strato58

That's a good question and maybe I have a vivid imagination but the car does not seem to feel as tight as it use to. Then again I might just be more use to my daily driver which is an M2 and it might just be a bit better handling car? The 997 seems to have more "float".

JG 996T

Could be motor mounts are shot. Or top mounts. Not necessarily dampers.
bilstein used to rebuild for a nominal charge. I think they stopped that practice

pressure ratio

Especially since I would bet you can order your Tractive coil overs with spring rates suited for what you are looking for in performance and comfort. I bet if you call TPC and ask them questions and tell them your goals that you will get some honest and real-world experiences. I mean they didn't bash the B16 set up. They know for many that it will be just fine for the cars intended use and budget.

I was in my buddies 997.1 Turbo for three days for a rally. He has the Tractive coil overs, DSC controller, and upgraded bushings & arms out back. The car was very comfortable to be in. Not harsh at all. This was on some not so great roads in Wisconsin, Illinois, and Iowa. It definitely was flatter while turning, braking, and accelerating than my stock suspension Turbo with a DSC controller. In non-Sport mode, I think they were just about as comfortable.

Also, people seem to not bat an eye at a five or six thousand dollar exhaust when it comes to improving over stock. Yet suspension is a very complex and important feature on a car. Just like tires, they are always working for you. A well designed and tested system can improve performance, just like an exhaust car for your motor. Yet people like to save money on tires and suspension components. I get it, I like to save money too. Some times compromises must be made. It just depends on your goals for your car and budgets. I just think suspension and tires usually don't get the consideration they should in many cases. Just my opinion of course.

Tom@TPC Racing

We do offer custom spring rates with Tractive coilovers. The popular spring rate choices are:
60/110 (336/616 in-lbs) Similar to factory GT2RS. Excellent road comfort, very good on twisties. Since these springs are relatively soft they pair well with stiffer sway bars.
60/120 (336/672 in-lbs) Increased rear spring rate good for tuned ECU.
60/130 (336/728 in-lbs) Another increase in rear spring rate increment good for bigger turbos, IC's, more aggressive ECU tune.
70/130 (392/728 in-lbs) Sporty yet comfortable street ride.
70/140 (392/784 in-lbs) Sporty front end feel with increased rear rate for tuned ECU.
70/150 (392/840 in-lbs) Sporty front end feel with increased rear rate for bigger turbos, IC's, and tuned ECU.
100/150 (560/840 in-lbs) Good street ride, put a sets Hoosiers on and can hang with Cup cars in HPDE events.

I'd like to point out that the rear weight distribution of the car "soaks up" the rear spring rates so don't be afraid of the higher rear rates, especially if the car has more effective rear wing. For example, on my 997 GT3 street/track car I started with 60/110 four years ago, then up'ed the springs to 70/130 shortly after, ran that for track seasons, then up'ed them 100/150, last year I up'ed them again to 120/180. The street ride is still decent and killer on track.

Tom@TPC Racing

For reference, I tested B16 997TT springs rates to be 290/665 in-lbs. In my humble personal opinion, these are on the softer side of the selection range for aftermarket coilovers and relative to the nominal weight of a 997TT, but that's just the personal opinion of some guy who works for a race team and an avid track driver. So someone like myself is absolutely not the targeted audience of the B16 product. If they did increase the spring rate they'd probably have sold less volume over the decade. Nonetheless, B16 remains to be a very good value for replacing aging OEM PASM shocks featuring mildly stiffer than OEM springs and adjustable ride height. Those who have B16 then later on added DSC have experienced how the increase in damping force can claim the softer spring oscillation(bounce) to the weight for the car. Same goes for B8 with drop-in lowering springs.

DiegoR

What is the DSC module you talk about? Could you let me know more details?

Thanks

ShatterPoints

I'd like to point out that while the spring choices are good they result in fairly high ride frequencies which can remain comfortable on the street but do add stiffness. Which is not the same as harshness. The more force the dampers generate + the rigidity and other reinforcements of the chassis the more harshness is transmitted... Regardless of the rear's ability to "soak" bumps.


