Thehm3
Thehm3
5/21/17 9:32 p.m.

OK fellas so I've got a FWD Mac strut car, I've got the stiffest rear ARB possible and I've got he mid range Front ARB (this is actually stock, there's parts bin 2 mm smaller and 3 mm larger)... Now with the combination of these two the front roll has become apparent. There's quite a bit of front roll, car feels really loose at highway speeds. I've not gotten a chance to AutoX the car yet, the best I've gotten is trying to put it through its paces in an open parking lot and at low speeds it seems to roll over quite a bit however the rear rotates around beautifully, it's very easy to place the rear end where you want it with the throttle. So my question is since a big sway bar puts stress on the outside tire, and makes the suspension "less independent", would adding a larger front sway bar to combat the roll give me better front end grip or would it rob front end grip? Would it remedy camber gain? Or will the stock bar yield more overall grip and I should just get used to the roll? This is considering all things are kept constant, we won't bother going into struts/springs here. Thanks guys!

Knurled
Knurled MegaDork
5/21/17 9:36 p.m.

If you're lifting a rear tire, no amount of suspension tweaking to the rear will change handling because you're already at 100% load transfer.

Adding more front stiffness will reduce understeer because of better contact patches, up to the point where the back tires are both back on the ground again.

Knowing which chassis it is would be helpful, as generalizations can be overruled by a car's specific quirks.

GameboyRMH
GameboyRMH MegaDork
5/22/17 9:45 a.m.

^This, sounds like you need more front bar.

trucke
trucke SuperDork
5/22/17 10:19 a.m.

Sounds like adding a larger front bar will negate the effect of the larger rear bar.

Sounds like you a re running in a street class, so you cannot change both. Get out and autocross it and see how much fun you're going to have before changing anything else!

Thehm3
Thehm3 New Reader
5/22/17 11:31 a.m.

In reply to Knurled:

I've not witnessed my inside rear tire lifting, but also like I said I've not pushed the car yet and I can't test it until well I compete (also don't care what class I'm in, I'm just there for fun and getting the most out of my car). But the question is what will provide more overall grip up front? The droop from the loose suspension or keeping the car flatter but I'm scared the larger front bar will stress the outside tire, the amount of rotation the car has right now is perfect, more grip up front would be even better!

Thehm3
Thehm3 New Reader
5/22/17 12:16 p.m.

Also guys like I said ever since the stiffer rear springs and stiffened rear bar went in the front tends to roll faster... The weight seems like it transfers faster and feels like the car is rolling over with less steering effort, yet the only modification up front are the stiffened lowering springs and matched struts. Anyone want to explain to me the physics of that?

trucke
trucke SuperDork
5/22/17 2:23 p.m.

It sounds like you are pretty new to autocross. Get some seat time and leave the car alone. That will make you a better driver and a faster driver in the long run.

Spend less time fretting over small changes to your car.

iceracer
iceracer UltimaDork
5/22/17 2:31 p.m.

Did you add stiffened lowering springs to the rear also ?

WildScotsRacing
WildScotsRacing Dork
5/22/17 2:40 p.m.

^^^What he said! The most effective mod you can make to any car is your driving skill. When you are new to performance driving, I can assure you that your car is currently orders of magnitude faster that your ability to drive it as fast as it is capble of. If you would like an eye-popping demonstration of this, at your first event ask one of the fastest drivers there to drive your car on a couple of runs while you sit right seat. Afterword, ask him what he thinks of the current setup/balance. You might be surprised at an experience driver's thoughts on your car as it sits.

Knurled
Knurled MegaDork
5/22/17 4:34 p.m.

In reply to Thehm3:

Lowering the front made the roll center lower, so even though the suspension is stiffer with the springs, it wants to roll more because the car's center of gravity has more leverage against the suspension's center of roll.

Thehm3
Thehm3 New Reader
5/22/17 4:34 p.m.

In reply to iceracer:

Rear is stiffened (about 2.1x the stock spring rate) however did not get lower, front is stiffened (about 1.5x the stock rate) and did get a tad bit lower about an inch or so

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