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Thread: Rear Toe in IRS Suspension question

  1. #1
    Senior Member Buzzsaw's Avatar
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    Rear Toe in IRS Suspension question

    I plan to attempt to align the chassis my self. Ride height is set at 4” in the front and 4 1/2” in the rear. My thrust angle I believe is OK. I have set a temporary camber on the rear wheels using an aluminum bar cut to fit the outside of my 17” wheels and a good digital angle gauge. I have ordered a good set of toe plates. I don’t have a lift and I am too big to get under the car at a 4 1/2” ride height to reach the toe arm turn buckle to make any adjustments. Are you guys without a lift putting the chassis on jack stands making an adjustment and the putting the chassis back on the ground (rinse & repeat)? Is there an easier way I am missing? Also do sway bars need to be removed front and rear?
    Thanks Ross
    MK4 kit delivered 11-5-2023 Forte’s Ford 302, Edelbrock Pro Flow 4 fuel injection, Tremec TKX transmission mid shift option, 355 ratio rear end, 17”wheels, 2015 Mustang IRS from FFR

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    Senior Member F500guy's Avatar
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    For my Miata I built 4 2X4 jenga blocks that I could put the car on and allow me to reach the alignment settings. They are long enough to roll the car back and forth about 12 inches to settle the suspension. Kind of Cheesy, I really need a lift but do not have room to put one. For the Cobra I did just that, take careful measurements when you adjust and snug the adjusters down so when you raise and lower it remains consistent. Kind of a PITA but works.Jenga Blocks.JPG
    MK IV Delivered June 27, 2023 Build Thread-https://thefactoryfiveforum.com/showthread.php?46069-Lance-s-Roadster-Build-Thread-Starting-the-Al-panel-slog

    "Build a Car" They Said "It Will Be Fun "

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    Senior Member Buzzsaw's Avatar
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    Thanks F500 guy. I thought of Jenga blocks too! Looks like Jack stands will be the best way for me.
    MK4 kit delivered 11-5-2023 Forte’s Ford 302, Edelbrock Pro Flow 4 fuel injection, Tremec TKX transmission mid shift option, 355 ratio rear end, 17”wheels, 2015 Mustang IRS from FFR

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    Senior Member CraigS's Avatar
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    I just jack the diff up and twist the toe link, drop it back down and roll and bump it to settle the suspension. When I get close I start snugging the jam nuts after each twist. No need to go full tight but the jam nuts will actually lengthen the bar going from loose to tight so I like to at least take out that slop. I made these up so I can track the thrust angle as I go.
    IMG_20170419_160647869.jpg
    The sign board fits in behind the front wheel w/ the short vertical against the main frame tube.
    IMG_20170419_160800746.jpg
    All this is a huge pain in the butt but w/o a lift I see no other way.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

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    Senior Member Mike.Bray's Avatar
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    When I was building street rods with all independent suspension I would remove the coilovers and install a fixed length rod to hold the suspension at ride height. With the suspension locked at ride height I could do the alignment while the chassis was up in the air on the jig. It wouldn't take much to do the same on the rear of these cars.

    My build thread https://thefactoryfiveforum.com/show...Roadster-Build

    Thread on Stainless Steel AN brake lines.

    Thread on fasteners and torque wrenches.

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  7. #6
    Senior Member Buzzsaw's Avatar
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    Quote Originally Posted by CraigS View Post
    I just jack the diff up and twist the toe link, drop it back down and roll and bump it to settle the suspension. When I get close I start snugging the jam nuts after each twist. No need to go full tight but the jam nuts will actually lengthen the bar going from loose to tight so I like to at least take out that slop. I made these up so I can track the thrust angle as I go.
    IMG_20170419_160647869.jpg
    The sign board fits in behind the front wheel w/ the short vertical against the main frame tube.
    IMG_20170419_160800746.jpg
    All this is a huge pain in the butt but w/o a lift I see no other way.
    Thanks Craig, your inside is invaluable to us rookies!
    MK4 kit delivered 11-5-2023 Forte’s Ford 302, Edelbrock Pro Flow 4 fuel injection, Tremec TKX transmission mid shift option, 355 ratio rear end, 17”wheels, 2015 Mustang IRS from FFR

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    Senior Member Buzzsaw's Avatar
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    I have sway bars front and rear do I need to remove/ loosen them? Or can they be left alone?
    MK4 kit delivered 11-5-2023 Forte’s Ford 302, Edelbrock Pro Flow 4 fuel injection, Tremec TKX transmission mid shift option, 355 ratio rear end, 17”wheels, 2015 Mustang IRS from FFR

  9. #8
    Senior Member F500guy's Avatar
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    Undo the ends when you do the alignment, then reconnect after and they should not be in tension or compression when you reconnect so adjust accordingly
    MK IV Delivered June 27, 2023 Build Thread-https://thefactoryfiveforum.com/showthread.php?46069-Lance-s-Roadster-Build-Thread-Starting-the-Al-panel-slog

    "Build a Car" They Said "It Will Be Fun "

  10. #9
    Senior Member Buzzsaw's Avatar
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    Quote Originally Posted by F500guy View Post
    Undo the ends when you do the alignment, then reconnect after and they should not be in tension or compression when you reconnect so adjust accordingly
    Thanks F500guy!
    MK4 kit delivered 11-5-2023 Forte’s Ford 302, Edelbrock Pro Flow 4 fuel injection, Tremec TKX transmission mid shift option, 355 ratio rear end, 17”wheels, 2015 Mustang IRS from FFR

