daaa nope

I don't think I understand your question when you reference "wrap the string around the tire"?

String alignment involves essentially drawing a square box around the car - making sure the run along the sides of the car (via strings) are parallel and bisect the rims down their center. Then you measure the distance between the leading edge of the rim to the string, and the trailing edge of the rim to the string. The difference between the two is how you get the measurement. As the rim is (obviously) solid and does not flex, it's the most accurate measurement you can take. The rubber tire flexes, the sidewall/shoulder is not necessarily consistent in width (especially when measuring in fractions of a millimeter.)

It's generally understood/expected that you take measurements from the edge of the rim. The differences between a 20" rim and a 19" rim, for 1mm of measured distance, is .017 degrees. Not enough to really make a difference especially when most people can barely get it to within a millimeter anyways. Note that this is also how most (all?) pro race teams do this. I can tell you the team I drive for uses the edge of the rim and said they do not care about rim size, they use the same spec (I asked about this when I was setting up my own personal car.)

Reedy

This isn't talked about much but I have found one thing at the racetrack recently that opened my eyes. That being the soft suspension setting is not only giving me faster lap times, but makes the car more progressive and enjoyable to drive at the limit. I was at a local track on the weekend that is quite bumpy but even on the smooth sections of track I found the softer setting was less nervous, and had SIGNIFICANTLY more traction on corner exit.

Previously I just defaulted to using the hard setting on the track but the way it feels now I don't think that's useful on even the smoothest racetracks.

Looks like hard mode on my GT4 will be relegated to only being used to help prevent my splitter from scraping on steep driveways.

I'd be interested to see how the DSC controller affects this balance. I might get one down the track but my recent experience makes me question everyone who is uprating their springs. Stiffer isn't always better.

TRZ06

I submit that the quality of the damper is what matters more. You can have a stiffer spring, yet have better chassis control with high quality damping. I'm sorry to the Porsche fan bois out there, but the stock PASM damping sucks, especially when you are at 8/10ths and above on a less than ideal surface.

I am not sure if it is just the limits of the adaptive dampers, or if the damping curves are poor, but what ever the reason is, it sucks.

It also is more complicated than just damping and springs. You also have to take into account the natural frequency of the car and, which needs to be part a of the equation. Getting proper damping is like black magic and not many really get it right or optimal.

I have said it many times before, but in my experiences from having many performance cars from Audi, BMW, Porsche, Ford, and GM.
GM (in the 6th Gen. Camaro & Corvette) does chassis and suspension tuning the best. This is not to start a MFG war, but this is from my personal experiences. GM just gets it right.

Case in point, go spend some time in all of the car forums and (especially in the Audi & BMW, a little less in Porsche but still there) and see how much owners talk about adding aftermarket suspension (like major changes, not the small stuff). Then go spend some time on the 6th Gen Camaro and Corvette boards and you rarely hear about owners wanting or feeling the need to swap out their OEM stuff (at least on the performance models).

enduro

I suspect the lack of C6Z major suspension upgrades derives partially from the ownership demographic of its track guys (bang for the buck) and partially from its leaf springs -> you need to put coilovers where the shocks used to be. I never saw a ton of support for coilover conversions tho I know they exist. Now the fact that it was 4 double wishbone suspension is a good thing in thy; wish I'd tracked my Z so I'd have a better A|B comparison, and maybe some of its compromises would make more sense. For example, I never ran mine on fresh cup2, never got its tires warm, never got a track alignment.

But with that said, I'm not a dismissive of the GT4 damping as you are. It took me a bit to get comfortable in the car as it drives much different than others I've owned, but I will say that it does very well at 10/10ths (tires squealing but not squalling) in 100 mph sweepers on a track that's generally accepted as 'rough'. I will likely eventually go full magic coilovers, and my opinion may change after I do them, but to be frank, upgrading the suspension on my M is a higher priority and will get attention this year, as the Porsche is very good as-is.

daaa nope

In my opinion, Porsche seems to go the route of "undersprung, overdampened."

My last toy car, a very heavily modified 987.2 Cayman - I had 600/700# springs on the car, mounted to a JRZ RS2 2-way shock. The car was more compliant on the road than my 718 Spyder.

