Protocav

Very exciting!! Can't wait to hear more about this.

Thanks again for all the pictures and info.

bmwtye

Im also interested in hearing about this new DSC controller solution for .1 cars. I cant stand the .1 gt3 suspension and how it is bouncy and feels all over the place and unsettled easily.

Tom@TPC Racing

If your ride height is too low it will be bouncy. This is normal reaction from most shocks as you may be riding on the bump rubber. Especially when paired with relatively soft springs(~240/600), which has good amount of oscillation over bumps but that is the characteristic of a stock .1 car, it moves around more than a stock .2. I thought my stock .1 shocks & spring work pretty well after dialing out rear bumpsteer and a good alignment. If the bumpsteer/geometry is set good the movement shouldn't unsettle the car easily. Believe it or not the ride quality actually improved when I swap for .2 front springs(~270) to slightly reduce rate of movement. It got even better when I put a stiffer front bar on to further reduce oscillation and rate of movement. BTW, if you have you front bar set at full soft or one from full soft to get the car to slide, this will increase front oscillation/bounce.

Tom@TPC Racing

Update:

The Damptronics that were installed this weekend with 500/730 springs work freaking awesome on the street! If you didn't know it has these spring rates you wouldn't believe it! I barely believe it myself driving home from work today. Any stiffer than that will go pass the sweet spot for a streetable track car for my tolerance. I think I'm right on the edge of the sweet spot. Because the car had a pretty good setup before the shock/spring swap, I set the car to EXACTLY the same ride height as before to keep the alignment settings the same. Although I will align it again for good measure and for any spring settlement. Just can't do it this week because the shop is too busy. Got about 100 miles on so far. I tried to induce oversteer(when there's no other cars around, of course) in 2nd gear when the roads were damp, it just won't do it, it just hooks. Even on tight turns that are very bumpy and I put that gas pedal DOWN!!! The rear end has so much feel its like a race car. The 500 front springs just sets with the steering wheel movement. Its very firm but not harsh. Loving it! I like the think its a the combination of shocks, springs, and the monoball upper mount

Will update again with the installation of the DSC and 3-axis accelerometer.

Alan C.

Tom,

I rode back to Cincinnati with John after he purchased your 997.1. I was looking forward to a rough ride but the car felt great on the street. A very nice street/track suspension.

Ur20v

Tom,

Unfortunately no, the rear spring perch sit firm against the top mount relying on spring deflection, not ideal but works- same as OEM. If I had time I would have made new perch's the same as the fronts which articulate fine and more critical to the need for free steering movement as well as suspension.

Jay

manuxc

Thanks Tom !!
Do you accept to let us know the setting of your car ? toe, camber, bumpsteer value, ride height ...

Tom@TPC Racing

Glad to hear you guys had a good ride home. I completely forget that I swapped out the 450 front springs for 500 a month before I sold the car to John. The 50 in-lb spring rate increase produce the opposite effect to conventional wisdom. It "absorbs" bumps better, another words, it feels more controlled over bumps. If I hadn't sold the car to John I would have added more front toe out for even better corner entry with the more controlled front end. As is, that car is still really good and John drives more on street than I do so I left it alone. John said he had a lot of fun at mid-ohio. I was thrilled to hear that!

bmwtye

Tom

Is there any chance these new rear mounts are something you guys will make and sell, or is this only going to be a one off for your project?

Tom@TPC Racing

I'm going to provide more info once I get my DSC installed. I didn't realize there's already a thread going with a number of driver feedbacks-
http://www.6speedonline.com/forums/9...ension-10.html

Tom@TPC Racing

This is a one off project on my personal car. If there's enough demand I'll take it to the boss.

Tom@TPC Racing

I will give some details but not all because every race team should keep a trick or two...

