How to screw up your cars handling and ride - step by step!

[boredom.is.me]

@gramicci101 Your explanation is completely backwards. A 25mm spacer will change a +48 to a +23. A plus offset means that your mounting face is to the outside of the wheels center line. The higher the offset, the more the wheel will be sucked in.

The Mach V Awesome, 17x9+42, is 228.6 mm wide, with the center at 114.3. The +42 offset places the hub surface at 42 mm in from the outside edge, or 72.3 mm away from the centerline.

The mounting face will be 42mm from the center line. Offset has absolutely nothing to do with the wheel width. Backspacing depends on width.

[gramicci101]

Originally Posted by SomeoneWhoIsntMe

Alright, now I see what you're doing. You think offset is the width minus the backspacing in metric. Frontspacing, I guess. Offset is the offset from the mounting pad to the centerline of the wheel. That's why they call it offset.

Apparently I had backspacing and offset swapped.

[boredom.is.me]

Now if you don't mind, may you please edit the other two posts? It would suck if someone else came along not knowing and didn't look further than your posts.

No offense intended.

[Racecomp Engineering]

I think I should do a "What can I gain from modifying my suspension?" thread too since there's 3 topics on the page right now of worrying that doing anything at all will ruin the car.

- Andy

[Turkish]

Originally Posted by Racecomp Engineering

I know that sometimes there are extenuating circumstances like budget, timing, significant others, looks, class rules, etc.

Please don't take the list as an insult or a shaming thing. These things happen to all of us. Sometimes when you do one mod it means you really should do another and there's some overlap there.

The point is to do your research and plan carefully. And be honest with your goals, budget, and timeline.

- Andy

The part that sucks about budgets and planning mods is that period between mods that should complement each other, but due to budget constraints they have to be separated. That is me currently with my suspension, still paying off the shocks and springs I installed a few months ago, then saving up for the alignment goodies to finally dial in the setup. Glad to see this post and I have tried really hard to not do mods that are a step back away from the end goal. As has been mentioned before, the CSG and RCE guys are invaluable to this forum and people like me rely on honest, no agenda help from experts. Thanks!

[Rampage]

The OP is worthy of a place in the Good Automotive Sense Hall of Fame. Some of the discussions following it.....not so much.

If you are just cruising the streets of LA, Jersey, Florida, Chicago or any other metropolitan area then by all means go ahead and use staggered wheels, huge rubber, low offset, high camber, big drop, etc. You will be fine in the stop light gran prix and a hit at the local cruise ins. But, do not take the car up into the hills and canyons and drive it hard on twisty roads or you will end up starting one of those "I crashed my FR-S/BRZ but it is not my fault" threads.

To RCE: Sage advice and very admirable for a aftermarket supplier. Thank you for a great post. It is too bad that so many will ignore the wisdom in it.

[litemup]

Originally Posted by Racecomp Engineering

I think I should do a "What can I gain from modifying my suspension?" thread too since there's 3 topics on the page right now of worrying that doing anything at all will ruin the car.

- Andy

Bottom line - people will do what they want and, except for the most coldly rational, will be biased toward the advice that supports their goals.

It's boring to do the math. It's a buzzkill to painstakingly create and follow a test plan with enough emotional detachment to gather relevant data. Especially when the results confirm what few want to accept which is, especially for this platform, it's really really tough to "improve" on the design agreed upon by dedicated professionals after years of R&D.

IMHO, doing anything to change the geometry/dynamics of this vehicle before first really understanding it, is a crying shame. This thing is a gem.

Edit: Except for the part where they left out the oil pressure gauge. WTF?

[Racecomp Engineering]

Originally Posted by jdmblood

in terms of spring rates for coilovers. i hear everyone throw out numbers followed by a k like 6k, 7k etc etc. with a 2 inch drop, what would be the reccomended spring rate to run on a coilover setup? does it become stiffer the higher the number goes or lower?

