997.2 GT3 track car suspension

[jimmyslr]

MaxA said:

I'm planning to fit the TPS DSC PASM module to get the best out of my B16 Damptronics, as I plan to keep the car a road car. If I ever need to replace the suspension, I'd probably look at Ohlins.

A track car, however, should be at another level, and I would be looking for something a bit more adjustable and exotic, not just a set of KWs or some such. And of course you'd need to think about all the rest of the suspension, the arms, joints and bushes, ARBs etc.

I'm interested in this if it really is plug and play, plus easy to swap out. Did you find any useful sources of information or comment? It seems US-centric thus far, with Parr as the UK distributor but not much information.

[Steve Rance]

A better option would be to sell the RS for a lot, buy a 996 cup for not a lot and pocket the difference. They can be road registered resonably easy - a 997 cup not so. If you particularly want to keep the RS, I'd go cup rose joints/uni balls. i'd maybe keep the final drive as there as not be a huge gain using cup final drive on a ring only vehicle. Fit a cup diff and a decent set of thick piston dampers with matching spring set specifically for the ring - which will be soft by race standards. If you go KW, the clubsport version is very good value as it shares the valving hardware and internals with the much more expensive Race version. If not, try the usual high end manufacturers; JRZ, Moton, Ohlins - the high end kit.

The problem is that you would end up spending a lot of money to devalue a car that still would not be as quick as a cup car because it will be too heavy. I think, what you are looking for is a cup car though, and its a lot cheaper and easier to buy one than to convert an RS into one - but if you ave the inclination and the budget, it can be done.

[bryce86]

I have considered the Cup car route but the road legal set up as well as the general set up to run one does not appeal to me so much. I've yet to hear anything good on the cost of ownership / running side of things as well. The all out no nonsense certainly appeals but perhaps all a bit too serious for non competition. You've said yourself Steve that the closing speeds amongst the road going stuff can be scary as well as frustrating just to try and tie two consecutive corners together without me getting in the way with my road going GT3!

The KW Clubsport - maybe Manthey or other - seems to be quite appealing. A nicer price point than the others that are more than likely beyond my capability. The extra three grand could buy me some nice rose joints and kinematics etc come the time.

[Steve Rance]

I understand your sentiment. Interestingly there was a gen 2 3.8 RS at Silverstone earlier in November which was similarly modified and very quick on intermediate race tyres. The car had the same mods as my earlier post and on passives but i am unsure of the manufacturer of the damper. Mike Wilds was driving it for a customer. He said that it was lovely to drive and almost as fast as a cup car.

[isaldiri]

jimmyslr said:

I'm interested in this if it really is plug and play, plus easy to swap out. Did you find any useful sources of information or comment? It seems US-centric thus far, with Parr as the UK distributor but not much information.

yes it is just a plug and play from the pasm control module at the passenger footwell to be replaced by the DSC sport one.

[Harris_I]

bryce86 said:

The KW Clubsport - maybe Manthey or other - seems to be quite appealing. A nicer price point than the others that are more than likely beyond my capability. The extra three grand could buy me some nice rose joints and kinematics etc come the time.

I've gone the KW Manthey route on a 996 GT3. In theory it's supposed to be a 'Ring specific kit, but in practice I found it to be not a million miles off the pace of a 996 Cup on more expensive Sachs dampers on a medium to high speed smooth circuit. (Albeit with the road car on various Cup-style mods, so a reasonable degree of equalisation across the two cars).

So whilst it's supposed to be a compromise, it surpassed my expectations on track.

On another note this sounds like a fun project. The journey is half the reward.

[gtsralph]

jimmyslr said:

I'm interested in this if it really is plug and play, plus easy to swap out. Did you find any useful sources of information or comment? It seems US-centric thus far, with Parr as the UK distributor but not much information.

I recently bought one directly from TPC as I could beat the Parr price because I already had US dollars.

Fitting is easy, assuming the connectors are not too tight but all covered in Tom and Mike's videos on the DSC Sport web site/youtube.

