Swaybar question regarding classification

[islandmon]

Will an addition of a larger front sway bar and new end links affect classification from F Group on the 08 Subbie STi?

Thanks,
Jim

[AScoda]

No, swaybars are free. Unless they are welded on.

[islandmon]

Drew: Thanks for your help. As you can see in the picture there is significant roll. The STi is the first AWD car I have autocrossed and it has a ton of understeer built in. I think I am going to try a larger (adjustable) front sway bar (and new end links) run that a few times then re-evaluate as to whether I think I also need a larger rear sway bar.

Also, can anyone confirm that an aftermarket catback exhaust is allowable in production classes?

Thanks,
Jim

[Native]

Yes, exhaust is a free-bie, just like the sways - do whatever you want and stay stock.

Are you sure you want a larger front bar? If you just do the front, you'll make your understeer worse...If anything, get a bigger, adjustable rear bar and stiffer endlinks

[Jamie]

Yes, exhaust is a free-bie, just like the sways - do whatever you want and stay stock.

Are you sure you want a larger front bar? If you just do the front, you'll make your understeer worse...If anything, get a bigger, adjustable rear bar and stiffer endlinks

He might -- on many strut-suspension cars, better front-end camber control (by reducing body roll) outweighs the adverse effects of greater roll stiffness on that end.

Jim -- from the FAST website, here are the restrictions on suspension modifications. Pretty basic:

Welded chassis reinforcement, including welded roll bars/cages
Alternate or altered springs
Altered suspension geometry (relocated pickup points, alternate suspension parts to increase factory alignment adjustment range such as camber kits, camber plates, or slotted strut mounts)

Keep in mind that our "production" rules are pretty liberal -- most other clubs are more restrictive.

[Native]

He might -- on many strut-suspension cars, better front-end camber control (by reducing body roll) outweighs the adverse effects of greater roll stiffness on that end.

Understood. Just spitting back some old-school (2004) WRX suspension tuning. The stock floppy rubber end links and skinny rear bar made for lots of understeer. Add the stock alignment and it was even worse. And from what I've read, newer models have gotten even softer, per Jim's pic above... 8)

Regardless, maybe he ought check out nasioc.com and see what the guys with the newer models are doing.

[Jamie]

Just spitting back some old-school (2004) WRX suspension tuning. The stock floppy rubber end links and skinny rear bar made for lots of understeer. Add the stock alignment and it was even worse.

That's right...I forgot you had a Scooby your daughter maintains for you.

[Loren]

Body roll is not in and of itself a bad thing. (some of the best handling autocross cars on the planet have LOTS of body roll... watch a stock Miata or Lotus Elise)

What's important is balance. If your car has too much understeer (typical of FWD and AWD cars), fitting a larger rear bar will improve the balance and reduce the understeer.

Alignment is also a huge factor. If you're understeering, see if you can add more negative camber to the front.

And then there's tires and driver input. You need grippy tires to prevent understeer on a FWD/AWD car. And if you have mondo power, you need to have smooth throttle inputs.

Body roll is NOT your problem. You can "fix" body roll if you want, but it's not going to make the car any faster around an autocross course without addressing the other issues mentioned above.

[WAFlowers]

Body roll is NOT your problem. You can "fix" body roll if you want, but it's not going to make the car any faster around an autocross course without addressing the other issues mentioned above.

Says our resident suspension guru! (Listen to the man.)

[shakedown067]

Body roll is not in and of itself a bad thing. (some of the best handling autocross cars on the planet have LOTS of body roll... watch a stock Miata or Lotus Elise)

Just look at Steven's car for that example. That puppy has got TONS of body roll.

[Native]

lol - look at that body roll! And I'm barely turning Let's hear it for bumpstops!

[Jamie]

Body roll is not in and of itself a bad thing. (some of the best handling autocross cars on the planet have LOTS of body roll... watch a stock Miata or Lotus Elise)

True if suspension maintains wheel camber well. That's the issue with many strut-suspended cars and body roll -- ask any water-cooled VW driver. Context....

[Loren]

Body roll is not in and of itself a bad thing. (some of the best handling autocross cars on the planet have LOTS of body roll... watch a stock Miata or Lotus Elise)

True if suspension maintains wheel camber well. That's the issue with many strut-suspended cars and body roll -- ask any water-cooled VW driver. Context....

But, then... body roll isn't the real problem. The real problem is poor suspension design. 8)

More negative camber (sufficient to make up for the camber gain inherent in that suspension design) would be a better solution than trying to eliminate all body roll.

[Alizarin]

re-evaluate as to whether I think I also need a larger rear sway bar.

Yes, but not as big as you would for a sedan. You've got some extra weight back there that a sedan doesn't have.

I am not 100% up to date on the new suspension geometry they put in the rear of the new hatch models but your front setup is pretty close to mine. You'll lose camber as the body rolls, so having a larger front bar helps offset that camber loss. Having a larger rear bar with a larger front bar will help keep the balance of the car.

[islandmon]

Thanks for all the great feedback. As with most things, there seems to several different schools of thought regarding suspension set-up for autocross with GR series STi's (2008+). I have had a lot of discussions on the main Subbie forums (I like IWSTI) and the Subaru performance forum.

I had the alignment tweaked about as far as the stock suspension will let me go on negative camber: -1.3 on the left front, -1.5 on the right front, -1.3 on both rears. 6.5 degree caster in front 7 rear, 0 toe.

The last event was the first time I have run the car on the new Star Specs. Liz had run them once the previous Brooksville event. I really like these tires and this alignment. The Hoosier R6's we ran in May were too much of a change to match our driving skills.
So I think we are good running the Star Specs and I think we will improve the understeer with new front end links and a larger front bar. I can always add a larger rear too.