Dear all,

I’m a new member here and I would like to share some of my knowledge and experience if somebody is interested. It is up to the reader as usual. I also would like to apologize for any errors when it comes to language then English are not my mother tongue. This is my first posting and I hope that some members will find it interesting.
I have a 997GTS cabrio MY 2011 and I do some 5 track events and some 5 slalom activities all with Porsche Club Sweden. I really like my car but there was obvious shortcomings concerning suspension (soft), turn in capabilities, body roll, stability when braking heavily from high speeds (150 mph +) and I was not that excited bythe ride height and stance either. The cabrio is only delivered with standard chassis from Porsche and equipped with standard tire and not R-compound. I keep the same pace as some GT3’s but I would like to catch them. If you only is interested about lowering your car to get the looks you should stop to readhere. Note, a US car have a little bit higher ride height than a Rest of the world one because of US requirements for pedestrians and bumper height.

I have spent a lot of time on different forums, talked with professionals etc so herefollows my story. The thing was that whoever I talked to wanted to sell their equipment. Nobody really knew and there was a lot of bull****. Therefore I decided to find out and not spend 3/5/7/10 K on useless parts.
The car was standard cabrio with PASM suspension. So let’s start from basics. For you that have the basics you can skip this part. (Following is for 2WD with manual gearbox. 4WD and PDK have different settings)
Porsche delivered 997.2 (not GT3 models included) with 3 different suspensions. Standard suspension that we can label “S” have the highest ride height and is not equipped with PASM that is Porsches active suspension management that is adjustable dampers that could beset in two positions by driver by pushing a button. These cars have a springrate equal to 27N/mm front and 43N/mm rear both linear.
Next level is the cars delivered with PASM suspension (adjustable dampers ). These cars have a ride height that is 10 mm lower than then “S” one. A normal misunderstanding is that it is the dampers that makes the ride height lower when the PASM button is engaged but on the contrary these cars are delivered with different spring that are 10 mm shorter. The PASM button just makes the dampers harder and does not influence the ride height. Let’s label this suspension “PASM”. These cars have a spring rate equal to 33N/mm front and 56N/mm rear linear.

The third suspension that these cars can be delivered with is the Sport suspension (on Porsche language M030). It includes PASM and has a spring that is additional 10mm lower that means that is 20 mm lower then “S” suspension. Let’s label thisone “SPASM”. The spring ratings are 36N/mm front and 65-95N/mm rear and they are progressive in the rear and linear in front. The progressive spring is “soft” initially but becomes stiffer when compressed compared with the linear one that have the same rate all the way. As a reference a GT3.2 have 49N/mm front and 115N/mm rear both linear.
My car was delivered with the PASM suspension and I found it weak, especially when tracking and especially in compressions where it bottomed out. In corners and slalom I had turn in weaknesses and problems to reach Apex, the tires was shredded on the outside shoulder due to lack of negative camber (standard it isdelivered with 0,4 degrees negative camber front compared to a GT3 that isdelivered with approx 1,5 degrees negative camber) The more negative camber you have the more surface contact the tire have during cornering. On the negativeside is the tire wear. The more negative camber the more tire wears on the inside of the tire. It is a compromise. A standard Porsche with PASM suspension could be adjusted to get approx 1 degree negative camber without putting new parts on it. That is to less for tracking. A GT3 have approx 1,5 degrees negative as a compromise taking the tire wear in mind. After talking to Michelin they says that max negative camber for a standard tire is approx 1,5negative. If exceeding that you start to lose grip again. An R-compound cantake up to 3 degrees negative but most seriously tracked GT3 run about 2,4degrees but with extensive tire wear. Sufficient negative camber is a must for good turn in at entry, mid and exit of corner.

Please see tables below from Porsche AG service literature, where they express camber in degrees and minutes.There are 60 minutes on onedegree. My car have -25 minutes that makes 25/60 = 0,4 degrees. Next table is for the GT3’s that have 1 degree and 30 minutes equals 1,5 degrees. (RoW=Rest of the World)





The rear camber is almost exactly the same on a Carrera or GT3RS so nothing to discussabout that.
My next problem was body roll. The original swaybars are not that stiff and non adjustable.The standard sway is a weak piece of metal. An adjustable one makes it possible to controlbody roll and understeer/oversteer so the the sway is more critical to turn in and handling than anticipated.Less understeer – soften up the front sway as an example.

