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Thread: Project 'Ultimate Handling', a champion's perspective.

  1. #1

    Thumbs up Project 'Ultimate Handling', a champion's perspective.

    In a serious attempt to the understand the effects modding the Z8 will have I?ve asked Craig Stanton, the 2005 GT Champion (congratulations Craig!) to be our test driver.

    On Dec 22nd we ran 175 track miles at Buttonwillow Raceway, configuration 13. I did around 100 or so miles in the drivers seat, and Craig did the rest. The mission was to set a performance baseline for the standard car from which we could understand the effect of upgrades as we make them.

    Here are some lap times to give you an overview of the day?s results.
    Craig ? DSC on: 2.14
    Craig ? DSC off: 2.04
    Fastest Elise of the day: 2.06
    Fastest GT3 of the day: 2.02 (on MPS Cups)
    My laps times averaged about 2.18, so I?m a lot slower than one needs to be to really feel out the car at it?s limits, so you can see why it is so important to have someone with real ability at the wheel.


    Here is a quick Q&A with Craig.

    AM: How did you think the Z8 handled and performed overall?

    CS: I really enjoyed it, it is very, very stable and well mannered platform, with none of the chassis flex that convertibles can exhibit at the track.

    AM: What did you like the least about the car?

    CS: The clutch delay valve, it really forces you to slow down the changes, and really takes away from the driving pleasure.

    AM: What would you most like to see changed in the car?

    CS: Handling wise the car needs to be much crisper in the way it transitions, the side to side body roll is too pronounced, exaggerating the impression of the car?s weight and making feel a bit cumbersome and slow.
    The adjustable shocks and sway bars you?re fitting should take care of of this, but I?d also suggest getting rid of all the rubber bushings in the suspension and steering mounts, if you could find someone to engineer the correct solid bushings. I wouldn?t make the springs that much harder, I?d prefer set the car by tuning the compression and rebound damping and the sway bar position. Increasing the spring rate may well detract from the daily driving pleasure of the car making it too harsh for the street. The current springs let the car squat nicely when you get on the gas, and give a great set as you power out of a turn.
    I?d like a better clutch with a lightened flywheel, and certainly the Quaife will make a big change to the way the DSC works. Currently the DSC interrupts progress much too much, which is a combination of being a brake activating system with an open diff.
    The Quaife will give the car far better overall mid-corner under power dynamics. It is a unit with a good racing pedigree, and was used to great effect by Tommy Kendall and the Rousch Team the season they tried every unit in thier car to find 'the one', and the Quaife was it.
    Lightening the wheels and brakes will make a difference too, and going to a larger diameter wheel will remove the sidewall roll we were getting.

    AM: How did you feel about the run flats, on the flying laps you had them howling somewhere between agony and ecstasy the whole way around the track!

    CS: They are really great tires, very forgiving, they talk to you nicely giving good feedback of how their traction coefficient is doing, and they showed no sign of spending a hard day at the track afterwards. Apart from the slight sidewall roll I?d say they are a pretty impressive sport tire.

    AM: When we step up to the 20? rims do you have any suggestions for a good all round road and track tire?

    CS: No, when the time comes just see what's out there, and try to pick the best.

    AM: Thanks for taking the time to help us out on our project, maybe you?ll be wanting a Z8 too by the time we have it dialed in!


    Below Craig chases down an Elise, showing just how capable the Z8 is out of the box.
     
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  2. #2
    DSC Off Orcatek's Avatar
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    Great write up. I'm looking forward to reading the progress as you make the mods. Since it sounds like you are going to do all the mods, I would be interested in the hearing what order he felt they should be done. Of what he would do if he could only do one or two mods. Kind of a priority list.

  3. #3

    This is a copy/paste of my work order.....

    UPGRADES

    Replace open diff with Quaife LSD. (supplied by me)
    NB: This is the naked unit, it needs to be packed into the diff housing with the correct shimming.

    Replace clutch and flywheel with Dinan lightened unit. (can you supply Dinan parts?)

    Replace clutch delay valve (supplied by me)

    Fit UUC short shifter kit. (supplied by me)

    Replace suspension with Cartridge suspension units. (supplied by me)

    Fit Cartridge swaybars. (supplied by me)

    Replace mufflers with Eisenmann units. (supplied by me)

    Fit solid transmission mountings. (supplied by me)

    Fit hardwire from fusebox to beside rear view mirror for power to Valentine 1 unit. (do you need anything from me to do this?)

