Understeer Solutions? Sway Bars?

[OICU812]

Wouldn't running say -2.2 to -2.5 up front and -1.7 to -2.0 in back clean this up alot? Several guys locally doing Auto X are either -2 all around, or slightly more in front always seems with their BRZ & FR-S.

[Racecomp Engineering]

Originally Posted by OICU812

Wouldn't running say -2.2 to -2.5 up front and -1.7 to -2.0 in back clean this up alot? Several guys locally doing Auto X are either -2 all around, or slightly more in front always seems with their BRZ & FR-S.

yup...

- Andy

[Gopherboy6956]

Ok - Let me try to take in all of the above posts and respond as so that it makes sense:

I do not want to change my springs at all. I'm very happy with the level and being square.

I guess I was unaware that the rear camber was, not ideal.

I would be perfectly willing to go to something like -2.5 front, -2 or -1.5 rear.

What is the advantage of that, though?

The reason I like the rear sway idea, is because of the adjustability. Once i get the car figured out, i'd like to have something simple like that to adjust between the road course and AutoX.

(Keep in mind HPDE is not a fiercely competitive event for me, it's just the fun of it - I am not willing to drive the bleeding edge when there is no incentive except for a timed lap - Don't want to throw 30k into a wall - so i will be less interested in changing the car setup to cater to it)

So, if the three points on a rear sway make a big difference in oversteer/understeer (again, once the car is setup correctly) then that would be awesome.

Unfortunately I didn't bring out my GoPro this weekend - I never do anything with the footage after I get it

Also, if it helps - I plan on running Rivals next year instead of the ZII's

[DylanFRS]

Originally Posted by Gopherboy6956

I do not want to change my springs at all. I'm very happy with the level and being square.

I am confused, you don't like the way the car handles but you are happy with the spring rates you are running?

Originally Posted by Gopherboy6956

I would be perfectly willing to go to something like -2.5 front, -2 or -1.5 rear.

What is the advantage of that, though?

Since the front of the car is a strut setup, you are not getting extra camber on compression. (not much at least) The rear of the car has the multi-link instead which gives you additional camber on compression.

[Gopherboy6956]

Originally Posted by DylanFRS

I am confused, you don't like the way the car handles but you are happy with the spring rates you are running?



Since the front of the car is a strut setup, you are not getting extra camber on compression. (not much at least) The rear of the car has the multi-link instead which gives you additional camber on compression.

I am happy with the firmness and the little amount of body roll in turns with the stiffer springs - that's what i'm referring to.

So having more negative camber in the front while cornering will ________? Keep it from understeering and provide better grip?

[Dezoris]

Fix your alignment issues first before attempting to add something to a setup that may make things more complicated. And difficult to dial in. If you drop your rear camber to 1.5 the car will rotate again. And be more neutral in autox. Go simple first. Rivals are a good tire but grip levels are close to ZII so its not going to change things all that much.

[7thgear]

Originally Posted by Gopherboy6956

I would be perfectly willing to go to something like -2.5 front, -2 or -1.5 rear.

What is the advantage of that, though?

ohh how i wish to be in your shoes...


anyway, there is no "advantage", you are simply adjusting the car's behaviour to fit your desired goal.

Like i said at the very beginning, if you want less understeer you have to either add grip at the front or reduce grip
at the rear.

Increasing front camber from 1.5 to 2.5 in the will give you slightly more grip (in the front) during cornering while reducing the rear camber in the will reduce grip in the rear by a small amount during cornering.

[CSG Mike]

Originally Posted by Gopherboy6956

Ok - Let me try to take in all of the above posts and respond as so that it makes sense:

I do not want to change my springs at all. I'm very happy with the level and being square.

I guess I was unaware that the rear camber was, not ideal.

I would be perfectly willing to go to something like -2.5 front, -2 or -1.5 rear.

What is the advantage of that, though?

The reason I like the rear sway idea, is because of the adjustability. Once i get the car figured out, i'd like to have something simple like that to adjust between the road course and AutoX.