Let’s make a small conclusion now. The Porsche is designed and manufactured to be safe.With 65% of the weight on the rear axle it have a basic construction that promotes oversteer. Therefore Porsche have safeguarded themselves by delivering the car with almost no negative camber and swaybars that promotes understeer to make it safe when going to the shopping mall but not optimal for tracking events.The GT3 on the other hand have settings that promote tracking and are hopefully purchased by persons with driving capabilities.
I also hada problem during heavy braking from high speeds. After discussions with severalpersons their conclusion and experience is that the rear toe design are less than satisfactory from factory. The Porsche is delivered with toe-in both frontand rear. Toe-in is expressed as a plus (+)

In the rear the toe varies. The toe links (one on each side) have rubber in both ends and the adjuster for the rear toe is an eccentric adjuster covered in rubber. That means that you fix a toe when you do your alignment. That is a static one. Then when you drive the car the wheel starts to move during acceleration or brakingand the forces that appear due to all rubber in the bushings and adjusters. The toe goes toe-out and back toe-in all the time depending on the rubber andacceleration/braking forces. This makes the rear end unstable and it is something you would like to prevent. Even the GT3’s have toe links dressed in rubber.Only the RSR have real ones with ends made of metal.
Another issue is that when you lower your Porsche the original toe links can’t be adjusted to a level where you want it. You will end up out of tolerance so a new to link is a must also for alignment reasons.
So here Iam a little bit wiser. Now I started to think about the features I wanted.

- Track competent
- Possible to drive over speed bumps and up on drive ways without problems
- Nice ride, not GT3 stiff, then I use car daily
- Nice stance and drive height
- Reasonably priced parts
- Parts that are weather sealed to avoid dirt and water destroying them
- If possible Porsche genuine parts

It will never become a GT3 and that is not the intention but I would like to have the car better track oriented and not destroy the day to day driving. A compromise.
I understood that I can spend a fortune on shocks but when the remaining parts are weak it will not make anything better. It is like a chain, all parts have to be included to make a strong package. I also wanted to do the chassis modifications first. To put on R-compound tires on a car with 0,4 degrees negative camber is a waste of money.

So then I started to look for springs. There are a lot of manufacturers making complete units including spring and damper but the negative side is that those parts do not include PASM functionality that I wanted to keep. The only ones I have found that provides complete units including PASM functionality is Bilstein but they are rather costly. So therefore I looked for separate spring with the intention to keep original dampers. The main aftermarket providers of springs are H&R, Eibach, Techart, GMG and probably many more. Anyhow, after contacting these different companies only H&R was prepared to share their spring rates. I knew my present ones and wanted a stiffer spring but to buy from somebody that are not prepared to share the information what they sell disqualified them. H&R have two different spring kits, one for the “S” and“PASM” chassis and one kit for the “SPASM”. The H&R springs for “S” and“PASM” have a rate of 30N/mm front and 55N/mm rear linear that are the same as standard. Conclusion; these springs only lowers the car to get the looks and you will have the same ride as standard. The “SPASM” springs from H&R have a rate of 40N/mmfront and 85N/mm rear compared to Porsche “SPASM” 36N/mm front and 95N/mm rear. I have friend that have H&R springs and they lower the car to a level where you get problems with speedbumps and drive ways but you get the looks. On the other hand the Porsche “SPASM” springs have stiffer rates and does not lower the car that much so you get problems at daily driving so I my decision became easy at the same time I could use some genuine parts. Also when you lower the car a lot and uses genuine dampers you will run the dampers in a precompressed level all the time ans with the Porsche springs i limited that problem. Also it looks like there are people out there getting problems with their H&R springs when they have a tendency to sag over time. When I started to look for suppliers etc I searched all over the place both in Europe and in US but I have to say that Ionly met two companies and gentlemen that knew what they were talking about. It was Ira Ramin at Tarett Engineering http://www.tarett.com and Chuck Moreland at Elephant racing http://www.elephantracing.com/index.htm, both situated in California. These two companies really know what they are talking about and in the end the result was great. Many others have too many ifs and buts and can’t really answer if the parts they sell will fit and if you ask them technical questions they do not have a reply but Ira and Chuck knowsPorsche and basics like the connection between understeer/camber/swaybarsettings to get a proper dialogue. Great people to do business with.

So I decided togo with the Porsche “SPASM” spring named M030 to get what I was looking for in my features. You find them here.This is the RoW edition that makes a noticeable difference to a US car. Please remember to order a lower springseat as well for the rear springs then the seat is different for the progressive spring compared to the linear. Pretty straightforward.

Next step was the camber adjustment. Either you can change to a GT3 lower control arm or you go for an adjustable camber plate. Looked all over to get what I was searching forand found it here. Elephant racings adjustable camber plate is weather sealed both in top and bottom, I believe the only one in market with this feature. Better engineered and manufactured then genuine Porsche. I selected the camber plate instead of GT3 lower control arm then I get the same functionality to a lower cost. I set the front camber to minus 1,5 degrees. Please note if you change the camber the toe-in will change as well and have to be adjusted. I have learned that you canchange the camber 0,25 degrees maximum. If more the toe have to be readjusted.

Next step was the toe links in the rear. There are a lot of simple aftermarket links that basically is a straight threaded metal bar with no weather seals. I found a beautiful piece of engineering here with all wanted features including bump steer adjustability so you can dial in the link so it matches your new ride height. Note that the link has an angled head. It’s a masterpiece. To be ordered with a locking plate that replaces the original eccentric rubber mount in chassis. With this toe-link you then get possibility to get desired static toe even with lowered springs, you get a toe-in that will not vary during acceleration/braking and you get the bumpsteer adjustability so you can get the link in parallel with the lower control arm. Also ordered the same toe link for front but it is not that critical there. The standard car have a static toe-in of 10 minutes (see table) in the rear. Then when you drive it the wheels strives outwards so you get closer to zero toe during highway use depending on all rubber. Now when my toe is fixed and all fitments are solid the recommendation was to set the toe-in to 5 minutes then the toe will be the same static and dynamic then the Wheel can't strive outwards. So I run with slight toe-in all the time.Front toe is set to 2 minutes toe-in compared with standard 5 minutes becauseof the same reason. The closer to zero you set the toe in front the better turnin capabilities you will get. See GT3 table that have a static toe of zero fromfactory.

