EVIL_EV0

iTrader: (6)

^ I can tell there is a tad bit more roll with the OEM bar but not enough to make me miss the perrin.

I haven't had the chance to test out the new alignment or friction modifier yet. I'm hoping the alignment will bring the oversteer back in check.

I'm still lost as to spring rates in the rear. I know the magical setup for non-hard-core racers is 10k front and 12k rear but usually those stiffer springs assist with getting more rotation and that is something I no longer am on the hunt for.

I guess my question is .... when setting up the car for performance rather than trying to dial out understeer what spring rates should I go with?

mrfred

iTrader: (50)

That's more rake than stock. I suggest raising the front 1/4" and lowering the rear 1/4". Or if you don't mind some fender gap at the front, raise the front 1/2" and lower the rear 1/4". That will better match the front and rear roll centers and make the front more roll resistant. I'm sure it won't fix the issue, but it should help some.

LetsGetThisDone

iTrader: (1)

Exactly what mrfred said. Car has a lot of rake. Lower the rear 1/4", and raise front 1/2". The front is too low.

DaWorstPlaya

iTrader: (31)

That doesn't sound right. Stock ride height is about 15" Front and 14" Rear, measured from the wheel center. Sounds like you are measuring from the ground to fender lip. Measuring from the wheel center to fender lip removes wheel+tire diameter out of the equation.

So, if you take wheel diameter out of the equation, you are looking at about an 1" rake over stock. I would take Letsgetthisdone's advice and raise the front 1/2" and lower the rear 1/4". Which will give you about a 1/4" rake over stock. But prepare for the car to become more tail happy after that.

kaj

iTrader: (60)

When I went from stock to a 1/2" rake, I noticed a difference. I was able to drive the car back to back to compare. The car pushed a bit less. Definitely something to add into an alignment equation. Then I did the Diff. Then I did a rear sway bar. The car just gets better and better.

mrfred

iTrader: (50)

In concept, raising the front should reduce the front roll moment thereby geometrically stiffening the front suspension in cornering. Lowering the rear will increase the roll moment slightly making it softer in cornering. This should move the car more towards understeer rather than oversteer.

LetsGetThisDone

iTrader: (1)

The multi link rear suspension of our cars has a much more stable roll center than the mac strut front. Lowering the rear will help reduce over steer.

mrfred

iTrader: (50)

I agree, and this is the reason I think raising the front will provide the most benefit. Lowering the rear by 1/4" will have a minor improvement on CG and minor increase in roll moment, but raising the front will have a bigger improvement on roll moment while not substantially affecting CG. It gets back to how these changes affect roll stiffness at the front and rear.

mrfred

iTrader: (50)

I guess I'll reiterate that I think the ride height changes will have a relatively minor corrective effect.

LetsGetThisDone

iTrader: (1)

Combine a bunch of minor changes; ride height, sway bar, alignment, and possibly corner balance and you end up with a decent change.

EVIL_EV0

iTrader: (6)

The rear sway bar... I keep hearing people saying running the stock bar helps increase rear grip. But what does it do to the front grip. You see I'm not seeking oversteer I have plenty of that. But I do want to increase grip any way I can.

I will try the ride height changes but honestly I'm a little nervous about that because I was previously told I want that 1" of rake for additional downforce while doing high speed track days.

LetsGetThisDone

iTrader: (1)

Swayabrs effect the handling balance, whether it adds grip to the front, or takes it from the rear by making it stiffer, it increases oversteer. Make the sway bar softer....whether it takes grip from the front, or adds grip to the rear, you are reducing oversteer.


The rake isn't going to effect downforce much, if at all.

kaj

iTrader: (60)

Who told you this?

kyoo

iTrader: (29)

i've always said, unless you're rule restricted, you first want to do the rear diff & the acd tune, and then design the rest of the setup around that

kaj

iTrader: (60)

I agree about the rear diff. Correcting that to where it should be just makes sense. To tune the car around a "disabled" differential doesn't, to me. I guess you COULD. But I don't much see the point.
If the diff wears out, are they going to stack the next set of plates in the wrong order, too?