991.2 C2 GTS, first impressions and tyre pressure /suspension questions

[Gorsh]

(This is an identical post to one on PH, so apologies to those who read both).
My long awaited GTS is finally here, collected it last Saturday and have now put 800 miles on it mainly in North Wales. Arrived home in the IOM yesterday, so only been on roads I know well very briefly.

First impressions? It looks great from all angles - the wide rear especially looks the business, and the interior is a lovely place to be, it has the full GTS interior with silver stitching. The 18 way seats are great (although I'm still tweaking the adjustment occasionally). Despite taking it easy and not allowing the revs to go high I can tell it's very fast - the way it picks up speed on a light throttle seamlessly changing gears at around 3k revs feels very good. Compared to my previous BGTS it's a lot more refined, a bit of tyre roar is all that intrudes when cruising, I do hear the engine and exhaust a bit when it's accelerating, I dare say that will increase when I open her up - just trying to get well over the 1000 mile mark first. I haven't heard it from outside the car when it's on the move, but at idle I notice the exhaust is quite noisy from outside. I've taken to be detailed this morning and my wife said it was loud when I started up and drove off - only a little of the noise is heard inside the car, so a good car for long drives.

The one area where I'm not sure about yet is the ride quality on bumpy roads, the ride feels choppy - it's hard to describe really, but the stability on corners is superb, it's in a straight line on a bumpy (not potholes, just uneven) surface at over 50mph, a single bump like a grid is well handled with no bounce so it feels well damped on single bumps or depressions in the road, the ride is not jarring either except a bit at very low speed. It just doesn't seem to handle bumpy sections like I think it should - it feels like the car is struggling with these surfaces. It may just be me of course expecting too much it - it's been a while since I sold the Boxster and the Boxster did jump around a fair bit on bumps, but I don't remember feeling it was choppy like this car is. I have the -10 PASM and PDCC on the car, I have tried the sport chassis setting, it certainly firms it up and gives more control, but at the expense of a ride too solid on a bumpy road - I do feel the sport chassis will be very useable though on a decently surfaced road, it doesn't feel so hard that it's for track only.
The tyre pressures are something I haven't looked at yet, the TPM tells me it is set at full load and comfort and the pressures are between +0.2 bar and +0.4 bar over. I took the car out last night and unticked the comfort box on the TPM, when I parked up a warning came on saying the tyres were underinflated. So this is an area I can experiment with to see if I can improve the ride quality - I'd be very interested to hear what tyre pressures and TPM settings you all use? And how critical are the tyre pressures in the respect of ride quality and handling?

I chose the -10 PASM because the C4S I test drove had sport PASM (-20) and PDCC, it rode really well but was too firm on typical B roads for me, so I decided on the -10 for a bit more compliancy - I did drive a -10 car too (albeit only a short drive), it seemed absolutely fine, it didn't have PDCC, but I decided to opt for PDCC on the basis that it would add extra body control to complement the -10 PASM.

I don't know if I've got a but of OCD here lol, the car is really very very good - but this ride quality is bugging me right now.

This is the best photo I have so far - will take more and some of the interior when I get it back from the detailer tomorrow.

For those who have read this far - sorry for rambling a bit - but I would appreciate your opinions - thanks.

 

[RussellFunnell]

I just kept the std spec suspension, not really sure what the difference is as I wasn't to concerned at the time.

However, coming from the 991 C2S Cab which are normally a little softer sprung apparently (or it would be in the GTS Cab) the new GTS is a lot firmer ride which was noticeable on some of the bumpy N Yorkshire country roads. I didn't find it choppy but rather quite planted, lively and exciting, if a bit bumpy at times. It will be interesting to see if the stiffness generates lots of rattles going forwards, in consciously listening for them already as not expecting any/many in a coupe compared to the last 2 Cabs - has anyone had any experience in this area with GTS's past or present.

 

[Gorsh]

I just kept the std spec suspension, not really sure what the difference is as I wasn't to concerned at the time.