The last step is the adjustable swaybar. Therer are a lot of suppliers but when you ask if their sway will fit bolt on without interference they often get vague. I found my sways here. I selected the genuine GT3 swaybar both front and rear. Tarett even supplies an adaptor plate so the rear GT3 bar will fit on a Carrera.2 without chassis interference. Excellent! The front bar is bolt on.
I combined them with adjustable weather sealed droplinks both front and rear. The rear sway have 3 adjustments positions and I put in center. The front have 4 adjustment position and I put it second from full stiff to avoid too much oversteer and any unwanted snapsteer initially. (Stiffest position is the one closest to the “bar” itself)

Total cost; approx 4,000USD.

The result is great. I have turn in like a GT3, firm bur not stiff suspension, the looks, stability under braking, limited body roll. A perfect compromise on a limited budget. Done some 3 track events and 2 slalom events so far. All things came together better than anticipated. Next step are the tires. The chassis is nowdays more competent than the tires and also new brake pads are on the list with better “feeling”because the speed became much higher now. Chases down the GT3’s and passes them all of a sudden. Laptimes improved some 2,5 seconds on a 1,8 mile track. No regrets!

/Andreas


After


Front with toe link, droplink, swaybar and camber plate


Rear with swaybar including adaptor against interference , drop link, toe link

 

impressive.
kudos for all the research. I'm sure many will appreciate all the time you spent researching and sharing it.

 

Wow, incredible write up. This should become a sticky. Thank you!

 

Rep power for you!

 

Thanks for posting this information! Rep to you.

 

Very good post, I learned something today.


Nice job.

 

That was a really nice write up. Every time this topic has popped up in the past, I had a hard time understanding it. Your details were very helpful. Now I'm worried that I will feel like my C4 is lacking when I take it to the track next month LOL...!!

 

Anyone know how much the X74 springs will drop the car?

 

Nice write up and a lot cheaper option than I did. You got great results for what I consider a bargain price. I took a different route with my car took the whole thing apart 24 hours after I bought it (shortest warranty in history) rebuilt the entire car from the chassis on up. Having parts made in titanium and magnesium is not cheap and getting them built to my design specs was even more difficult. It took almost two years to build my car one of the reason it is 8 years old with only 16k miles. I have always believed no car is perfect from the factory or should I say perfect for me.

 

very interesting!

 

Excellent write up. Thank you for taking the time to post. When you were researching did you determine if the M030 springs for use on the 997 were exactly the same as on the 996? I took a look at the Elephant Racing site and they list the following part numbers for both 996 & 997, which in the PET system show up only against the 996. M030 front spring set c2 - 99634353316 M030 rear springs - 99633353162 Is this what you used?

EDIT: if you could please post the height from the ground to the top of the fenders that would be VERY MUCH appreciated.

 

Thanks for showing interest

I used following springs that is M030 in Europe for C2 MY 2009-2012 ;

99734353149504 front silver/silver marking
99733353188504 rear silver/silver/yellow marking (should be 99733353173504 but replaced in PET by 88)

I see that you have a 997 C2 and this is appropriate parts for European spec. The partnumbers you provided front 99634353316 is according to PET for 996 US M030 and a little bit higher than European M030 ones. The rear 99633353162 is a European M030 so Elephant provides a mix of US and Euro spec and it is still for 996. I would go for the ones i ordered than it covers MY2009- for 997. I have the car tucked away at the moment but will measure it in the weekend for you and send you measurement both before and after

Only thing to remember is that rear spring is not bolt on. You also need a new lower spring seat then the M030 spring have a Little bit different diameter (bigger) compared with stock one in lower part due to progressivity.

Plans for coming season is that I'm fitting R compound tyres; Dunlop Maxx Race, new brake pads; Pagid RS 29 together with steel braided brake hose; Goodridge Phantom Black

Also making the front antirollbar a little bit softer by moving the droplink one position for less understeer and making the front camber from -1,5 to -2,0 degrees for better turn in

 

Thank you very much for clarifying. I had been looking at those parts on PET also, so it is great to have validation.

Regarding the rear lower mount you reference; I see the two lower washers in PET which are marked specifically for the 030 setup. (position 13 & 14 in the attached image) which have the following part numbers. Is this what you are referring to?

997 333 523 00
997 333 513 01

 

nice write up

 

Does anyone know if the sports suspension was offered in any markets in a non PASM configuration for the 997.2?

I am trying to determine if the stock NON PASM shocks would be well tuned for use with these M030 springs?

Thanks