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  1. #1

    Default Stock Ride Height Measurements

    Hello everybody,

    I'm going to replace my steering rack over the winter and I was wondering if I need to address any other issues, such as potential bump steer problems. I measured my front fender - from the cement, along the centerline of the wheel, to the inside lip of the fender and I'm about 25-3/8" on both sides. What is considered lowered? If I recall, I installed the motorsport "B" springs about 20 years ago, but I can't be sure (other than it rides pretty rough).

    Thanks guys,
    Howard

  2. #2
    FEP Super Member xctasy's Avatar
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    Quote Originally Posted by at_the_junkyard View Post
    ........

    Using the calculator (I believe all would fit on a 7" wide rim). Nice to have choices either way !!

    205 70R14 = 25.30"
    215 55R16 = 25.31"
    225 50R16 = 24.86"
    235 50R16 = 25.25"
    Quote Originally Posted by gr79 View Post
    approx TRX tire outside dia in inches

    size/new tire od in inches/.25" wear

    190/65/390- 25.08/24.83
    220/55/390- 24.88/24.63
    180/65/390- 24.57/24.32

    The smaller dia will 'change' a 3.45 rear gear to around 3.50-3.55 as they wear out.
    The 180 drops the car a little closer to the ground, say 1/4" or so?
    Each tire size looks different mounted due to rim width.




    Meaurements were based on the old TRX tires, with some pretty good data from the 83-86's in any normal tire.






    Depends on the crushed, at load tire height.



    If you find the darstedly metric hieghts, divide them by 25.4, and you get inches.

    667 mm (26.25") at the front is possible, but you'll have no end of gaurd problems, so 652 mm is the normal maximum, with 627 to 640 the ideal.



    BF Good Rich states the stock unloaded, and loaded wheel diameter.

    The stock Fox wheel varied from 618 mm (24.33" loaded) in the 13" wheels to about 643 to 630 loaded in the TRX's (25.31 to 24.80"). The biggest at the front without too much problems avoiding the front valance is 652 mm loaded (25.67"). At the back, you can go up to 711 mm (28") loaded.

    The call size of the tire governs the amount of road to wheel arch distance. The car has to have been around the block and settled before measuring on a flat cement forecourt or weightbridge being best.

    I got 635 mm for my Fox with 630 mm 200/60 HR 390's.

  3. #3

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    Iirc, on a level surface, with the correct tires, with the correct rims, with correct air pressure, and new isolators that have settled (take ~1 month for rubber), the front fenders are ~~27" to ~~27-1/4" high.

    However, remember Ford's unparallelled fit and finish!
    It had to meet super mega strict standards! The gaps and fit and finish had to be acceptable to a blind man standing in the opposite direction and a mile away.
    WOW, what unparallelled fit and finish standards! ;-)

    Correctly, for the height and frame alignment, there are specific measurements points on the frame.

    The fit and finish directly of body panels (like the front quarter panel or hood) from the factory are horrible, at best.
    So, a variance of fit of finish of +/- ~1/3" was no big deal.



    Example: My car: Notice fit and finish of the front quarter and hood - the panels were never touched at this point:
    (hood later removed for engine rebuild)





    Since *I* didn't want to touch my from-the-factory quarter panels, and I needed 17" tires to clear the M2300K brakes, and I wanted firmer springs, that meant that I couldn't go much lower than stock GT-automatic-'86 height.

    From:
    http://www.veryuseful.com/mustang/te...Mach1_springs/

    =========
    1986 Mustang
    Mach1 Springs, Steeda 1/4" front spring spacers (placed on top of the isolator),
    BBK poly top & bottom isolators, new Fox FCAs,
    Tokico 5-way adjustable struts (set on 4 out of 5).

    The front fenders sit ~26-7/8" from the ground
    and that's with 245/45/17 RE730s (@32 PSI) which are the correct diameter for the car.
    The Mach1 springs are rated at 600lbs/in vs the 425/530 lbs/in stock GT springs.
    =========




    .

