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Front wheels stick out unevenly

Discussion in 'S-197 Mustangs' started by cidsamuth, Jun 23, 2019.

  1. Norm Peterson

    Norm Peterson Member Established Member

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    It's not about whether I believed you, it's about how well were all of the conditions that would lead to misleading measurements under control? Obviously, you weren't correcting them for any known alignment-setup issues, they just are what they are.

    Flatness and side to side slope of the place you set up on to get those measurements.
    Tire inflation pressures (all four).
    Tire tread depths being equal, at least side to side.

    Hopefully, the magnet didn't pick up any little piece of magnetic grit between measurements. I hope you realize that I'm not picking on you here. But whenever you're making precision measurements you do need to think of all the potential sources of error that could be involved, and then do what it takes to either minimize them or allow you to correct for them.

    I could make the difference between those readings look closer to -0.4° (not exactly 0° or -1.00°), which would be what you'd get from cambers that are both about -0.25° and the car on a side to side slope of only about 0.2" over the front track dimension (62" or so, depending on wheel offset). If you haven't specifically checked your setup area for levelness - and avoided setting a wheel on any local high or low spot - it could easily be that much out-of-level.

    Tires/suspension need to be as free of sideways preload as possible. You need to gently roll the car in a straight line into position in your setup area and gently brake it to a stop. You know how when you let the car down off the jack that that corner doesn't settle all the way back down until you drive it? That suspension movement situation is what you have to intentionally minimize, because otherwise sideways tire scrub will hold the car up on that corner and that end.

    It's at least possible that your car is unsymmetrical with respect to its front control arm pickup points or its fenders, or the fender locations relative to the suspension hard points, which would cause equal cambers to produce unequal amounts of this 'tuck'. At the 1/8" to 3/16" level, maybe all of these cars are?


    Norm
     
    Last edited: Jul 2, 2019
  2. biminiLX

    biminiLX never stock Established Member

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    Adjust it to make your eye happy then monitor for even tire wear. Your main goal is appearance based on these posts, so make good for your goal.
    -J
     
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  3. Norm Peterson

    Norm Peterson Member Established Member

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    Agreed that for OP it's strictly an appearance matter. Otherwise I'd have pushed harder for camber settings around -1.0° or so where any differences in 'tuck' should become less obvious because the tires would be further away from the sheetmetal (what you're at least subconsciously using for visual reference). Small differences in small distances being more obvious visually than small differences in larger distances.

    It's just that he's kind of caught himself between making the amounts of 'tuck' even and making the cambers even, where making either one of those better makes the other one worse. And he notices unevenness in either. A "some of each" approach, where he'd be looking for some closest-to-satisfactory combination of differences in tuck and differences in camber where neither one is "perfect" may or may not work for him. Hence my suggestion of a little careful fender rework, as differences there seem less likely to be noticed than either of what he's dealing with now.


    Norm
     
  4. cidsamuth

    cidsamuth Active Member Established Member

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    Agreed on both.

    I have visually (and with a level) set the left camber to match the right. I understand differences in floor level might have affected it. As set now, tuck is within 1/16” of each other, which is satisfactory even for my OCD.

    I realize I might have thrown the toe off doing this. I have a different shop checking everything this Saturday for a price I can live with, so I’ll report back.
     
  5. cidsamuth

    cidsamuth Active Member Established Member

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    The answer was a little in between. They set up the right to -.85 camber and the left to -.67. In doing that, much of the tuck difference seems gone, but it’s still there. I think it’s a k-member position thing and will just accept it.

    He did set the toe up to be towards the max “toe out” allowed .... -.01 (left) and -.04 (right) for a total toe of -.05 degrees. Should I be concerned with that? I know factory spec has max at -.05 per side and max of -.10 total.

    The tech said he did this for better handling and, as it is in spec, it would not cause tire wear issues. Truth? I does feel like there is a little more tramlining on heavily crowned back roads.
     
    Last edited: Jul 6, 2019
  6. Norm Peterson

    Norm Peterson Member Established Member

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    Toe out is inherently a less stable condition than toe in. It can improve overall front cornering grip, at least under some conditions of steer angle and cornering g's. But you pay for that by being busier at the steering wheel keeping it all going straight a good part of the time.