(Keep in mind HPDE is not a fiercely competitive event for me, it's just the fun of it - I am not willing to drive the bleeding edge when there is no incentive except for a timed lap - Don't want to throw 30k into a wall - so i will be less interested in changing the car setup to cater to it)

So, if the three points on a rear sway make a big difference in oversteer/understeer (again, once the car is setup correctly) then that would be awesome.

Unfortunately I didn't bring out my GoPro this weekend - I never do anything with the footage after I get it

Also, if it helps - I plan on running Rivals next year instead of the ZII's

You're increasing grip in the front under cornering, increasing the limit, and thus, giving you less oversteer.

However, the spring rates affect how your suspension loads; you're making the front work a LOT harder with square springs, so they give out faster than the rears, making you understeer. Aligning to give the front more grip is a band aid in this case. The real fix is to add a rear sway (or do both sways, but make the rear stiff in comparison to the front, relative to the stock sway balance), or change springs.

I'm not one to recommend parts that are not necessary. There are plenty of cases where an alignment helps, and this is one of those cases, but it will only "just help", not solve the issue.

[Racecomp Engineering]

Originally Posted by Gopherboy6956

So having more negative camber in the front while cornering will ________? Keep it from understeering and provide better grip?

Yes. It really is that simple.

Originally Posted by CSG Mike

I'm not one to recommend parts that are not necessary. There are plenty of cases where an alignment helps, and this is one of those cases, but it will only "just help", not solve the issue.

There's more than one way to set-up a BRZ/FR-S, with advantages and disadvantages to all of them. For a driver like the OP that values stability on the track and is happy with the level of firmness and body roll he currently has, a proper alignment will do what he wants.

I do agree with the OP that the adjustability of a rear swaybar would be helpful (bump it up a notch for auto-x) but IMO the alignment needs to be taken care of first.

- Andy

[Gopherboy6956]

I think I'll start with Camber, and then go from there. Still interested in getting a rear sway, but i'll change one thing at a time.

I'll be going into garage mode here pretty soon anyways (You know, North Dakota and all) so we'll see how things go next year!

Thanks all!

[Kostamojen]

I'm curious why you were running so much rear camber in the first place?

[Gopherboy6956]

Originally Posted by Kostamojen

I'm curious why you were running so much rear camber in the first place?

Seemed like a good idea at the time... I went from Stock everything to wheels, tires, suspension, alignment in a few days before an event. Didn't have a ton of time to research.

[Draco-REX]

Originally Posted by Gopherboy6956

I would be perfectly willing to go to something like -2.5 front, -2 or -1.5 rear.

What is the advantage of that, though?

As you enter a turn and transfer weight to the outside tires, the body rolls to the outside as well. Because our cars have a Machpherson Strut design for the front suspension, every degree the body rolls translates into a degree of positive camber added to the outside tire PLUS a fraction due to suspension compression. In the rear, you have a similar result, but the rear suspension design gains negative camber under compression, so it isn't a full 1:1.

What's happening in your situation is that you're quickly going positive up front while the rear is staying closer to square with the road. So to counteract this, you need more negative camber up front so you can afford to lose some to body roll. Reducing the rear camber will nudge it further into positive and reduce rear grip slightly, to assist with rotation.

[Draco-REX]

Oh, and as a side note:

Sway bars will reduce body roll which, in turn reduces camber loss. However, by linking the two sides of the suspension more firmly, you're essentially shifting more weight to the outside tire, off of the inside. This can actually reduce the overall available grip. Often this loss of total grip is balanced by a more controlled suspension. But a well set up and more independant suspension will have a greater ultimate grip level and be better behaved over rough surfaces.

This is why I'm not convinced that sways are the answer for this car as opposed to say, a Subaru impreza (rear sway first thing!). Our cars are so well set up from the factory that body roll isn't as big of an issue. So we can take advantage of that fact with smaller sways.

(Granted, I have had some moments of doubt on this stance. There's a set of RCE sways sitting in my garage, still in the box, in case I change my stance on them again..)