Alignment
The camber requirement will vary for different tires so there's not one magic number that's good for all. Some people tune camber by how the car feels, while some tune camber by tire temp, and some just do what the tire dealer/rep tells them what camber the tire needs(which may or may not be ideal for whatever suspension is on the car but the tire people usually aren't responsible for rest of your car, just the tires). This is my basic alignment for a street/track car on popular streetable tires.
Front Camber -2.5 deg
Front Toe -0.5mm
Rear Camber -2.0 deg
Rear Toe +2.0mm

Bumpsteer
This is an interesting and lengthy topic. On my car I use TPC Racing adjustable rear toe links to adjust(reduce) bumpsteer. Its not only because I work here, its because the outter pin that goes into the upright is "almost" exactly the same as the latest version of .2 Cup car. So why not just buy the Cup car links? 1) they are $$$ 2) they are $$$ and 3) they only offer one size spacer which is fine when you are using Cup uprights, subframes, and Cup ride height. TPC links come with different size spacers to accommodate for any combination of street and Cup parts, and various ride height ranges. By changing the arrangements of the spacers for a specific ride height the toe curve(toe deviation) changes as the suspension travels. This has a direct impact on rear stability going over bumps and on/off the gas. Bumpsteer is also influenced by the pivot point of the rear toe link, which is the eccentric bolt in the subframe. I set mine in the middle(bolt-head at 6 o'clock), and also influenced by adjustable thrust arm bushings(if adjustable). Thrust arm bushing adjustment changes the angle of the upright, the upright doesn't travel up/down, it travels at an arch pivoting off the point where the thrust arm connect the body. Rotating the thrust bushing in the control arm will change the size of the arch which changes toe curve. We have experimented to such a degree that we can actually dial in the amount of corner exit push to increase rear grip. I run this car's arch at about 6mm wider than stock(which consequentially increases the wheelbase) and put both spacers below the joint with eccentric at 6'clock for minimum toe deviation throughout the entire suspension travel. This mean rock solid rear grip. On my previous 997 with very similar suspension I used the thin spacer up and thick spacer down. Every car will be different due to variables but you can minimize the setup time by duplicating someone else's effort using the same parts.

And here's the shameless plug of the day- TPC Racing toe links use super kickass hi-end Aurora bearings!

Protocav

Ok, i just read through all of this and I'm a little bit confused on the DSC. Is it really an active controller that changes the damping characteristics "realtime" based on conditions? What if you want to run different/stiffer spring rates...is there a mode that you can run that is not active but will allow you to make the damping more aggressive than factory to match these stiffer springs?

bmwtye

Im curious how a stock gt3 suspension, with maybe upgraded springs, and the DSC and 3-axis accelerometer would be in comparison to the Bilstein Clubsports

Tom@TPC Racing

Revalving a "sealed" shock for stiffer spring involves changing shims and/or piston to produce a certain dampening curve to control the oscillation of the spring. This procedure is desirable when the force of a spring is outside the control range of a specific valving arrangement(shims/piston design). But stiffer doesn't necessarily mean more tire grip. Adjustable shocks, such as JRZ, have a much greater control range than a sealed shock. Typically a JRZ RS Pro have a range suitable for say 400-1200 springs, which is a very wide range. DSC is fully active And have the dynamic range beyond this to cover as much spring as you would ever want in a 997GT car! DSC range shadows over many adjustable shocks. The dampening curves are demand based. So the driver is not stuck with a stiff ride when there's little to no input(again, stiffer valving doesn't always equal to more tire grip). The input includes brake line pressure, steering angle, vehicle speed, g-force. All this data is in CAN. The .1 cars need a better accelerometer but the .2 car already have it. The algorithm of DSC is written as such that it shapes the dampening curve of the individual shock for real time situations for optimum grip. For example, trailbraking will stiffen up to outside front proportionate to the vehicle speed, brake line pressure, etc. Straight line heavy breaking will stiffen both front shocks to reduce dive(which also reduces front end toe steer). The 600/800 is well within the control range of DSC and for the stock PASM shocks. DSC has three different modes, the modes are switched via the PASM button. All modes are fully active with the difference in mode being the peak stiffness. Sorry if this confused you even more.

The developer will make a video seminar. I will document my installation but I'm going to steal the show from the developer.