Hi - I have spent a week searching on here and found some very good posts regarding what setups people are running for track-only cars, but I'm still uncertain on which way to move forward with mine. I will try to outline the car in brief first - this is track-only, not street driven...
Car - E36 Sedan, ~1150kg/2500lbs
Engine/Transmission - 3.0L 290-300hp/270lbft, ZF S5D-310Z 5 Speed, 188mm Kaaz 1.5 Way LSD (3.64 Ratio)
Suspension - HSD Monopro Coilovers, 10kg/mm Linear Front Springs (560#), 10kg/mm Progressive Rear Springs (560#). Camber/Castor Adjustable Top Mounts. Approx 70-80mm Droop F+R. Hardly any preload on the front springs (Both Adjustable On HSD)
Bushes - Completely Polybushed Front + Rear, M3 Trailing Arms, M3 Front Hubs, E30 Front Wishbones, Solid Mounted Rear Subframe, Camber Adjustable Rear Arms
Sway Bars - 25mm Front (To Wishbone), 15mm Rear - Both OEM BMW
Wheels - 17x9 Square
Tyres - 255/40 Semi-Slick
Alignment - Front: -3.5 Camber, 0 Toe -- Rear: -3 Camber, 30min Toe In (Total)
The car drives well, but feels soft, and lacks the turn in it used to have. This seemed to change when I moved to a square setup with the wheels. It also seems to roll to much. Balance at speed feels OK, its easy to control on oversteer, when it happens.
I understand the rear spring rate is less at the wheel, due to where the spring is located - I'm unsure whether to change to a linear rear spring (and increase the rate), or to change to aftermarket sway bars, or both?
Any suggestions welcome.
Stiffer front sway bar and stiffer, linear rear springs should solve all of that. I ran a 32mm hollow front sway bar and 12k rear springs, on slightly less tire (245 RE71R), and would never describe my car as soft on the track. I don't think you need as much rear camber, and I would dial out the toe-in to make it turn in better.
Turn in response also highly dependent on tires. What exactly are you running?
PCA HPDE Instructor
current:
2004 M3 convert 6sp man - low mileage beauty!
past:
1995 BMW M3 3.2
2004 M3 convert SMG
2003 BMW 540i6 Alpine White M sport (I want her back!)
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