Sway bar technicals | FerrariChat

Sway bar technicals

Discussion in 'Technical Q&A' started by Auraraptor, Jan 14, 2005.

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  1. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
    13,958
    MO
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    Omar
    I was wondering, what is the effect of increasing sway bar size in the front relative to the rear?

    In the rear relative to the front?

    Too much both ways?

    Thank you.
     
  2. Steve B

    Steve B Formula Junior

    Dec 23, 2003
    521
    Naperville
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    Steven L. Biagini
    I believe that increasing the diameter of the rear sway bar will decrease understeer (or increase oversteer) while increasing the diameter of the front sway bar will increase understeer (or decrease oversteer).
     
  3. stephens

    stephens F1 Rookie
    Lifetime Rossa

    Feb 13, 2004
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    Stephen S
    Correct, this link has more detailed info http://www.wtrscca.org/tech.htm
     
  4. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    37,072
    Cowboy Capitol of the World
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    Brian Crall
    In good old boy-ese, bigger front bar= push. Bigger rear bar=loose.

    Do you know the difference between push and loose?
    Push is when you get to see the accident.
     
  5. samtheclip

    samtheclip Karting

    May 30, 2004
    176
    Buffalo, NY
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    Sam Pasceri
    Anybody having any luck with Saner? I have tried to email them a few times with no luck.

    -Sam
     
  6. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
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    Thank you everyone this is just what I wanted to know!
     
  7. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    Be careful with self diagnosis though. Excessive understeer promotes oversteer. You need to make sure you're in the window.

    On a road car, there's more to gain from Tyre pressure and type, camber, caster and toe before changing anti roll bars.... but basically, a quick fix for most road Ferrari's is to fit a stiffer rear anti roll bar.
     
  8. Mike C

    Mike C F1 Veteran
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    Aug 3, 2002
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    Mike Charness
    VERY slow to respond to emails and voicemail, but once you get John on the phone, VERY knowledgeable and helpful.
     
  9. seschroeder

    seschroeder Formula Junior

    Apr 25, 2002
    251
    Alexandria, VA
    Full Name:
    Steve Schroeder
    I agree with the above, the rear bar on my 82 308 GTSi is quite small. Question now is - were does one obtain a larger rear bar??

    Thanks in advance.
     
  10. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    28,945
    socal
    Not sure about that...most road rear engine ferraris are prone to snap oversteer by design ala 911 syndrome even if cars are set up safer with factory understeer there is faulty driver input, the classic let off the gas or brakes on in turn. So becareful with barchanges. A stiffer rear bar will make for more rear oversteer ala the old pre911SC. You need a proper diagnosis on a closed course then adjust the suspension accordingly like Ffixer said then make aftermarket changes to suit your driving style. Many people have messed up their ferrari suspension with new wheel tire combos. Ferraris are very sensitive to chassis changes thats why they feel like ferraris when you drive them.
     
  11. pad

    pad Formula 3

    Sep 30, 2004
    1,426
    Tequesta, FL
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    Paul Delatush
    Would someone post the dia. for the stock 308 QV bars?
     
  12. LarryS

    LarryS Formula Junior

    Nov 14, 2003
    302
    Fremont, CA
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    Larry S
    <Would someone post the dia. for the stock 308 QV bars?>

    84gts rear, 18mm, .710
    Larry
     
  13. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    fatbilly...snap oversteer is exactly what I meant by excessive understeer causing oversteer.

    You'll find that most rear engine Ferrari DO like a stiffer rear bar, but as I said, proper diagnosis is needed.

    Most 3*8 models have different size rear bars between GTS/GTB. Also you may find the 348/355 Spiders have different bars to GTS/berlinettas too.....It can be quite easy to "borrow" one to try as a start point.
     
  14. Mike C

    Mike C F1 Veteran
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    Mike Charness
  15. Mike C

    Mike C F1 Veteran
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  16. samtheclip

    samtheclip Karting

    May 30, 2004
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    Sam Pasceri
    No pictures with that link.
     
  17. Mike C

    Mike C F1 Veteran
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    There sure are... just scroll down past post #32 in that thread and you'll see several.
     
  18. JTranfield

    JTranfield Formula Junior

    Dec 29, 2003
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    NYC, London
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    J Tranfield
    Before you put on those sway bars I noticed you said you had updated the rear sway bar bushings. Where did you get these from? Thanks.
     
  19. Hubert

    Hubert F1 Rookie

    Jan 3, 2002
    2,642
    The Left Coast
    Fisrt off, we're talking about anti-roll bars, not "sway" bars.



    But before we get there, lets get a better, working picture of what roll bars do and are:

    A roll bar is a bar of metal that connects two wheels on the same axle to the chassis. It's job is to control the rate of lateral transfer between the two wheels. Lateral transfer of load between occurs under cornering and can has an effect on camber changes and the tire's contact patch. Because roll bars can limit or reduce the body roll and have an effect on the rate of the lateral load changes, they're considered to be an integral part of the overall or total roll resistance of the car's suspension.

    How it works: as you corner, the outside wheels compress and at the same instant the inside wheels unload, this simultaneous action is body roll. The roll bar limits body roll and lateral load changes becuase of the fact that it's connected to both wheels and the chassis, therefore the only way for this to change would be if the bar twisted - the bar's resistance to twist, therefore defines the increase in roll resistance.

    So ... if you remove the front bar you reduce the roll resistance of the front suspension and in effect soften the suspension. If you remove the rear roll bar, the same would happen. If you removed the front and kept the rear, the car would be more prone to oversteer and if your removed the rear and kept the front the car would be more prone to understeer.

    The same pattern as above would apply if you adjusted the bars front to back and back to front; ie., putting too fat a bar on the front will actually induce understeer as the rate of lateral loading is increased significantly and youre overworking the front tires sooner; and if you go too fat on the rear your induce oversteer by the same physical phenonmenon.
     
  20. JonBrent

    JonBrent Formula Junior

    Nov 10, 2003
    732
    Heaven on Earth
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    JB
    Another thing to consider is that spring rates can be played with to have the same affect, so I've read.

    As an aside, I thought the 911 snap overstear was attributed to suspension geometry coupled with worn bushings, so that while under cornering loads, the rear wheels would have positive toe out. Any truth to that? I find it hard to believe it's all weight distribution...
     
  21. chrismorse

    chrismorse Formula 3

    Feb 16, 2004
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    chris morse
    I once heard the difference as:

    Oversteer is where the back end comes around and the passenger is scared.

    Understeer is where the front end goes straight ahead and the driver is scared.

    hth,
    chris
     
  22. robertgarven

    robertgarven F1 Veteran
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    Feb 24, 2002
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    Robert Garven
    well the rear bar on the gt4 is tiny, I would like to get the gtb bar which is a little fatter.
     
  23. Mike C

    Mike C F1 Veteran
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    Actually I updated the A-Arm bushings with urethane bushings from Energy Suspension. They're also available from Nick's Forza Ferrari and even special order from places like Autozone. The new urethane anti-roll bar bushings came with the bars, courtesy of Saner Performance.
     
  24. JTranfield

    JTranfield Formula Junior

    Dec 29, 2003
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    J Tranfield
    Thanks.
     
  25. don_xvi

    don_xvi F1 Rookie

    Nov 1, 2003
    2,934
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    Don the 16th
    Do you have terminal understeer?
    I don't know anything about the GT4, but I found my GTS to be a little unsettling for a street car on a drop-throttle freeway entrance. Perhaps it goes back to my theory: "Never set up an autocross car to push and never set up a street car or road race car to oversteer!"
     

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