Measuring bump steer:

[PedalOnTheRight]

I searched and found nothing conclusive. I made an excel sheet measuring bump steer but believe I've set it up incorrectly, I know everyone is pretty busy, but can someone help me out with a good way to measure bump steer?

[PedalOnTheRight]

I searched and found nothing conclusive. I made an excel sheet measuring bump steer but believe I've set it up incorrectly, I know everyone is pretty busy, but can someone help me out with a good way to measure bump steer?

[Cement Legs]

Look in Miliken Race Car Dynamics... there is a good setup in there using dial indicators and a plate the can bolt to your hub.

[awhittle]

A couple of 6ft pieces of aluminum square tubes C-clamped to the front disks and a tape measure and a calculator.

AW

[PedalOnTheRight]

Thanks for the responses. I'd be easy if we had a car built, I'm working on next year's chassis right now, so using the rack, tie rods, upright and suspension points, I need to develop a good way from there. I know there are knowledgable guys outhere who have done this a million times. Like I said, I thought my excel sheet was just fine in conjunction with my solid edge model, but my numbers dont seem logical.

[Blake_DFSAE]

I believe our suspension program calculates it...

[mtg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Blake_DFSAE:
I believe our suspension program calculates it... </div></BLOCKQUOTE>

But its a good idea to actually measure it, because there aren't many cars that built with super-mega accuracy where the kinematics program shows exactly what the car is really doing.

It's really easy for things to become different than the computer model (welding distortion, slop in bolt holes, measurement mistakes...)

By the way, I'm a little skeptical about PedalOnTheRight's forum name. That was one of "my phrases" when I was at UMR. I remember talking to some guys from the Wash U team at a St. Louis autocross before I graduated. Did somebody steal a quote?

[PedalOnTheRight]

haha, actually no. I'm a sophomore at Wash U, and havn't talked with anyone from rolla about forum names or anything in general really. One of my "phrases" as well; guess I just got there first!

....I know that suspension programs make it easy to calculate, just wondering if anyone does it the old fashioned way...

[Marshall Grice]

what exactly are you looking for? If you have your suspension modeled then move it and measure what ever you want.

[Blake_DFSAE]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by mtg:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Blake_DFSAE:
I believe our suspension program calculates it... </div></BLOCKQUOTE>

But its a good idea to actually measure it, because there aren't many cars that built with super-mega accuracy where the kinematics program shows exactly what the car is really doing.

It's really easy for things to become different than the computer model (welding distortion, slop in bolt holes, measurement mistakes...)

By the way, I'm a little skeptical about PedalOnTheRight's forum name. That was one of "my phrases" when I was at UMR. I remember talking to some guys from the Wash U team at a St. Louis autocross before I graduated. Did somebody steal a quote? </div></BLOCKQUOTE>

Agreed. But ours ia a 2007 car as well i.e. nonexistent.

[PedalOnTheRight]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Marshall Grice:
what exactly are you looking for? If you have your suspension modeled then move it and measure what ever you want. </div></BLOCKQUOTE>

I have it modeled, I just believe that I was measuring my bump steer incorrectly. In front view, what's the best place to measure bump steer when raising and lowering your upright?

[Marshall Grice]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> In front view, what's the best place to measure bump steer when raising and lowering your upright?
</div></BLOCKQUOTE>
the plane that forms the face of your hub measured WRT vehicle centerline(top view) in degrees. Ignoring camber of course.

if you want to do it from the front you'll want to measure at the wheel centerline (axle line)