To clarify on my end, by posing my questions, it wasn't my intention to create doubts about DSC. Macca, BillC3, and others have already expressed generally favorable opinions on their experience with it. My questions were intended to enable me and others to quickly get a general technical understanding of what DSC does and how it does it, enabling it to surpass PASM, without having to do a lot of reading from other sources.

 

Called DSC, great friendly service, sounds like the product is solid and more importantly, can continue to be tuned and updated via USB with tune files they send you.

Screw it, I'm going to give it a shot. Can't hurt and install/removal is 10 min. Sorry for the topic derail Joe, hopefully the product fits the spirit of thread.

 

GT4 install instructions and pictures? thanks carl

 

 

Looks like a piece of cake!

 

Yes, sorry for the thread derail Joe...

Just FYI, re those LCA monoball ends that I bought, I'll use them on the rear and get the cup monoballs for the front. All's not lost...

And I'll be having a go with new MPSPC2s on the front and half worn but nearly fully heat cycled rears for a Targa Tour on May 14, then next trackday on 5 June. Be interesting to read your impressions if you've already done this by then. What are your plans re tyres?

Ohhh.. and just re reading my post, the DSC went straight back in after that last session.

 

Nice, Eric! Looking forward to see how it affects your laps and data (both of which are well established pre-DSC).

I also think that it's great you can customize your own file, based on analyzing your data (and make allowances for future suspension alignments or mods)

 

No need for apologies, it's a relevant topic, and this thread allow for 'ramblings', which is why I added it to the title.

Yes, those standard monoballs will work perfectly for the rear, so no loss and it works out perfectly.

I'm not sure what to do with tires quite yet. I have at least one day left on the front tires. I guess it depends on what the rears look like, but I might try it out once and see what happens.

 

Joe. I think the types of tracks we run may be the difference in the geo vs tyre wear we are experiencing. Your local and my local track are quite different configurations, lengths and no doubt surfaces. The average speed for example at my local track with the GT3 is knocking on 128 kmph (80mph) with a Vmax at 232kmph (long uphill straight with a kink and a 100km tight hairpin corner at the end). There are two other straights where I would achieve 160-190kmph, one has a sweeper at the end (115kmpg max nominal apex) and the other a tight right hand corner (65kmph). The curcuit has lots of elevation changes with positive camber (banking) on 3 corners. Leong in the GT4 runs the same track with me. Track length is around 2.8km andbest times in the GT3 approx 72s

I have now played with settings ranging from OEM 100% stock (tyres, bars and geometry) to -2.0F+R plus soft sway bar front and at our local track I am yet to determine a descernable difference in tyre wear (at least within the limits of the 24-30 sessions that constitute heat cycles for the MPSC2). Whilst the increased negative camber does aid to prolong extreme wear on the shoulders of the front tyres the difference in longevity is probably no more than half a day track work at day 5 or 6 by which time the tyres are already suffering from heat fatigue and loosing 0.5s a lap on a short course). I can get 6 days out of the MPSC2 on -2.0F+R but the last day the times drop off even more.

For this reason I cannot see any benefit from increased negative camber for my 991 GT3. My lap times are not improving with more negative camber, infact the car turns in better and is fractionally more stable under brakes on the factory settings.I see the negative camber as primarily a factor to address tyre wear on this track. The limitation as I say is why push the tyre wear beyond the heat cycle restriction unless you are happy with a day extra driving on greasy tyres as the trade off. The factory geo works very well on the road and there are no compromises (actually the -2.0 setting makes little differnce to handling on the road to be fair).

Leongs GT4 exhibits quite different wear characteristics than the 991 GT3 out of the box. We have run session together in Jan where both cars 100% stock and his front tyre shoulder wear is twice mine (at least). He addressed with with -2.5F in March when we did 4 tracks together in the South island. By the time he finished that tour his fronts were again at the limit and mine were good for two more days (tread not heat cycle). I had -2.0F at this time. We both had run 3500 road miles touring as well on that tour. I ran one more day at our local track on the MPSC2 to find they had heat cycles out but would have given another day at least and 500-1000 road km if I had continues with them. leong put on Tropheo R then started setting the geo up for these...

In terms of the latency for the DSC controller I refer to a situation behereby the car is transitioning from speed map to brake map to G map. On our local track we have two examples where normally this transition will happen within 1-1.5s. With a "fixed shock" system you are dealing with the known mechanical and physical characteristics of the chassis all the way through this transition, the chassis is telling your bum where its is in relation to some fixed parameters you know mentally from your time and experience with the car and on that track in those corners. With the DSC system the maps are changing rapidly to accommodate the dynamic changes created by the sensors in the car and switching between maps that control the shocks for each of these inputs. Over 6 track days on 5 different tracks the system was mostly benign and I didnt feel any interference but on three tracks I did feel latency and particularly on our local track this occurred on two specific corners, both important to fast and smooth lap times. Subsequently we have made some changes to the mapping to address this and it has improved the situation markedly although the car does not yet IMO perform as predictably and well here as the fixed damper OEM solution yet. The shocks may indeed have a 100ms response time but I was referring to the latency felt by my bum which is not the shock response time but the time between the physics of the situation changing and the car setting into a predictable response. For example, at or local track, a long uphill straight with a kink hitting vmax 232kmph immediately before braking to under 100kmph and turning in for a sharp downhill right hander negative camber corner (apex speed 115kmph approx). We move from speed table to brake table to G table and the resolution of the transition here with the stock program was not adequate to transition the car for a nice turn in. with software changes we have smoothed this by changing the threshold of when one tables reverts to another, but in my mind this is the perfect example of where the factory OEM shocks are a limitation to getting the response times down enough to enable confidence and speed of transition for the set up under trail braking.

