Stiffer Springs = Oversteer
 

I up graded my suspension (2nd phase) with springs at 700f/900r on KW V3 coil overs, along with GT3 RS LCAs, and Tarret camber plates.

Went to the track and got alot of oversteer (PSM kicking on way too soon) on this current setup.

Afterwards the rear H&R 24mm solid sway bar was replaced with an OEM hollow GT3 4 way (20.8mm) adjustable to full soft, and the front H&R solid 25mm bar was adjusted to full stiff.

The car does not have as much oversteer as before after some "testing" last night. But still need to dial out more oversteer.

I figure going to a bigger bar up front (OEM hollow GT3 5 way 26.7mm diameter) full stiff would work.

The KWs are set 75-80% on bump and rebound

Anything else I may be overlooking?

TIA

I would normally suggest softening up the bump a bit in order to give the rear time to settle as the power goes down, however I'm puzzled by the comment "PSM comes on way too soon". If you really want to isolate it I would suggest turning off the PSM and feel what the rear is doing. I would want to make sure it's not something else that's making the PSM squirrely on you.
Not often our cars get accused of oversteer.

Had the track club "hot shoe" give my car shakedown, and he was barely able to run 1 second faster with the PSM "off" as with me with the PSM "on".

Before it took a bit to get the PSM to kick in. Now it is coming on going thru a mundane curve or corner .

You can't turn off PSM with the dash button. You just numb it down a bit. Disconnect the connector to the PSM pump to take it totally out of the loop so you have a blank slate to work with. PSM sux for track work and if you are a decent driver then get rid of it. The set up I runfor comparison is:

No PSM, ABS only
JRZ RS coilovers with 600F/800R rates
Front camber -2.3
Rear camber -2.0
Front sway: stock
Rear sway: H&R set on middle
RWD w/Guard LSD
235/40/18 and 315/30/18 Nitto NT01
15mm rake front to rear

Car is very neutral on corner entry and midturn but oversteer can very easily be induced on corner entry with trail braking or in the turn with power due to the LSD. Good luck.

pwdrhound I agree. But need the "nannies" on just in case not to hit a guard rail, etc. during this phase. No safe run-off on the freeway ramps and transitions.

I disconnected the rear sway bar tonight and still got a little oversteer. The R888s at freeway speed do not get the tires real grippy.

A track day is coming up this Friday. Maybe take the day off to do some proper testing.

Going to triple check all the rebound and bump settings tomorrow. Could be I have one side set soft and the other firmer.

Are the front and rear tires the same model and age?

Whar air pressure are you running?

Are you running that same brake pad compound front and rear?

Is the car loose on corner entry, mid corner or corner exit?

I would definitely get your aligment checked if you haven't.

Later, Steve

Tires same type and age (within a few months).

39f/44r PSI

RS19 f / RS14 r

Loose between mid corner and corner exit. Remember I am doing this on public roads/freeways.

My alignment was done after the suspension upgrade.

What pressure rise are you getting in the tires at the track? Your front pressure seems really high, but dropping front air pressure is going to give you more front grip (which you don't need right now).

Since your not getting oversteer at corner entry, I doubt your brake pads are the issue.

Is the biggest issue when you start trying to put power down on corner exit?

I would definitely get your alignment checked. Nothing in your setup, even with the H&R bar seems like it would cause excessive oversteer.

Later, Steve

Steve,

The oversteer started when I went tracking right after I got my second round of suspension upgrades. Had the front sway bar set to full stiff and the rear to full soft after my first session, due to the oversteer. Even the club hot shoe said the car was really twitchy after driving for a full session with the bars adjusted. He suggested I disconnect the rear bar to see what happens, which I did not do until last night, then drove around town. Same issue, but not as bad as before.

At the track I run the fronts at 32-34psi hot and the rears 34-36psi hot.

The oversteer/twitchiness occurs when going around a curve exiting or entering a freeway at a mildly spirited pace.

Going to check the springs if by chance are the wrong ones (too soft/stiff) were installed.

Bringing the car tomorrow to a shop to double check the alignment.

Thank you for your input.

Let us know what you find. My guess is there is a toe issue in the rear.

Later, Steve

What toe and camber settings are you using for the front and rear?

What are your toe settings for the front and rear?

are you running r888 in the back? 36 psi is at max for r888 44 is way over inflated

What toe in the rear ?

44psi for the street, track 34-36psi hot