4ocious

You may remember my earlier thread “Do I really need a DSC?” Well, it turns out I do, but my TTS also required a lot of suspension work to reach that conclusion. For reference, my TTS has 40K miles.

Briefly, my TTS ride was very harsh and uncomfortable. So I bought a DSC to see if that would straighten it out. It helped but not a lot. Next, I looked at the springs that appeared to be non-OEM. In fact they were. Ok, they must be replaced too so I bought a full set of Eibach ProKits. I contacted a local highly reputable shop (RRT Racing in Sterling, VA) that I knew could replace the springs and do the alignment.

Within a day, RRT called to say my harsh ride resulted from major rear suspension problems that extended beyond springs. They recommended I immediately replace my rear PASM shocks (2) that were leaking, four (4) upper control arms with bushings, both steering knuckles, both wheel bearings and other minor parts. This, in addition to the spring replacement and alignment was not going to be cheap! OMG, what should I do?

I purchased my TTS about a year ago from Carmax and I bought their extended warranty. I asked RRT to contact Carmax to see if they would cover any of the estimated $4K in additional repairs (parts and labor). Carmax looked at the car and said they would cover the additional costs because it was a safety not a wear and tear issue. That left me owing the original shock replacement and alignment costs. What a relief!

Yesterday I picked-up my car and immediately noticed how much my former harsh ride had turned into a planted dynamic handling TTS. It was a lot smoother, there was less jarring, and it no longer felt as though it was going to bottom-out going over a bump. My DSC, new Eibach’s and new rear suspension made a world of difference and my former complaints have turned into words of praise. For those of you who doubt the Carmax commitment to after sale customer service and the worth of their extended warranty I am proof they keep their word and honor their warranty. To-date Carmax has spent over $13K to repair my TTS that is now in like-new condition and my extended warranty has more than paid for itself.

Thank you RRT Racing and Carmax!

Pclemg01

I had purchased a DSC late last fall and had not installed it until this past weekend due to weather. I agree the ride was a little on the harsh side prior to the DSC replacement. My car was stock other than FVD exhaust from the previous owner. After the replacement, the ride over normal road conditions were smoother. I have not tested the limits yet, but for me the mod was well worth it. Keep in mind, for reference sake, my previous car was a 01' BMW m roadster with koni coilover shock all around, and that was alot smoother than my porsche stock suspension.

ShatterPoints

Out of curiosity... why keep PASM and lower the car with springs? You are removing damper travel and losing a fair range of performance. DSC will allow you to fine tune what little travel you have left but you are leaving damping forces on the table...

911 Prospect

Thanks for sharing your story and that is impressive service by CarMax! Circuit City still going strong after all these years...
Question regarding your Eibach Springs. I had a car with the Eibach Pro kit (springs and shocks) and while it handled a bit better I was nervous every time I went over a mild bump. Apples and Oranges as my other car was a very high horsepower Mustang so it will naturally react differently to the springs, but can you actually drive the 911 on average roads and not hold your breath over every bump? Like many others, I would love to adjust the ride height from stock, but I'm not sure I want to compromise the quality over even smallish bumps.
Thanks in advance for your input!

MadScience

Any idea what put your car into this state in those 40k miles? I really hope that that's not normal.

Nate Tempest

Judging by how incredibly overdamped the factory 'stiff' pasm setting is, I would think you could remove some damper travel and still have ample damping to match the stiffer springs. I have read that the PASM shocks will wear more quickly with reduced travel (and this thread seems to be anecdotal evidence in support of that), but up to that point I would expect them to ride fine (if perhaps not as good as an aftermarket electronic shock like the Bilstein B6).

4ocious

I don't know if it's normal or not. RRT Racing said they thought it was premature hence the safety issues and Carmax agreed it was not normal wear and tear. IMO it may have something to do with the unknown brand aftermarket springs that were used to lower the car before I bought it. I asked for the old springs and will take a look at them this weekend to see if I can determine who the manufacturer is. Speculation here because I'm a real novice when it comes to suspension but would spring tension failure place additional stress on the shocks and torsion bars that would cause them to fail early?

bondjockey

JG 996T

Perhaps more anecdotal evidence of the havoc caused by lowering springs alone.

I have GMG springs in a box in the garage and will not install until B8s arrive.

cstyles

Ummm correct me if I am wrong but the OP had original springs on his car during this whole sh*tshow, not lowering springs. He's just added them now. FWIW, TPC Racing has high regard for the OE PASM dampers matched with Eibach springs and DSC controller. Eibach is a mild drop and is still well within the working range of the PASM damper. Of course other springs, with more aggressive drop, will not be.

There is not a single user report of PASM shocks / Eibach springs / DSC controller that has a complaint, as far as I can tell. And for the fella above re: guys with springs not taking their cars to the track... I can tell you that this setup is fantastic on the track, and for the 12 track days I already have booked this season (including this coming Saturday and Sunday), I have no intention of making any changes to the PASM / Eibach / DSC combo

cstyles

Just to clarify, are you saying the springs that came off the car were aftermarket lowering springs? Or they were original Porsche springs? I see in your later post you reference that they may be unknown lowering springs.

Glad you got the issue resolved, it was a long time coming and I am sure you're enjoying what feels like a new car now.

@911 Prospect - it took me 2 years and 25,000 km before I destroyed my front aerokit lip with the Eibach springs on Not bad in my book...

JG 996T

I said 'perhaps', and the way I read it - he had aftermarket springs. If you're good with your eibachs - glad to hear it.

Rambler_13

cstyles

Ya I think the way he worded the issue around the springs just has me confused. I highly doubt all that damage was caused by just springs though. One of my PASM shocks was replaced under warranty at under 30,000 miles with 100% stock suspension due to a leak, and I have had friends with other 997 PASM shocks also replaced for same issue.

I agree that the B8 shocks with PASM functionality are the way to go once departing from the OE dampers. I will choose B8's with PASM over coilovers when the day comes for me to replace my shocks.

ShatterPoints

Based on my conversation with TPC that is not the case. The PASM dampers are similar to every other semi active suspension. They have 2 damping profiles which operate on a % range. Something like 10%-75% total damping in "normal" mode and 15%-85% in "sport" mode. As they are only semi active each individual profile can adjust itself within the given range, due to latency in the system combined with dynamic road conditions the system has to predict what is best while not switching too abruptly between force settings so that you do not experience unpredictable behavior. The dampers as a whole are not "over dampened" most if not all factory cars are designed to be under dampened, unless you're getting something from the factory for track use where you may encounter critically dampened setups. Removing damper travel will alter how it performs period. Using the previous % ranges you end up changing the range, for example from 10-75% to 25-75%. With in that range the damping curve will be different as well, with less travel the piston and valving do not react to damper velocities the same as it would at factory ride height. As for wear that is more of a function of spring rate and how well it is matched to the available damping, usually lowering springs are stiffer than OE and as a result often do not match well with factory damper rates, you could also argue low pro tires assist in this issue as well since the tires too act as a spring to a degree.

The vast majority of people overlook ride rates when just putting springs on the car, across all cars I've owned this seems to not change much. I totally get the look cool factor if thats what motivates the majority of owners. Personally I was curious why keep the PASM dampers if the rears needed replacing AND he was already going lower. It would have been beneficial, again IMO, to have gone with a shorter damper to match the spring.