I do want to state these are just my personal opinions and I am not a professional driver nor in any way an expert. I struggle enough to communicate what my bum feels to the DSC technician who was supporting me on the day but he did a stella job of identifying through the traces what was happening then telling me in much clearer terms what i was feeling in those situations then making adjustments accordingly. The product has legs there is no doubt, and I believe once we have a bunch of guys using and tuning the system it will become incrementally better although it may need different maps for tracks that have remarkably different characteristics. However, there will be some who just dont gell with a system that is dynamically changing parameters constantly. One of the biggest complaints I heard of the older PASM systems on track was this but with the 991 GT3/RS and 981 GT4 the factory has done a wonderful job in my opinion of making the whole OEM PASM benign (like with RWS) and its not a noticeable issue any longer. The balance for DSC is getting it set up to be similar again but with the added benefits of stability (over crests and unleaded where it is very good) and stiffness where needed (under brakes, and in fast sweepers where it is very good). IMO out of the box it is not quite yet the panacea although folks with benefits still to be found form a new platform (GT4 etc) or who have limited seat time on these modern chassis (as I did before getting the GT3) may find the benefits to their lap times to be much greater. Im enjoying the process so far but look forward to new maps with improved thresholds for my car/track.

If i have a complaint about DSC it is that the supplied software is not particularly user friendly for the weekend track warrior. The UI needs work. Simple things also like having the units changeable to metric would be nice for us that speak in metric. As an observation recently the logic behind "quadrants" may need consideration also for some tables. My thoughts working on this for a very short time with the DSC agent here was that there needs to be more "bleeding" between each corner of the cars dynamic responses to sensor inputs than a simple "cross hair" structured mapping table. I think the table may need to look more like a cross turned sideways for some tables (like the shape of teh back of an envelope). But now Im getting deep into tech land and I am just a hack and no geek and to be fair have not spent too much time trying to understand the software and the switches as I have limited time in country to drive my cars on the track and with a fly in/out attitude I really like to just "shut up and drive" when I pick up the car and head to the track.

Final opinion is for 41200 its a no brainier for GT4/3 users to get out there and try the DSC system and then give feedback to its creators and load up new maps as they are supplied. I bought the system to make 4000 miles of touring between tracks in march with my wife more comfortable on thee road and I believe the system benefited us in that regard. I was a bit skeptical to whether the benefits would translate markedly on the track or if I would even enjoy the system vs a fixed system approach. I was pleasantly surprised the system was benign enough to enjoy on the track and even though I have had to drive around it a little and get some changes made I think it shows promise...

 

A small hijack, what role does 'lack of 991 GT3 rear wheel steer' play in front tyre wear on GT4?

 

Supposed to arrive next week. If so, will try it on the 17th at HPR. Maybe we can throw it in yours for a 2nd data point if you want.

 

I do not think it should really be a factor. GT4 is midengine and the GT3 is rear engine where RWS helps the rear-end bias- but I could be wrong but I do not believe that mid-engine cars have more tire wear up front than rear engine cars

 

IMO, there are too many interacting factors to judge the effect of RWS alone on tire wear.

Driving style can also affect tire wear. If you find yourself wearing the front tires too fast despite reasonable tire pressures, try higher corner entry speed and more trailbraking. When playing with a new car, I always try adapting to the car before trying to make the car adapt to me.

 

Macca, no doubt that tire wear rate and patterns will differ based on the track. I've seen it with just the 3 tracks I frequent here locally. I do believe you are correct that alignment changes on the 991 GT3 (and even the GT4) do not give a huge benefit in terms of performance, and that the real goal is improved tire wear/longevity. I drove a factory stock GT4 at Laguna seca and really didn't feel any difference in performance/handling characteristics vs. my GT4. The only caveat to having driven a stock alignment GT3 and GT4 and finding no big difference in handling was that the stock alignment cars weren't mine, so I wasn't pushing quite as hard, which is likely when you will really see any significant difference.

I terms of wear on the FRONT tires, with -2.7 on both the GT3 and GT4, the wear pattern AND rate are nearly identical. The outer edges are beat up, but overall wear is fairly even.


Front tire? I don't believe it plays a role. Rear tires? I think it plays a big role. With -2.4 camber on the rear of both the GT3 and GT4, the rear tires are perfectly even wear on the GT4 vs. on the GT3 the outer edge is worn significantly more (much more than the front outer edge). I think the change in toe from RWS kills the outer edge of the rear tires on the GT3

 

^ If the wear problem is mainly at outer edges, you might try running higher pressure to move the contact patch inwards, and not hammering the car during initial laps until pressures are high enough.