I got my Turbo 1 1/2 years ago, well modified. I need to sort out an issue where the car feels twitchy / hunting / unstable especially at higher speeds and when switching lanes. Had it at Road Atlanta once and would not push it past about 120mph as it felt unstable. Instructors 993 Turbo was rock fricking solid past 120.

Before I ditch my entire coilover setup for a new one $$ - what should be my priority things to do.
I will be having a local shop do the work, but fear that they may sell me on total replacement but not solve the issue.

Currently have:
JIC Cross 15 pt coilover
8/12 kg (assume these are my spring rates - seems very stiff, but have seen posts where others have run this with no complaints)
GT3 rear sway bar set to middle hole
Tarret Rear Sway bar drop links
Tarret Rear Toe Links
Lowered to GT2 specs

Hard to say what the exact specs were from previous owner.

Had a full alignment done a few months ago, no change. Front splitter was replaced with stock, rear wing is stock - no change. Tires are Sumitomo set just under spec pressure. Fudged with coilover adjustable settings with no significant change - currently at full soft in rear and about 6 click from soft in front.

Suspension is quite stiff - would prefer a bit softer, but that is not the ultimate deal breaker. Thinking I am going to lose control at speed is not good.

Start over and go with shop recommendations?
Fudge with different springs / revalve coilovers? (prolly cost close to full replacement anyway)
Something else?

Daily driving, ~3 autox per year, would like to do ~2 DEs per year - but not until I get this sorted.

Looking at
MCS 2 way for about $7,000 (coilovers, labor, alignment)
KW v3 for about $5,500
PSS10 seem to be about $4,500 but may not satisfy me.

 

i spoke with olsen motorsports about the same feeling in my car. first thing they asked was when the jrz shocks i have had been overhauled. my reply was most likely never since new. they responded that coilovers should be rebuilt every 2 yrs. most likely 5 yrs on my setup. they suggested sending my jrz coilovers in to them for a rebuild and then discuss how i wanted them to ride, ie: street, race or drag. the quote was 850$ plus shipping. this is route ill try this winter before i ditch my setup for a new setup.

my springs are 600/800 and they felt that was fine for the street but that the shocks need to be rebuilt to absorb more of the road contact

 

driving on track or street when it's feeling "twitchy"?

have you tried different alignment settings?

 

Mostly street driving where I observe the twitchiness. On track and autocross - it feels very good. Noticed more on the wide open straights where it takes more steering wheel input to stay stable (if that makes sense), lane changes and sweeping turns at speed are nervous. Low speed, around town driving - aggressive twisties in 2nd/3rd gear feel OK (albeit stiff).

Previous owner had done an alignment prior to my ownership. I had an alignment about 6 months ago. Would have to dig up the settings. Mine was done by a reputable local shop - full string alignment, they know what they are doing. But no, I am not tracking and tweaking individual alignment settings.

32krazy - my gut tells me you may be onto something. I have no idea when the previous owner installed the coilovers or what condition they were in (would assume 'used' based on some of the other mods I have seen him do). Any way to tell if the shocks are shot?

 

Based on support available from/for JIC - I tend to agree with you Tony.
I'll look into Ohlin, they were on my short list of ones to consider, just have not looked into them yet. Ultimately, I will likely go with what my shop is most comfortable with. I know they use MCS (Motion Control/Moton) alot and the MCS HQ is in our same town.

 

Is it me or did everyone miss the tires that are being used. I'm not trying to insult anyone because I purchased a set of stock wheels with the same tires but I can say for sure on the track or off, the car felt very twitchy and unsafe. Over 120mph was just scary!! I have a set of michelin Super Sports and the car is rock solid at 180mph plus. I'm sure certain adjustments need to be made to your suspension but as long as you are using those tires my opinion is it will never be correct.

 

What you're feeling will more than likely be fixed by an alignment.

If you haven't already done so, start there.

Later, Steve

 

More info on this? Anyone know what the price is compared to say the KV v3's which are around 3kish.

 

As mentioned previously,, tires and tire pressure can make a huge difference.
You may want to mess with the tire pressures. Or go with some performance tires.

Just for comparison, I am running kw v3's and the car is rock solid, one hand on the wheel at 160.

 

Do you have adjustable front drop links? I recently switched mine to Tarret and it made a significant difference. After lowering the car on coilovers, the drop links I had before were putting pre-load on the front swaybar, which made the front feel a little nervous. The only reason I switched is because the ball joint eventually went bad. I was expecting to just fix a broken part with the new drop links, so I was surprised to find I also got a big improvement in the initial turn in feel.

 

Spring rates are ~450F/675R which are not stiff at all.

Do you have enough travel from the top of your coil overs to the bottom of the bumpstops?

I had Sumi's in the past and no issues at 120MPH+ at the track.

 

I would get some good tires, first. Even if it doesn't fix this issue, which I think there is a high probability it would, it would improve every other aspect of driving. My current go to pick is the Michelin Pilot Super Sport. 100% of the tires in my driveway are that model, 16 of them.

I would think if the shocks need to be rebuilt you would feel signs at speeds slower than 120 MPH.

 

Consider adjustable upper rear control arms and 964RS or other semi solid motor mounts and 997 tranny mount. PSS 10 are a street only coil over and a step back from what you currently have. Hopefully you're still running 18s" as 19s" look good but don't handle as well.

 

^ very good point about tire pressures - would start there.

 

As expected a wide range of responses....
I'd think that it is not tires as many run the same without a common link, on my second set - however I will go with Michelin Pilot Sport 2 next time around.
Running stock 18" wheels.
Tire pressure = doubt it. Started at stock 36/44. Typically run 34/42. Have run much lower on the track. No change to effects.
Had a full alignment done about 6 months ago - no change.
Gotta think it is the coilovers, not knowing what condition they were in when the previous owner installed them.

I'll work with my shop to test drive and narrow it down better though. Don't want to jump to conclusions before having good evidence.