I have a couple questions for those running PSS10 in their 997TT. I just had a set put in my turbo. I'm a little disappointed in the ride quality. It feels bouncy to compare with my stock set up. Also I can not tell the difference between the normal and sport. I told the installer that I want a inch drop but cause I didn't measure the height of my car before I can not tell if it's a inch or more. It does look low and sets nice(need spacers). I'm just feeling like it should not be so bouncy. Almost feel like its riding on the bump stops.. So how does your car ride with the pss10? How low did your car drop? Does anyone know how many inches the from the ground to the fender edge a stock turbo set so I can measure mine to compare? The shop is looking into it for me but I want to get some of your opinions.. thanks Chris

 

You can adjust the dampening and make it more stiff. That is part of the reason you got coilovers over springs.

Go back to your installer and have him adjust this for you.

 

See my other post re. the ride height measurement. I would measure for you but I don't know what the reference points are and my installer is off for the weekend. I've been told fender is not precise enough?

oc997: this version of PSS10 is Porsche 997 PASM specific, is actually called Damptronics, and does NOT have manually adjustable compression & rebound rates.

 

Cannga, the reason I was going to use the ground to edge of fender is that would be the easiest to check. I measured mine on a flat garage floor and the front fender measured 25.75-26in. and the rears measured 26.75in. I measured it in the center of wheel. If someone could do this it could give and idea how high/low my car is. Also i have stock tires with good tread....


oc997, Cannga is correct about the pss10 not as adjustable as non pasm coilovers..

 

Just re-measured: front is about 26.5 left & right; rear is 27 left, 27.5 right.

 

So you re measured from the other thread that you started? Why is it different this time? I measured like I posted earlier. flat surface, from ground to lowest part of fender edge running the tape measure long the center of the wheel..Your car is stock height with stock wheel correct?

 

I just had the Bilsteins and H&R sways installed in my car and have the same experience. "Bouncy" is a good way to describe it and like you I'm wondering what can be done about it. On the other hand, took the car for some spirited drives and the handling and responsiveness improved dramatically. Didn't measure the drop with the install, but car looks better and I did put on a set of wheel spacers (factory 5mm) to compensate for the drop. Be interested to hear what you find out.

 

Hmmm, sounds like the shock portion of the damptronics is fine but the spring rates could stand to be "progressively stiffer" like the GMG set up.

I was contemplating damptronics but this has me thinking. Based on this 'bounce' it makes me think that if you want to stick with PASM then the stock shocks with a GMG spring + sway setup might be the best and most cost effective way to go. Anyone had or driven both and compared them?

 

I'm think my car is lower then it should be but I was hope to find out from a few others what the stock car height is.. You are right about handling and responsiveness..

 

meaker,

Yes stock height, stock wheel. My front and rear stock numbers are less than an inch higher than yours so IMHO whatever the problem is, it probably is not from too much lowering, no?

meaker & rockamoto,

Just curious, what cold tire pressures are you using please?

 

Hey Cannga,

Using the on-board tire pressure monitor, the cold pressures are 33 front and 39 rear. I also had a friend who used to drive competitively take the car for a spin the car as well after the install, he had the same feedback as Meeker and me, better than stock when pushed hard, but not as composed on bumpier roads.

 

I have sat in one turbo with H&R sways and damptronics on stock wheels.. i find that the overall ride and handling has improved dramatically.. Personally i don't feel the bounciness or floatiness as compared to stock.. But his ride is very low, at least 40mm drop..

 

My air pressure is like 42 and 35.

 

Hi Guys, i need an update on that subject.

i’ve upgraded the coilover on my 997TT with PSS10, sport version ( not the comfort one)
if the handle improved right away, i feel the rear bouncing too much.

is there something to do ? Is it normal ?

Thanks for your expérience on that purpose.

 

To address suspension issues you need to know what the spring rates are first and foremost. A vendor claiming "30%" or "X%" stiffer than stock does not mean anything. The best thing to do is buy springs which you know the rates to. Suspension is extremely subjective and everyone will have an opinion on what spring rates you can or should run. It is important for a few reasons:




1. You would want to know the spring length so that at a given ride height you will know if you are engaging the bump stop excessively if at all.

2. Springs transmit stiffness and shocks transmit harshness. ALL off the shelf aftermarket (non race) coilovers have FAR too much total damping and will contribute to your bouncy ride, in terms of the harshness you feel.

3. The more spring rate you run, the less damping you need. This is because on the street you will never use the full suspension travel under normal driving conditions. If you run high spring rates AND lots of damping, you will cause the damping response to slow down and you will bounce around on the springs quite a lot.

4. Springs contribute a large portion of the roll resistance for the vehicle, followed closely by the anti roll bars. High spring rates AND roll bar changes are counter productive.

5. Springs are respond to velocity. Anti roll bars respond to displacement. Meaning shocks and springs together will affect weight transfer and driver perception far more than the roll bars will.


The rear of the 997 bounces around because the rear shocks run a very high rebound to compression ratio. This causes the chassis to be pulled into the bumpstops (jacking down) and the car wobbles at the rear and is disconcerting to say the least. When this happens and the chassis hits the hard bump stops your spring rate temporarily becomes infinite. With no more travel there is nothing for the shocks to dampen anymore. I myself experienced this issue and went through all the bushings and engine mounts to eliminate the cause. I ended up learning a great deal about suspension (specifically dampers/ shocks) and found what the issue was. I ended up getting a custom valved coilover set installed and the car is COMPLETELY different in a great way. If you are going to keep the PSS10 I would recommend getting a softer bump stop to put on the shocks in the rear. You could also get a shorter bump stop, or both softer and shorter. That will lessen the bouncy / wobbly rear but not cure it. The main potential for improvement is that the OE bilstein bump stop for the rear of the 997TT is extremely hard. A softer but equal length bump stop will help decelerate the chassis more than deflect it.