    -0.05° total isn't too far "out" (you're probably holding the steering wheel a tiny bit off-center on a perfectly level stretch of road and have about -0.025° at each wheel). But I think that eventually you'll tire of the twitchiness. +0.05° should be a lot tamer, and shouldn't cost you any handling, not any amount that you could ever measure by the seat of your pants, anyway.


    Norm
     
  7. cidsamuth

    cidsamuth Active Member Established Member

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    With it technically within Ford spec, you would still consider it “twitchy?” It would be hard for me to complain when it’s still within spec. When I called them for just an explanation earlier, they acted like I was insane for even questioning it when it was still in spec.

    In the 30 miles or so I drive it today, I didn’t necessarily feel “twitchy.” It just felt more sensitive to the right leaning decline in the roadway on backroads, ie I had to steering against it a little. It didn’t jump around, nor did it feel unstable on the interstate. It did not pull to one side or the other on flat roads
     
  8. gimmie11s

    gimmie11s Dont be a Hybred Established Member

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    What a colossal waste of time.
     
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  9. Norm Peterson

    Norm Peterson Member Established Member

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    "Twitchy" isn't tied to a number, it's whether you have to do any extra work keeping the car going in a straight line.

    Running down toward the gutter on crowned back roads and steering left to compensate for that is something else.

    You might be able to complain on the basis that the car now wants to run down toward the gutter more than it used to, and get total toe back to a small + number (i.e. toe-in).


    Norm
     
  10. cidsamuth

    cidsamuth Active Member Established Member

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    NTB was open today, so I swung by. They redid the toe to be the factory 'preferred' +.05 per side for a total of +.10 ... while I was in the car. The tramlining is all but gone.

    Watching the screen as he adjusted, I was surprised to see the camber change very, very little as he adjusted toe. Conversely, when they messed with camber yesterday, I could see the toe change more significantly. Can't say it has been fun, but it was cool to learn a little something through this.

    And the .2ish degrees difference in camber between the two wheels mitigates (not eliminates) the tuck differences enough for my liking while not seeming to have any negative effect on handling. That is consistent with what both techs (from yesterday and today) assured me.

    All's well that ends well. Thanks Bimini and especially Norm for the input.
     
  11. Norm Peterson

    Norm Peterson Member Established Member

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    Good to hear you've got everything dialed in to your satisfaction.

    0.2°-ish cross-camber is well within Ford's spec for cross (0.75°) - a perceptive race car driver or any of Ford's own test drivers would probably be able to pick up on it but the rest of us would just be guessing.

    Having noticed that camber affects toe more than the other way around, now you know why toe is the last adjustment in the sequence. For similar reasoning, caster is usually the first adjustment, assuming that the car in question has caster adjustability (or a mfr-allowed procedure for creating caster adjustability).

    If you know the name of the alignment tech who just did this last alignment tweak, it would worth the effort to have that same individual do your future alignment work. He's willing to do what it takes.


    Norm
     
    Last edited: Jul 8, 2019
  12. cidsamuth

    cidsamuth Active Member Established Member

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    Hmmmm. As you know, Ford's spec for camber is 0.00 to -1.5 degrees with a "preferred" of -.75 degrees. I figured those specs assumed about the same camber on each side within those specs.

    Are you saying that, technically, Ford allows for up to .75 degrees difference between the two? Every tech I talked to insisted that any difference over .5 would create pulling.
     
  13. Norm Peterson

    Norm Peterson Member Established Member

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    Yes, that's the spec - at least the one in the factory shop manual. Another document I have calls for 0.70° maximum cross (and lists two sets of ± tolerancing from factory preferred). Both those cross numbers are sloppy-loose IMO and I agree with your techs. Especially when I know it's not that difficult to bring the cross down below 0.2° using DIY measuring methods in the driveway.

    You may have missed a late edit I made to my previous post (more information, not a correction).


    Norm
     
  14. cidsamuth

    cidsamuth Active Member Established Member

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    Got it .... and I def will reuse that tech again. Cheers
     

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