However, coming from the 991 C2S Cab which are normally a little softer sprung apparently (or it would be in the GTS Cab) the new GTS is a lot firmer ride which was noticeable on some of the bumpy N Yorkshire country roads. I didn't find it choppy but rather quite planted, lively and exciting, if a bit bumpy at times. It will be interesting to see if the stiffness generates lots of rattles going forwards, in consciously listening for them already as not expecting any/many in a coupe compared to the last 2 Cabs - has anyone had any experience in this area with GTS's past or present.

Your Cab would have had the -10 PASM like my GTS. Many of our roads here in the IOM are 'lumpy' in places, so I wanted the extra suppleness of the -10 PASM. It's just when my car hits a section of road at 50 - 70 mph which has a series of irregular lumps and bumps which seem to unsettle the car - I wonder if the PDCC is overcompensating trying to keep the car stable in this situation? On a road with smoother undulations at the same 50 - 70 mph the car is stable, but maybe sometimes verging on being a little soft with just the slightest hint of 'float', but on corners it's flat and composed. It's probably normal and just me being paranoid as I did agonise over which suspension options to choose. I'll get some miles on the clock and see how it feels then - if I'm in doubt I can get it checked out at the OPC in late September as I'll be in the area. I'm happy with the firmness and suppleness of the -10 PASM.... just hoping adding the PDCC wasn't a mistake. If it was then it's an expensive one, and I expect it's not easily taken off - or even if it can be taken off. But thats overreacting at this stage, I'll probably get used to it and then forget I ever thought it was an issue.

 

[Gorsh]

To update - it was suggested on PH that tyre pressures might be responsible, I checked them today and they were set on max pressures, so reduced them to 2.1/2.4, and what a difference! Also gave the suspension a good workout to settle it in, and now the car seems very good indeed! Even with the -10 PASM it is firmer than my BGTS was (PDCC might be affecting that), but it's absolutely fine. Handles very well when pushed along a twisty road too so thats great.
So no more worries! I'm happy now.
Got it back from being detailed today - a couple of photos...

 

[cymro]

Lovely car you have, Initially I found the tyre pressures too much when I took delivery, now keep them set to 2.1/2.4, even with -20mm suspension, the ride is just correct for me.

 

[Gorsh]

Lovely car you have, Initially I found the tyre pressures too much when I took delivery, now keep them set to 2.1/2.4, even with -20mm suspension, the ride is just correct for me.

Thank you. I'm relieved I can tell you! The maximum tyre pressure the OPC's seem to set need to come with an explanation that reduced pressures are on the sticker if we wish to change for better ride quality.
I love this car now, I'm so happy with all the options I chose and am looking forward to getting some miles done and gradually opening her up!

 

[RussellFunnell]

I'm going to try those pressures, my connect app says my front tyres are currently +0.3 and rear +0.5 bar

 

[SteveR_Chester]

Hi Gorsh - that is a beautiful thing!
Keep us posted on the tyre pressure vs suspension ride quality as you run the car in. I've got a similar spec car on order, and have been thinking about the -10/-20 options.

 

[Gorsh]

Hi Gorsh - that is a beautiful thing!
Keep us posted on the tyre pressure vs suspension ride quality as you run the car in. I've got a similar spec car on order, and have been thinking about the -10/-20 options.

