I have been driving this car pretty hard for the past 5 years and I'm familiar with its behavior in most conditions.

I have ~3000 on my Bilstein/Eibach Pro/285 RE-11s. At low/moderate speeds and sharp corners, the thing is vastly improved. Dive/squat are way better controlled and in general, the car is more composed.

On Saturday, I ended up following a fairly new ('12-'13?) BMW 1M through one of the local country roads at a "brisk pace." It was fun and while I had NO problem keeping up with him, I noticed that the car was quite nevous feeling when under a cornering load on some of the higher speed sweepers....possibly due to some imperfections in the pavement, though these roads appeared to be in good shape.

Looking back, I think this was the first time I had put the new suspension to the test in those conditions...and sadly, it matches up with the stereotypical criticisms of the S197/SRA...I never lost control of the car but it actually spooked me a bit.

Is there any suggested mod path to minimize this?

Lighter wheels?
Watt's link?
Softer springs?
Slow down?

Suggestions are welcome.

 

Oh... forgot to mention, the wheels are 19x9.5 RTR wheels with the -33 offset...not sure is the weight or offset of these wheels might be a contributing factor.

I'm also running about -1.5* camber in the front.

 

Sounds about normal for these cars. I get the same, had it with my Steeda springs and have it with my H&Rs now.

I've always wanted a watts link. I think a watts link, urethane bushings to replace all the rubber parts, and a bump steer kit could go a long way to get rid of most of that "jittery" feeling. I'm also going to do a shock tower brace.

 

Thanks. There are plenty of soft rubber parts still in my suspension. I have stock sways and LCAs...but I can't help but think that some compliance would only help. It felt more like the rear end was just insufficiently responsive to the bumps...like it just had too much inertia and ended up skipping and almost losing contact with the road. Creepy feeling...

I'd be interested to hear how your shock tower brace changes your car. Mine came with one (Brembo package) and I've never driven without it...it's certainly a worthwhile mod (any stiffness you can add is worth its weight in gold)...but at the very least, I'd have to say that this won't totally cure your jitter problem since mine has the brace and still does it.

IIRC, the Watts link will allow the axle to travel up and down without the left-right shift that the panahard bar causes as the axle moves...this could be a huge component in keeping the rear end stable. Can anyone verify that?

 

Shock tower brace is in the trunk, tied the shock towers together. I have the stock strut tower brace, as I have a Track Pack car. I added a shock tower brace to my 2000 V6 (along with a strut tower brace, but I had the strut tower one on for years before I installed the shock tower brace), and it made a big difference for rear end stability. The car became more neutral and eager to rotate.

I rode in a Parnelli Jones Saleen around the same time, which had the Saleen Watts Link setup on it. It felt amazing around crap SoCal roads. That's what sold me on the watts link design for our cars. I want that feeling. One day...

 

Cool! You did say "Shock tower brace" which would be the rear. The fronts are struts. My bad.
I may look into installing one in the rear myself.

Good report on the Watt's link. That's promising.

 

I am most likely going to do the Steeda X-brace that ties in the whole rear bulkhead with the shock towers. I see it as a mini cage that bolts in.

 

OP, I saw that you were originally considering swapping the GT for a Boss 302. I, too, had "jitter" issues with my '14 GT trackpack, but the issues went away when I did some suspension work. After using a GoPro to video the front/rear underside of the car across twisty mountain roads we have around here, as well as on the local track, I determined that the "jitters" centered on rear axle control issues.

Since the track pack has higher durometer control arm bushings from earlier 302's, and the object was to improve high speed handling in the curves rather than launch traction, I focused on other things. I did some fairly standard replacements (Koni Yellows, sway bars, etc.), but three items seemed to do the trick: the rear Whiteline sway bar (interesting and different design, worked well), a good boxed panhard brace (people install the bar, but often ignore the flimsy OEM brace that allows a lot of lateral movement in the twisties), and standard Boss 302 springs (I tried several aftermarket springs before settling on these).

YMMV, but both the feel of the car and videos of suspension components indicated that these worked out well. For what it's worth, the "standard" of handling I was measuring against was my own '07 Mazda Miata NC, which I track regularly.

 

I have Strano adjustable front and rear bars waiting for my next round of suspension parts, and at that time I'm doing the BMR PH brace too!

 

Don't forget the Whiteline, or Steeda adjustable upper control arm. Installing this on my GT Trk pk made a world of difference in stabilizing the rearend.

 

I have the BMR and their mount waiting also.

 

Did you see a solid improvement from the panhard bar brace? I was in the market for watts link but I was scared of by the possibility of noise and some stories of less durability.

I have koni sports, steeda sport springs, steeda billet lca, steeda torque box brace(welded), steeda lca relo brackets, steeda adjustable pan hard bar, ground control cc plates, and white line sways. I've gotten rid of a lot of the weirdness in the twisty bits. I thought what I had left was just the nature of the beast. You guys have me thinking I may need to look at the shock brace and panhard brace. Lol, laser red has me considering a watts link again.