Need advice on wheels,etc. (Setright, others?)

[1 Lucky Texan]

OK guys, I MAY buy some Kosei or other wheels for my new WRX Wagon (perhaps after the first of the year - no immediately anyway) and it appears the '06 will have 17x7jj 55 offset (I assume hubcentric) I have some questions.

 

The Kosei double racers I covet are 48 offset. is this too much difference?

 

Does increasing the neg camber on the front cause longevity or other detrimental issues (bearing or steering/suspension wear?)

 

Would those issues be worse with a smaller offset wheel? (seems like rubbing would be less likely at the top if the wheel were 'outboard' more - I dunno)

 

What's the jj mean on the wheel spec?

 

Thanx guys

 

Catl

[jamal]

http://forums.nasioc.com/forums/showthread.php?t=335263

 

48mm is a little low, especially for a wagon. But, at the most, you might have to roll the fenders.

[Setright]

Wow Texan, I get mentioned in the topic heading. Thanks

 

To the point: The JJ is the shape of the rim edge where the tyre mounts. Should fit most tyres.

 

The rubbing issue is also dependant on tyre size. Avoid the temptation to go for very wide tyres. Stick with a rim/tyre ratio around 80-90% and you will get the best handling, too.

 

Offhand I would rate a 205mm wide tyre as spot on for a 7 inch rim, but you might have to stretch to 215mm to conserve the right overall diameter, without resorting to high profile tyres. What's the standard size?

 

If you drive like me - stick near the posted limits, but fast around corners - your tyre wear will BENEFIT from a little added negative camber up front. Turn-in will also improve and make the steering feel more responsive.

Be aware that this does change the grip balance and while that may eliminate understeer, it will introduce oversteer. Just how I like it!

 

Not knowing the stock angles, I would guess they are -0.25 front and -1.0 rear. Adjusting the front to -0.5 will give you all that you need, without making the handling dangerous.

 

If you have rubbing issues with the tyres, a little more camber can tilt them inward enough to avoid contact. HOWEVER, this probably means getting new camber bolts for front and rear. If you increase the front to -1.0 you need at least -1.5 on the rear to keep things safe.

 

 

The 48mm offset means the entire wheel will move OUT of the wheel-well by 7mm. I would prefer 50mm, but you'll most likely be fine with 48.

[1 Lucky Texan]

The specs from cars101 are;

 

17x7jj alloy

215/45R17 all season, offset 55 (2.17)

 

I doubt I'll run wider tires, certainly not unless I find other good sources that there wouldn't be rubbing/fitment issues. The stock car will be far beyond my driving abilities anyway!

I plan to add a muffler and adjustable (whiteline) rear bar - likely set for 'mild' initially. Probably add any wheels/new tires in late winter/early spring. I''' be adding window tinting at that time - fairly inportant in Texas - and I'd like the tint to 'match' a gray wheel. The Kosei's are affordable, lighter in weight (anyone know the weight of the stockers on the '06?) expose the new red calipers nicely (bling!) and come in antracite and grey.

I doubt I would change the rear camber but others have noted some nice improvement with more camber up front and MAYBE with the top of the tire in some more would reduce the odds of fender rubbing.

 

Just looking for some experience, most of the above is based on my desires coupled with poor memeory of what I've read. lol!

 

Carl

[Setright]

Ok, sounds like I will have to start getting ready to be very jealous of your ride

 

 

Try the front camber adjustment, BEFORE you fit a stiffer rear sway bar. The difference will amaze you!

 

You might find that more camber and a stiffer sway bar will make the rear end hard to control. It'll feel great on turn-in and when you go round bends you know well, but you risk some serious OH!versteer if you have to brake hard mid-corner due to traffic or other obstructions.

 

I expect that harder end links on the stock sway bars will provide enough stiffness to give accurate handling, without getting it sideways all the time

[1 Lucky Texan]

Ok, sounds like I will have to start getting ready to be very jealous of your ride

 

 

Try the front camber adjustment, BEFORE you fit a stiffer rear sway bar. The difference will amaze you!

 

You might find that more camber and a stiffer sway bar will make the rear end hard to control. It'll feel great on turn-in and when you go round bends you know well, but you risk some serious OH!versteer if you have to brake hard mid-corner due to traffic or other obstructions.

 

I expect that harder end links on the stock sway bars will provide enough stiffness to give accurate handling, without getting it sideways all the time

 

It's easier to install with the muffler- but, I suspect with camber adjustments up front you are correct. I've read elsewhere (spdusa.com) that rear bars can be twitchy and give little warning (compared to lowered/stiffer springs for instance) when you 'exceed the performance envelope' and oversteer.

 

Now I must force my self to listen to the wisdom of others!

 

Carl

[Setright]

.....................

