onefstm

Today, I installed the updated DSC box along with the 3-axis accelerometer. Overall, the install took a little over an hour. Since I have a GMG bar in the back, I was concerned that it may be tough to get to the ECU panel behind the seats. However, with the passenger side seat out, I was able to pull up the carpet and remove the panel. One 10mm was partially blocked by the rollbar mount but I was still able to remove it with a little effort. Following Tom's lead, I also soldered the connections. However, snap on connections would probably be adequate. If you follow Tom's pictures, install is really easy. I would put the difficulty on the same level as an oil change. Once the 3-axis accelerometer was installed, I swapped out the DSC unit.

Ok, now to the driving impressions. First off, let me say that I do not like the two modes offered by the stock system. The standard mode was too floaty with the sport mode two stiff over rough pavement.

With the TPC box in the first mode, the car is really flat and does not exhibit the float of the stock system. Actually, it is really comfortable. After a little smooth pavement driving, I hit a curvy backroad. The first thing I noticed was that there is no dive underbraking. The car seemed completely flat. Next thing I noticed is that the car seems to be really flat all the time. Could be placebo, but I felt the right side of the car completely stiffen on a long left hand turn. Lane changes too seem instantaneous. Next, I tried the two stiffer modes. With these two modes, the ride is not harsh at all. It did seem stiffer but not beneficial on this backroad.

Overall, the suspension was much more confidence inspiring on the road. Before I did not feel comfortable really pushing the car on the street. My 993 was much better from this perspective.

Later this year, I will have hard track data for comparison.

On a side note, I also just had cup cables installed and water lines pinned. Really love the cup cables so far. Notchy and much more solid shifting. I did not notice much of an increase in NVH.

For the money, both the TPC DSC unit and cup cables are awesome mods. Worth every penny. Can't wait to try them both on the track.

Jamie_GT3

Very cool, just needs those rear spherical mount adapters and we've got a new inexpensive setup for the track! New springs and new DSC controller and off to the races... Anyone compared the shock curves for the 4.0RS vs the new DSC profile curves? I haven't driven one but I've heard it's the best combination...

John Chan

Be honest, I would like to have 3 active modes and keeping 2 factory modes, total of 5 modes. The reason is for fail safe in case the 3 axis input fail or off calibration, I still have 2 factory modes to work with. If TPC offers 5 modes, I am in. Especially my OE shock is revalved for stiffer spring rate and I really like it on a flat track. The only down side is the sports mode dose not like me climbing the FIA curb. As soon as one side hit the curb, the rear start to rotate. I hope the active mode can address this part (cheater!). I am expecting the active mode will change our driving, not sure if it will be a cheater device in terms of club racing

Tom@TPC Racing

Nice write up! Thank you for sharing.

George from MD

Tom I really want to thank you for saving my WE. It went from scary hell to eating up the run group thanks to you.

For the readers Tom took an hour of his own time and adjusted my toe in at the track- he didn't have to and I sure appreciated it.

Tom@TPC Racing

To be honest, changing springs to say 400/600 or 450/600 only makes a marginal difference if you already have DSC. I experienced this from installing DSC on customers cars with stock springs and with the spring rates mentioned above. The reason is because DSC accomplishes the same level of support, and only stiffens the PASM shock(s) of the particular corner of the car that requires more support. When the spring rates are 500/700 or 600/700 is when I begin to feel a bigger difference from the spring rate increase alone. At this point the street ride quality is still not bad but not as supple and relaxed as before. The point I am trying to make here is if you want ultra smooth street ride and the performance of 450/600 springs only when you are driving aggressively, then just go for DSC and save you money on springs. I did it on my car the backward way by doing springs before DSC.

According to PET, the 3.8 RS and 4.0 have the same PASM box; so the stock set points are the same. They also share the same front PASM shocks. The rear shocks are different and springs are different.

Tom@TPC Racing

Thanks for your honest inputs. I will forward your inputs to the DSC developer. IMHO, your shocks are valved too stiff for sport mode if the rear of the car is upset by the curbs.

Tom@TPC Racing

My pleasure George! Glad that little bit of work made a difference.

FFaust

Great showcase for TPC, and good insight into the thought process behind such a build. Almost makes me want to "upgrade" to a 997.

Our PCA CI has had issues tuning his 997.1 GT2 PASM so I'll let him know that you now have the DSC.

