Wheel spacers cause increase in body roll?

[240shorty]

I just received and installed a pair of Kics Project wheel spacers on the rear of my s14. (Rear only, no fronts) Took it for a test drive following and did some slalom at around 55-65 mph. Now prior to this, my car (which is lowered 2") has exhibited very little body roll during similar manuevers. But after installing the spacers, there is noticable body roll when slaloming at this speed. Does this make sense? The spacers are 25mm which is approximately 1".

You would think that the 2" wider base would give more stability in cornering due to lower effective center of gravity, or moving it more toward the center of the car. But perhaps, just perhaps, moving the rear wheels further from the rear shocks makes them less effective at dampening. Or maybe the difference in wheelbase from front to rear is a factor as well.

I know alot of people are running wheel spacers, so I am curious to see if others have noticed a similar effect, especially when running them in the rear only. It shouldn't be much different than running a lower offset, wider wheel; except that there is a little less tire width in contact with the road surface. Let me know what you think.

I guess there is a small chance that I am just imagining the difference, but I don't think so. I was pretty impressed before by the lack of roll, but now it is only average.

[Yoshi]

from a leverage standpoint, what you say makes sense... longer arms = more leverage at the fulcrum point, but I wouldn't think 2" would make that big a difference, especially 2" cumulative.

I have kicks 20mm spacers up front to comp for my staggered setup... perhaps my 1.5"/wheel wider stance in the rear +20mm wider up front offsets the slight change in geometry, but when I got my new rims in back (17x9) and spacers up front, my handling abilities went WAY up. I was shocked at how much better I could corner... and like you, maybe it was in my head, but it sure seemed like I had LESS roll.... so I dunno what to tell ya m8 :/

[OptionZero]

could it simply be that you have wider track in back, therefore more stiffness in back...shifting the balance of the car front /rear during transitions? I dont even know if that made sense, i just took a stab

theoretically you would be helping side to side weight transfer, but since you only did the back, that upset that front/rear weight transfer dynamics as well, and that may have caused the "roll" you felt

[MakotoS13]

your wheelbase used to be parallel (or whatever stock is) and now the rear sticks out more. you've just upsetted your suspensin geometry in respect to how weight is distributed in a turn.

i would think that the car would pitch forward and to the front corners but thats it.

[SoSideways]

I know what you're talking about.

I have stock S13 SE wheels in the front with 195/60/15 ES100s, and I had just recently installed a pair of Enkei 92 Mesh in 15x7 0 offset, with 205/50/15 Hankook HRII H405 tires in the rear.

Now when I corner, I feel more body roll, but the grip level is definitely higher. I just contributed to the fact that since I moved the wheels outward via lower offsets, that I had added more leverage on the outside of the fulcrum, thus lessening the spring rate/damping from my suspension.

However, I doubt I am correct, seeing as I am still pretty new to suspension set ups and dynamics and such, but that's why I'm here, is to learn about that stuff :)

[crzycav86]

yeah, basically you increased the grip by lowering the weight transfer. the increased grip will make your body roll more because you have a higher frictional force.

[Var]

I was under the impression that a wider track will decrease body roll and have less weight transfer.

[OptionZero]

yup,...but its mainly that he only did one end of the car i suspect.

[TurDz]

Since most dynamics is heavily influenced by relative grip (front to rear, side to side), modifying the rear the way you have may have negatively affected the front end.

All I can say is Var is correct, a wider track creates less weight tranfer, i.e. more equal tire loading.


the increased grip will make your body roll more because you have a higher frictional force.

The statement above is very ambiguous. I think what you are trying to say is, and this is a very plausible explanation, due to the higher grip levels in the rear, you are actually experiencing more roll in rear. This can be analogous to the very apparent increase in body roll when a stock-suspension car is equipped with high grip tires for Auto-X. While roll is significanly increased, overall grip has drastically increased as well.

I am not going to contribute any more guesses as it may lead to more inaccuracies. I hope someone can chime in a give him a correct answer.