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Thread: Trick with steering rack?

  1. #1

    Trick with steering rack?

    Came across this when getting ready to install a steering rack..

    The height of the rack in relation to the lower A-arm is important for the geometry to be correct. Position the rack at the correct height so the front toe-in change (bump-steer) throughout the travel does not exceed 1/8 inch.

    To check bump-steer, assemble the suspension without the spring and move the spindle through its total suspension travel. Measure the toe-in at full spindle down, full spindle up, and center travel. The toe-in should not change more than 1/8 inch. Small height changes in the rack, even 1/32 of an inch, will affect the toe-in. There is no short cut, this is a time consuming process.

    does anyone have any tips or tricks as to how I go about installing this rack without completely screwing up my suspension geometry.

  2. #2
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    Re: Trick with steering rack?

    The tie rod will be approximately parallel with the lower a-arm. This is a trial and error job that you will just have to do. Your toe change should be less than 1/8 per side. Hopefully you will be able to get it to less than 1/16. If this is a custom installation it is also important to have the tie rod the right length as that affects bump steer also. It is difficult to change the length so it is important to get that figured out when the suspension is designed. Some times you just have to get as close as possible to zero bump steer and live with whatever that is.

  3. #3

    Re: Trick with steering rack?

    Quote Originally Posted by txbuilder
    The tie rod will be approximately parallel with the lower a-arm. This is a trial and error job that you will just have to do. Your toe change should be less than 1/8 per side. Hopefully you will be able to get it to less than 1/16. If this is a custom installation it is also important to have the tie rod the right length as that affects bump steer also. It is difficult to change the length so it is important to get that figured out when the suspension is designed. Some times you just have to get as close as possible to zero bump steer and live with whatever that is.
    so essentially if the lower control arm is flat my tie rod should be flat... I weld up the rack brackets and bolt everything up tight then check toe in.. if its off grind everything off and re try?

  4. #4

    Re: Trick with steering rack?

    Quote Originally Posted by Upper-Deck
    Quote Originally Posted by txbuilder
    The tie rod will be approximately parallel with the lower a-arm. This is a trial and error job that you will just have to do. Your toe change should be less than 1/8 per side. Hopefully you will be able to get it to less than 1/16. If this is a custom installation it is also important to have the tie rod the right length as that affects bump steer also. It is difficult to change the length so it is important to get that figured out when the suspension is designed. Some times you just have to get as close as possible to zero bump steer and live with whatever that is.
    so essentially if the lower control arm is flat my tie rod should be flat... I weld up the rack brackets and bolt everything up tight then check toe in.. if its off grind everything off and re try?
    i am going through this right now also on my build.i used to race stock cars and did this alot. this is all trial and error.you will have to either raise the rack up and down or the ends of the tierod.their is no fast way of doing this.but once you get it it makes a car handle alot better.but starting with the tierods with the same angle as the lower a arm is a good place to start.

    john

  5. #5
    Senior Member AdrianBurton's Avatar
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    Re: Trick with steering rack?

    this might help
    http://www.fulltiltboogieracing.com/...rexplained.wmv

    He is doing the adjustment on the rear of an IRS mustang but the process is the same

  6. #6
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    Re: Trick with steering rack?

    Quote Originally Posted by Upper-Deck
    Quote Originally Posted by txbuilder
    The tie rod will be approximately parallel with the lower a-arm. This is a trial and error job that you will just have to do. Your toe change should be less than 1/8 per side. Hopefully you will be able to get it to less than 1/16. If this is a custom installation it is also important to have the tie rod the right length as that affects bump steer also. It is difficult to change the length so it is important to get that figured out when the suspension is designed. Some times you just have to get as close as possible to zero bump steer and live with whatever that is.
    so essentially if the lower control arm is flat my tie rod should be flat... I weld up the rack brackets and bolt everything up tight then check toe in.. if its off grind everything off and re try?

    Can you make an adjustable rack mount?

  7. #7
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    Re: Trick with steering rack?

    THANK GOD he used a video to save a million words.....just sitting through the video made me want to shoot myself in the head!!!! I kept yelling "just get on with it man!!! I don't care about the 2x4's under the car lift!!!"
    LOL ;D ;D

  8. #8
    Senior Member nicktruman's Avatar
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    Re: Trick with steering rack?

    I got some awesome software called "circle track analyzer" it helps you set the car up correctly and predicts what the handling will be.
    Attached Images Attached Images  
    Regards
    Nick

    Twin turbo V8 Zonda inspired thingy

  9. #9
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    Re: Trick with steering rack?

    i was just going to suggest something like what nick mentioned. you should be able to work out your hieghts before you actually start it will save you a bunch of time. also do not forget that you will need ackerman in their also if you have the rack in a straight line with tie rods mounts on the spindle you will pull you hair out trying to figure out why oh heck with this i could be here all day. just remember to place the rack UP to 3/4 forward or backward of the centerline from spindle/tierod mount to the other spindle/tierod mount.

    to the front of the center line will create a more stable feel with a slightly slower steer.
    to the rear of the center line will create a more nimble effect with a faster steer

    question is do you want it to feel like a caddy or a porshe.
    when aligning the tie rod with the control arm it will get you close. a smart lever (a good one) will aid in this greatly but remember you want to put the tie rod in the same plane as the lower control arm mounting points. what about at the ball joint? well thats where all the trail and error is played in. also remember to make sure you are doing this with the car on a flat surface area. and all four corners of the car are sitting at exact ride heiights. the slightest variance will throw it all out of whack. good luck and proper planning will save a ton of time on something that will take even longer to do.

  10. #10
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    Re: Trick with steering rack?

    This might help (asumeing your doing a Fiero kit):
    http://www.fiero.nl/forum/Archives/A...-2-090909.html

    http://www.fiero.nl/forum/Archives/A...-2-060145.html

    I have one more link saved on computer but that link has come and gone.So if anyone needs a little more info.Contact me.
    The road to life is full of flat squirrels, who couldn't make up their mind!

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