  4. #4

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    Thanks alot for the replies guys! Lots of good info. Looks like my car is lowered some.

  5. #5

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    Since my first measurements were done in a parking lot, I finally got time to double check my measurements (on level ground) and I do only have 25.375" at the front fenders and about 26.875" at the rear. The springs are a very old set of the motorsport "B" springs so I'll probably update them over the winter. The look is cool but the ride is very uncool. I see that the B springs are only suppose the lower the car by about an inch so mine must be very worn or on the low end of the tolerance. I would like it to be around 26.25" or so, when all is said and done.
    Last edited by twinturbohow; 01-01-2018 at 10:53 AM.

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    There is a Ford spec. On ride height and it’s measured at the wheel well and not the frame. I have posted it here a few times. iRC it was about 25.5”. There are also spacers in case you need to level the car out. The asc cars came with the B springs. I may have posted the ride height on the Asc site.
    Fox Body/3rd Gen MCA Gold Card Judge
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    88 Mclaren Mustang Vert 20K miles, 89 Mustang LX Sport Vert,
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    14 Mustang CS/GT, 15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

  7. #7

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    Quote Originally Posted by KevinK View Post
    There is a Ford spec. On ride height and it’s measured at the wheel well and not the frame;
    Fwiw, the proper car height is always measured at the frame.
    They (Ford), may have also released "guidances" for fender height. However, that's not what any dealer body shop would use.


    Quote Originally Posted by KevinK View Post
    iRC it was about 25.5”.
    Not for any GT, or regular Stang.
    The wheel diameter itself is ~25.6" (check tire rack for tire diameters).
    There are tons of photos of stock Stangs directly from the factory (just get a dealer Mustang sales brochure from ebay) . Every single one of them has space between the top of the tire, and the fender.

    Even not adjusting for parallax error (https://www.google.com/search?q=parallax+error ), on a photo, a person could do a simple ratio of the tire diameter (25.6") and the gap between the top of the tire and fender. That gets the gap distance. Add that to the tire diameter, and you have the fender height.


    Doing the above on the attached pictures (found on ebay), I get a gap between the top of the tire and the fender to be ~~2.2".
    Note, the tires and the fenders did change a few times on the aero cars.
    So, the stock fender height for an 85-93 Ford Mustang GT, directly from Ford, was ~~27.5".
    Ebay search term:
    (85,86,87,88,89,91,92,93) ( Sales, Brochure) mustang

    Of course, if people want to maintain the incorrect assertion that the Ford Fox 5.0 GT fender height was below 27" from the factory, people can go ahead and make their own conspiracy theories.
    Yes, the Government went an stole and replaced every Ford Mustang sales brochure ever made.
    And, the Government did the same for every magazine and paper article.





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    Name:  Mustang85SalesBrochure.jpg
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    Quote Originally Posted by KevinK View Post
    The asc cars came with the B springs. I may have posted the ride height on the Asc site.
    From the ASC Mclaren web site, it looks like those cars also had some gap (but, not much) between the top of the tire and the fender. So, again, the stock fender height would be greater than 25.6".

    https://www.ascmclaren.com/

    https://www.ascmclaren.com/mustangpics.htm











    .

  8. #8
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    I thought we were discussing the ride height of the Foxbody. The only time one would refer to body frame measurements is when there is damage or unexplained differences in the way a car sits. For quality control and dealer trouble shooting Ford published ride height specs. In its service repair and reference manuals. I have looked up but I don’t have access to it right now. The numbers I quoted were off the top of my head and I started that.

