RonCT

Thanks Larry - I may do that. Talked with a Bilstein expert in CA and here's a concept... With OEM there was a little movement in the rear on hard braking into uneven pavement (Lime Rock is terrible). Stiffen up the springs with the Damptronic kit and add in stiffer H&R Sways and that compounds the situation. He said the Damptronics were designed and tested to work with the stock sways and suggested I go back to them. Sound like a reasonable theory? The electronic dampening is probably throwing everything off here and adding in aftermarket items like stiffer sways may be making it worse.

Larry Herman

I think that someone with tuning knowledge should drive your car. I do not see how stiffer sway bars would drastically affect the car under braking. I have found that too much rebound in the rear usually causes the back to become squirrely during braking on uneven surfaces. The fact that it is happening to you with the Damptronics set on normal is puzzling because I would think that both the compression and rebound would be softer on normal. You need to first try the sport setting just to see, and then run the 18s to see if that makes an improvement.

RonCT

The problem with the back end at Lime Rock started with OEM everything. The pavement undulates in the braking zones because it's in bad condition. So a little undulation and most of the weight up front during threshold braking, causes the rear to move a little. Add stiffer springs of the Damptronics and a little lateral movement becomes more. Then as the car is swaying a little, the stiffer sway is compounding it a little more. The 19s vs. 18s could also contribute to this (but I can't try 18s again without buying another set of wheels and tires).

One of the problems is it takes pushing the car to a 1:03 or lower lap at LRP to get this to happen, which means it's really difficult to try to resolve it on the street or in light track duty. I'm sure we'll find the solution and it may take some experimentation. But all of your thoughts and comments are helpful, especially those that might debunk or reinforce a theory...

Gary R.

Bring it this Thursday, i'm sure we can easily get some 1:03's down...

RonCT

The low 1:03s weren't a problem last Thursday, it's getting back into the low 1:02s that were eluding me due to the uneasiness of the back end The whole idea of the suspension change was to turn low 1:02s into low 1:01s or below... Had to call off this Thursday due to my allergies (I was a mess last week and went home early) plus I have this sorting out to do...

mdrums

Ron, bring that car down to Florida and experience the bumps of Sebring! I hope the stock sways work out for you...keep us posted. Best of luck!

see ya, Mike

Qwickrick

If I go into the T1 braking zone hot and late, the bumps get my car unsettled as well. If I brake earlier in the zone, no problem. Probably just the stiff suspension and lousy surface, and nothing at all to do with your sway bar settings.

Sean F

I like it when the rear moves in the braking zone, it turns easier

RonCT

Maybe the theoretical question is this... If the new track-oriented suspension performs worse than stock on Lime Rock's terrible pavement, could I expect that on every other track, I'll enjoy superior performance? Once Lime Rock is repaved, it won't matter much, but going from planted and quicker laps to wild ride and slower laps didn't give me a lot of confidence in the new set-up.

Sean F

Personally, I would not recommend shaking out a suspension at LRP. Are you going to Cups, Ron? Maybe give it a shot there and then think about which way to go.

BTW, PM Joel Furey. He is thinking about bringing a coach to Cups who you could hire for a couple of sessions. He is the kind of coach who could drove your car and would definitely sort it out for you. He's good.

RonCT

Thanks much for the idea - I will be there for Cups & Saucers and figure that's a great place to tune things. Dan will be there and has offered to spend whatever time is needed to tweak what we can tweak (sway settings is about it because Damptronics are not adjustable). My hope with this thread was to try to discover if there's some known issue or limitation out there with Damptronics that would suggest we need to modify the set-up. For example, the theory Bilstein threw out there with respect to lateral movement on hard braking for the stiffer suspension being compounded by the stiffer sway. If that's a valid theory and something a reader of this forum knows from experience, then I'd rather know that now and make the adjustments. For example, if one of you RL members were where I am with a 997S / Damptronics / Stiffer Sways 6 months ago and learned from trial / error that going back to the softer sways was the better set-up, then I could fix that now and go to Cups & Saucers knowing I had the right combination (vs. getting there and having issues that I can't solve on the spot).

coryf

Have you done a time difference plot on trackmate to see where and how much time was lost between the 2 days? Looking at peak g numbers will not give a good comparison due to spikes. Maybe the 18in tires are a smaller diameter and the car accelerated better? Warmer outside temps equals less power or slicker track? If you have data from both runs you can know for sure.

RonCT

That's what I did - I compared comprehensive data from both days. The temperatures were almost the same October 1-2 and 4/24, the wheel / tire weight combos were actually lighter this time (Volk 19s with PSCs are quite a bit lighter than the Fikse w/ RA1s - especially at the back where the 18" RA1 is about 30 lbs). There are two things missing - one is braking capability and it's not the tires or pads - it's that the rear end is so upset that I simply cannot hold the car straight approaching threshold braking. Not even pushing hard I was running low 1:02s in October and for the same "feel" I could only find low 1:04s. I did push to get to low 1:03s, but it was extremely unsettling. So right now I'd say the differential is 2 seconds trying to adjust to some version of apples-to-apples.

Larry Herman

Ron, it sounds more like the system you bought was Damntronics!