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  1. #1

    Default Foxbody steering settings

    I think need to do another round of frontend alignment adjustments on my 1986 GT.

    It has SN95 spindles and HPM caster/camber plates, X2 ball joints without spring spacers, new A arm bushings, MM strut tower brace, MM bump steer kit, stock 86 sway bar and sway bar links, low mileage stock 1993 GT springs, and stock replacement struts with shim placed such that they add more positive caster and allow the use of camber bolts for the struts. The car sits 1" lower than a stock 86 in front with a very slight rake to it. Nearly perfect stance IMO albeit I am soon to cut the rear springs until level.

    The camber bolts have allowed me to achieve exceptional camber results and having straight up struts gives minimal tire rubbing on a 245/45/17 on 1994 tribar rim with a stock 86 k member and stock A arms rather than longer ones. (Pretty unheard of afaik)

    Right now I am running with the struts centered in/out with the strut shoved all the way to the back of the opening. I have measured -2 degrees of camber on both sides and the placement of the strut lets me totally max out caster. I'm running 1/16" of toe in.

    The car has awesome turn-in with negative 2 camber and the Ackerman correction from the SN95 spindles proves very impressive for steering feel. But due to the camber I'm seeing some inside edge tire wear and the car tends to wander a bit on uneven road surfaces. It's a bit of a chore to drive it long distances at interstate speeds now.

    I am considering taking the car to run the standing mile down in Texas legally sometime soon too for some "before" numbers.

    For a street car that's occasionally going to see track time at SCCA events and will also likely get its sway links disconnected and slicks bolted on for some 1/4 mile action what are some sane steering settings.

    HPM caster/camber plates sheet says one thing, several other sources say another. I've seen as little as -1 camber to -2.25 camber being recommended. I'm at -2 which is .25 past HPM plate recommendations.

    I am looking for thoughts.

    I want to eliminate the current sense of wandering while retaining the majority of the handling performance up front. (I have a MM panhard bar in storage so it's coming soon out back)

    Is there a lot of improvement to be had simply by adding a lower K member brace?

  2. #2
    FEP Super Member
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    Find links from Jack Hiddley , and I think those may answer your questions .
    clowns to the left of me , Jokers to the right

  3. #3

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    Thank you for the reply. Find in the forums or google abroad?

  4. #4

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    Many resources, many answers.

    HPM
    -1.75 camber
    Max positive caster, equal both sides
    1/16" toe in


    MM street
    -1 camber
    4 degrees caster, equal both sides
    .5 degrees toe in


    MM race
    -3 camber
    Max positive caster, equal both sides
    0-.5 degrees toe out



    Here's what I'm considering right now for new settings:
    -1.4 camber (split difference between HPM and MM street)
    max caster equal both sides (I'm at 4.5 right now afaik)
    1/16" toe

    I have a gauge so I can dial it all in myself

    The main thing I'm wondering is if I'm still going feel like I still have too much camber on the street. I think right now it would be a joy on the track but -2 is for sure too much on the highway - it's a chore driving it there.

    Too bad decreasibg negative camber adds more toe out. It would be way too easy to just move the plates at the track and also get more toe out. It's looking like a degree of camber needs about 1/2 turn of tierod adjustment, but messing with the bump stack to do it without removing the tires or jacking it up can be fussy.
    Attached Images Attached Images   
    Last edited by erratic50; 02-14-2017 at 03:22 AM.

  5. #5
    FEP Super Member
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    Jack is one of the top designer/engineers at MM.
    Usually always find his info on the Coral .
    clowns to the left of me , Jokers to the right

  6. #6

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    I'm familiar with him by name. His specs for street and race are actually in the MM caster/camber instructions. (Pic above)

    I guess I am just not wanting to take an entire degree of negative camber out because the front feels SO good in turns right now.

    After driving on a few 60 mile trips on the interstate I am finding the road manners at 80-85 leave a bit of something to be desired. I want to find the sweet spot where I lose as little as possible on cornering while getting back some road manners. I can't imagine -1 will give me what I want given the many many recommendations for camber out there.

    I guess I was hoping for some feedback like mine is set at X and it does Y, etc.

  7. #7
    FEP Super Member
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    Take small amounts out , until you find the sweet spot you are after ..
    Others opinions , may not match your style of driving .
    I run a lot of negative camber , and have no problems at high speed .
    Remember tires can be a factor in getting the results you are after as well .
    clowns to the left of me , Jokers to the right

  8. #8

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    You can't run too much negative camber on the street of most Fox Mustangs as they have not enough caster to provide stability.