(BTW I don't have a GT3 - see below)

I ran back to back tests at Silverstone on Goldtrack's October 24 day with Chris Franklin (Centre Gravity) and Gary Marsh ([e-mail]). We started with the DSC installed and then with the OEM PASM box. On road it is more compliant and on track it reduces initial dive on braking and stiffens loaded front on cornering and softens rear dampers through exit (amongst several other things).

I think the reason it is more compliant on the road is that it runs Bilstein dampers from full soft (1500ma) to 400/500ma hardest whereas (perhaps) PASM might not run to 1500ma.

It operates through calibration tables (maps) defining a range of 31 data points for damper stiffness from soft to hard (front dampers are set to the same values [in ma] across the axle, similarly rears) with separate maps for Normal and Sport.

These damper calibration maps are accessed by other maps covering e.g. longitudinal and lateral G-force, first 1 second of braking, and acceleration which define which of the 31 data points to use for each damper.

So an illustration,

1. braking straight hard for a corner, the Braking map operates above a specified speed and brake pedal force thresholds for 1 second, and then

2. entering and through the corner the G-Force map takes over and stiffens the loaded front, and exiting softens the rears to help power out depending on the G-force loadings.

My car is a 981 Cayman S PDK with an Ehresmann 991 Carrera 3.8L engine and fully adjustable suspension fitted by Centre Gravity. It certainly helps road comfort as the car has quite stiff Eibach springs. On track, it makes a noticeable difference in braking stability and getting on power earlier out of corners.

I am at Goodwood December 3rd and Silverstone December 10th to gather some more experience. Chris Franklin and Pete have got a day off and will be at Silverstone on the 10th so come and have a chat if you are at either day.

I am loaning my DSC unit to CG over winter so Chris can understand how to optimise maps for particular requirements to best meet the needs of his clients.

[nigelonich]

bryce86 said:

Dedicated track car, not for road use ever, at the Nurburgring.

Would you change the suspension, to what, and why?

For my 996 GT3 Clubsport only really used at the 'ring nowadays I actually tried to spend lots on high end Ohlins but the UK Agent convinced me that Ohlins Road & Track were perfect for this track. I was initially put off with how affordable they are (£1600) for the GT3 and I am happy to say that the quality and the handling has been great so far as you would expect from Ohlins.

I had Centre Gravity set them all up with 'ring settings for the geo at the same time so that helped too.

I know that most people go for £4k+ systems from KW, Intrax and Ohlins but IMHO its worth running a set of these for a season.

Good luck!

[Fl0pp3r]

gtsralph said:

I recently bought one directly from TPC as I could beat the Parr price because I already had US dollars.

Fitting is easy, assuming the connectors are not too tight but all covered in Tom and Mike's videos on the DSC Sport web site/youtube.

(BTW I don't have a GT3 - see below)

I ran back to back tests at Silverstone on Goldtrack's October 24 day with Chris Franklin (Centre Gravity) and Gary Marsh ([e-mail]). We started with the DSC installed and then with the OEM PASM box. On road it is more compliant and on track it reduces initial dive on braking and stiffens loaded front on cornering and softens rear dampers through exit (amongst several other things).

I think the reason it is more compliant on the road is that it runs Bilstein dampers from full soft (1500ma) to 400/500ma hardest whereas (perhaps) PASM might not run to 1500ma.

It operates through calibration tables (maps) defining a range of 31 data points for damper stiffness from soft to hard (front dampers are set to the same values [in ma] across the axle, similarly rears) with separate maps for Normal and Sport.

These damper calibration maps are accessed by other maps covering e.g. longitudinal and lateral G-force, first 1 second of braking, and acceleration which define which of the 31 data points to use for each damper.

So an illustration,

1. braking straight hard for a corner, the Braking map operates above a specified speed and brake pedal force thresholds for 1 second, and then

2. entering and through the corner the G-Force map takes over and stiffens the loaded front, and exiting softens the rears to help power out depending on the G-force loadings.

My car is a 981 Cayman S PDK with an Ehresmann 991 Carrera 3.8L engine and fully adjustable suspension fitted by Centre Gravity. It certainly helps road comfort as the car has quite stiff Eibach springs. On track, it makes a noticeable difference in braking stability and getting on power earlier out of corners.

