Bump steer vs Roll Centre correction

[OzS550]

I'm trying to get my head around Bump Steer and Roll Centre correction when you lower the car. I'm using the BMR min drop springs with 21mm or 7/8" drop at the front.

Am I right that Roll Centre correction is most critical and worth me installing the Steeda Extended Ball Joint front control arm lateral links?

And am I also correct that bump steer becomes more of an issue with cars even lower?

These Steeda products are costly here in Australia, the front control arms are $341- and the bump steer kit is $374- so if I don't absolutely need to do the bump steer, I won't.

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[Nagare]

If you feel the car is fine as is, don't spend more money just because other people find a benefit from a certain part. There are a lot of things that are "essential" to forum members, that you would never notice an issue with if you hadn't found these forums.

 

[GT 550]

Hey Michael fwiw I think @Nagare is spot on. Unless you're perceiving an issue don't waste your money particularly at the prices we need to pay for things here. I lowered mine on the same springs and can't tell the difference. 1" is a rule of thumb, anything lower and you'd probably need to look into doing something. Put the money towards the 'before' dyno test when you get the tune

 

[Norm Peterson]

I'm trying to get my head around Bump Steer and Roll Centre correction when you lower the car. I'm using the BMR min drop springs with 21mm or 7/8" drop at the front.

Am I right that Roll Centre correction is most critical and worth me installing the Steeda Extended Ball Joint front control arm lateral links?

And am I also correct that bump steer becomes more of an issue with cars even lower?

Bump steer mainly becomes an issue when you install the roll center correction kit and you don't correct the resulting change in bumpsteer. Lowering the car and not doing any roll center correction doesn't mess with the bumpsteer nearly as much as specifically tinkering with the roll center geometry does.

In most cases, planning on either doing both the Roll Center and Bump Steer corrections or not doing either one (until you can specifically identify your own need to) would be the way to go.


Norm

 

[myblkshadow19]

i had the bump steer kit from steeda installed on mine after lowering this past weekend and i can't tell a bit of difference in the steering at all. only when tracking the car are you gonna mess with the roll center and bump steer......

 

[Nuked]

I currently have the BMR handling springs with the roll center arms installed, no bumpsteer kit. Bumpsteer is about the same, maybe a tad worse than when I had the stock arms and BMR Performance springs. FWIW.

 

[Bluemustang]

Installing the Steeda lateral arms with roll center correction does more to change the bumpsteer than the change from your typical lowering kit. That's why it is typically suggested to go together.
Don't underestimate the effect of the geometric roll center. There is some magic there. I highly recommend it provided that you don't need near -3 or more front camber (since you lose some static camber from the arms) and your wheels aren't already too close to the strut (since you lose 5mm or so of track width also). Aside from those things, it's only benefits. More front grip and better steering feel and response.

 

[OzS550]

Bump steer mainly becomes an issue when you install the roll center correction kit and you don't correct the resulting change in bumpsteer. Lowering the car and not doing any roll center correction doesn't mess with the bumpsteer nearly as much as specifically tinkering with the roll center geometry does.

In most cases, planning on either doing both the Roll Center and Bump Steer corrections or not doing either one (until you can specifically identify your own need to) would be the way to go.


Norm

Installing the Steeda lateral arms with roll center correction does more to change the bumpsteer than the change from your typical lowering kit. That's why it is typically suggested to go together.
Don't underestimate the effect of the geometric roll center. There is some magic there. I highly recommend it provided that you don't need near -3 or more front camber (since you lose some static camber from the arms) and your wheels aren't already too close to the strut (since you lose 5mm or so of track width also). Aside from those things, it's only benefits. More front grip and better steering feel and response.

Very much appreciate everyone's input to this and I having been giving it a lot of thought and more research. Have read through the original Steeda post for these items and the ensuing discussion and together with the above comments, I now have a better handle on this.

I think I will do the Steeda correction arms with bumpsteer and look forward to seeing what change in handling I notice. (I note Steeda seem to be the only company doing roll steer correction arms.)

I assume there will be no problem achieving -1.5º or so camber without any other hardware or clearing the strut as I'll be using my OEM PP wheels with standard rubber.

 

[Bluemustang]

Very much appreciate everyone's input to this and I having been giving it a lot of thought and more research. Have read through the original Steeda post for these items and the ensuing discussion and together with the above comments, I now have a better handle on this.

I think I will do the Steeda correction arms with bumpsteer and look forward to seeing what change in handling I notice. (I note Steeda seem to be the only company doing roll steer correction arms.)

I assume there will be no problem achieving -1.5º or so camber without any other hardware or clearing the strut as I'll be using my OEM PP wheels with standard rubber.

Yeah I think you'll be able to fit no problem. I'm running 19x11 ET24 and 305 wide tires up front and still fit but barely. I would recommend camber plates though for proper alignment adjustment. You want a good alignment before adjusting the bumpsteer/tie rod ends IMO for best result.

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