Crown

I should add that although us amateurs think of anti-roll bar as a way to, of course, reduce roll in corners, the pros would also use sway bar to influence its handling. Ask any pro and they will immediately link sway bar to understeer/oversteer characteristic.

To make car oversteer: the setting is full soft front, full stiff rear.
To make car understeer: the other way around, increase front stiffness, reduce rear stiffness.
Because the 4WD Turbo has a tendency to understeer/neutral steer, whereas at the track pro's like a little oversteer, the usual recommendation for the Turbo then is: Full soft front, full stiff rear.

In other words, the sway bar serves two functions, not one:
1. Enhance roll stiffness
2. Affect handling behavior, more specifically understeer/overteer.

What this implies of course is, stiffer is NOT always better. I mean it is to a degree, but one must keep in mind the front-rear balance. In additiion, stiffer sway bar in some way makes your car acts like it has solid axle. So stiffer sway may adversely affect road adherence.

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

Anyone with too much free time today might want to solve this puzzle: We know there are solid sway bars (H&R), and hollow sway bars (GMG, RSS). Hollow sway's advantage is it is lighter, but is this weight sprung or unsprung??!!

BEFORE you answer, take a look at the sway bar's connection again. Each sway bar has 2 connections: at the chassis bushing (sprung?) and at the coilover (unsprung?).

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

Due to the tremendous forum response and interest , I'll post the following article on this topic of sway bar. The first page, which I won't post here lest people fall further asleep on me, has some calculation of stress and a formula that's used to calculate stiffness (proportional to diameter to fourth power for solid bar, outside diam. fourth power - inside diameter fourth power for hollow). As always, "life is school"; a seemingly simple component is quite a bit more complicated on further discovery.

The bottom line, based on my very informal web survey, is that, assuming equal torsion stiffness, a hollow sway saves about oh, maybe 1-3 kg per bar over a solid one & nearly all of the weight is sprung (the drop link that connects the sway to the suspension is probably unsprung -- Good rule of thumb: if you jack the car up on its frame, any part that droops is unsprung mass.).

Some people state that a hollow bar is more likely to be damaged/broken than solid. I have not seen any report of this on any recent Porsche forum so my vote remains with a hollow sway. I still think the GMG bar is a top choice, because it's made by Eibach and was tested and tried by a company with professional Porsche racing experience.

Anyone has anything to add to this incredibly exciting subject?

http://www.whiteline.com.au/docs/bulletins/Hollow%20vs%20Solid%20Swaybar.pdf

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

cannga:

I should add that although us amateurs think of anti-roll bar as a way to, of course, reduce roll in corners, the pros would also use sway bar to influence its handling. Ask any pro and they will immediately link sway bar to understeer/oversteer characteristic.

To make car oversteer: the setting is full soft front, full stiff rear.
To make car understeer: the other way around, increase front stiffness, reduce rear stiffness.
Because the 4WD Turbo has a tendency to understeer/neutral steer, whereas at the track pro's like a little oversteer, the usual recommendation for the Turbo then is: Full soft front, full stiff rear.

In other words, the sway bar serves two functions, not one:
1. Enhance roll stiffness
2. Affect handling behavior, more specifically understeer/overteer.

What this implies of course is, stiffer is NOT always better. I mean it is to a degree, but one must keep in mind the front-rear balance. In additiion, stiffer sway bar in some way makes your car acts like it has solid axle. So stiffer sway may adversely affect road adherence.

And, if you have done your homework and gone through the other 20 pages of this thread , then you would know that the anti-roll bar is not the only determinant of roll stiffness. The other determinant is, of course, the spring rate. So then, the 2 components:
1. spring rate
2. anti-roll bar
determine the total roll stiffness of  the car.

