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Bump Steer Kits...Are They Necessary and When?

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That's interesting. So the takeaway from this on bumpsteer kits is....If running stock to 0 toe, then bumpsteer kit is pretty useless. However if some degree of static toe out is already employed, controlling the amount of toe out added in compression could be a good idea.
Is it more about compression during a corner or actually hitting a bump?
Seems to me that cornering aspect would be more useful, and just people think of actual bumps when hearing "bumpsteer". If I'm running toe out and turn right, weight is transferred to the left front, and compresses. Then if the toe out increases on that side as result of the compression the tire is turned less, and that's the tire with the most traction.
Also any insight into situations where the car is using different sized wheel and tire heights, wouldn't that change the geometry of the control arms?
If you have your car lowered significantly (more than 1") and/or you have front geometry correction, there is a good chance you may need bumpsteer correction. On the S550, lowering more than 1" is considered quite low and it's not like the S197 where 1-1.5" drop is basically necessary. The geometry of the car is pretty good. Don't overdo it. The lower you go, the stiffer you'll need to make the car due to the increased roll couple and reduced ground clearance. IMO the only reason to go to a 1.5" drop or thereabouts is if you plan to have significant front-end aero and need to get your splitter height down. At that point, the above about stiffness is especially true.
 
If you have your car lowered significantly (more than 1") and/or you have front geometry correction, there is a good chance you may need bumpsteer correction. On the S550, lowering more than 1" is considered quite low and it's not like the S197 where 1-1.5" drop is basically necessary. The geometry of the car is pretty good. Don't overdo it. The lower you go, the stiffer you'll need to make the car due to the increased roll couple and reduced ground clearance. IMO the only reason to go to a 1.5" drop or thereabouts is if you plan to have significant front-end aero and need to get your splitter height down. At that point, the above about stiffness is especially true.

did you ever pickup your winter tires from AAA😂🤣😂
 
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For those interested in the subject, one reason that the S550 has less of a problem (compared to S197) in this regard is because the double ball joint setup. It creates a longer ‘virtual’ arm. The longer the arm, the less horizontal change under compression and droop.
that and the massive suspension travel needed to get the S197s to handle. Although, I can't remember anyone using a bump steer outside od the sn95 and foxbody platforms
 
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Exp. Type
HPDE
Exp. Level
Under 3 Years
San Diego
Addressing only the benefit of bumpsteer correction: it makes a difference, if you find yourself driving around it.
In my case, I always noticed that after hitting a bump in competition, I was forced to immediately correct steering to remain on the line I desired - this was happening due to toe change under varying levels of compression - bumpsteer! How much? I measured!

View attachment 15739

Word of caution: if you have plans within a few hours of tackling this, be prepared to cancel them. Getting this setup, measuring, making the necessary spacer changes, remeasuring (rinse, repeat, MANY times) is a very time consuming process! But what I can say is that I took out 6mm (~3/16") of total toe OUT on the stock setup (prior to installing the link/kit), to within 1mm (~1/32") of total toe IN from static ride height -> 1.5" compression. FWIW, I'm only lowered ~1.5" from stock up front.

You don't know what you don't measure! :)


I'm about to install some suspension components. The FP Track Handling Kit, along with some IRS braces and bushing supports.

I'm planning to install a bumpsteer kit and measure it myself along with the performing the rest of the alignment.

However, the one element I'm not clear on yet is how to go about measuring bump steer since the strut needs to be installed without the spring in order to run the suspension through its travel. I'm planning to install Steeda adjustable camber plates. I am wondering how to keep the camber settings correct when needing to uninstall the strut, remove the spring, then install the strut again? Also, do the camber plates work without the springs installed?
 

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