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Discussion Starter #1
I don't know if we'll be able to get to the bottom of any of this, but I'm sure not going to unleash this on the peanut gallery on Facebook for their outrageous madness. So I'm just here to get a few more heads besides mine thinking about this to see if I'm overlooking any easy stuff.

I'm in the middle of trying to sort out a high-speed oversteer condition on my track car. This is kind of a new phenomenon, and really started happening really bad since I went to heavier front springs (up to 650# springs from previous 500#). In the past, the car was really quick to lift the inside rear wheel in a corner, so I took measures to stiffen up the front end in an effort to keep the back tires on the ground and improve rear grip. Now the rear tires are staying down, but the rear end is ALARMINGLY loose in transitions. The easy rule of thumb is to firm up the front and soften the rear to promote understeer - but I have the front as firm as I can manage, and the rear as soft as I can manage, and it's worse than ever.

Here's where I'm set up right now:

Alignment: standard OEM-spec

Dampers: KSport adjustable. Running full firm front, full soft rear

Springs: 650# front, 250# rear

Sway bars: 19mm SVT Contour front bar, 21mm Roush rear bar

I experiment with tire pressures, but I've found that having the fronts near 40psi and the rears around 35psi give me more consistently good results.

The back half of the car is stripped out for track use, so although I haven't had it corner-weighted, I'm figuring that it is very nose-heavy anyway, which I'm sure is a major contributing factor, but anyway...

The way I see it, I have a few things I could do to address this.

SWAY BARS
The SVT Contour front sway bar is smaller than the Cougar bar, which softens up the front to aid in turn-in response and front-end grip. I do still have the stock Cougar front bar that I could put back in for even more front roll resistance. Likewise the Roush rear sway bar, which is massive compared to the 17mm Cougar rear bar. I could swap the original part back in, but I do hate to soften the car any more for track use.

TOE
Rear negative toe (toe out) promotes rotation/oversteer; it's a fact. If a car is pushing too much, dial in some negative toe to balance it. So a simple test for me would be to twist out my adjustable rear toe arms to gain a little more toe-in than at present, and see how it responds. However, any toe adjustment away from zero creates some scrub in a straight line and can reduce speed in the straights. So this isn't an ideal solution, although not as problematic for an autocross car as, say, an open-track HPDE car.

CAMBER
Negative camber increases grip in corners. I have very little problem with any kind of front end grip, partially thanks to the increased negative camber up there. However, there is no off-the-shelf solution to introduce any negative camber into the rear suspension for this platform. So all this has got me thinking about trying to add negative camber to the rear - even just a little bit. The rear strut mounts aren't identical to the front ones, although I'm thinking they might be similar enough to adapt the SPC camber/caster mounts somehow to at least get one more degree or two. I really have no idea without getting a set out and messing with them to find out if it's even doable for the average non-engineer who doesn't weld. My adjustable dampers do not have the perch on the side that rests on the subframe like the OEM struts do, so I have some room behind them to move, if I had a way to do that. Does anyone have any thoughts about how to possibly add in some negative camber on the rear axle without completely re-engineering the entire suspension back there? Has it been done?
 

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You could make longer control arms. Follow the same basic pattern as the toe arms, but use a clevis rod end on the outside of the tube instead of the hemispherical rod ends you probably have on the toe arms. All the parts you need should be readily available from Jegs, Speedway, McMaster, or Grainger, its just a matter of finding the dimensions you need.
You would have to lengthen your Toe arms to match, but thats no big deal.
The hardest part would probably be deciding what to do about the end-links, but I suspect you could find some sort of clamp that would work. Maybe something like this on the control arm side with a spherical rod end on the swaybar side.
 

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The trailing arms should have enough flex to move a little I think, or you could put a spacer at that joint to keep them straight.
The strut mounts should have plenty of flex in them
 

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One benefit of this plan is you could put them back to vertical pretty easily when your not on the track.
 

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Discussion Starter #5
Interesting thought. This would also considerably increase the rear track, which also helps stability.
 

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my car (stock front bar, aussie rear) only oversteers when i brake hard and turn at the same time, or if i do something stupid. granted im running a lot more tire than you, but its been this way for quite some time.

depending on the surface i run the front and back struts the same
i have zero toe in the rear and -3* front camber
 

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Discussion Starter #7
I definitely think I have too much front strut right now, because the front end will skip up and down under power on a bumpy surface and give ma lots of tire spin. So taking out some front damper is definitely in the cards for traction's sake, but that sure won't help my corner balance...
 
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