I am at Goodwood December 3rd and Silverstone December 10th to gather some more experience. Chris Franklin and Pete have got a day off and will be at Silverstone on the 10th so come and have a chat if you are at either day.

I am loaning my DSC unit to CG over winter so Chris can understand how to optimise maps for particular requirements to best meet the needs of his clients.

Top post Ralph, very insightful! I shall be paying Chris at CG a visit with my DSC module equipped motor in due course :-)

[jimmyslr]

Fl0pp3r said:

Top post Ralph, very insightful! I shall be paying Chris at CG a visit with my DSC module equipped motor in due course :-)

+1

Thanks Ralph

[Harris_I]

gtsralph said:

2. entering and through the corner the G-Force map takes over and stiffens the loaded front, and exiting softens the rears to help power out depending on the G-force loadings.

My car is a 981 Cayman S PDK

For a rear-engined car, surely this would work against trail braking and is the reason why the original PASM is so horrible on track?

[gtsralph]

The braking map operates only for the first second of braking and is triggered only above specified brake pressure and speed thresholds. The various maps (G-force, Brake, Accelaration, Speed, and Damper Velocity) work together depending on the car's behaviour so the system's net "instructions" to the individual dampers changes during load transitions.

The system and maps were developed by TPC Racing on their GT3 Cup cars running in IMSA and other race series in the USA so whilst the answer to your question is beyond my direct knowledge, I would guess it probably copes with the circumstance behind the question.

[Steve Rance]

I was concerned about the same issue. Almost all of the corner time in a 911 is made up from braking to apex. That is a very clever solution. If the map can accommodate a trail then it will be a big improvement on the original system. For a properly set up GT car the diff should provide all of the braking stability required but it's well known that the standard 997 GT Diffs wear quickly leaving the electronic ABD system to take over by braking individual corners at the rear to help settle the car on initial braking. This system is not as good or as predictable as the mechanical diff. It's easily remedied by upgrading the diff on any 997 GT3. It will be interesting to know how the DSC unit is programmed to work with the ABD system. Ideally it should not interfere at all with a good strong diff unit. it's function should be to either over ride the ABD system or lot not interfere with a properly functioning mechanical diff.

Edited by Steve Rance on Thursday 1st December 06:48

[gtsralph]

Steve Rance said:

I was concerned about the same issue. ...... It will be interesting to know how the DSC unit is programmed to work with the ABD system. Ideally it should not interfere at all with a good strong diff unit. it's function should be to either over ride the ABD system or lot not interfere with a properly functioning mechanical diff.

Edited by Steve Rance on Thursday 1st December 06:48

Steve, if you are at Goldtrack's Dec 10 Silverstone event, Centre Gravity will be there so maybe they will be able to provide some useful information to your and Harris_I's earlier point

[Fl0pp3r]

gtsralph said:

Steve, if you are at Goldtrack's Dec 10 Silverstone event, Centre Gravity will be there so maybe they will be able to provide some useful information to your and Harris_I's earlier point

If you guys could feed any of that useful info back on here after the event, that would of course be AWSOME

[MaxA]

Thanks to fellow Pistonheaders for comments on the TPC. There are also useful threads on 911uk.com and Rennlist. It's the next thing on my mod list. The 9972 is too soft in PASM off - body control is a bit too loose- and it's too hard with PASM on (although it's OK at the track).

[ttdan]

MaxA said:

Thanks to fellow Pistonheaders for comments on the TPC. There are also useful threads on 911uk.com and Rennlist. It's the next thing on my mod list. The 9972 is too soft in PASM off - body control is a bit too loose- and it's too hard with PASM on (although it's OK at the track).

PASM is always on. Its just soft range or hard range.

[gtsralph]

Fl0pp3r said:

If you guys could feed any of that useful info back on here after the event, that would of course be AWSOME

Today at Silverstone was very wet with a number of stoppages including a race spec Mercedes AMG GT3 visiting the barriers on Hanger Straight. We didn't get much additional useful data but I suggest those interested in DSC contact Chris Franklin at Centre Gravity as he is planning on developing its use for clients.