Tom@TPC Racing

Thank you. Setting up a GT2 is same as a GT3 except for one added element; the turbos on a stock GT2 kicks in pretty abruptly which upsets the chassis. That's why many of our Turbo/GT2 customers go for our linear turbo power delivery package. They didn't do it for the increased peak power, they do it for wider powerband and smooth turbo engagement. Also the turbo cars need a lot of front rebound(resistant to upward movement) to reduce excessive weight transfer to the rear caused by abrupt torque delivery on exit.

onefstm

Tom, this post was very relevant to me. After feeling the improvement of the new DSC box, I was going to call you Monday about ordering rear toe arms and 400lb front springs. It sounds like I will not notice much of an improvement since the box now allows for substantial stiffening of the front struts. The only thing that goes through my mind is, would the 400lb front springs require the front struts to work less and thus prolong their life? My car is 70% street/30% track and Im thinking that 400/600 springs would be a nice compromise.

Second, with the rear toe arms, is the benefit the aurora bearings and proper positioning of the eccentric bolt? My bolt is currently at 5:00 with a proper toe setting, even with low ride height.

BTW, I am having a lot of fun with these mods. The new DSC box actually makes the car much more fun on the street. The stock box was too floaty in non-sport and your prototype box (not functioning to its potential) was too stiff. The new box is the perfect balance. I'm super excited to get the car back on the track.

onefstm

I'm still running side mufflers but decided to open up these vents today. It was hard to believe that the factory has the bumper slits and even ducts in place without cuts in the heat shield.

There still appears to be a decent clearance between the shield and side mufflers, which would allow the fender air to exit. However, I fell maximum benefit would come from side muffler delete. Maybe I will explore this option if it does not drone.

Note - I feel the the lower cutout should be lower. My cutouts do not directly line up with the lower duct. Next time I remove the bumper, I will extend this cutout lower.

Tom@TPC Racing

For 70% street/30% track with DSC, I'd either leave the front springs alone or go with 350 fronts. The stock .1 rear springs are close enough to 600. I have driven cars with 350/600, the nice thing about 350 fronts is that it feels like 400 when you're leaning on it but it feel like 300 gliding over bumps. A good balance between track performance and road compliance. If its the other way around(70% track/30% street), and you are willing to tolerate stiffer street ride, then I'd go with 500/700 or even 600/800.

To answer your question about the impact on the life of the shocks, I think any addition wear to the internal seals is very minimal. Eventually all shock seals do wear out over time and usage, but based on my observation since the first functioning DSC from 5+ years ago, it'll take a long time and a lot of use for the seals to wear out(aka blown shock). The seals hold the pressure so that the fluid inside the shock is forced to go through the orifices, that's typically how dampening is achieved. The seals will withstand enough pressure to stand up an entire corner of a car solid, ever heard of the term "locked up shock"? The seals are holding more peak pressure now then with stock PASM normal mode but less peak pressure and I less duration of time than with stock PASM sport mode(hence the better ride over bumps you are experiencing), and the seals are subjected to less up/down movement inside the bore of the shocks with DSC. That was probably TMI so the cliffnotes answer is the wear is not much if anymore than stock. One example, we have a locally PCA DE instructor with 4 full seasons with DSC. Actually you could call it 8 seasons because him and his gf share this car in different run groups and he gives rides. We replaced One shock couple months ago due to leaking seal. The other three shocks are from 2010. This car is 997.2TT with 600+whp, full interior with roll bar(weights ~3550 lbs), have been running on Hoosier R6 265/325-19. IMO, they hold up very well.

The benefits of TPC adjustable rear toe link over stock link are 1)replace the large inner rubber bushing with racing quality Aurora spherical bearings for zero toe change from rubber flexing, 2)allowing for toe adjustment without changing the pivot point(geometry), 3)allowing for greater range of toe adjustment to accommodate for very low ride height and/or use of shimmed out lower control arms and/or offset thrust arm bushings, and finally 4) TPC outter joint is the closest design to the factory 997.2 Cup that I've seen and we have the toe curves mapped out to achieve minimal toe deviation throughout the suspension travel for increased rear tire grip, so there's no time consuming and costly experiment required on your part. Please pardon the shameless plug in this paragraph, I have to do it for using company time and resources.

Very glad to hear you are having fun with the DSC. Looking forward to your feedback after tracking your car.

Tom@TPC Racing

Very neat cuts. Good job! Opening the top vents alone will reduce a good amount of the pressure. The ended up craving out a chunk of the lower black plastic to create a path of lower resistance which was probably overkill. And there has got to be less pressure inside the rear bumper with the side mufflers in place because the mass restricts the total volume of air going in. I know this because at one particular race event we weren't allowed to vent the rear bumper but rules didn't prohibit making a rear inner fender to prevent air from going in and pressurizing the rear bumper. It worked, we picked up at few mph. Shortly after an official told us to take them off. Anyway, even with the reduced pressure by the mass of the side mufflers I still think venting will help by creating a "draft" to let some heat escape.

OpieT

Brilliant thread! Amazing.