JETPILOT

iTrader: (51)

The tires I want to run are 245/35/19 Front and 295/3019 Rear.

This is a 50mm difference. The OE width difference is 20mm. So it is 30mm more than OE. I imagine it will induce considerably more underseer than what was built into the car in the first place.

Can I alter the oversteer to neutral with a set of adjustable swaybars?

I imagine I will have to stiffen up the rear settings while softening the front settings. Will there be enough adjustment in the sway bars to correct the understeer?

JET

palepony

iTrader: (8)

JET

are you still running the D2 coilovers? with their understeer bias in their spring rates?

both the tires and the spring rates may be hard to overcome.

think of the tires/spring rates as the basis for your car's behaviour and use the sways to tweak, not the other way around.

good luck though and be sure to post back your results

pp

JETPILOT

iTrader: (51)

Yes I am still running the D2's with the 15K/13K spring rates. Would dropping to an 13K in the front help much?

JET

palepony

iTrader: (8)

it would certainly help of course.

what type of driving you do? drag, road course/auto-x, of course street?

reason i ask is, why the 245/295 combo? with your power you could step up to 265 in the front.

pp

JETPILOT

iTrader: (51)

I track the car.... Sebring, and soon Road Atlanta. The tires I want are only offered in that size. Pirelli P-Zeo Corsa System. 295 in the back is the widest I want to go on a 10" rim. So that leaves me with trying to make the front work. I would go with a 275/30/19, but they don't offer it.

JET

palepony

iTrader: (8)

since you have already purchased your coilovers and not your tires, i would do the following in this order.

1. change your tire size choice
2. then assess your handling
3. try and tweak with sway bars
4. then assess your handling
4. if not achieving your goal, change spring rates
5. then assess your handling
6. tweak with sways

can further tweak with tire pressures/alignment

pp

JETPILOT

iTrader: (51)

Thanks....

JET

Q45tech

Normally one matches the spring rate RATIO [the real wheel ratio after correcting for mount offsets and angles] to the front - rear weight ratio.

Then you fine tune the desired steering wheel under, neutral, oversteer with sway bars.

Gary King

iTrader: (19)

I run Conti Sport Contact 2's 255/35/19 front & 295/30/19 rear combo and TCS and ABS are fine. Eibach Sways set at Medium Front & Rear. Car handles great, will push in tight corners though. 245/35/19 seems small with a 295/30/19.

Sisith

iTrader: (13)

I run 245/35/19 and 275/35/19's. I had really bad understeer until I got my hotchkis sways put on. I set them to full stiff front and full soft rear and it really helped this weekend at a driver training course. I could really feel the front grabbing now and was able to use the gas to overcome the understeer. It shaved seconds off my times...definately worth getting sways

palepony

iTrader: (8)

Q45tech - the principle you describe is sound. however, that is just the starting point to which you can work from. taking into account all the other factors, you may change that starting point. interestingly, different manufacturers have chosen very different spring ratios front/rear (some favouring front bias, others rear). that being said, the OP already has his coilovers, so he will have to work from that.

Q45, curious have you calculated the real wheel ratio? i would be very interested in your results. i believe someone had calculated it before on this board but i have misplaced the post.

sisith - your comment makes little sense towards achieving a neutral handling car, as setting your sways bars as you describe would induce even more understeer behaviour. perhaps a typo?

pp

Sisith

iTrader: (13)

No its not a typo. I agree that stiffer front sways should induce MORE understeer but in my case it reduced body roll allowing my front tires to keep proper contact on the road. I will soon be moving to 275 tires all around which should make my car even more nuetral and have better turn in characteristics

DavesZ#3

iTrader: (26)

Search the AutoX/Road forum for "swaybar" and you'll find a bunch of posts on this. Counter to what you would normally see, the Z understeers less with a stiffer front sway. Most people are using the stiffest on the 3way Hotchkis or second stiffest on the new 4way Hotchkis.

Q45tech

"the Z understeers less with a stiffer front sway".

How many less degrees of understeer vs steering wheel angle vs tire slip angle at what G load? Are you speaking of power on or steady state?

palepony

iTrader: (8)

please continue discussion, interesting reads here

thanks dave, i had read that before, and read it again. certaintly, it makes sense that a stiffer sway up front would maintain front camber and improve front end grip. however, it seems that those users are mostly auto x-er's bounded by rules that do not allow running a stiffer rear. i drive roadcourse at higher speeds and would be worried about entry understeer.

what caught my eye in sisith's post was that not only did he run a stiffer front, but is running full soft in the rear. sisith, what springs/dampers do you run?

i admit my experience with sways is limited to other vehicles, cause my sways for the Z haven't arrived yet (andy?). so, the more data the better.

thanks and appreciated

pp