  11. #10
    Senior Member Buzzsaw's Avatar
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    Has anyone used the Tenhulzen 2 wheel Alignment System to aline caster, camber, and Toe? Are you happy with the ease of usage and accuracy of measurements?
    Last edited by Buzzsaw; 10-01-2024 at 01:18 PM.
    MK4 kit delivered 11-5-2023 Forte’s Ford 302, Edelbrock Pro Flow 4 fuel injection, Tremec TKX transmission mid shift option, 355 ratio rear end, 17”wheels, 2015 Mustang IRS from FFR

  12. #11
    Senior Member Mike.Bray's Avatar
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    Quote Originally Posted by Buzzsaw View Post
    Has anyone used the Tenhulzen 2 wheel Alignment System to aline caster, camber, and Toe? Are you happy with the ease of usage and accuracy of measurements?
    I used this https://www.amazon.com/dp/B00PB7V3SU...fed_asin_title

    With this wheel adapter https://www.amazon.com/dp/B0157QU9IO...fed_asin_title

    And these turn plates https://www.eastwood.com/quicktrick-...term=triggered

    My build thread https://thefactoryfiveforum.com/show...Roadster-Build

    Thread on Stainless Steel AN brake lines.

    Thread on fasteners and torque wrenches.

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  14. #12
    Senior Member JJK's Avatar
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    Mike, I used the exact same ones , they work great.
    Mk 4 complete kit w/IRS delivered (mostly) 10-31-22. BPE 347FI w/TXK. First start July 2023. Completed build February 2024. Officially legal 05-17-2024.

  15. #13
    Senior Member Mike.Bray's Avatar
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    Quote Originally Posted by JJK View Post
    Mike, I used the exact same ones , they work great.
    Hahaha! I remember! Glad it worked out for you.

    I have to admit my car drives and handles really well. Goes down the road straight as an arrow.
    My build thread https://thefactoryfiveforum.com/show...Roadster-Build

    Thread on Stainless Steel AN brake lines.

    Thread on fasteners and torque wrenches.

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  17. #14
    Senior Member Buzzsaw's Avatar
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    Funny Mike, I have the same caster camber gauge and mounting jig saved in my Amazon Hold for Later file.
    MK4 kit delivered 11-5-2023 Forte’s Ford 302, Edelbrock Pro Flow 4 fuel injection, Tremec TKX transmission mid shift option, 355 ratio rear end, 17”wheels, 2015 Mustang IRS from FFR

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  19. #15
    Senior Member CraigS's Avatar
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    No question that is a really nice piece but it is a lot or $. I use this gauge
    https://www.longacreracing.com/shop....y---NO-ADAPTER
    mounted on a piece of shelf cut to fit onto the wheel rim.
    Align tool.jpg
    The gauge has a 1/4" course hole in it so easy I loctited a stud into it and use a few nylon and steel fender washers to attach to the board. You want it tight enough that it doesn't sag but loose enough that you can rotate it to center the bubble.
    Lately I have added a small piece of sheet steel (A Simpson mending plate) so my magnetic laser can hang there for checking rear thrust angle.
    20210501_093241.jpg
    BTW, I use this for checking toe
    https://www.longacreracing.com/shop....Standard-Style
    or a home built version of this
    https://www.longacreracing.com/produ...etitle=Toe-Bar
    A few years ago I got a pair of these toe plates, Now I can only find them from temu which I refuse to click on so this is a screen shot.
    toe plates.jpg
    They make turning the steering a little easier for checking front caster but here is the best part. They can roll on their bearings about 2inches in and out so with the car up, I push them in. When I drop the car back down after making an adjustment all I need to do is bounce it some to settle the suspension. No need to roll it back and forth. A huge advantage.
    Last edited by CraigS; 10-02-2024 at 07:27 AM.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

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  21. #16
    Senior Member Mike.Bray's Avatar
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    Forgot about my toe plates, thanks for showing them Craig. They work great also.
    My build thread https://thefactoryfiveforum.com/show...Roadster-Build

    Thread on Stainless Steel AN brake lines.

    Thread on fasteners and torque wrenches.

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  23. #17
    Senior Member Buzzsaw's Avatar
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    Mike and Craig thanks for your caster, camber and toe setting equipment suggestions. You guys really help us rookie builders.
    MK4 kit delivered 11-5-2023 Forte’s Ford 302, Edelbrock Pro Flow 4 fuel injection, Tremec TKX transmission mid shift option, 355 ratio rear end, 17”wheels, 2015 Mustang IRS from FFR

  24. #18

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    Fold up a plastic garbage bag to go underneath the tires. That makes the suspension easy to settle without rolling it back and forth.

    Get two pieces of fishing line, and attach a weight to one end. Tap the other end to the top of the round tube, one at each end. Hang both pieces so they hang down the same side.

    Using a laser level, cast a laser beam from the front (or rear) of the car so that it intersects both pieces of fishing line, about 2-3 inches from the floor.

    Now you have a laser line exactly in line with the frame rail to measure off of. You can set your toe in exactly to the frame, and not just to the other tire.
    Last edited by Bob Cowan; 10-03-2024 at 01:05 PM.
    .boB "Iron Man"
    NASA Rocky Mountain, TTU #42, HPDE Instructor - Retired 10/24
    BDR 1642: Coyote, 6 Speed Auto, Edelbrock Supercharger
    Member: www.MileHiCobraClub.com
    www.RacingTheExocet.com

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