I would agree with this as well, I went 50/90 or ~286/514 which gives me 1.96hz front and 2.18hz rear which is right on the upper edge of sporty/GT and the lower end of performance/ track oriented. I went with this because I DD my car and Austin roads aren't the best. If I was in say SFL or wanted to track the car more I'd have gone slightly stiffer on the springs and targeted 2.1hz FR and 2.5hz RR. I think it is also important to note that body control with springs on the softer side does lean towards shocks as the primary method but the overall roll couple matters the most, which is where the sways come in. With the correct damper settings you can achieve fast settling regardless of spring choice. You just want to make sure you give yourself the ability to achieve that.

MoeMonney

Look here: https://www.dscsport.com/porsche/#997

nzskater

This is really interesting. Based on this I'd go for 70/140 or 70/150 as I don't often DD and love a decent B road run or track day. It makes me wish I could justify the spend on these...

Tom@TPC Racing

Generally when shocks are worn out they lose most or all of their damping resistance. The best way I can describe how worn shocks feel is the following: lack of control over bumps or "crashing" over bumps, lack of road feel all the time. Or leaking oil externally.
An experienced mechanic and very often the car owner will be able to detect these symptoms on badly worn shocks. When shocks are badly worn these symptoms become very apparent, like driving with almost zero tire pressure!

Fun fact, on the extreme side of things, the fleet of 991 Cup cars that we race in IMSA Cup Challenge we dyno test shocks regularly, same as pro engine builders/suppliers for racing series dyno test engines regularly to ensure there's no degrade in performance or within a certain performance tolerance. When a shock loses a few percentage of its original damping force its gets rebuilt or replace. This is for use in a competitive spec racing series. Again, this is an extreme practice, completely overkill for road use, HPDE, and open track days.

For "general" usage, a shock would have to lose 20%+ damping force for the symptoms to be detectable by driving(in non-racing environment). Another data point is each Tractive shock design is tested to 18.5 Million continuous stroke cycles in a 400F degree dyno room. Afterwards it must be within 8% of its original damping value before the design is approved for production.

Tom@TPC Racing

Good point. Another way to phrase this point is "more feel" for the road, but not to be characterized as uncomfortable nor harsh. My opinion is that this "sportier" feel is partly attributed by the spring rate and partly attributed by the spring design. See pics below.


The spring design found on most coilovers is narrow-diameter, linear-rate. Same design used on factory GT2/GT3/RS road cars and factory race cars. This is a common design among prominent brands of springs for high-performance and racing applications.



The factory non-GT road cars use a wider-diameter, conical-shaped, progressive-rate design that reduces the road pavement frequencies. In Layman's Terms, it numbs the feel in an effort to improve comfort for touring.



Here's the two designs side by side.

ShatterPoints

Springs affect ride frequencies no matter the design. Tires, shocks, sway bars etc all have a spring force and on paper all have to do with the big picture. The spring shape would only really affect deflection and not enough to make large changes to frequencies. Linear vs progressive DO have design differences which change things up a bit. Linear springs will always have the delivered stiffness (road feel). Progressive springs will have a range of stiffness based on coil engagement through the sweep/ movement of the spring, going from softer to stiffer. Something people do not talk about often is the choice of bump stop as well. Most street car and non race aftermarket options tune the dampers to pull the car down onto the bump stops which result in an infinite spring rate.

So the design considerations I would say a consumer should or would want to have are:
1. Build quality
2. Do you want Linear or Progressive? (driving preference dependent)
3. How stiff (how much road feel) do you want? (driving preference dependent)
4. Is the spring choice matched well with the shocks/ dampers? (you would need damping values + force vs velocity graph etc in order to make the decision)

DiegoR

Thanks! Sounds like the fix for the B16 damptronics harshiness they have. I just don't know where to find a replecment front (main) coil spring) for one damper that has a broken coilspring. If i could find a coilspring to replace it then i will buy this module

Tom@TPC Racing

Let me know the part # of the spring. I may have a new one in my stash.

DiegoR

PM sent Tom