Steering Sway

[vimal01997]

Hey guys, pretty new to the Forums, although I did do my research throughout the forum and read similar issues before making this post. Clearly I couldn't find a proper answer. Anyways, I've got a 2015 Performance Pack GT with eibach sway bars, sportline springs, IRS subframe braces and k member brace. Now, there were no issues on any of these parts, I have driven 6k miles on them. This issue happened possibly after getting new tires installed in the rear.

When I go highway speeds, my steering seems like it's tougher to turn. Meaning, when there's a curve, it seems like the car wants to go straight instead of giving me support throughout the turn. It's almost like I have to force it to take the curve because it doesn't want to take it. Also, I don't know if this is related, but I started getting this problem at the same time; When I brake pretty moderately (not too light yet not bashing the pedal), my car pulls to the left when I brake from highway speeds. None of these issues are noticeable at lower speeds like 55mph and below. The car is a lot harder to control whenever steering input is required. I was spiritedly driving and noticed that when I make quick lane changes, the car pulls back on me. For example, say I'm making a quick lane change into the right lane, therefore, I steer right, and my steering pulls me back to the left. It's like the steering is saying "Nope, we're going to go back into the left lane we just came out of", and I have to force correct it. I did get an alignment done after two new rear tires, getting it rechecked in a few days due to this issue. I will post the alignment sheet below. Would this possibly be due to me running Pirelli PZERO Summer tires in front and Continental ExtremeContact DWS all seasons in the rear? (I had all season Pirelli zero in the rear and had no problem).
Really confused on why the car is acting this way. I played with the steering at highway speeds a little, gave it a little kick, and noticed the steering kicks back at me. if I give it a little push to the right, the steering pushes back to the left.



(Btw when balancing one of the rear continental tires, mechanic did mention it was just slightly out of round, not noticeable enough though)

Also, Am I supposed to be aligning my car back to "OE Specs" or the "Eibach Spring specs"?? really confused on this.

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[Jetnoise]

What does eibach say to do?

"Slightly out of round but no enough to notice" well someone noticed....
I'd reject the tire

 

[Guard]

I am no expert but have been on google and researched how Camber, Caster, Toe affect alignment and suspension performance.

One of the potential reasons why its difficult to turn is because your camber is more negative than normal due to the drop. From the alignment sheet, the car will pull LEFT because there is a 0.5 "spread" (degree difference from left to right (2.0-1.5=0.5)) and the right hand side camber is MORE NEGATIVE than left. The car will pull in the direction where camber is less negative camber because the tire with more negative camber will push the opposite direction. Ideally you want camber to be the same on both sides but it is not always the case. The more the difference in camber, the more the pull.
FYI, The negative camber will wear out the front tires fast over time.

The one thing that no one tells you is that CAMBER IS NOT ADJUSTABLE (same goes for caster) on this car. The reason why it is not adjustable is because the POSITION OF THE STRUT is fixed between the vehicle body and spindle. There is no adjustment that allows for the strut to change position on the vehicle body or spindle. The Strut controls both Camber and Caster

To fix that, you'll need either camber bolts or camber plates. Camber bolts are cheap and adjust camber at the spindle. Camber plates are more expensive but it allows you to adjust both camber and caster however you want it at the vehicle body (top of the strut)

The only thing the alignment shop is able to do is adjust the toe, everything else is fixed.

 

[vimal01997]

I am no expert but have been on google and researched how Camber, Caster, Toe affect alignment and suspension performance.

One of the potential reasons why its difficult to turn is because your camber is more negative than normal due to the drop. From the alignment sheet, the car will pull LEFT because there is a 0.5 "spread" (degree difference from left to right (2.0-1.5=0.5)) and the right hand side camber is MORE NEGATIVE than left. The car will pull in the direction where camber is less negative camber because the tire with more negative camber will push the opposite direction. Ideally you want camber to be the same on both sides but it is not always the case. The more the difference in camber, the more the pull.
FYI, The negative camber will wear out the front tires fast over time.

The one thing that no one tells you is that CAMBER IS NOT ADJUSTABLE (same goes for caster) on this car. The reason why it is not adjustable is because the POSITION OF THE STRUT is fixed between the vehicle body and spindle. There is no adjustment that allows for the strut to change position on the vehicle body or spindle. The Strut controls both Camber and Caster

To fix that, you'll need either camber bolts or camber plates. Camber bolts are cheap and adjust camber at the spindle. Camber plates are more expensive but it allows you to adjust both camber and caster however you want it at the vehicle body (top of the strut)

The only thing the alignment shop is able to do is adjust the toe, everything else is fixed.

Thank you for the reply. I did have adjustable camber bolts put into the front, so I do get the fronts aligned. I am going to get the fronts aligned to as close to factory specs as possible. Though on my alignment before this one, I did have just as big of a difference in alignment in the front, and that is probably why it pulls, but it did not sway crazy like this. I literally cannot take curves while accelerating without the car pulling and wanting to sway all over the place. Any details you might know on that? Would that be alignment? Something loose? Or the fact that I'm running continentals all seasons in the rear and Pirelli summers in the front?

 

[Guard]

Thank you for the reply. I did have adjustable camber bolts put into the front, so I do get the fronts aligned. I am going to get the fronts aligned to as close to factory specs as possible. Though on my alignment before this one, I did have just as big of a difference in alignment in the front, and that is probably why it pulls, but it did not sway crazy like this. I literally cannot take curves while accelerating without the car pulling and wanting to sway all over the place. Any details you might know on that? Would that be alignment? Something loose? Or the fact that I'm running continentals all seasons in the rear and Pirelli summers in the front?

I did a google search on the difference between summer and all seasons tires and here's what I found (below). It seems like summer tires have significantly more grip than all seasons.

https://www.bridgestonetire.com/tread-and-trend/drivers-ed/summer-tires-vs-all-season-tires

"All-season tires perform well in warm weather, but they may offer less grip than summer tires, sacrificing some steering, braking, and cornering capabilities. This trade off is necessary for all-season tires to be able to provide acceptable performance in light winter conditions and provide longer tread life."

"Summer tires are ideal for high performance vehicles, and are built for speed and agility. They offer increased responsiveness, cornering, and braking capabilities. This is typically attributed to specialized tread patterns and rubber compounds that allow for improved precision on the road. The tread patterns of summer tires have less grooving and put more rubber in contact with the road. They are designed to provide maximum road-holding grip. The tread compounds of summer tires are designed to remain more flexible, allowing for better traction and grip. Summer tires may have shallower tread depths that allow for more stability when pushed closer to their limits."

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