The point of the shock/spring combo is to facilitate correct weight transfer. How much weight goes where, and how quickly it gets there when transitioning. Stiffer is definitely not always faster... 100% spot on.

I don't mean this as a negative, so please don't take it this way: but what you experienced, likely what's happening is your pace just isn't loading the car enough on the "stiff" setting to allow full transfer of the weight to that tire. Not full transfer means you're not working the tire, you aren't getting the camber change, etc. Set the car to the soft setting, it lets more weight move around before the spring really holds the load - now you have more weight settled into that corner, suspension is compressed more which means your rear tire is more vertical and thus putting more meat down square on the pavement (assuming you have some camber in the rears).

The problem with how Porsche sets cars up IMO is that with the wrong springs, the dampers only do so much. They can slow the rate that the spring has to pick up the load - but the load eventually transfers. If the springs are too soft, you're never going to get it to really handle right. So setting it to "stiff" means hopefully you're done with the turn before you've totally loaded/over-loaded the corner.

The DSC box gives you more dynamic suspension - now instead of simply "soft" or "stiff", now the box calculates what the car is doing and will dynamically adjust. It's pretty neat and likely cures some issues but in the end, to really maximize things, you need a better spring/shock setup.

The stock stuff is really good for probably 90% of the people out there. Hardcore canyon carvers or trackday guys will eventually want something more if they have the pace. I'd normally also include autocrossers in there but outside of a DSC box, spring changes aren't allowed in the competitive clubs unless you jump up to the modified classes. My Spyder won't see track use aside from maybe touring laps for fun. Car is too expensive and I've had a big enough wreck in my past to really not want to be on track anymore without a full rollcage, fire system, 6pt harness, etc. Not going to "ruin" my Spyder like I did my Cayman! And frankly it's just not possible for me to drive fast enough on the street to get the "high"... so for the pace I maintain on mountain roads, the stock system works good enough.

Reedy

There is definitely a skill element to it that I lack. I have just found with the stiff setting trail braking and hand speed on turn in have an extremely small window to get it right. If you turn into a corner too quickly then the back end quickly bites you and murders your corner speed rather than slides progressively in a way that you can react to, it needs to be anticipated.
What I found with soft was that window in which you get a little bit of slip but not too much is a bit larger which makes driving fast a lot easier. Someone with more skill than me might be able to keep the car in this narrower window but it is way smaller than what I am used to with other cars. The more I drive the car at the track the better I am at anticipating it but having a car that is overly nervous is not particularly enjoyable.

Here's a couple of videos from my last 2 track days so you can make a judgement for how hard I am pushing.

Alignment is essentially the same as DSC recommended 75% track 25% road.

Josh_357

Got my specs pushed a little further today. So far it feels better than my home string job to get me by. Testing at AutoX this weekend and track soon.

Front LCA 6mm shims
Rear LCA 4mm shims
Rear Tarett adjustable toe links

lovetoturn

Yes the stiffer springs will definitely help with the nose dive, and I am looking forward to that. I tend to lick the stamp and send it when braking into corners on my hot laps, so I suspect that I will still have a bit of rear end instability when braking down from 130 to 50 on our back straight here at ECR. Since I have to adjust ride height and realign the whole car after a front spring change, I will make a small incremental change in the rear toe while the car is on the alignment rack. This will move a bit closer to the Clubsport rear numbers. Plus, I want to be more prepared for when I am going 150 mph down the back straight at COTA before standing on the binders.

The other above comments about the increased compliance of a suspension helping with the handling of a car and opening its performance window are the reasons why I chose to only upgrade the front springs on my GT4. I wanted to firm up the front a bit to be able to carry more speed into the corners, but leave the rear alone to be able to put the power down coming off the corners. We shall see how that works out here pretty soon. Again for reference, the rear springs will stay at 80 Nm, and the fronts will go from 45Nm to 60Nm.

lovetoturn

Also, with sway bars, you are not just stuck with the three settings of S--M--H. You can put one side of the bar on one setting and the other side of the bar one higher or lower. This way you have five settings in total for a bit more adjustment. I might call them S--SM--M--MH--H. That way you don't have to go all the way from a front/rear of M--M to S--H, which brings the rear of the car alive but possibly too much for some. A more gradual approach could be to go from M--M to SM--MH. That way you shift the balance of the car, but in a much more subtle manner. You are only moving the bolts a total of 2 holes instead of 4 holes for both of the bars.

