Pinpoint suspension failure / incorrect geometries.

Discussion in 'Corner Carver Racing Tech Discussion' started by Macman45, Jul 2, 2021.

  1. Macman45

    Macman45 Resident Geriatric

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    My 09 has about 50k miles and is pretty tight, and has a slew of suspension upgrades. Eian has / FRPP sway bars front and rear, rear LCA’s, adjustable shocks/struts, and lowered 2”. Rides good.

    my issue is lag when turning, specifically during spirited driving. At speed, whip the wheel one way and the car finally responds. I get in my challenger, which is a land yacht, and it comes right over. Something isn’t “planted”

    I first thought sway bars but they’re brand new, poly bushings, and adjusted to an aggressive setting.
    I do not have adjustable end links, just the factory fixed length.
    Some of the racers suggested the bar isn’t flat and I’m experiencing body roll despite having poly bars.

    any suggestions? I have factory front LCA’s, seem to be fine but considered GT500 front LCA’s. Problem has to be up front.
     
    Last edited: Aug 11, 2021
  2. OX1

    OX1 forum member

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    What tires, what size?
     
  3. Macman45

    Macman45 Resident Geriatric

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    255/45/18 on stock 18x8.5 bullets. Nitto NT555
     
  4. Juice

    Juice forum member

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  5. Macman45

    Macman45 Resident Geriatric

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    255/45/18 on stock 18x8.5 bullets. Nitto NT555
    im afraid you’re right, it’s awfully low but is a good look. Lotta negative camber.

    you don’t like those nittos ehh? They were all the rage and highly recommended when I got them. What’s the latest and greatest now?
     
  6. Mustang Terlingua

    Mustang Terlingua Junior Member

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    Findin that sweet spot is a give & take on roll center on first gen Mustangs with leaf springs. I use a spherical joint at the front eye in the spring & at the shackle at the frame rail. Most people go to stiff on front & rear springs. Also lowering the car & gettin bump steer cuz of the steep angle on the tie rod to center of rack on S197. I had several customers cars I replaced parts & they were very happy with the ride on the street & still had quick steerin response. I know it is old verses new but Y'alls article previously explains roll center very well. $R6D2JRD.jpg
     
  7. Juice

    Juice forum member

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    The 555 is a decent street tire, not very sticky for track use.
    For track, a 200 treadwear tire or less. Full slicks are 100 or less treadwear.
     
  8. Norm Peterson

    Norm Peterson corner barstool sitter

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    Driver error. You're most likely loading your tires too quickly, a little like what shocking the tires means to drag racers, except sort-of sideways while cornering.


    Which bars, and at which settings?


    A head-on picture while cornering would be helpful . . .


    Norm
     
  9. Norm Peterson

    Norm Peterson corner barstool sitter

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    Both of those are deficiencies as far as turn-in response is concerned.

    8.5" really isn't wide enough to properly support 255/45 tires during enthusiastic or aggressive cornering. Period.

    The 2008 GT500 mounted 255/45-18 tires on 18x9.5" wheels.

    I don't like those Nittos either. Never did. NT555 wasn't a very good tire when it was a brand new offering something like 15 years ago. It just had the "right look" in its tread design and got huge support from the big-box Mustang supply houses based strictly on price and appearance. I'm afraid popularity in this instance has meant that a great many people either wrongly associated mass-market appeal with performance goodness or didn't care as long as they could get the popular thing.

    Not intentionally flaming you here . . .


    Norm
     
  10. OX1

    OX1 forum member

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    I have the same size. Too much sidewall with 18's, IMO. I tried the orig Mich PS's in stock size 235's before these, and they were not that great in turn in either. I also tried 295 NT05's and 305 NT01's (all in 18's). None of them had the turn in of a 245/40R19 PS4S.
     
  11. Macman45

    Macman45 Resident Geriatric

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    Norm, appreciate the insight. I think you’re off a bit on some things. GT500 actually had 285 on the rear, on a 9.5” wheel. 8.5” is ample on 255’s.
    I think we’re missing the issue a bit, it’s not hard cornering it’s simply steering lag. It’s not the wheels or tires. It’s either being too low and raising the roll center, I buy that, or ive got a warn bushing up front.

    tire brand is definitely not causing it.

    Anyone got some suggestions on worn steering / front suspension components?
     
  12. OX1

    OX1 forum member

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    Nitto does seem to offer sizes others don't sometimes, especially in 18's (or at least they did). For me the tire I did want only came in 265, and I wasn't sure I wanted that large a tire on the front, but I had a 9" wide rim I liked, so I thought a 245 was a little light, if I wanted any curb protection at all (sometimes the woman drives). In hindsight, should have gone with the 265 PS4S.
     
  13. OX1

    OX1 forum member

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    Well, did it ever not have "lag" with this setup? If it always did, that is why people are suggesting tires.
     
  14. Macman45

    Macman45 Resident Geriatric

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    no no. Just driving down the road the car lags like a pickup truck. A baby could be steering and it’d do it.
    Norm[/QUOTE]

    That was in the first post. FRPP/Eibach, middle setting in front.

    can’t really do that down the road. 45mph it just rolls around.
     
  15. Macman45

    Macman45 Resident Geriatric

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    It did it with stock 235/50 from the factory. BFG’s
     
  16. 07 Boss

    07 Boss Senior Member

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    If you actually soften the front sway bar you may get more bite up front. Too stiff of a sway bar will promote more understeer. I have no front bar and my camber is -2.5*, initial turn in is great. What happens after that is another story but....
     
    Macman45 likes this.
  17. RED09GT

    RED09GT Equal Opportunity Offender S197 Team Member

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    Check the alignment before throwing more parts at it.
     
  18. Norm Peterson

    Norm Peterson corner barstool sitter

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    I meant to say the GT500's front wheels/tires were 255/45 on 9.5" wide.


    For a grocery-getter, maybe.


    You still have to wait for the tire to distort laterally against however much lateral stiffness is there. Turn-in response is clearly 'softer' with tires on wheels that are relatively narrow for the tire size. Even on "measuring width" wheels, steering response isn't all that crisp.


    Either is possible, but wasn't mentioned.


    Different tires (and wider wheels) certainly do make for differences in steering response (been there). Too bad you can't try the wheel/tire setup I bought for HPDE (285/35 MPSS on 18x11 wheels, all four corners). It's noticeably crisper than my street setup (265/40 MPSS on 18x9.5 wheels, all around).


    Norm
     
  19. larry Stark

    larry Stark Junior Member

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    When you lowered your car did you correct for bump steer. If not as you turn your tires you are going into positive camber.
     
  20. Norm Peterson

    Norm Peterson corner barstool sitter

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    Bumpsteer correction affects toe rather than camber . . . the small effect you might get from tire steering angle (and that effect on operating camber) while driving would be negligible.


    Norm
     
    Vorshlag-Fair likes this.
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