Generally you want stiffer springs with a lower drop, but it can depend on a few things (tire choice, how you're using the car, how much travel you have, etc).

6k is short for 6 kg/mm, or 6 kg to compress the spring 1 mm. So a higher number means stiffer.

- Andy

[Efferalgan]

What do you guys think about a staggered setup for a HKS-supercharged GT86 (>250 whp) for 95% street use with Ohlins R&T (<1'' drop) + Whiteline sway bars (20/16mm front/rear):

Front: Advan GT 18x8 ET45 with 225/40 Dunlop Sport Maxx RT
Rear: Advan GT 18x9 ET52 with 255/35 ?

Fine/good or bad/stupid?

[7thgear]

Originally Posted by Efferalgan

What do you guys think about XYZ for for 95% street

given the above... do whatever you want


although, given Moscow roads, I don't think you want wide wheels/tires or a drop...

[hyper4mance]

I was trying to find some good suggestions for alignment specs, but it seems more difficult than expected. My current setup is RCE yellow springs, whiteline camber bolts, and the rest on stock suspension.

I do have 3 sets of wheels which must all work:
1) WRX (summer DD) - 17x8 +53 - 235/40/17 SP Sport 01 (I have 20mm spacers for these)
2) Weds tc105 (autox/trackdays) - 17x8 +42; 245/40/17 RS3 V2
3) stock brz (winters) - 17x7 +48, 215/55/17 X-Ice 3 [not as important, just needs to avoid rubbing]

With stock suspension and the camber bolts my last alignment was:
FRONT: -1.6 camber, 5.8 caster, 0 toe
REAR: -1 camber, 0 toe

The front's I'll try and get as much negative camber as possible, but should I leave the toe at 0?

Also for the rears what is a good setup for camber and toe? I was thinking a modest -1 camber and unsure how much to toe in. I'm open to suggestions

[wparsons]

You'll be tight with the +42 and 245's up front at -1.6, I doubt you'll get any more camber without rubbing unless you run camber plates.

I have 17x8 +45's with 225/45/17's and -2* up front with almost no clearance. Enough that it doesn't rub, but not enough to run any more camber without going to camber plates.

[Racecomp Engineering]

Originally Posted by hyper4mance

I was trying to find some good suggestions for alignment specs, but it seems more difficult than expected. My current setup is RCE yellow springs, whiteline camber bolts, and the rest on stock suspension.

I do have 3 sets of wheels which must all work:
1) WRX (summer DD) - 17x8 +53 - 235/40/17 SP Sport 01 (I have 20mm spacers for these)
2) Weds tc105 (autox/trackdays) - 17x8 +42; 245/40/17 RS3 V2
3) stock brz (winters) - 17x7 +48, 215/55/17 X-Ice 3 [not as important, just needs to avoid rubbing]

With stock suspension and the camber bolts my last alignment was:
FRONT: -1.6 camber, 5.8 caster, 0 toe
REAR: -1 camber, 0 toe

The front's I'll try and get as much negative camber as possible, but should I leave the toe at 0?

Also for the rears what is a good setup for camber and toe? I was thinking a modest -1 camber and unsure how much to toe in. I'm open to suggestions

For the front, get as much negative as you can with the bolts without rubbing. 0 toe is good.

For the rear...do you have camber adjustment? I suppose you do if you have -1 degrees camber in the back. I'd be happier with -1.5 or even a little more depending on how much you get up front. 0 toe or just a tiny bit of toe in.

- Andy

[hyper4mance]

Originally Posted by Racecomp Engineering

For the front, get as much negative as you can with the bolts without rubbing. 0 toe is good.

For the rear...do you have camber adjustment? I suppose you do if you have -1 degrees camber in the back. I'd be happier with -1.5 or even a little more depending on how much you get up front. 0 toe or just a tiny bit of toe in.

- Andy

Ah maybe I got confused. All i remember was there was something u can adjust on stocks for the rears, maybe that was only toe. In that case, 0 camber rear...lol

Thanks for both of your replies!