As mentioned, as important as roll stiffness is the roll stiffness distribution; how stiff the front is in relation to the rear (& vice versa). Why is it important? The roll stiffness distribution affects how the car will handle:
more front roll stiffness = more understeer,
more rear roll stiffness = more oversteer.
Note that the difference between spring and anti-roll bar is that the anti-roll bar could be adjusted a hell of a lot faster than swapping out springs; an important factor if you are trying to adjust in a limited amount of time. I've been told that professional drivers go through this adjustment as a matter of fact before races (among many other things of course).

This is an example of how amazingly complicated suspension set-up is. It's more than just about buying the most expensive system like Moton and get the springs so it is "not too harsh for streets."
Implied is of course the overwhelming advantage of Bilstein, at least for amateur drivers: Spring rates pre-set by the same engineers who design the OEM coilover. One reason why I repeatedly state Bilstein is a no brainer recommendation -- it's like getting a Sport suspension option offered by the Porsche factory itself.

(Not all, but nearly every thing I post could also be found on this fantastic and very cheap book: http://www.amazon.com/Speed-Secrets-Professional-Driving-Techniques/dp/0760305188 ).

--

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

Revision to 997.2 Turbo's suspension below. Comparing it to this thread almost brings tears to my eyes.
You think someone at Stuttgart has been reading our complaints, or peeking at my interminable rambling & ranting on this thread?

A little surprise at the sway bar revision though. Perhaps softer sway is used since spring is now stiffer, keeping total roll stiffness the same (If you've done your homework and read through the incredibly boring posts above, you would know what that sway bar revision implies! LOL).

Regardless, those of us without the Bilstein, if this doesn't convince you... BTW, for the record, I still think you would still need Bilstein for 997.2. I suspect PAG's "marketing plan" for Turbo still hasn't changed and those astounding low 3 sec 0-60 acceleration times mean stiffer springs are even more critical to control front-rear weight transfer (squatting).

>>>>>>>>>>>>>>>>>>>>>>>>>>
http://www.caranddriver.com/reviews/car/09q4/2010_porsche_911_turbo_-first_drive_review/2010_porsche_911_turbo_page_2
The overall suspension calibration has also been revised with stiffer front anti-roll bars, a softer rear bar, variable-rate rear springs that are now stiffer, and a revised calibration of the adjustable shock absorbers controlled by the Porsche Active Suspension Management (PASM) system. Basically, these changes have reduced rear suspension movement during hard driving, with the goal of improving handling stability at the limit without compromising ride quality.

--

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

Cannga

Thank you for the wonderful treatise on the Damptronic.

I hate to ask this but as an expert on the subject would you recommend these for typical NE urban broken/repaired road usage? I'm ok with the normal PASM except for the floaty disconnected cornering. The sport setting is ridiculous at low city speeds. My track time is limited to non-existent, the last time I tracked I got a headache from all that cornering and braking and ; )

When I read everyone's critique of 997tt going soft I wonder if Porsche had me in mind when they set this up.

So how firm is firm, your scale is useful but I'm still wondering if the ride 'comfort' might improve from less floating. I guess the only solution is to beg a ride on them first but if anyone has an opinion on the comfort issue in urban road conditions I'd be interested.

Thanks in advance.

Bob

While Wisconsin is not the same as Toronto, we have our fair share of winter induced cracks in the road and pot holes, and I find the standard setting on the Damptronics very compliant and easy to live with.

Webtool2:

Cannga

Thank you for the wonderful treatise on the Damptronic.

I hate to ask this but as an expert on the subject would you recommend these for typical NE urban broken/repaired road usage? I'm ok with the normal PASM except for the floaty disconnected cornering. The sport setting is ridiculous at low city speeds. My track time is limited to non-existent, the last time I tracked I got a headache from all that cornering and braking and ; )

When I read everyone's critique of 997tt going soft I wonder if Porsche had me in mind when they set this up.

So how firm is firm, your scale is useful but I'm still wondering if the ride 'comfort' might improve from less floating. I guess the only solution is to beg a ride on them first but if anyone has an opinion on the comfort issue in urban road conditions I'd be interested.

Thanks in advance.