Thanks Steve - I will update this thread as the mileage increases.
I think which suspension is best will depend what the roads are like where you will use the car most. Here in the IOM we have some great roads - some with good surfaces and lots with variable surfaces. Now that I've got the tyre pressures right I'm very happy with the -10 for my needs, it is still firmer than my BGTS was, but as stated above I also have PDCC so I'm not sure how much that contributes to the firm feeling - as like PASM it's on all the time with the Sport Chassis button making both PASM and PDCC firmer and giving tighter body control. Despite being fairly firm the ride is very acceptable as it's well damped - just like a good sports car should be. My decision to add PDCC was entirely because I was going for the -10 suspension, I thought and hoped it would complement the slightly softer ride (and it is only slightly softer) by adding more body control.
However, most owners seem to be happy with the standard -20 Sport PASM, not many choose PDCC and are still pleased so it's obviously a very good setup. I drove about 700 miles mostly in North Wales before bringing the car home, the roads there are mixed surfaces, some good and some a bit bumpy and my car felt good (apart from a few bumpy sections where I was concerned) even with the high tyre pressures - it was only when I got home on familiar roads that I knew that something was wrong with the ride - but tyre pressures fixed that. I'm also pleased that when on a good surface I can use the Sport Chassis setting and it is great - ride is more solid but the body control is amazing giving a great drive (that setting is far too harsh on normal roads), so I have settings to suit all occasions.
If you can get hold of any 991.2 Carrera with the Sport PASM - give it a try on familiar roads, then try the same with the standard PASM (all 991.2 cars have it as standard now), that will give you the best idea which you prefer. If I lived in an area where the roads were mostly good I would almost certainly have gone with the -20. My test driving was done in North Wales and I deliberately went on cross country bumpy roads as well as good surfaced roads, it was the best I could do to 'simulate' the roads at home.
Good luck! Choosing all the options isn't easy!

 

[jeffpeck]

SteveR
I had the same dilemma as you when trying to decide which suspension I should choose; should it be -20 or -10 and should I also have PDCC? I was concerned a -20 Sports suspension would be very firm and more susceptible to grounding, particularly on the many traffic calming humps around. I hoped that the PDCC would not only stabilise the car but also help the ride comfort. There was only one way for me to decide and that was to try out the various combinations so a quick visit to PEC Silverstone was arranged where I drove a 4GTS with -20, PDCC and rear wheel steering. I spent most of the morning driving on normal and typically potholed roads outside the circuit. It was soon apparent that, for me, the combination of -20 Sport Chassis and PDCC was too firm and I felt that PDCC, when engaged, exaggerated every bump in the road. I didn't like it and I know my wife would have hated it! I'm sure PDCC is great if you spend loads of time on the track but for everyday driving, which is what the majority of us do, personally, I can't see the point. Needless to say I went for -10 PASM 'Normal Chassis' which, pleasingly, comes with a button to engage the 'Sport Chassis' mode when you want to firm things up. Now, a couple of months on from taking delivery I know I made the right choice. The ride is smooth and the car handles like a dream.

 

[BigCat]

SteveR
I had the same dilemma as you when trying to decide which suspension I should choose; should it be -20 or -10 and should I also have PDCC? I was concerned a -20 Sports suspension would be very firm and more susceptible to grounding, particularly on the many traffic calming humps around. I hoped that the PDCC would not only stabilise the car but also help the ride comfort. There was only one way for me to decide and that was to try out the various combinations so a quick visit to PEC Silverstone was arranged where I drove a 4GTS with -20, PDCC and rear wheel steering. I spent most of the morning driving on normal and typically potholed roads outside the circuit. It was soon apparent that, for me, the combination of -20 Sport Chassis and PDCC was too firm and I felt that PDCC, when engaged, exaggerated every bump in the road. I didn't like it and I know my wife would have hated it! I'm sure PDCC is great if you spend loads of time on the track but for everyday driving, which is what the majority of us do, personally, I can't see the point. Needless to say I went for -10 PASM 'Normal Chassis' which, pleasingly, comes with a button to engage the 'Sport Chassis' mode when you want to firm things up. Now, a couple of months on from taking delivery I know I made the right choice. The ride is smooth and the car handles like a dream.