    A couple of notes.

    1) The spacers you have between the strut and spindle can't have any affect on the caster setting. This may not be obvious at first glance. The caster angle is defined by the location of the ball joint pivot in the FCA and the strut pivot in the c/c plate bearing. It makes no difference how these two locations are connected, straight line, infinity symbol, mobius strip, etc. None of that changes the caster angle.

    2) If you have X2 ball joints, make SURE to actually bumpsteer the car accurately. If the bumpsteer curve isn't good, you will have instability no matter what the alignment is set to. Guessing doesn't count.

    3) Set the caster to maximum positive, but equal side to side. Make sure that this is set before the suspension is bumpsteered.

    4) The more negative the car has, the more unstable it will be on rough roads due to camber thrust. This will vary somewhat with tire type.

    5) Since you are using eccentric bolts to adjust camber, you have some control over SAI (steering axis inclination) and scrub radius. If you adjust the eccentric bolt and camber plate to minimize scrub radius, that will improve the cars stability some, especially on rough pavement during braking.

    http://www.ls1gto.com/forums/attachm...0&d=1323194045

    To measure scrub radius, place the car on a concrete surface. Turn the steering back and forth a few times. Back up the car about 12". Look at the front of the front tires. There will be scrub marks on the tire. Find the center of these circular marks and make a point there. Then measure from that point to each side of the tire. For maximum stability, you want both of these dimensions to be equal. With a strut car, this is rarely possible.
    Jack Hidley
    Maximum Motorsports Tech Support

  9. #9

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    Jack - thanks for the reply.

    Good point on scrub radius. I'll see where I'm at on this.

    To your point on caster, my next step is to get it aligned at a shop instead of using my caster and camber gauge and doing toe measurements. After I don't get the results I want I am sure my next step will be to bump steer it.

    I have the proper equipment to actually measure the bumpsteer as I bought it with the MM bumpsteer kit. I'll eventually get to it. It can't be too far off right now but it certainly will improve with measurement and adjustment - the entire purpose of the kit.

    After looking at at the spring and A arm and strut arrangement a bit, I believe using my spring compressor and parts from my press I can pull with the spring compressor through the opening in the A arm and get to maximum bump on my struts without removing the coil spring at all. At least that is my current plan of attack when it is time to bumpsteer it.

    I have a lot of adjustment available to me with the caster/camber plates and the camber bolts. I believe the farther out the struts are the closer to vertical the struts will be which in theory may help get closer to the ideal scrub- certainly near the best I can achieve. Struts that far out comes at the cost of some positive caster since the only place the max positive caster is available is when the struts are at the back in the middle of the strut opening. It also costs some negative camber - I think I can only get a degree or so negative when the struts are tipped out that far.

    Where should the priorities sit - with scrub or positive caster?

    Great info - thanks for your input!

  10. #10

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    It depends on how much scrub and caster there is currently. You need to measure each before making a decision.

    Above you mentioned that you had 4.5 degrees of caster. For your combination of parts, that doesn't seem correct. Post what you find once the car is put on an alignment rack for caster and scrub.
    Jack Hidley
    Maximum Motorsports Tech Support

  11. #11

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    Quote Originally Posted by erratic50 View Post

    I have the proper equipment to actually measure the bumpsteer as I bought it with the MM bumpsteer kit. I'll eventually get to it. It can't be too far off right now but it certainly will improve with measurement and adjustment - the entire purpose of the kit.
    I would be careful about guessing @ your toe change through travel. If you have the equipment you should measure it. You have made quite a few changes to the suspension and you would be amazed @ how much a small change between the inner and outer tie rod heights affects the toe curve. IMO an accurate bump curve (within reason) is much more important in freeway driving than track driving. When I am on the track I am constantly correcting the wheel anyway and in many cases I can set an intensional bump curve that works to my advantage. When I am on the freeway I have the cruise control on and I am usually drinking coffee and a twitchy steering wheel is a PITA.

    To be clear, I haven't wheeled a race car in many years. I do however make a living designing suspensions for them and set them up on a daily basis. JH seems to have a good handle on suspension dynamics and is giving you good input here and I dont want to get in the way of that. The only point I am making is don't overlook the importance of measuring the bump curve. By doing that you may be able to fix more than you think.

  12. #12

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    I've been meaning to get back on this for weeks now. I've been out of town M-F for several weeks for work and stuck doing higher priority repairs on other cars on the weekends. Except this weekend - I'm just absolutely as sick as a dog.....

    Heres hoping I'll get to it before the SCCA events go into full swing. My car is not terrible but also not really ready either.

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