Bob

Hey Bob, thanks for the kinds words. First, 997.2 TT's suspension has been changed to use stiffer spring and stiffer roll bar (exactly like our mods!), so I think this is the final nail in the coffin for the worthiness of 997.1 TT's stock suspension system. I'll write more about this later but it's obvious PAG makes 997.1 way too soft. Purely a market-driven decision and obviously a mistake IMO.

My personal experience with Bilstein is only for Los Angeles freeways & streets, as a daily driver, for which I could say the Bilstein is beyond reproach. Yes it is stiffer (no way around this), but it is not bad at all. Not remotely so.
For comparison, Bilstein suspension Turbo's ride quality feels, to my not completely reliable derriere's sensor, stiffer than a Corvette Z06, perhaps similar to stock Ferrari F430, and perhaps, a little softer than Lamborghini and Ford GT.

See bbywu's response above for Bilstein experience in a place where white things fall from the sky ("Snow," they are called, right? ). Basically, while it's stiffer, I don't recall reading any "intolerable" complaint at all even for New Yorkers. I really think you are safe here.

BTW, as you mentioned, the first version of PASM Sport is a design flaw. What happens is PASM increases dampening force to increase suspension stiffness, and because the 997.1 spring is so soft, the dampening force gets jacked up to off-the-chart level. That's been my reasoning for ranting and raving anyway.
What's interesting is that I have just read in Excellence Mag that PASM's version 2 has been revised, and lo and behold, what was reduced? The dampening force.
So there is the second reason to use Bilstein, hugely better and more useful use of the PASM Sport setting.

Don't forget to change alignment also: Front negative camber like GT3, gentle front toe out. Have fun and good luck and ask questions here if you have any.

--

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

I may not be a 10/10ths guy but I appreciate what Porsche represents and I think your mods bring it closer to the original concept. I am also mods driven. I consider this to be a hobby as much as anything so thanks to you this is now a 'must have'. I had an SL for a while which had all the ride comfort anyone could ask for but I disliked it for its disconnected barge-like deportment and composure. It did however corner relatively flat and could develop considerable cornering forces until the tires gave up. Interestingly my fading memory recalls there was little difference between comfort and sport settings. I would say their suspension engineers nailed that assignment for the boulevardier genre.

I think I'll try the Bilsteins and alignment then after maybe the anti-sway bars as described.

Thank you and to bbywu also.

I find this all of this endlessly  fascinating. Keep up the good work, it is read with great interest and appreciation.

Bob

Yes, in my wife's Lexus GX470 , the settings don't change nearly as drastic as the 997 either (no kidding).
PASM version 1 is problematic because Porsche got greedy with the dampening force in the Firm setting. The suspension as a result has very little compliance left and wants to do the mambo with road bumps. There is this jittery & harsh sensation to the suspension system in the Firm setting. Curiously enough, I feel that this is a problem with all 3 variants of 997 that I've driven (GT2, C2S, and Turbo).

You could do Bilstein and alignment at the same time. But... to make the process educational, you might want to consider doing it in 2 stages. (This is the basic "rule" of suspension change btw: One change, one axle at a time.) The cost difference is exceedingly small -- about $200 for the extra alignment if you do it in 2 stages, but the lesson learned is promised to be invaluable!

Have fun.

--

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

Gentlemen;

 While searching the German site here:

http://www1.carparts-cat.com/webkat.asp?SID=0014999411143794018004&ROOT=1

I found the above KOMFORT model above.

Has anyone tried this version?

Thanks, Bob

^There has been much confusion about this. You do NOT want the Komfort model GA5-D81, it's really for the C4. The one you want is GA5-D598.

1. 008527 GA5-D598 Sportsuspension B16 damptronic

2. 008790 GA5-D581 Sportsuspension B16 damptronic

You want 1, NOT 2.

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

ahhh got it, thanks.

Updating Porsche 996 and 997 spring rate data. Source "web research" plus Excellence Magazine.
Unit in lbf/in (conversion factor 1 N/mm = 5.71 lbf/in).

