Bruce In Philly

Something to think about.... see below. The EE guy also writes for Road and Track.

http://www.roadandtrack.com/car-cult...ave-less-grip/

Peace
Bruce in Philly

Marshal_Mercer

I have found that ride control modifications, including handling, is often best done through dampers' adjustments. That assumes that the spring-rate, ride-height, and alignment geometry are correctly set.

swoardrider

This is part of the magic of an active suspension like PASM. It can allow the use of softer springs because some of the spring rate of the loaded wheel can be increased via the PASM computer telling the shock valve to change orifice size in a matter of milliseconds, in Layman's terms

Petza914

Even better is a fully active setup like TPCs DSC controller, which really improves upon the stock PASM capabilities.

kisik

Along with correct alignment (> -2.2deg front) and TPC/Tarett sway bars to complete a nice "package" deal with dual purpose cars even for 20%/80% street/track. Nothing will replace triple adjustable JRZ for 100% track car especially with support suspension specialist on a track helping you to "dial in" last click/sway hole/tire pressure.

swoardrider

Except of course the active DSC/ 3-way Tractive set up. 😉 There is a reason why active suspension tech is currently banned in the big leagues of motorsports.

Bruce In Philly

I posted this to see what kind of reaction I would get..... didn;t get it.

I thought folks would take what he said about aftermarket being stiffer and not always the best for traction and post some reaction. In other words, there are many folks who want to have fun by "improving" their suspensions only to result in less performance, or grip... actually getting the opposite of their intentions.

I came within a hair of swapping out my 2000 Boxster S suspension for no other reason than entertainment... thinking I could "improve" the car. I forget which setup was in vogue at the time... there were a few.... but as chance would have it, my indy had the same car in as me with the mods I was considering.... so he invited me out when he took the car for the post-work test drive. Man was I lucky this happened. On tiny bumps, the car was smoother, but became stiff fast.... really fast. Gone was the more annoying sports car bang, but in came the jarring and jostling that threw me around. And given that stiffer springs actually lessening traction on real roads.... well I dodged an expensive bullet.

Now after all of that, I was not happy with my 2009 C2S PASM suspension feeling it was too bang bang on expansion joints et al, and yet wiggly or something. I experience way better in my stock Boxster S. So I pulled the trigger and installed the DSC module, and after a few minor tweaks with my laptop, have the car I always wanted. And it was low risk and dollars.... 5 mnts it is in, and swapped back out if not happy. BTW, I do not track my car but I want a sports car suspension... and therein lies the issue: what is an "improvement"? https://rennlist.com/forums/997-foru...y-opinion.html

I guess the moral of my story is be sure of what you want to accomplish and go in wide eyed with understanding of the trade offs.

Peace
Bruce in Philly

shekmark

So, this is interesting and I suspect not new info to many Rennlisters who are really into suspensions for racing.. Where does an H&R or Eibach lowering kit fit into all this? That's where I thought you were going with this thread, that lowering our cars for looks lessens the on road performance.

WhipE350

I suspected your posting was expecting a different reaction. This takes me back to your original posting of DSC that I appreciated so much. Your observations of a 997 are so much like mine. I too came from a Boxster (well four of them) and the first thing I noticed was the expansion join bang, I'm like just because the suspension is stiff doesn't mean these road surfaces shouldn't be "muted". Then the annoying one, the uneven 90 degree turn "wag and hop". I replaced my rear shocks and it made a huge difference, they were worn, however there are still roads I turn on to that I simply can't enjoy them like I did with my Boxsters. I just slow down and accept it.I want to try the DSC, I never use the sport setting on PASM unless on nice roads. When I turn on sport I just turn off PASM sport. In fact I'm wondering if I can use my Durametric to have PASM sport not come on. The problem is I have a 997.1 and it isn't a simple swap and replace, it requires the DSC Accelerometer. Seems easy enough to install though, just wondering if it gives the same result as a 997.2.

Petza914

From my experience in my .1, yes it does. I have a full track suspension in my car and the DSC lets me drive it on long trips in complete comfort using my normal mode settings. I'm not far from you in Clemson and it's been to Charleston a couple times, Columbia a few times, Charlotte and Atlanta often. It's worth the time and trouble to do the .1 install where you have to pull the rear seats, the Bose sub and tie into the twisted pair of DME wires under there.

WhipE350

Thank you. I've been back there when I did my rear shocks so not too hard. Now to justify the money, I bought and installed an exhaust recently...

Petza914

I think someone posted a used v2 one for sale yesterday in the Marketplace either here or on 6speed. Might save you a couple $s.

Tom@TPC Racing

Thank you for sharing the article and the video. Good general info indeed on spring rate relative to tire-to-road contact(very important stuff). The tires need weight distribution to work optimally as per the video, but not too much weight transfer that it becomes over loaded, which can happen during hard barking and hard cornering. Beyond the general info, some cars do perform better and feel better with stiffer spring rates(stiffer to a certain degree of course) to mask suspension geometry-induced instability(aka bumpsteer) during the suspension travel. Knowing how much the geometry(toe angle in particular) changes during the course of travel and then selecting the spring rate and damper rate to optimize the balance between weight distribution and the least amount of unwanted toe steer is ideal. With modern electronic suspension technology such as DSC, finding this dynamic balance for all driving situations is more easily achievement since the DSC technology can re-shape the damper rate curve and produce resistance to travel in an "as needed" manner(no more to compromise comfort and no less to cause instability). True to the info in the video, we generally select the softest spring rate we can get a away with for a given application when using DSC and then manage the spring travel rate and frequencies via damping force.


The wiggly you experienced before installing DSC was bumpsteer. I am very glad that you custom tuned your DSC for your personal preference. DSC right out of the box is very good, but custom tuning like you did is a satisfying experience. Track or not track, satisfaction for the win!

PS- new generation of racers not only want speed, they want speed and comfort to maintain their peak performance.