[dre99gsx]

Looking for some feedback here. I'm noticing many of my corner speeds are slower than some similar E46/E92 M3s on typical 100-200TW tires. So, this last event, I worked my way up to increasing my corner entry speeds to see what happens.

I tried a few techniques on some corners, letting off brakes a bit earlier, a little less trail braking, etc. What I noticed is the faster I come into the turn, the sooner I need to add steering input to help point the car to the apex.

What this does in effect is cause the rear end to want to suddenly kick out around mid corner where I'm holding maintenance throttle. It seems I have more than ample front end grip...

Here is a step by step process of what I am working with:
To catch ya'll up, I'm on Toyo RR 255fr/295rear. My alignement is -3.6/-2.2 camber fr/rear, 0toe/-1/8" toe fr/rear. I'm on HR 25mm front sway at medium stiffness, stock 3.0si rear sway sports (19mm). KW Clubsports on 10k(560lb) fronts/ 700lb rears. I have about 2mm rake.


- I corded my Toyo RR last event, so I have new RRs up front, but 24HC old RRs in the rear. Yes, this is probably the issue, but I read everywhere that RRs can handle over 30HCs with not-to-much degradation. Perhaps everyone is wrong..
- Ignoring the heat cycle difference, I found that I'm wearing a bit of the sidewalls on these tires. I originally was running 26psi Cold ~ 34psi hot. I have since started 30 cold, reaching 40psi hot. I was wiping out sometimes on lap 1-2 on warm up because the too low starting pressures. I learned my lesson.
- At NJMP Thunderbolt Carousel, I can start at 55mph. As I give it slightly more gas (just a hair) to induce understeer, the rear slowly kicks out. I then went to full stiff on the the front ARB, added 2 more psi to front tires, and added 1.5deg more to rear wing. This helped reduce that oversteer to where I can feel it going out and correct it with much more confidence. So, step in the right direction.
- I'm planning to experiment further with an 18mm rear sway from the 3.0i which should help induce more front end push. I'm also considering going to -2.8deg camber in the rear.

So, am I reaching some inherit limit of the Z4 platform vs the E46 with regards to suspension geometry/loading/dynamics? Meaning, no matter what I do, given the weight/balance of this platform, it will be very difficult to extract faster consistent laptimes because it's just the mechanical limitation?

My confidence is just not there knowing that the rear end is unpredictable on mid corner. The strange thing is she grips real well at corner exit with power.