F355 track alignment recommendations | FerrariChat
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F355 track alignment recommendations

Discussion in '348/355' started by rexrcr, Dec 5, 2012.

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  1. rexrcr

    rexrcr Formula 3
    Rossa Subscribed

    Nov 27, 2002
    1,578
    Kalamazoo, MI
    Full Name:
    Rob Schermerhorn
    #1 rexrcr, Dec 5, 2012
    The following is what I recommend as a starting point when tuning your F355 for the track, this set up is optimized with either F355 Challenge suspension or my "sport" system for road cars or my "track" system for dedicated track cars:

    When setting up the F355 with the new (revalved) shocks and springs here is the order of importance as sometimes compromises must be made:

    1. Near 50/50 % cross weight
    2. Level side-to-side
    3. Simulate driver weight and about 50% fuel load (fuel load is not critical enough that you must drain tank, but if it’s significantly under ½ tank then fuel it to at least half full)
    4. Rake setting (difference in front vs. rear ride height)
    5. Toe settings
    6. Camber settings

    I measure ride height from the floor of the chassis just behind the front tires and just ahead of the rear tires; this is different from the Service Manual that specifies ride height measurements from the center of the inboard lower control arm mount fork.

    • Ride height, Front: 85 – 115mm Rear: 85 – 115mm
    • Rake: Level or close to level promotes stability and sacrifices turn-in somewhat; I suggest starting with no more than 15mm positive rake (nose lower than tail) and no less rake than zero. If the car is not turning in well start raising the rear ride height four turns at a time during testing. Do not alter front ride height at the track.
    • Toe, Front: 0 – 15’ toe out total. Rear: -25’ toe in total. (NB: I’m specifying toe out in front and toe in for the rear, this is critical. Oversteer/ understeer balance can be adjusted via rear toe in settings, more promotes stability. Toe out in front helps turn-in, toe in for the front helps stability.)
    • Camber, Front: 2.5 – 3.0 degrees negative. Rear: 2.8 – 3.4 degrees negative (NB: should have more negative camber in rear vs. front)

    This much camber may necessitate changing the lower control arm mount forks. Always torque lower control arm mount forks properly and replace the nuts with new Nylocks after a few uses. Check lower fork nuts pre/ post track events.

    I also suggest using the computer controlled damping system. You may lock the shock adjusters with small hose clamps or with silicone RTV (must set overnight). If locking adjusters set rear full counter-clockwise (that’s full-hard) and fronts the same initially. If car understeers on turn-in set front adjuster 15 degrees from full hard and lock in place. Adjusters must be mechanically locked or internal hydraulic flow will eventually set them full soft (clock wise). Full hard to full soft is less than 90 degrees so adjusters are very sensitive.

    Call or email with questions!

    For a road car the compromise is ride height, just keep it as high as practicable, but use the rake and alignment recommendations with the exception of camber/ toe. This much camber combined with this much toe will increase tire wear rates. Closer to WSM camber and toe will increase tire longevity.

    Best,
    Rob
     
  2. m5guy

    m5guy Formula 3

    Aug 17, 2008
    1,627
    Ventura, CA.
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    Greg
    #2 m5guy, Dec 5, 2012
    Rob, thank you for posting. Seriously, we all benefit when information like this moves into the forum as reference material. When I last had an alignment done, we set the ride height at approximately 100mm based on the measurement zone you provided, and my camber settings were more conservative. I am going to go back and review against what you have posted.

    Thanks again!

    -Greg
     
  3. cf355

    cf355 F1 Rookie

    Feb 28, 2005
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    chris
    #3 cf355, Dec 5, 2012
    How do the ride hight measurement locations compare to the wsm locations?
    Same? and if different by how much?,
     
  4. cf355

    cf355 F1 Rookie

    Feb 28, 2005
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    chris
    #4 cf355, Dec 5, 2012
    Last edited: Dec 5, 2012
    I decided to see how the "floor of the chassis" height measurements compare to the lower suspension mid bolt measurements as recommended by the factory.

    First the oem suspension measurements are as follows:
    Frt 162-171mm / RR 182-191mm / Stagger 20mm stock (w/ challenge set to 25mm)

    My car (street) measures as follows:
    Frt 164mm at suspension mid bolt (vs floor of chassis behind frt whls 139mm)
    RR 185mm at suspension mid bolt (vs floor of chassis ahead of rr whls 140mm)

    note: I didnot get my laser level out so my measurements could be out a mm or so
     
  5. apex97

    apex97 Formula Junior
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    Nov 25, 2006
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    Edward Zabinski
    #5 apex97, Dec 5, 2012
    Wow! You peeled to Kimono back a bunch there Rob! :)Thanks for posting, this is an excellent starting point for anyone going to the track on any tire with a 355.

    Still lots of unspoken voodoo magic in dampers and spring rates, as there should be, but this should be very helpful to new guys.

    It maps with my 360/430 set ups really close too. Great post!
     
  6. bobzdar

    bobzdar F1 Veteran

    Sep 22, 2008
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    Richmond
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    Pete
    #6 bobzdar, Dec 5, 2012
    I have H&R springs on mine with front set at max ride height and rear set to match and its at 124-125mm from the chassis floor front and rear. Rear adjustment is about half way up. I am at minimum height to where I can get into and out of my neighborhood. Just thought I'd add an fyi for anyone considering those springs, it can't go any higher than that with the stock adjustment.

    Are those alignment specs for any particular tire?
     
  7. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    9,728
    #7 Mitch Alsup, Dec 5, 2012
    I find it easier to remember that a small change in rear ride height has 1.6 times as much change in the oversteer/understeer relationship than a similar change at the front.

    So, for track use, put the nose as low as you dare, and then tune with rear ride hieght. {I was helping a challenge car guy and his mechanic set up his F355. It was pushing like a pig--I could see it on the track. So I went over and told him what I was seeing. He indicated he had already lowered the front twice that day. I told him to raise the rear a couple turns, and presto, it went from a pig to a lead contender.}

    (I never needed as much front camber as you indicate, and my car turns in quite well-- sometimes too well! Also note that rear ride height is playing into the whole set of relationships.)
     
  8. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    29,004
    socal
    #8 fatbillybob, Dec 5, 2012
    There is always a camber limit with streetcars turned racecar unless special tweeks are done. I kinda find that if I'm not using all the camber I can dial in I'm not driving fast enough.
     

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