle that reduces the total aerodynamic coefficient. Thus, high-speed stability is achieved without compromising handling and comfort.
    Another challenge is related to body motions, which are generated by road unevenness and disturbances at high speed. These motions must be well controlled to provide the desired degree of stability. Body motions induce aerodynamic instabilities in the flow field under the vehicle. This instability leads to downforce losses and variations, which reduce the car's stability. Effective body-motion control was achieved via a specialized damping control system.
    Figure 4: The geometry of the rear suspension and toe arm.
    The design of short wishbone suspensions is in clear contrast with the common practices and guidelines for suspension design. Two major aspects were considered: to determine a kinematics that guarantee the required performances and to define the correct tolerances to maintain a standard level of performance for all production units. During preliminary design, engineers adopted on-center handling as a reference standard for stability. The various design parameters required a compromise between different combinations of camber and track variations that were simulated with the help of numerical methods. The most promising combinations were also tested on prototypes. Tire manufacturers were involved in the design process to allow the tires to be tailored to the suspension geometry (Figure 4) for maximum performance.
    After kinematics selection, assembly tolerances were calculated. Previous experience was used to determine the maximum admissible wheel angle variations during wheel travel for the best on-center handling characteristics of the car. Since the length of the suspension wishbones was well under the minimum ever developed by Ferrari, a reverse engineering approach was used to calculate the required tolerance levels. Checks for camber, toe-in, track, and other variations during wheel travel were made.
    Figure 5: Rear suspension toe-in variations due to an error in the vertical position of the toe arm.
    Figure 5 is a rear suspension toe-in plot as a function of an error of ±1 mm (0.04 in) in the toe arm's vertical position (with other points unaltered). The figure shows the large consequences of such an error. This kind of error is unacceptable not only for the amount of variation, but also for the sign reversal, which would lead to a substantial change in the car's behavior. Without adequate tolerances for the suspension's bolting points, the desired stability is impossible to obtain.
    To achieve the necessary tolerances on an all-aluminum frame that is assembled by hand-welding around 150 pieces, the entire assembled frame is machined on a dedicated CNC unit. This procedure, which is normal for Formula 1 racecars (and was applied to the chassis of the Ferrari F50 in 1995), is somewhat unusual for a GT car with a 2500 units per year production run.
    Figure 6: Damping control system
    Although all of the latest Ferrari GT cars feature electronic damping control, a more sophisticated system was needed. The 360 Modena system was developed with Mannesmann VDO and uses Sachs Boge adjustable shock absorbers with proportional valves.
    Figure 6 shows the system structure, which features open-loop control. The electronic control unit (ECU) receives the inputs and calculates the current intensity required to control the proportional valve of each shock absorber based on predefined maps. These valves have exceptional response time; the time required to switch from minimum to maximum damping (from 0 to 1.8 A) is only 0.04 s. This quick reaction time allows optimization of handling and safety without compromising comfort.
    Figure 7: Front vertical acceleration damping control map.
    Six raw data inputs consist of three acceleration sensors on the car's body, vehicle speed from the ABS system, brake pedal switch, and car setting (normal or sport). Two of the accelerometers measure the body's vertical acceleration, front and rear, and are placed at the top of the right suspension attachment points. The third accelerometer measures lateral acceleration and is placed behind the front bumper. The vertical accelerations of the unsprung masses are obtained from the filtered signal of the measured vertical body accelerations. Vehicle acceleration is obtained by numerical derivation of the ABS system speed signal.
    The predefined maps provide the current intensities required to control the shock absorber's proportional valves as a function of each input quantity. An example of how these maps work is presented by the front acceleration map that controls the damping of the front shock absorbers (Figure 7). Using the signals coming from the front vertical and filtered accelerometers, the damping value (as a percentage of maximum) is chosen for the front shock absorbers. The same applies for the rear shock absorbers, which are controlled by a similar map using the signal coming from the rear vertical accelerometer. Lateral control is obtained via a map, which uses lateral acceleration and vehicle speed as inputs. Longitudinal control is achieved by reading the car's speed and its longitudinal acceleration (by derivation of the speed signal). When braking, the brake pedal switch drives a harder setting for both front and rear shock absorbers.
    To ensure safety, the system strategy is to select the hardest setting for each shock absorber among all the values calculated from the different maps. Additionally, the driver may stiffen the shock absorbers another 30% in sport mode.
    Information was provided by A. Visconti, R. Fedeli, and A. Longhi, Ferrari Automobili S.p.A.



