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 Post subject: need some help please.
PostPosted: Thu Mar 08, 2012 1:51 pm 
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Joined: Thu Mar 08, 2012 1:11 pm
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On my build I have a k frame with steering rack, lower control arms and spindles all from the same vehicle.
From the factory it uses a rear steer setup however because of engine placement I'm forced to move the steering rack forward for clearance.

What I did simply was flip the spindles around so it would now be a front steer design. My problem is this.
now moving the rack messes with all of the oem steering spec geometry and whatnot. is there a way to create a simple jig that I could also flip around and essentially have it show me where to place the steering rack. thus allowing me to build in the mounts to where the jig places the rack.

I've tried to think of a few ways to mount/build a jig but I'm unsure where I should mount the jig to the spindles. (top of spindle where it mounts to McPherson strut, spindle arm which the toe arm bolts to, in relation to the lower ball joint, mount to spindle center where spindle bolts to the hub)???

Also I'm aware the steering is now backward so I'm sourcing a miata rack to fix the front steer issue now.

Any help with this issue would be great and very much appreciated.

Thanks!


Did a quick paint image in case I dont make sense. :D

Image


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PostPosted: Thu Mar 08, 2012 3:25 pm 
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Joined: Mon Apr 12, 2010 5:40 pm
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Location: san francisco bay area
Gotta work the numbers. ..

Wishbone, SusProg3D, something. Turning the upper mounting point into a lower BJ mount is easy, it's all in the shape of the adapter.
Positioning the new lower mount is the problem, you have to calculate for camber and caster.
I would think it's preferable to keep the (now) upper balljoint resting angle close to 0 degrees included as well. I could see it ending up at a -14 to -17 degree included.
You'd probably need to rotate the lower BJ and the lower mount off of horizontal but thats not a big deal.
It would limit the amount of anti-dive you can attain, probably not enough to worry about.
You also have to consider whether or not the (now) upper BJ is designed to handle the new weight load direction, the BJ could theoretically punch thru which would be catastrophic.
If the joint assembles thru the bottom, I wouldn't use it as an upper joint. .. There's typically just a circlip holding everything in place under the copper cap.

edit>> I just realized I had assumed you meant that you flipped them upside down. .. I bet you meant left to right huh?
Still. .. you would have to run the numbers either way.

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PostPosted: Thu Mar 08, 2012 4:39 pm 
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Wow that's awesome!!

Awesomely bad.

You now have severe reverse Ackerman steering, in layman's terms your rear steering arms are inside the ball joint line and forward steering arms are outside the ball joint line - dump the idea and back to scratch I'm afraid...

I suggest you wonder over to the spindles sticky thread and see what's around, maybe some Toyota Previa spindles or others that come from the factory with front steer steering arms with proper pro-Ackerman.

Here's my pretty picture, red is centerline of ball joints (and front of car), blue is steering arm combined front or rear and hopefully you get the point why yours is wrong.

Attachment:
Ackerman.jpg
Ackerman.jpg [ 10.55 KiB | Viewed 447 times ]


And this is what yours should look like, notice the arrows on both are now pointing to the center of the car towards the rear differential ....

Attachment:
Ackerman2.jpg
Ackerman2.jpg [ 37.91 KiB | Viewed 444 times ]


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PostPosted: Thu Mar 08, 2012 5:35 pm 
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Joined: Sat May 02, 2009 1:03 pm
Posts: 924
Location: The Humid State of North Carolina
cheapracer wrote:
Wow that's awesome!!

Awesomely bad.

You now have severe reverse Ackerman steering, in layman's terms your rear steering arms are inside the ball joint line and forward steering arms are outside the ball joint line - dump the idea and back to scratch I'm afraid...

I suggest you wonder over to the spindles sticky thread and see what's around, maybe some Toyota Previa spindles or others that come from the factory with front steer steering arms with proper pro-Ackerman.

Here's my pretty picture, red is centerline of ball joints (and front of car), blue is steering arm combined front or rear and hopefully you get the point why yours is wrong.
CR... Might not be all that bad!

I had the same issue with mine.. needing a rear steer to now be a front steer. How I cured it was to not only go front to back but top to bottom.

If mirrored and rotated, you end up with a double negative and it appears to return to normal. My rough numbers when measure on my car showed me I was at least in possession of most of the original geometry. I didn't get to the point where I could accurately measure it, but I saw enough to ease my worries.

Hit the search function Kingpin... there was a small discussion about it somewhere on here not too long ago!

Cheers and Happy Building!

KS

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