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When I got my 997 in 2010 I read this thread thru and thru looking for tips and got lots of great ones. I did get the Bilsteins and the TPC module, and then replaced with DSC coil overs because I'm close to TPC and they maintain the car. Made it at least as much better as the Bilsteins were over the stock shocks.
1. Basic Principles:
Say you have installed Bilstein and were happy at first but now want to go to the next step, firmer, stiffer, more like a GT3. What to do? Besides the first and important step of adding R compound tires, this leads to discussion of further modification of the Bilstein, stiffer springs. Note that nothing comes free and this "upgrade" WILL sacrifice comfort for handling. Anyway, IMHO, here are the steps for a "Turbo to GT3 conversion": 1.R compound tires: Don't ever underestimate the difference a tire could make. This is a key component of imitating GT3: you want GT3 handling, you need R compound tires such as Michelin Cup, Pirelli Corsa, Toyo Roxes R888, etc. No way around this. Why? Not just increased traction, but more importantly the stiffer tire sidewall that hugely influences suspension behavior (makes the car stiffer with less body roll). 2.More negative camber, -1.2 front, -1.6 rear. This means you max out the front negative camber, and keep rear camber same as factory setting of -1.6. 3.Stiffer and adjustable anti-roll bar. For adjustment of understeer/oversteer, body roll, and ride comfort. Combine this with rear Tarett Drop Link Here for even better feel of tightness and control - you will love it, guarantee. 4.Bilstein basic or with stiffer springs: A basic Bilstein with R compound is outstanding and already transforms your Turbo to something that is very fast. However, if you want to take the GT3 in tight corners & curves, and if you want to duplicate the subjective feel, IMHO even stiffer springs are needed. This is where the beauty of using coilover comes in: it's designed with that in mind, the ability to change springs to your need and taste.
2. How to change springs for Bilstein:
Keep in mind there is a limit as to how much you could increase the spring rates. Per Swift, the normal rule of thumb is that you can go up to +/- 4 kgf/mm (224 lbs/in) in additional/reduced spring rate from the coilover's stock rates. What this means is that since the Bilstein starts at 336 front/560 rear, you could go up to about 564 front and 784 rear without having to re-valve your Bilstein shock absorber. For reference, a 911 professional race car would run in the 1000-1200 spring rate range (anyone pls correct as needed).
First some basic technical information for the Bilstein springs - they are weird in that their ID is 70mm, not industry standard and making it difficult to find replacements. Second, don't worry about the helper springs (in the Bilstein these do not contribute to the rate; they are "helper," not "tender" springs), all you need to change are the main springs:
Front: Helper 80 lb/in spring rate, 60mm length; main 336 lb/in rate, 151.5 mm length; ID 70mm for both helper and main springs.
Rear: Helper 80 lb/in rate, 60mm length; main 565 lb/in rate, 200 mm length; ID 70mm for both helper & main.
There are two places you could get springs that fit Bilstein: Hypercoil and Swift Springs. The springs you want to look for is 70mm ID, 6 inches long front, 8 inches long rear. The process is very easy and cheap - labor should be around 300-400 per axle.
Swift Springs: http://www.swiftsprings.net/products...r-springs.html
Hyperco: http://www.hypercoils.com/PDF/70mm.pdf Currently my car is set at 392 front/600 rear - versus Bilstein's 336/560. The front spring is Swift Spring part # Z70-152-070: Internal Diameter 70mm, free length 152mm=6 inches, spring rate 7 kgf/mm=392 lbs/inch. (Previously # Z70-152-080 spring rate 8 kgf/mm=448 lbs/inch) The rear spring is Hypercoil part # 8P0600: Internal Diameter 70mm, free length 8 inches, spring rate 600 lbs/inch.
The springs are cheap and directly replaceable for the OEM Bilstein springs. If you are into more advanced level of suspension tuning, the springs are the place to play around and have fun with. It's an easy process and the change will be easily noticeable.
The stiffer springs make steering response more immediate (no free play) and precise. Soft/mushy steering IMHO is one of the biggest problem of the stock Turbo compared to its GT2/GT3 sibling. The car is definitely on the firm side but has extremely fast reflexes and minimal body roll. This is the best all around car that I've ever driven: for me, perfect mixture of handling vs. comfort, precise steering, precise suspension response. I love every second that I am driving my Turbo baby!
As I get older, I am slowly backing up the aggressiveness. This week I had the front spring rate lowered to 392, from 448, so now the car is more or less at the "often seen/classic" rate of 400 front/600 rear for this rear engine car. The GMG sway bar setting is changed from soft front + medium rear, to soft front + soft rear.
I remain happy as a clam lol with the combination of Bilstein Damptronic, GMG Anti-roll Bar, and Bridgestone RE 71. It brings the 997.1 Turbo to what I consider to be theepitome of a sporty daily driver for me: firm but still comfortable, much more precise and tighter than stock especially the rear. Car corners as if on rails, with very little body lean, yet the suspension is still compliant. I have a newer car (BMW V8 M3 modified with Ohlins) but the favorite by far remains my beloved Turbo.
For those in Southern Cal, a shout-out to West End Alignment in Gardena, in case you don't already know about this shop. West End is VERY well known among Porsche enthusiasts, and actually is located close to where I live, but this is the first time I've used the company.
