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Hey Eric, car is buried in storage otherwise I would. How have you been?
 

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Installed, just use the spacers that come with the kit to get the steering rack control arms level with the ground when all four wheels are on the ground.
 

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Discussion Starter #5
Installed, just use the spacers that come with the kit to get the steering rack control arms level with the ground when all four wheels are on the ground.
Thanks, but I want some pics to compare what it'll look like when done, I've never tackled this or really paid attention to a car that has had it done.


I'm doing good freaking Steve, thought you were dead, haven't seen you post in a long time.
 

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I'll try to get pics later this week. However, mine is on an 86 (narrow k) using sn95 a-arms and 95 sn95 spindles. The bumpsteer kit is MMs tapered version, not the bolt through. I found that following MMs instructions regarding the initial spacer stack worked very well. My steering arm is near parallel to the lower control arm at ride height. I should bump steer the car the correct way but since I didn't have the right tools when I put the stuff on, I did the best I could with my crude methods.
 

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the tie rod end is not parallel to the control arm, it is parallel to the line connecting the center of the ball on the balljoint and the center of rotation of the pivot bolt. Trying to eyeball the bumpsteer by comparing the tie rod end and the control arm is not the best way. Checking bumpsteer with a guage is a great way to reap the benefits of the bumpsteer kit as well as checking to see if you have any odd suspension issues, like a bent spindle.




See, one spindle is bent. Did not really notice it until the bumpsteer curve was all out of whack. A little help from Jack Hidley, and the problem was solved. Once again, the excellent MM tech service helped me figure out the bumpsteer issues and help me with some tips on how to use the gauge.
 

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Discussion Starter #9
Thanks guys, I appreciate it. I just wanted an idea what it should look like.

A picture can sometimes give more information than a sheet of instructions.
 

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How about a bumpsteer video instead? I made these animations of a SolidWorks model for a thread in the General Tech forum. They seem relevant here, plus I spent half the day doing them this weekend:) Most of the text here is cut and paste from the other thread, so just ignore any ranting that I didn't edit out.

The exact location of all the pivot points in the steering system of a Mustang to minimize bumpsteer is a complicated problem to solve. Way beyond a 10 minute internet discussion. Here is a ROUGH approximation to the correct solution. When viewed from the front, the tie rods and FCAs should be parallel to one another. To tell when they are parallel to one another, you must be able to see inside the ball joint so you can see where its pivot point is. Unless you have taken your ball joints apart to find this location, there is no way you are going to know where it is. The bottom line is that if you want to adjust the spacers in a bumpsteer kit, you can't do it by eye. You must measure the bumpsteer curve on the car or copy a set of suspension parts, alignment and bumpsteer spacer stack from another Mustang with a known good bumpsteer curve.

The bumpsteer curve refers to a graph which has suspension travel along one axis and wheel toe (in inches at the tire or degrees) on the other axis. Here is an example of one:

http://home.comcast.net/~jhidley/Bumpsteer_graph.JPG

I realize that it is difficult to visualize how moving around different points in the steering and suspension system could affect bumpsteer, so I made a simple suspension model in SolidWorks and animated the results. This makes it easy to see the bumpsteer behavior. The model is intentionally simple to make the bumpsteer behavior simple. The FCA pivot axis is parallel to the centerline of the car, so there is minimal caster change with suspension travel. The FCA is represented as two different links joined at the pivot point of the ball joint. The K-member is just a flat plate to mount the front control arm pivot and the steering rack to.

http://home.comcast.net/~jhidley/bumpsteer_model.jpg

Case #1:

The height of the outer tie rod has been adjusted to give minimum bumpsteer given the locations of the other points in the suspension/steering system. In this case, there is a total of 0.14 degrees of toe change over the entire 6.7" of suspension travel. This is barely visible in either video. Note that the tie rod and the FCA are NOT parallel. If I make them parallel, the bumpsteer gets about twice as bad.

Front view. Watch the end of the steering arm pointing towards you:

http://home.comcast.net/~jhidley/Bumpsteer_good_front.avi

Side view. Watch the end of the spindle pin:

http://home.comcast.net/~jhidley/Bumpsteer_good_side.avi

Case #2:

The height of the outer tie rod has been raised 0.7". Notice that the tie rod and FCA are no longer even close to parallel. The length of the tie rod has been adjusted so that toe is still zero at ride height. In this case, the toe changes from 2.8 degrees in at full bump to 2.2 degrees out at full droop. This is total change of 5 degrees from case #1. 35 times as much toe change!

Front view. Watch the end of the steering arm pointing towards you:

http://home.comcast.net/~jhidley/Bumpsteer_bad_front.avi

Side view. Watch the end of the spindle pin:

http://home.comcast.net/~jhidley/Bumpsteer_bad_side.avi
 

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Those video's are gold. Thanks Jack. Makes the behavior of the spindle very obvious using the full range of motion of the suspension which I've never really tried thinking through. It was easier to picture bumpsteer in my mind at one end of travel or another, but not through the entire range of motion.
 

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Discussion Starter #12
Well, what I needed were just a few pics of what it should look like. I had a stupid attack and ####ed up. Problem will be completely fixed today. Thanks for the help.
 
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