Mikey B

I recently purchased a 993 TT. Before taking delivery I asked the dealer to change the springs to lower the car to to the ROW height. It turns out he put Eibach springs on the car which I believe lowered the height more than the factory ROW springs would have. Upon further investigation I also learned that the ROW 993 TT's had many suspension differences other than just the springs. Can anyone shed some light on this for me? Is it true that the springs should be matched to the shocks and if so, have I adversely affected the handling characteristics of the vehicle by going aftermarket and not factory? The reason I am asking is that car does not feel as rock solid as I would expect at speeds of 100 mph+. This is surprising to me given that these cars were designed for autobahn cruising at speeds of 150MPH+. The car feels a little skittish at high speed and does not inspire the confidence that my '02 BMW MCoupe does for instance. Perhaps it is just me and I am not accustomed to the car, but I would love to hear other peoples comments.

md11plt

Hi Mike and welcome!

First of all, there is an unwritten rule that no one may post questions unless there are pictures of the car you are asking questions about. I’ll let that go for now but we will all be expecting those pictures soon.

In the 993 DIY section, there is a thread about suspension install. It has a lot of info about springs and ride heights. I think most would agree that your shocks, regardless of miles, are shot. Most would also agree that you need to match springs with shocks. Most aftermarket springs are too stiff for new stock shocks let alone 10 year old shocks. You might go on to the Eibach web site and make sure you got turbo springs (look for part numbers on the springs). N/A and turbo springs are not interchangeable due to different weights and distribution.

Lastly, alignment will play a big part in how you car feels. Do a search and get an idea of what others are running. The lower springs will require a new alignment. If this was not done, that may be the majority of your problem.

Pictures.

Tom

Mikey B

Hi Tom,

Thanks for explaining the rules to me I hope you enjoy the photos...

The car was in fact aligned by the shop that installed the springs so that's not it. The springs appear to be Turbo Eibachs although the last 3 digits of the part number don't match. Perhaps they are an older version, I will have to investigate further. How can I tell if my shocks need replacing?

md11plt

Now that’s what I’m talking about!

Like I said, most would agree that your shocks are toast due to age. Do a search on shocks and you will find a days reading. I am happy with the PSS9s I got from Viper Bob, but since you have already sprung for springs, you might just want some Bilstein HDs. These will also allow you adjust the ride height. Remember the alignment.

chris walrod

Welcome to Rennlist !

First of all, just because the car was aligned doesnt mean your trouble isnt related to alignment. As you'll find searching archives, you'll notice several folks complaining of high speed instability just after suspension work, and subsequent alignments.

One thing to quiz the place that aligned the car is about kinematic toe settings, and their method of doing so?

Are you shocks original? If so, they are done.

Check the cheap things first -- tire pressures -- set them to 36F and 38R (cold) -- go for a drive and feel the car out.

pstoppani

Yes, generally, you want springs and dampers to be a matched set. Nothing wrong with going aftermarket, especially since you'd never want the stock dampers ever again (even new ones), but you need to make sure the springs and dampers are well matched.

If you are interested in a close to stock ROW setup, www.carnewal.com make a nice setup which uses the ROW springs and matches them to Bilstein dampers; they also include the rear matching swaybar. (Go to the Suspension sections then P93 Turbo section and select the "Euro M030 w/ Bilstein HD shocks" item).

I think it is important to realize is that "skittish" to one man is "responsive/alive" to another. So, it's a bit relative. I'd say the 993s are move "alive" than an MCoupe for sure.

However, "skittish" handling is also commonly the result of alignment.

Steps I would take (as others have suggested):

- if the car has stock dampers, replace them with something better
- if replacing dampers/springs, decide what your goals are. If you mostly want to keep it close to stock, then the carnewal.com ROW kit is a good choice. Others, like me, prefer the PSS9 suspension. There are others to choose from.
- check your tires. pressure? sizes? I've noticed the car feels much more skittish on some tires; most skittish with wider front tires than stock (225's).
- whether you change the suspension or not, find a reputable Porsche alignment shop and tell them what the car does and what you want it to do. These cars are EXTREMELY sensitive to alignment settings, so you are best off discussing it with the shop. Again, if sticking with mainly a stock like setup, tell them you want a stock/street alignment.

Mikey B

Hey Guys,

Thanks for all the input. You mentioned not to go for factory dampers even new ones... Why not? Aren't the factory dampers properly matched to the rest of the suspension? It would seem to me that for street use and highway cruising the factory ROW setup would be great considering that these cars were designed for the autobahn. Or is it that newer design dampers are simply better than what was available 10 years ago?

pstoppani

The factory dampers last about 30K miles; for the money, you can get much better dampers.

Steve Weiner-Rennsport Systems

Mikey:

Factory shocks are German-made Monroes and are of very dubious quality and are well known for a relatively short life (about 30K). Shock valving should always be matched to spring rates for proper handling and ride quality.

There are much better alternatives depending on what you do and how you drive your car.