Civic caster kit cause bumpsteer?

[shaundrake]

Does whitelines caster kit for the EG Civic cause bumpsteer?

I have found that moving the upper balljoint to increase caster causes bumpsteer. Whitelines kit for the EG Civic spaces out the two pieces of the lower control arm. Does this cause the tie rod not to be perpendicular to the knuckle? If so, that would cause bumpsteer.

[shaundrake]

Well... put it this way. It's highly likely that the Whiteline caster kit for EG Civics causes bumpsteer, which means that they are actually detrimental to handling. I have proof that the 96+ Civic caster kits (the kit that moves the upper balljoint back) causes bumpsteer. I suspect that the kit for 92-95 Civics (the kit that spaces out the two pieces of the lower control arms) also causes bumpsteer. When the weather improves, I will take toe measurements under bump and rebound. If bumpsteer is present (it's not on stock Civics) I'll be throwing this kit in the recycle.

[Wayne]

Hello,

I just need to ask you a couple of questions in regards to the comments that you have posted, in regards to give any type of answers.
I have found that moving the upper balljoint to increase caster causes bumpsteer
Did you measure the bumpsteer before and after carrying out the caster changes, or just afterwards ?
Whitelines kit for the EG Civic spaces out the two pieces of the lower control arm. Does this cause the tie rod not to be perpendicular to the knuckle?
The Tie rods aren't perpendicular to the knuckle in standard form.
If bumpsteer is present (it's not on stock Civics)
Have you measured the bumpsteer on a standard Civic ? I ask this as we have got measurements here for an EK model Civic for the front end, and over a range of 60mm of suspension travel (30mm compression through to 30mm raised) from ride height the vehicle had 4mm of toe change, which is quite an amount of change.

I look forward to hearing from you.

Regards
Wayne
wayne@whiteline.com.au

[shaundrake]

Wayne, thank you for the reply. I've read that if the tie rods are not perfectly parallel to the control arms at all extremes of suspension travel, there will be a change in toe angle, thus bump steer. When you move the upper ball joint rearward, the tie rod gets swung down and to the rear thus putting the tie rod out of alignment causing bumpsteer.

As for measuring bumpsteer on a stock Civic; instead of "stock" I should have said it was measured with and without a caster kit. The caster kit was an upper ball joint style kit, this particular kit was not a Whiteline product, however it is the same method that Whiteline uses on later generation Civics. The test was done on an EG, lowered 2 inches with the toe set to zero, with toe measured at 1 inch and 2 inch bump and 1 inch rebound. Toe was measured within the limit of what you would expect to see in actual race conditions.

1" bump showed negligible toe change
2" bump showed negligible toe change
1" droop showed a toe change of ~-.1"

with caster increased 3 inches by moving the upper ball joint back

1" bump showed a toe change of ~.13"
2" bump showed a toe change of ~.25"
1" droop showwed a toe change of ~-.20"

The dynamic camber gain from increased caster at the steering angles you would expect to see in the tightest corner is only about .1 degree. Even assuming the camber gain was significant it would be so closely tied to steering angle that the car wouldn't have enough camber in high speed corners and enough or too much in slow corners. Caster is useful for stability and steering feedback improvement only. If you need more camber, increase roll stiffness or lower the car more to increase static camber, don't increase caster. Caster is useful for improved steering feedback and stability. (solo-x, Honda Tech)

So the question is: does spacing out the LCA's cause enough bumpsteer to negate the benefit of an increase in caster?

[Wayne]

Hello,

To answer your question, it is something that I do not have measurements of in order to work off, so I would have to say that I am unable to give you a definate answer as we have not carried out this particular measurement on the EG Civic to compare both before and after measurements.

Back to your previous message,
I've read that if the tie rods are not perfectly parallel to the control arms at all extremes of suspension travel, there will be a change in toe angle, thus bump steer This is correct but seldom seen on any vehicle, as most production engineers design bump steer into the vehicle suspension in order to achieve under-steer, thus making the vehicle "safer". Therefore if you were to check the bumpsteer of any vehicle, you will find that it has bumpsteer.with caster increased 3 inches by moving the upper ball joint back How do you measure Caster ? It is generally measured in Degree's, not inches.
Our caster camber kit that adjusts the top arm has an adjustment range of +/- 0.66 degree, barely enough to cause the changes that you are quoting. You have claimed that you have increase the caster by 3 inches at the top control arm, can you please explain how you have managed to do this ?

Cheers.
Wayne
wayne@whiteline.com.au

[shaundrake]

"inches" was a typing error. I meant "degrees". Sorry about the confusion. As I said, the caster method we used on the upper control arms was not a Whiteline product, however it works on the exact same principle as the Whiteline kit, which is to move the upper balljoint back to increase caster.

I hope that Whiteline has not lost interest in the Honda Civic and will continue to develop and test on it.

My goal here is to learn more, whether it means being confirmed or corrected. If I had the choice, I would rather find that the Whiteline LCA caster adjustment kit for the EG Civic does not cause significant bumpsteer compared to stock. However I fear that the upper balljoint style kit may have more cons than benefits.

I have very much enjoyed Whitelines quality of products and customer support, and I have learned much from the tech articles made available on this site. Thank you.

[Wayne]

Hello,

It is very good to hear that you have learned a lot from all of the tech articles posted on this forum, that was exactly what we had intended when developing this forum.

With regards to your questioning about the bump steer, as I stated earlier, we have not carried out the measurements to compare before and after, but theoretically there is no reason why it should negatively effect the baseline bumpsteer & any effects are going to be negligable with the amount that our caster kits offset the adjustment.

Cheers
Wayne
wayne@whiteline.com.au.