    Typical numbers that I have measured:

    88 ASC Vert. Stock 20K miles
    Rear fender well, 26 1/4"
    Front fender well, 26 3/8"

    89 LX Vert. Stock 145K miles
    Rear fender well, 26 5/8"
    Front fender well, 26 1/2"

    85 ASC Vert. Stock 130K mles
    Rear fender well, 26 1/2"/ 26" sagging on right
    Front fender well, 26"

    ASC used springs similar to the Ford Motorsport B springs which are still available from Ford Racing

    Not every dealer would have a frame rack but any dealer could make a measurement at the wheel well. I will look up the Ford details and post up for those who do not have a frame rack.
    Fox Body/3rd Gen MCA Gold Card Judge
    84 SVO 24K miles, 85 Mclaren Capri Vert. 84 GT Turbo Vert.
    88 Mclaren Mustang Vert 20K miles, 89 Mustang LX Sport Vert,
    03 Mach 1 7900 miles, 74 Mustang II, 69 Mustang, 67 Mustang, 07 GT500,
    14 Mustang CS/GT, 15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

  9. #9
    FEP Super Member xctasy's Avatar
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    We are discussion pavement to guard depth.

    The issues is this.

    The ground to wheel arch dimension is changed by the loaded wheel raduis. Which is half the static diameter of the wheel, minus 2.2 to 3.3%.

    The problem is a stock tire has 0.5" tread depth, sometimes more depending on load class.

    Point being....if the tires are worn down to minimum legal tread depth, the quoted wheel arch to road depth will vary by at least half an inch, and by the difference in the loaded wheel radius.

    The variance in quoted dimension is based on at birth, loaded, unworn stock tire depth.

    Springs settle, springs don't seat properly into the perch, and tires change. After a few million load cylces, so do the springs.

  10. #10

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    Quote Originally Posted by xctasy View Post
    The issues is this.

    The ground to wheel arch dimension is changed by the loaded wheel raduis. Which is half the static diameter of the wheel, minus 2.2 to 3.3%.

    The problem is a stock tire has 0.5" tread depth, sometimes more depending on load class.

    Point being....if the tires are worn down to minimum legal tread depth, the quoted wheel arch to road depth will vary by at least half an inch, and by the difference in the loaded wheel radius.

    The variance in quoted dimension is based on at birth, loaded, unworn stock tire depth.

    Springs settle, springs don't seat properly into the perch, and tires change. After a few million load cycles, so do the springs.
    Also, the spring isolators compress over time, and may even wear away completely (like the bottom spring isolators on a Fox/sn95).

    And, it gets worse with tires.
    Tire diameter varies by tire pressure.
    Tire pressure varies by temperature (by a non trivial amount). Here in New England, this year, we've gone between ~100F and -2F!
    So, for a car tire, without adding air, and assuming no air leakage, a tire that is 32PSI at 100F, would be at 23PSI at -2F. (http://www.1728.org/gaspres.htm)

    Tire diameter can also vary as the tire ages, because of more sidewall flexing (more prevalent on the cheaper tires).

    Then, there's the fact that tire sizes are like dress sizes.
    The tire diameter, sidewall width, contact patch, etc will vary - even between the same size and type (like all-season).
    Put on cheap "225" width tires, and the contact patch is often less. And, the diameter is also often less.

    Different tires types (extreme summer verses cheap all-season) also have a different amount of sidewall flex. That's important, because the tire specs (like diameter) assume a specific load.

    Above, are some of the reasons why, by law (often State or local laws), garages and tire shops have to replace all four tires at once.
    The issue is that ABS, traction control, and/or stability "may not work as designed" unless the tires are all the same type, all worn the same, etc.

    Fwiw, imho, the bigger issue is often the diameter differences.
    Kinda by definition, in ABS and traction control situations, tires will have different gripping ability. That gripping ability is also very dynamic, as the road, suspension, and speed all change.
    Note that stability control systems are much more sensitive to not having all four tires the same type, age, width(as defined by stock), wear, etc.

    I kinda went off on a tangent.
    However, the point is that tires, and how they can differ, are important in some cases.


    Fwiw, officially, I say follow all of auto manufacture's and tire recommendations!

  11. #11
    FEP Super Member erratic50's Avatar
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    What I have observed from all of this and a few measurements in my 86

    Stock low miles GT springs plus X2 balljoints with caster/camber plates on SN95 spindles drops the front a full 1.5 inches.

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