Stock 997.1 Turbo:
Front: 206
Rear: 457 Linear 

Stock 997.2 Turbo
Front: 206
Rear: 514 Progressive (342 initial, 514 final) 

Bilstein Damptronic for 997 Turbo
Front: 285 Linear
Rear: 570 Linear
Helper springs 115 front, 145 rear (don't count towards rate).

Stock 996 TT:
Front: 187 Progressive
Rear: 340 Progressive

Stock 996 GT3:
Front: 225 Linear
Rear: 550 Progressive

Stock 997 GT3:
Front: 257
Rear: 600

--
 

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

Extremely interesting thread from 6speedonline. I would advise anyone who has or will install Bilstein to take a look.

Initially problem was discussing here http://www.6speedonline.com/forums/997-turbo-gt2/195985-help-bilsteins.html
Bilstein shaft was broken at the neck while car was backing up at low speed. Car seemingly had installation problem, with popping noise coming from the broken corner from day one. "Lively" discussion ensued. Some think it's defective material, some think it's installation error.

Finally, answer from Bilstein, as posted by AWE Tuning, a well known (and well trusted) tuning shop and BIlstein dealer:
http://www.6speedonline.com/forums/997-turbo-gt2/195985-help-bilsteins-8.html
I have been talking with Bilstein management as well as their engineering department regarding this thread and this failure. I've also been privy to information that was sent to other end users that have now become concerned thinking they made a bad choice on which aftermarket suspension they have gone with.

Let me state that we have been a direct dealer with Bilstein since 2005. Their products, customer service, and support have been outstanding. We are proud to be partnered with them. Simply put, they are a low maintenance product for us. Failures are something we just don't worry about.

We have also used many of their coilover kits on a variety of shop vehicles that see abuse. We stand behind them 100%.

So back to matter at hand.

Please take a look at this picture and pay close attention to the washer that is circled in the diagram. It's the 6th part from the top.




Bilstein's engineering department has informed us that failure to install this small tapered washer, that is an OEM piece, will put undue stress on the upper stem of the damper. Failure to install the washer can cause it to snap as in dkbrent's case and can also cause noises that some people hear if the front coilovers are not assembled correctly.

Now here is a diagram of how things would look if it was NOT installed correctly:

http://www.awe-tuning.com/media/misc...ingspacer2.pdf


Here are also some other tech notes that were passed to me to share with you.

- This design is Original Porsche.
- If you were not aware, Bilstein is the OE supplier for Porsche.
- Bilstein aftermarket parts are made in the same facility as the OE parts.

Some things that should be noted during install.

-With the use of a new upper strut bearing during install you may not see the spacer.
-If reusing the OE strut bearing, the spacer may sometimes stick to the OE strut therefore not being transferred the aftermarket strut.
- Air tools and over torquing can also lead to excessive stress.

Drkbrent and I have been emailing regularly. He has sent me his broken part back and I should have it within a day or so. It will be sent directly to Bilstein for evaluation.

I have also advised him to check the assembly of the side that has not broken to see if this washer is in place.

Thank you all for your patience and I will provide updates as I get them.

--
 

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

BTW, the above case is "under investigation" still and I will update when the time comes, but for now my opinion is that, all things considered, this is very likely to be installer's error until proven otherwise.

Another reminder that us humans are the weak link and the most important thing in modding is first and foremost: find an experienced tuner. You don't want to be a guinea pig when it comes to your car (or anything else in life I guess).

--

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

^^^It's now confirmed that the above problem is an installer's error. He forgot to use a washer . Again everyone please remember: No rookie is to touch your car when it comes to modding. Pick the tech like you would pick your own doctor: Experience, experience, experience.