I can tell the difference between the OEM of M--M to M--MS, and then M--MS to M--S. Just one hole of movement can make a difference when pushing the car on its limits. You say softer on the rear bar though, what gives on that one??? But my car is different with 20mm larger front tires of 265/35-19 and 1/2 wider front wheels, but only 10mm larger 305/35-19 rear tires. That alone pretty much takes out any understeer you might find in this car and negates the need for a stiffer rear bar. In general, a softer rear bar means better compliance on that axle, a smoother and broader window of rotation, and better traction off the corners. I like all of these things.

daaa nope

It looks like you are very timid with the throttle application.

What bar settings are you running? My gut reaction is to suggest you need more front bar or less rear bar (or both). Especially if you followed what seems to be the common RL advice of "full soft front and full stiff rear". I have a lot (a LOT) of track and W2W racing experience, in Boxsters and Caymans, and have won national championships. While I have not tracked my 718 Spyder, I have done a bit of autocross with it (on very fast courses with speeds that do top out with me hitting the rev limiter in 2nd - so quicker in some spots than some of the corners you have on your video).

On middle/middle settings my car was a handful when pushed and I was constantly chasing the rear. Sure, it rotated nice, the nose tucked right in - but I had to wait...wait... wait... to get back under power. I think for n00bs etc. they like the quicker rotation because they're otherwise just going too slow into the corner, and/or just abusing the front, shoving it too deep and with too much wheel input. You're already working the balance and working the wheel.... IMO if you can get the rear settled, you will be able to pick up the throttle earlier/heavier.

Off-throttle a stiff front/soft rear it will make the car push a little bit more, especially in cases where you already over-drove the front (if you are HARD on the brakes and try to shove the car in deep + give it wheel input, it will plow) - but it will allow you to also get back to throttle a lot sooner and more aggressively. Learn to work with it, being smoother on the way in, and picking up the throttle later - it will help.

Reedy

Bars are middle/middle.

I went back last night and pulled 3 seconds off my PB. THREE SECONDS.

The hesitation in getting on the throttle you talk about is much improved with dramatically improved traction in the rear. Corner turn in and trail braking I have more confidence in the car rotating around in a controllable way. And being able to hold a slide through corners has gone from almost impossible to extremely easy and satisfying to do.

The only difference between before and after is I am running the suspension on soft. I am telling you all, the hard mode is garbage. The car is beautifully neutral on this setting, on hard it goes from stubborn push to a lap ruining snap in the blink of an eye and it severely damages my confidence at the limit. On the soft setting it is completely transformed. Going softer on the rear bar and running in hard damper mode might do something similar for the balance but the wheels are noticeably more in contact with the road when running soft so my feeling is that it still won't be this good.

daaa nope

More control in a slide is indeed a big win.

But note - sliding is slower.

JCviggen

I've occasionally simply forgotten to press the suspension button on track heading out of the pit lane and been surprised afterwards how I didn't even notice till I got back.

Going to stiffer springs however dropped my lap times a lot. DSC made the car feel more predictable and consistent but not faster to the extent that the improvement was well outside of normal variance.

LZRD GRN

Thanks for the update!

Please update us on how this goes......

Cheers!!

Reedy

I'm talking about holding just that small amount of slip angle, not drifting. Being able to balance the car in that window is significantly faster than no slip at all. You can see the video above where the car is oversteering slightly in some corners but I don't even need to countersteer, I simply drive through it with a bit of throttle as the car is rotating naturally. It's a beautiful thing when you get it right.
If I was running the hard setting those would have all been abrupt moments of opposite lock triggering the stability control which certainly does destroy lap times.

Let's pick one specific corner.

Compare this timestamp (Hard setting):
With this (Soft setting):

Hard setting a) doesn't rotate on corner entry and b) snaps at the apex requiring a correction.
Soft setting rotates naturally on both corner entry and at the apex but doesn't need any kind of correction, just a little bit of throttle to settle the rear and drive through the corner. End result a 6kph higher apex speed, and you see that across the entire lap.