    I recommend this as a set up for a road 360 on the track....

    Street tyres, Pirelli.

    F Camber aprx 2 to 2.5-
    F toe aprx 0 to 0.5mm IN each side. Max 1mm total
    F caster is fixed. Check it's about 6 to 6.5 deg.
    F ride height aprx 90mm (at flat chassis area inside forward lower pickup)

    R Camber aprx 1.5 to 2-
    R toe aprx 3 to 4 mm IN each side. Max 8mm Total. (Trust me!)
    R ride height aprx 112mm (at chassis, not floor panel, on rail inside forward lower pick up)

    If you have a Challenge manual, you'll see where I mean for the ride height. These heights I've given are 2mm higher than std challenge. You can run up to 10mm lower than I've said here (80,102), but it's impractical on the road. Even the figures I gave will need to be relative to your local area, so go higher if you like, but keep the rake the same to start with....ie 22 mm higher at the rear.

    Remember that ANY change immediately effects other items, so your alignment guy will need to be very thorough. It takes me all day, and more to do a road car, due to the spring pre load making adjustment a slow process.

    One turn of spring platform is ABOUT 2 mm of chassis height.

    Corner weight it, with half a fuel tank and drivers weight in the seat. Get it as close as possible, but to within 10kg on each front wheel, and 20kg on each rear. You CAN get perfect given time. You're looking for perfect cross weight though at all times ie LR+RF = RR+LF

    Once its been "done" drive it around the block, and check it again, twice.

    When you get to the track, rake can be tweaked up or down one full turn, to trim under/oversteer. But unless you can do 5 consecutive laps all within 0.5 seconds of each other, you shouldn't mess with it.

    You'll need good front pads and race fluid at LEAST. Challenge discs and calipers on the front would be ideal.
     
  21. ClassicFerrari

    ClassicFerrari F1 World Champ
    Lifetime Rossa

    Jan 7, 2004
    16,798
    Toronto
    Full Name:
    Vasco


    Let me get this straight..............you have 3 360 Modena's? WoW, that's great. Something tells me you like the 360?

    All the best,


    Vasco.R
     
  22. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    20,575
    socal
    ferrarifixer,

    You said"..., rake can be tweaked up or down one full turn, to trim under/oversteer."" How does the rake effect over/understeer? Also, why not trim this with tire pressures?
     
  23. SR Ferrari

    SR Ferrari Rookie

    Dec 1, 2003
    48
    Ferrari fixer.
    This is a solid set up for a road course.
    Tire choice and compound Goven what set up you are going to put on the chassis.
    Tyre maufactures are going to give you a recommended hot pressure nitrogen filled tyres?
    Start your set up with air pressures at hot lap pressures.
    Set your ride heights driver weight in car and generally 50% fuel.
    Set your camber and toe.
    Disconnect your sway bars.
    look at your scale #s and cross weights.
    Adjust chassis corner weights you should be able to get the front the same but for a road course if there is a slight difference adjust greater weight left front.
    On many ocassions you will have a differential in weight on the rear no matter what you do with a rear engine car.
    Adjust rear as close as you can.
    Go back and check cross weights 51% lock it up.
    Make sure to fit your sway bars back so they are completly neutral and
    "NOT" binding.
    Lower your Tire pressures back to your starting pressures depending on the track you may have a different pressure in all four tires as you know its you grow pressures that are what you are after and temp spread.
    Key point to remember whilst adjusting your front toe steering wheel has to be dead straight and after you make your adjustment recheck your wheel and recheck you toe every time.
    The other key point so you achieve repeatability tire pressures up to running
    pressure when you go on the pad providing they have the chance to cool down or switch them out with a cold set.
    Run 0 toe total on the front.
    Always run 1 lap on any track bring the car in a look it over.(saftey check and engine bay)
    Run for a minimum of 6-8 hot laps
    The biggest mistake teams make is trying to get hot tire temps and pressures with not enough hot laps you will just waste time and never get the car set up.
    Once you have established the temp spreads and pressures you need to see, then you have a car you can fine tune.
    All Damper adjustments should be pre set prior to going on to your set up pad.
    Always ask you Tire manufacture what #s they like to see with temps and grow pressures in most cases this information is absolutly necessary as it can save you a lot of time the first time you go on the pad.
    And if your Driver says this car is S..T man get it back on the Pad.
    Kind Regards
    Wayne Hynes.
     