[Setright]

Yep, lowering just gives more camber. All that nonsense about lower center of gravity is...well...nonsense! In fact, lowering a strut suspended car like the Impreza will lower the roll center progressively more than the C-of-G and that would increase body roll. That's why the lowering springs need to be harder. Double wishbone all round would be ideal - like Honda used to do.

 

By the way, a 30mm drop will give around -1.0 degree extra camber and that means massive improvements in cornering grip.

 

(Take note that camber will affect braking in a negative manner, but you need to go further than -3.0 to feel the difference.)

[1 Lucky Texan]

Yep, lowering just gives more camber. All that nonsense about lower center of gravity is...well...nonsense! In fact, lowering a strut suspended car like the Impreza will lower the roll center progressively more than the C-of-G and that would increase body roll. That's why the lowering springs need to be harder. Double wishbone all round would be ideal - like Honda used to do.

 

By the way, a 30mm drop will give around -1.0 degree extra camber and that means massive improvements in cornering grip.

 

(Take note that camber will affect braking in a negative manner, but you need to go further than -3.0 to feel the difference.)

 

If I throw increased rear camber into the mix, how does that affect your feeling on adding a slightly stiffer rear AS bar? That is, stock springs struts etc. Just increased front and rear camber(probably need camber bolts for the rear) keep the stock links but put in the RASB? Still too tail happy? Honestly, if I ever put springs on the car, I really do not want to slam it - 3/4 inch or so would be great. But, initially I wouldn't mind tweaking it the easy/cheap way. Though I think your wisdom about brake/oversteer is good, especially for a daily driver like this car.

 

I always appreciate the insight from the regulars here like yourself. thanx

 

Carl

[Setright]

Yes, perhaps I am a bit of stickler, I don't know

 

 

I am often the only person who tries to tame the modding folk - especially on imprezasport.net - because I feel someone needs to be the voice not only of reason, but also for good handling.

 

I strongly suggest that you fit the lowering springs alone, to begin with. H&R and Whiteline should be good for some inch lowering without being too hard.

You can always tweak the handling with sway bars later.

 

The old Impreza's had bump steer, but the newer models do not, and that adds a potentail for a loose tail.

Bump steer means that the front suspension produces toe-out on compression. This means that if you brake in a turn, the wheel moves "up" into the wheel well and turns slightly outward. This counters the oversteer effect of braking.

It also makes the steering feel slighty slow. That's why the new cars don't have bump steer, to gain a more precise and alert steering feel.

[1 Lucky Texan]

Yes, perhaps I am a bit of stickler, I don't know

 

 

I am often the only person who tries to tame the modding folk - especially on imprezasport.net - because I feel someone needs to be the voice not only of reason, but also for good handling.

 

I strongly suggest that you fit the lowering springs alone, to begin with. H&R and Whiteline should be good for some inch lowering without being too hard.

You can always tweak the handling with sway bars later.

 

The old Impreza's had bump steer, but the newer models do not, and that adds a potentail for a loose tail.

Bump steer means that the front suspension produces toe-out on compression. This means that if you brake in a turn, the wheel moves "up" into the wheel well and turns slightly outward. This counters the oversteer effect of braking.

It also makes the steering feel slighty slow. That's why the new cars don't have bump steer, to gain a more precise and alert steering feel.

 

I have decided to forego the RASB and may begin just with the front camber as you suggested. Cheap, easy to undo or alter. Ansd sensible I feel. A good fit for my intended use for this car - at leats initially.

 

I seem to recal that there is some passive 4 wheel (rear wheel) steering built into these cars to help fight oversteer. I dunno where I saw that.

 

If I get lighter wheels in the winter/early spring, I will wait to see what that feels like before doing any other suspension upgrades. I suspect, IF the stock wheels are 20-22 lbs. (a guess - still no definitive answer) and I can get some wheels in the 15-17 lb range it may have the effect of stiffer springs - not sure.

 

thanx for replying

 

Carl

[Setright]

Lighter wheels will improve the wheel control and relieve the dampers a bit. Ride quality should improve and "float" over long undulations will be reduced.

 

No passive rear steer AFAIK.

[1 Lucky Texan]

JUST replaced the stock B'stone RE92 215/45R17 tires and 17x7 e55(IIRC) alloys

with Kumho EASX 225/45R17 on SSR 17x7.5 e50 alloys.

 

Using the freight scale here at work it appears I also reduced the weight at each corner by approx. 3.5 lbs.

 

I think the Kumhos are a little bigger diameter though - since the aspect ration is the same. Still, not bad - plus the white spokes look good on my white car!

 

No other changes made yet, no apparent rubbing issues this morning in normal drive to work. Slightly more noticeable road noise. Not bad and perhaps will settle down after a few miles.

 

wonder how much my stock wheels and tires are worth?

 

fyi

[Tiny Clark]

Damn, and I just throw gas and oil into the wife's Subie and leave the handling to my Beemer. It's a good thing that she can't tell the diff!!