If you are a seasoned veteran, Darin (shop owner) would of course set the alignment to your request, otherwise he would ask what sort of use or expectation you want from the car and recommends a setting. In my case (sporty driving on canyon roads), we settled on: Front: 1.35 neg camber, 1/32" toe OUT. (Basically the highest negative camber possible in my stock car with Bilstein.) Rear: 1.65 neg camber, 3/32" toe in.
As a side note, the alignment job thankfully corrected my steering wheel being just a slight hint off center, which is probably not noticeable by most people but bothered me, and my OCD, just a little bit.
Hello guys, I just bought a 2007 997.1 Turbo, and tomorrow I'm going to put 4 new tires (Michelin PS4S). Should I still use these alignment settings as reference? I will not track the car, will only drive in on the weekends on fast back roads and highway trips.
Hello guys, I just bought a 2007 997.1 Turbo, and tomorrow I'm going to put 4 new tires (Michelin PS4S). Should I still use these alignment settings as reference? I will not track the car, will only drive in on the weekends on fast back roads and highway trips.
Thanks!
Yes but to make it interesting/informative I would drive the car with new tires at present stock alignment for a few weeks or couple hundred miles (if not a daily driver) just to get used to what it feels like, then after that have the alignment changed. That way you know what it does.
Besides cornering improvement, the steering response will be sharper/quicker. I think you would like that also. Make sure to use legit shop for alignment change. Good luck and hope this helps.
Yes but to make it interesting/informative I would drive the car with new tires at present stock alignment for a few weeks or couple hundred miles (if not a daily driver) just to get used to what it feels like, then after that have the alignment changed. That way you know what it does.
Besides cornering improvement, the steering response will be sharper/quicker. I think you would like that also. Make sure to use legit shop for alignment change. Good luck and hope this helps.
Thank you.
I will follow your advice and use stock alignment for some time then :-) I would like the car to be as stable as possible as I do majority of highway miles, and some back roads attack on Saturday mornings.
I will follow your advice and use stock alignment for some time then :-) I would like the car to be as stable as possible as I do majority of highway miles, and some back roads attack on Saturday mornings.
Cheers,
Mario
You're very welcome. I've had the same settings for 10 years plus now. I drive a lot of highway miles too; the setting is very stable for me and tire wear remains good. Nothing exceptional except the car feels more sporty on weekend drives.
You're very welcome. I've had the same settings for 10 years plus now. I drive a lot of highway miles too; the setting is very stable for me and tire wear remains good. Nothing exceptional except the car feels more sporty on weekend drives.
Hello Cannga,
I installed 4 new tyres on my 997 Turbo and got an alignment (result attached bellow), the car feels nice but the steering gets pretty heavy under load (fast cornering), it's not unbearable but compared to a normal or modern car it required a lot more effort. Is this normal? Maybe a result of the increased front camber? I would like to reduce the weight of the steering, if possible.
I installed 4 new tyres on my 997 Turbo and got an alignment (result attached bellow), the car feels nice but the steering gets pretty heavy under load (fast cornering), it's not unbearable but compared to a normal or modern car it required a lot more effort. Is this normal? Maybe a result of the increased front camber? I would like to reduce the weight of the steering, if possible.
Thanks!
Sorry but I am no expert to try to diagnose anything, let alone over the internet. I could only tell you that there is not such an increase of effort in my car. If it were me I would ask my tuner to test drive the car.
Just curious - the final front camber -0 degree 58' left and 0 degree 59' right. That doesn't sound like much of an increase over stock no?
Sorry but I am no expert to try to diagnose anything, let alone over the internet. I could only tell you that there is not such an increase of effort in my car. If it were me I would ask my tuner to test drive the car.
Just curious - the final front camber -0 degree 58' left and 0 degree 59' right. That doesn't sound like much of an increase over stock no?
Yes it's around -1º degree on both front wheels, it's not a big increase over stock, but it was a big increase over what it was before the values were all over the place.
Yes it's around -1º degree on both front wheels, it's not a big increase over stock, but it was a big increase over what it was before the values were all over the place.
Got it. I would like to add that if anything adding front negative camber and especially the slight front toe out improves turn-in response and makes my car feel "lighter on its feet," more eager to turn. The steering responsive is more sensitive, subjectively faster, and most definitely does not require more effort. Hope this helps.
Ti can you please tell me what wheels you are using and what did you need to do when going to a 19" rim as far as the speedo. I want to upgrade to a larger diameter wheel. Thanks
Ti can you please tell me what wheels you are using and what did you need to do when going to a 19" rim as far as the speedo. I want to upgrade to a larger diameter wheel. Thanks
Hi not sure I understand your question. The stock wheels of 997.1 Turbo are 19 inches in diameter and my HRE P40 are also 19 inches. The P40 are direct replacement for stock wheels, so there is nothing to do.
If you are talking about going from stock 19 to 20, then sorry I don't have any experience. If you post question on forum or ask HRE or tuner, there should be good suggestions.
I am slowly backing up the aggressiveness. This week I had the front spring rate lowered to 392, from 448, so now the car is more or less at the "often seen/classic" rate of 400 front/600 rear for this rear engine car. The GMG sway bar setting is changed from soft front + medium rear, to soft front + soft rear.
