those main spring rates are way too high for the OEM shocks to control

 

He is running re-valved shocks so they can handle the higher spring rates.

 

if your read his post he states NON-REVALVED OE shocks!

 

I did read quite a few of the posts but may have missed the part where they are non re-valved shocks.

I think Paul's shop had a mix up in using the non versus re-valved shocks, but I would imagine he would switch to the re-valved shocks at some point.

 

I'm sure he did, and re-valving the OEM shocks to suit is a very good idea, this is what Porsche did when they raced the 997 GT3RS.2 at the Nurburgring 24h in 2010, and if you know what you are really doing you don't have use

 

It's me

What I did on my car is 600/900 with a re-valve.

What I was trying to propose in this thread is that there might be a way, without re-valving, to try some different spring and tender combinations to work on a bumpy track such as Sebring.

On own experience, using a 600# spring initially and mistakenly, on OE shocks that were re-valved to 450#s, has shown me that the 2 settings can do a fine job at dampening a spring that is 150#s over the re-valve spec. The Soft OE setting works on the street, the Firm setting was perfect on track.

With this data point, and data from others who I have spoken to who have tried firmer springs on the front shocks without re-valving, I stand by what I have written in this tread. A 997mk2 that comes with springs close to 250/650 would have no problems running the spring rates I suggested - using the 2 dampening settings to figure out what worked better.

This tread was started with the hopes of highlighting that the stock PASM shocks, with their 2 modes, are good shocks and flexible - and with some ingenuity, there might be a way to use them better at Sebring.

 

997gt3north...I have Sport PASM suspension on my GTS....Do you know how much softer it is than GT3 PASM shocks and springs?

If I have my Sport PASM revalved and use different springs how will this work with the PASM computer program in the ECU?

 

I do not know - sorry.

See if you can see part numbers on your springs to see if you can search this way. The other thing I would do is head down, or call, your local PCar parts guy, I'm on a first name basis with all of mine, and just start pulling part numbers for your shocks, PASM computer, and springs. Then see what cars share these parts, (TT, C2, C4, GT3, etc) - this would be for information purposes - ie what do you have on your car - rates, shocks, etc - before you start changing, you have to know what you have - I'm actually interested my self what would be on your car - you should be able to find this out easily on Monday.

Should you choose to re-valve, I'm 100% positive it will work with the PASM ecu. I spent a bunch of phone time talking to a Bilstein guy who wrote 1/2 the code / did all the early development work on the controller. Effectively, in 'Normal' mode, you are riding on the shocks as is with some additional valving coming into play when various yaw sensors are put into certain aggressive ranges. When 'Firm' mode is activated, a significant amount of additional valving, basically across the board, is used. In addition to this across the board increase, and just like in Normal mode, the PASM ECU can and does add tiny incremental additional valving in small and in increasing amounts when pre-programmed 'lookup table' ranges are determined with the yaw sensor inputs (but think of these potential additional amounts as secondary effects) - the big effect is the Normal and Firm setting.

Since the shocks in your car are Bilstein shocks, Bilstein in California is the place to send them. For what is basically 100$ per shock, they are taken apart, rebuilt and valved according to the exact spring rate you tell them you want. I've already posted in my writeup my opinions but I will state again - in my opinion, the did a perfect job on my shocks - the shocks and springs are perfectly matched. In Normal mode, they are perfectly match and the car drives 'softer' - in firm mode, just like with the OE setup, increased valving is added, via the PASM ECU, and the car firms up.

As I have mentioned, given the 2 modes, you have to spend a bunch of time thinking how you should set up 'your' car as you have an infinite amount of choices. You may determine that you want the GT3/RSmk2 setup so 260/660 is your choice. I have given an idea for a potential bumpy Sebring setup - but maybe that is not for you. Maybe a 450/750 setup, just slightly more than the RS is what you want - I actually think this would be a very good setup for most people, etc, etc, etc - so many choices.


First find out what you have - then go from there.


Paul

 

997gt3north...thanks for the reply!

Speaking of yaw sensors....at Daytona over 130mph on the 31 degree banking my car goes into PSM and Drive Off Assistant FAILURE. This knocks the car out of Sport Chrono Plus setting and puts PASM into normal mode. I can't get the car back into the stiffer shock setting untill I turn it off and restart it.

I had this same issue on my 2009 and it was thought that since I was using track wheels with no TPMS that this could be an issue. Well my 2012 GTS track wheels are stock sized and with TPMS and still I got the same failure mode.

 

Interesting. I will report this weekend.
TPS are failing, some work some of the time..

 

Unfortunately, this probably makes sense. At 31 degrees, the ECU likely thinks you are in a **** load of trouble and is very likely about to deploy the airbags when the hit comes.

If you think about what Porsche has done, they have likely picked a spring rate, let's say 200/450 in your case, and then Under Dampened and Over Dampened these effective spring rates, like they would on all cars with 2 mode settings - ie the GT3s. So, this is what I was alluding to in my other post about picking what you want to do. You can do exactly what Porsche has likely done but start with higher spring rates - say 450/750 and tell Bilstein you want they dampened for 400/700 - so you too would now have an Under / Over dampened setup (Soft/Firm), or you can tell them to actually revalve to your exact spring rates (450/750) and then you would have a (Best Average Setup, Really Smooth Track Setup). In the second example, a 31 degree banking would default the car to a setup that is very good on an average track - and you would likely be in this mode anyway unless said 31 degree banked track was silky smooth.

Since I don't drive on 31 degree locally banked roads, that's all I got for now.


Paul

 

Thanks Paul.... Daytona just got repaved and it is the smoothest piece of pavement I've ever been on...freaky smooth.

Yeah that 31 degree banking is playing havoc with the yaw sensors and putting the car into a default mode. I think BGB Motorsports and Napleton Motorsports who build ou Grand Am cars and Interseries cars havea program fix for this but I believe it is uber expensive.

 

Mike, this does not affect the GT3's?

 

It doesn't affect 997.1 cars I know...not sure about 997.2 GT cars.

When I ran Daytona on my 2009 997.2S I had this same issue and so did the other 997.2S car at this event. At that time 997.2 GT3 cars where not out.

2 weeks ago there was 1 other 997.2 and it was a GT3RS and I was staying right with him, he gave me a point by in NASCAR 2 but it was wet out and we were not getting over 120-125 on the banks. He was not out in the dry session later in the day and that is when I can get up to 130 and more on the banks and thus throw these failure codes.

 

I want to guess on this issue - I'm coming up with a 50/50 fair bet.

The old 997 mk1/gt3 with just TC but no SC, like the CGT, was designed as a true off, stole the TC program from the CGT, and was written long enough ago, pre some of the CAN BUS interface stuff, that the TC was a true add on, with YAW sensors - but it was an add on. I also think that Porsche would have done some very high speed / max speed tests with the CGT on those high banked tracks that there is no way they would want something going into 'protection' mode during one of these tests - all of this is a guess.

The 997 mk2/gt3 has SC/TC, and updated CAN BUS, so maybe, the software, it would make sense from a non duplication of efforts
perspective, that the mk2 may do as the non GT cars appear to do and default to 'I'm flying off a cliff and about to crash mode'.

It only takes one mk2 at 130mph to test it out?

My 1$ is that it wont trigger the default mode