  24. ferrarifixer

    ferrarifixer F1 Veteran
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    rake affects the aero centre of pressure and centre of gravity. A 3mm chassis height change at one end will make a noticable change in the balance.

    To reduce understeer, lower the front or raise the rear, depending on your ground clearance requirements.

    Fitting a rear wing to a 360 would change the rake requirements considerably.

    Set up is a wholly black art, and driver feedback is what governs it.

    The engineer should feed the driver information on his tyre use, and educate him on dynamic geometric changes of the suspension, to make his choices clearer.

    Regardless of what works on paper or in theory, if the driver don't like it, it aint gonna work.
     
  25. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    20,575
    socal
    Ferrari fixer,

    Are you comments about chassis rake tweeking over/understeer for the 360 in the discussion due to 360 aerodynamics or are your statements general rules of any chassis? I get confused since the 360 will generate downforce that lowers rake more in the rear, the effect of which is increased with a winged 360 right?
     
  26. ferrarifixer

    ferrarifixer F1 Veteran
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    Rake adjustments "generally" work on "most" cars. The 360 is particularly sensitive to them.

    The squat 360's get under high speed, is only VERY high speed, and most race tracks don't allow much time, if any, at the cars top speed, so it's not much of an issue.

    Unless you're spending, say more than 10 seconds at over 240kp/h or 150mph, the squat has little influence on race track set up requirements.

    Stiffly sprung race cars render it even more meaningless.

    In my experience, I can turn an understeering pig into an "on the nose" gem with a few tweaks to rake and anti roll bar. I've also got shocks and a wing on most of the cars I take care of, but it's only beneficial with drivers that can lap consistently near their personal limit.

    Wheel alignment is really only tweaked for better tyre management, from the base setting I gave earlier.

    For Pirelli slicks, the base setting has more camber. But the Dunlop and Michelin tyres like a similar figure.
     
  27. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,677
    On the F355 and F348, adjust only the rear ride height for oversteer/understeer relationship. The front geometry of these cars has a high speed twitch if the front end gets too low with stock springs.

    When I have someone take tire temperture profiles, I like to run laps until I can feel the tires get hot enough to transition from grip to slipping and sliding. Then pit after a hot lap and have the temp read in the hop pit (lane). Any cool down lap or even backing of 3 turn before the pit can alter the tempertures and profiles--only confusing the setup issues.

    Much of the long diatribe about underbody aero also pertains to the F355, but the F355 has somewhat less than half of the 360 downforce; and therefore no real porposing.
     
  28. ferrarifixer

    ferrarifixer F1 Veteran
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    The actual quantity of downforce is not too important. What is important, is managing it to behave how you want it to.

    Moving it's centre of pressure forward or backwards will gain more lap time than actually getting more specific downforce.

    Lowering the rear will give loads of "downforce", but the transition from high speed squat to heavy braking droop will cause such geometric instability that your lap time will suffer.........or worse.

    Try this.......measure your 360 rear camber and toe in at rest, with an empty fuel tank. Now put two people in it and a full tank, measure again. Now jack it up at the rear until the wheel barely touches the ground........scary isn't it.....hence the high static toe in figure I advise.

    It's imperitive to maintain rear toe in under all circumstances.
     

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