Meanwhile, I found this totally cool table. You might want to save it. Just looking at each scenario and trying to find the explanation is itself a complete basic education in car's handling! And check the part of the table that shows you could use tire pressure (within reasons of course!) to change understeer/oversteer behavior: front low pressure, rear high pressure, just like the anti-sway bar's stiffness, to reduce understeer.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
http://en.wikipedia.org/wiki/Car_handling

--

Regards,
Can
997 Turbo + Bilstein Damptronic ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

cannga:

Updating Porsche 996 and 997 spring rate data. Source "web research" plus Excellence Magazine.
Unit in lbf/in (conversion factor 1 N/mm = 5.71 lbf/in).

Stock 997.1 Turbo:
Front: 206
Rear: 457 Linear 

Stock 997.2 Turbo
Front: 206
Rear: 514 Progressive (342 initial, 514 final) 

Bilstein Damptronic for 997 Turbo
Front: 285 Linear **** Correction: it's actually 340 ****
Rear: 570 Linear **** Correction: it's actually 565 ****
Helper springs 115 front, 145 rear (don't count towards rate).

Stock 996 TT:
Front: 187 Progressive
Rear: 340 Progressive 

Stock 996 GT3:
Front: 225 Linear
Rear: 550 Progressive

Stock 997 GT3:
Front: 257
Rear: 600

 

Recently found out from Bilstein the actual spring rates for Bilstein Damptronic for the Turbo are in boldface above -- previous numbers quoted were wrong (and actually are numbers from the Damptronic made for the 997 C2). "Not my fault."

This thread now continues here, for "Bilstein, Stage 2" : http://www.rennteam.com/forum/thread/20149686/Lucent_spring_setup_for_Bilstein_stage_2_What_steering_what_cornering/page1.html

--

Regards,
Can
997 Turbo + Bilstein Damptronic "Stage 2" ( Review ) + GIAC ECU Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )

Just spent two nights reading this thread!
Well done guys - and thanks for putting together all this great info.

 ...Placed an order for a set 4 days ago :)
Should be arriving any day now!

Great - would be good to read your impressions once you've driven it

RT Moderator - 997.1 C2S GT Silver/Cocoa, -20mm sports suspension/LSD, PSE, short shifter, SportDesign rims, Zuffenhausen collection

Thanks for all of your info!

What do you think of adding a sequential gearbox on a manual car that will see 98% of its life on the street?

http://www.sequentialshifters.com/

Sequential shifting - whoooah!
Technology has sure come a long way to have something like this fitted on a road car. I'd be interested to know how reliable a system like this is. Very interesting! Thanks for post.

PS. My bilsteins arrived on Friday (found a set for $2500 out of TX)... now I have a painful 12 days to wait before my appointment to have them fitted.

A sequential shifter has to chop some major shift time from a normal manual.

It may be the Anti-PDK weapon

Yea, I like the idea a lot. Oakley sell such a system as well..

Does anyone have experience with these sorts of shifters? (Bikes don't count ;-) )

http://www.oakleydesign.eu/sequential-gear-shift

 stay away from oakley.. Check the forums on reports on them.

They still owe me money form that crap and faulty exhaust they sold me

Just got her back, Bilsteins installed with alignment and camber settings below. Didn't really get a chance to give her a serious test drive yet, but on the drive back from the service center the car feels much more sure footed, just solid all around.

As member mentioned, the suspension closes the gap between the off/sport settings. The difference between the two is definitely muted with a more sporty bias. The car no longer squats under throttle.

Overall a definite recommendation. Can't wait for the weekend to give her a more thorough work out.

Front
Camber -1.2
Caster 7.5
Toe 0.04

Rear
Camber -1.6
Toe 0.16

PS: Thanks Stuart and the Weissach (Vancouver) team, once again unprecedented, fast service!

Mikk:

Just spent two nights reading this thread!
 

Only 2 days? I am impressed with your speed reading skill.

Regards,
Can
997 Turbo + Bilstein Damptronic "Stage 2" ( Review ) + GIAC ECU Custom Tune ( Fast as a torpedo & reversible to stock - Review ) + Cargraphic Exhaust ( Oh heavenly noise! )