I have been struggling with some peculiar handling characteristics on my b13... the rear is unstable on turn-in and I find myself constantly trying to correct to catch the back end from coming around at autocrosses and to a far lesser extent at track days. at the autocross I usually have to run a large delta front/back tire pressure to settle down the rear. 20 psi rear in the rear seems to help, but I feel I am not maximizing my grip with band-aide solution. here is a run down of my setup:
tires:
Avon Tech Ra 205/50/15

springs/shocks:
8610 koni inserts (8610-1436 front, 8610-1437 rear)
front:350# 8inch
rear:250# 7inch
shocks set full soft in rear and slightly turned up front (cant remember the number of turns)

sway bar:
suspension techniques front/rear sway bars
1 3/16" Diameter Front Bar
3/4" Diameter Rear Bar

alignment:
front
-2.5 deg camber
2.6 caster
-0.05 deg toe

rear
-1.6 deg camber
0.0 deg toe


I am getting ready for an upcoming event and I am going to make a change in spring rates and sway bar... I would like to hear peoples opinions on my proposed setup... here it is:
same alignment settings
front 500# 8 inch
rear 350# 8 inch
keep the front bar and remove the rear bar.

My car has an open diff, so I am debating on whether or not to run a front bar at all. The main reason for the choice of rates are that I have a set of 500# springs available to experiment with so I was going to put the old 350#front springs on the rear. What do you guys think if this set-up? is it worth trying? I was planning on shaking it down at the upcoming autocross at Devens Ma and attending a track day at NJ motorsport park later in the month.

thanks
-dave

I would try a little toe-in in the rear before I made the spring swap. Also, I don't know anything about the Avons, but the low rear tire pressure may actually be costing you some stability, depending on how much they are rolling over.

Dave

I agree on the tire pressures.

You are running a miniscule amount of toe out up front right? Any way to get that to exactly zero? Also the full soft rear dampers, is your concern stiffening will make it oversteer more? I would increase the pressure and at least get 3/4 of a turn in to the rear dampers.

Rear toe in is a good suggestion if you need to tame it down a bit.

Unless something else is wrong (damper failure or the like) I am not seeing how the rear end should snap over steer with your setup. Everyone prefers different setups based on their driving style, I am assuming you have a lot of autocross and track day experience? Is this snap oversteer occurring even on full or steady state throttle or are you trying to lift throttle oversteer the car?

I autocrossed and tracked a B13 for quite a few years, lift throttle over steer was only an issue if I went into a turn way to hot, besides that I found the car to be very neutral... of course you learn to never lift.

For pressure, I ran a variety of street and R-compound tires and usually ended up at the same psi for most of them, 37F/35R hot. It's a good starting point at least.

As for the alignment, as others have mentioned... toe-in the rear (1/16) and that should help some too.

If you have your stock swaybars laying around, maybe try throwing them back on and seeing if your issue goes away or not... the ST bars always seem to get a bad rap on here. I ran the Progress bars and loved them.

Your spring rates look fine, I actually ran stiffer rear springs (350F/300R), but if your having issues with the car oversteering, then I wouldn't be adding more to the rear.

Get some spherical bearings for your ST bars. The bushings are likely binding. Also, check the bar for preload.

thanks guys,
I will try a little toe-in on the rear
I arrived on the lower rear pressure in steps, based on the cars behavior and tire roll-over. It felt more stable as I decreased pressure and got worse with more pressure. even with only 20 psi I still didn't get any rolling onto the shoulder. I think it has a lot to do with the tech-r/a construction and my neg-camber in the rear.

Unfortunately I don't have any stock sway bars to play with, maybe I should visit the local pick-and pull or the part-out section of the forum.
from what I can tell my rear s/t bar doesn't appear to have appreciable preload.... I think spherical end links may be tricky based on the design of the st bar. has anyone ever ran an s/t bar with spherical end links before? I was thinking about getting a set of progress bars but my strut housing don't have the stock mounting location for the end links.

what do you guys think about the 500/350 spring combination?
do you think I should run a front bar with the open diff? Would the benefit on traction out of the turn outweigh the benefit of body roll and stability through the turn?

thanks for the input guys
-dave

I think spherical end links may be tricky based on the design of the st bar

Use a small piece of channel and you can mount a heim to an ST style bar.

I was thinking about getting a set of progress bars but my strut housing don't have the stock mounting location for the end links.
You don't use the stock mounting point on the rear strut with the progress, they have a bracket that mounts to the lower mount of the upright.

I was able to adapt sphericals to the G20's whiteline bar. I assume that the G20 uses the same mounting methods, no? Have any pics?

Lower tire pressure = lower cornering stiffness = tires gernerate less lateral force and operate at higher slip angles.