    Fit Bosche Platinum 4 tip spark plugs. (can you supply these, or should I?)



    REPAIRS

    Repair/replace soft top canvas, there is a wear hole in canvas where they always appear, and unit isn't retracting fully to enable putting the cover on when it is down.

    Replace lock mechanism on drivers side CD changer cover/lid
    Supply CD changer cassette, and check system.

    Take dash board apart, and pad everything inside there with sticky felt to stop rattles and squeaks. (someone took the dash apart to fit a hidden K40 radar detector, and put it back together badly, hence the many rattles - also check the mount is solid for the K40 alarm within the AC duct.)

    Repair leather dash top, delaminating.

    Order ash trays to both driver and passenger side. (these were missing when I bought the car.)

    While rear valance is off check right side indicator for loose wire, it is intermittantly not working properly, (again I suspect the bad fitting of the K40 radar unit.)

    Change MAF units. (supplied by me).


    SERVICE

    Do a full service check up, and reset service light.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  4. #4
    Z8 Ate My Homework! Norcal's Avatar
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    Based on the comments about the springs.....

    do you think the new units may be too stiff? After a few years with the ACS springs, I'm seriously looking at a more compliant set up. I'd really like to do it before Santa Fe. Recently on a bad country road, I had a very hard time keeping traction in the corners due to the bounce and skip. I'm sure it would be faster, and more comfortable with a different set up. Do you know much about the coil-over units available in Germany? I really like the low stance, but at what price?

    Also, do you recall your lap times at BW, in the GT3, on the same course? Just curious.

    Thanks for the great detail in your write-up, I'm looking forward to your progress, perhaps the most comprehensive and professional sorting ever on the Z8.

    Thanks, Ian

  5. #5

    Yes indeed......

    I also found the ACS kit pretty harsh, it worked well on good roads and the track, but was exactly as you described on anything but a perfect surface. I also suffered some really heavy bottom outs with them which may have contributed to the frond end problems that car had.

    I have the KW coilovers here, but if my Cartridge kit is ready in time I'll put it on the car first, as it has far greater adjustability than the KW, plus we also have the option of making new springs for it should they not be perfect. The Cartrige set up has the advantage of being based on the settings that the factory found to be optimal for serious sport driving. The front springs are only a little stiffer, but the rear are quite a bit more so, which is meant to give a perfect balance, and eliminate a lot of the in built understeer.

    All my times in the my old GT3, and the day you ran with us, were for quite a different, and higher speed configuration (#25), thus the times don't mean much, but I was doing around 2:07's at best.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  6. #6
    Administrator thegunguy's Avatar
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    OT: For NorCal

    Have you had a chance to try a car with the Dinan setup? I've been very pleased with it. From reading it seems to be less aggressive than the ACS kit, but it still yields a good improvement over stock for the occassional track outing.

    As far as "softness", it's definitely stiffer than stock, but it's still a comfortable ride. Perhaps most telling, I've had no complaints from the wife.
    thegunguy

  7. #7
    Z8 Ate My Homework! Norcal's Avatar
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    No, not yet...

    I would really like to drive one, and see how I feel about it. I do have the Dinan Bars on. How much does it lower the ride height? And, do you have the caster plates? Do the caster plates make the front look High? I'm also very interested in the coil-over set-up.



    Ian

  8. #8
    Administrator thegunguy's Avatar
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    I have the full Stage 3 setup - bars, springs, and plates

    While the caster plates do add height back to the lower springs, I'm down a net of ~1/2" from stock at all four corners with 35psi and 1/2 a tank of gas.

    The coil-overs do seem really cool, but I personally can't justify the additional expense for the Z8, since it will probably only see the track a few times a year. However the Dinan setup seems to be a bargain for improving the handling of the car for weekend outings like NM.

    Anyway, I'm pleased with my setup as it fits my needs - yours may differ. I wish I was closer and could let you take my car for a few days.

    I cannot wait for the Z8 love fest in Santa Fe - it looks like we're going to have every mod and derivative imaginable. I foresee many comparison test drives.
    thegunguy