PDCC does not firm up the chassis, has no affect on the shock absorbers so it does not affect the ride quality it's purpose is to limit the car rolling outwards or leaning when cornering by adjusting the roll bars through electro hydraulic actuators thus keeping more of the tyre in contact with the road surface. I had this on my 991.1 GTS and noticed the lack of it immediately on my 991.2 C4s which replaced it and that has now been replaced by a 991.2 C4 GTS with the -20mm Sport PASM and PDCC. which I think is a brilliant, yes it's firmer but fine for me. As for grounding absolutely no issues at all (so far) and that's after 2000 miles, given the stiffer and shorter travel on the suspension with the -20mm Sport PASM it's what I expected. At the end of the day it's all personal preference but with PDCC, -20mm, rear wheel steering and for the wet days 4WD the cornering grip is outstanding, ?? and with PCCB great braking performance and no brake dust.??

 

[MartinP]

Hi BigCat,

I suspect the problem that arises here is coming from the use of the terminology. I agree that PDCC does not itself firm up the chassis as that function is separately carried out by PASM. But, we have only one button which has both a picture of a shock absorber and the letters PDCC on it. This button provides the option to manually change the PASM setting from 'Chassis Normal' to 'Chassis Sport' (indicator light on) and back again, stiffening and softening the ride accordingly. That is in addition to the PASM function which will adjust shock absorber tuning depending on driving situation.


In response to manually changing the PASM setting, the PDCC system automatically activates the corresponding on-road driving programme - or so the book says. I understand that to mean that in PASM 'Sport' mode the PDCC system will provide a stiffer response to body roll than otherwise.

Hence we only have one button which controls both functions where PDCC responds to the PASM mode that has been selected. Or put another way, in Chassis Sport mode both systems become stiffer. What I can't tell from the book however is whether PDCC has a softer setting corresponding to Chassis Normal mode or is it only functional in Chassis Sport mode. I guess it does have a softer setting, anybody able to confirm?

 

[Gorsh]

I understand PDCC is active all the time - just like PASM, the 'normal' chassis and 'sport' chassis effects both systems. My car (-10 with PDCC) rides a sunken grid or pothole just like I'd expect - firm but well damped. The PDCC is supposed to improve ride quality at all speeds and in all circumstances even if not cornering - I haven't driven with and without back to back so not sure how different it feels. My car has a fairly firm ride and damps out undulations and 'bumps' OK for a sports car, it can get a little 'jiggly' on a very uneven stretch of road (any car with firm suspension would), but on decent surfaces the car is rock steady in corners. I also feel the suspension works better when warmed up - from a cold start, the ride improves after a few miles (or maybe I simply get used to it!).

 

[jeffpeck]

BigCat - of course you're right about PDCC and it is all down to personal taste. My remark; "I hoped that the PDCC would not only stabilise the car but also help the ride comfort" was, for me, exactly what I wanted it to do and my hopes had been raised by Porsche's own description of PDCC in their 'build your car' section which reads "combined system offering active roll stabilisation and enhanced vehicle dynamics, agility and comfort". I am the first to admit my technical knowledge of these things is considerably lacking but my expectations were such given Porsche's wording.

MartinP - an excellent post and explains, to me, why I felt that every jolt on normal roads was being exaggerated.

Gorsh - my apologies. I didn't mean to hijack your thread! Please keep updating us all and enjoy your new GTS. It looks terrific.

 

[Gorsh]

Gorsh - my apologies. I didn't mean to hijack your thread! Please keep updating us all and enjoy your new GTS. It looks terrific.

Thank you for your comments - you haven't hijacked the thread as it's all on the same topic of suspension. I think if you had drove a car with -10 PASM and PDCC you would have felt it was fine, but as long as you are happy with your car that's all that matters. In a similar way I'm happy with mine - but I didn't drive a -10 PASM car very far at all - I'd been out most of the day in the -20 C4S with PDCC and didn't have much time before my flight home, I just knew like you that the -20 PASM and PDCC was too firm for me. My decision was to definitely have the -10, and I added PDCC as an extra hoping it 'did what it says on the tin', part of my reasoning was that a £2k+ option surely can't make the ride worse - and now I have got my tyre pressures sorted I'm very happy with the car. What I don't know is if I'm benefiting much from PDCC in road use - I would need back to back drives in -10 cars with and without it to know.