991 GT3 rear wheel steering - Page 3 - 911/Carrera GT - PistonHeads UK

Many of you may have seen this video already buts its of the RWS working on the 991 GT3. Picture of the setup is also shown. (Credit to Elephant Racing for both pic and video). Interesting to hear the thoughts people have after watching it work. Polarizing issue, likely to be more so after the video but .......... http://www.youtube.com/watch?v=GvQh2ue

Link is not working Neil.

Trev450 said: Link is not working Neil. I think this is it. http://www.youtube.com/watch?v=GvQh2ue--0g

...at 50-80kph is it fixed?

993AL said: Trev450 said: Link is not working Neil. I think this is it. http://www.youtube.com/watch?v=GvQh2ue--0g Thanks.

great when new, not nice when it starts to get play and the cars are 2nd hand,

Showing my limited technical knowledge here, but carrying on from mrdemon's post, the suspension components that pivot when the rws is operating appear to be bushed as opposed to having a ball joint or rose joint. Surely this is likely to accelerate wear to these bushes.

Trev450 said: Showing my limited technical knowledge here, but carrying on from mrdemon's post, the suspension components that pivot when the rws is operating appear to be bushed as opposed to having a ball joint or rose joint. Surely this is likely to accelerate wear to these bushes. Agreed, not the best engineered solution. I read elsewhere that the actuator is a toothed belt affair which would suggest a driven nut and a screw as the actuator. I'm not suggesting that there will be failures but if there are they will fail in position. At the max 1.5 degrees on one hub I would think it will make for some interesting driving. I'm not trying to be a doom monger, just thinking about it technically.

My first thought is fail-over position; if they are leadscrew actuated then is likely wherever they were at the point of failure. The advantage is that it can hold at full load, the disadvantage is if it occurs with high steering angle (of course). More steering angle and articulation than I imagined there would be, however, this makes me wonder about longevity and ability to hold geometry. Steering system for MOT purposes includes RWS and there are a significant number of tests carried out these days. And if the leadscrew wears (typically prone to this) this would show up as play. RWS has been around for a long time so would make sense to compare with other systems to see if they to work well with time & miles, and are not a maintenance / MOT burden.

It will be interesting to see if they cover this under extended warranty once the new car warranty runs out.

993AL said: I think this is it. http://www.youtube.com/watch?v=GvQh2ue--0g Thanks for fixing the link

fioran0 said: 993AL said: I think this is it. http://www.youtube.com/watch?v=GvQh2ue--0g Thanks for fixing the link

I will lay my cards out and say that I am not a fan of this stuff at all. I don't think it has any place on a GT3 type car but each to their own. Im not about to take on a Don Quixote position. No one is forcing anyone to like it or buy it and there are always alternatives (including in this case just removing the unit and putting a straight control arm back in.....aftermarket anyone?). If its for you great, if not no sweat. I often think that driving aids/systems don't exist for most people beyond the acronym. You don't tend to experience them physically from the driving seat so they don't take on a physical form. As such, it was interesting to see it doing its stuff in that video. Its real and it does something. My own view can be summarised as, why would you want something like that on your sports car and how could you have any satisfaction as a driver with that going on at the back? Anyone who has ever been behind a GTR and watched it automatically add yaw control 5 times as it goes round a corner will get the second part of that I am sure. The first part contains a long list of questions that I won't bore the forum with. I wonder having watched that video if we are at another junction in time when those making technology fail get the human element to existence and experience. I also wonder what anyone looking at a 991 GT3 and seeing that video will think. indifference, hesitancy, thumbs up? Edited by fioran0 on Tuesday 8th April 12:27

Shooting from the hip here, but I'm with Neil (Fioran0)on this. The GT3 should embody the very essence of chassis feedback and that should translate to the seat of the pants of the driver, and not be masked by driver aids. In my opinion, RWS can be categorised in much the same manner as PDK (yes here we go again). It is another layer between the interaction of car and driver. And before the shouts of "its what the market demands" are repeated, the fact that it has not been offered as an option in the same way that PDK hasn't, suggests to me that Porsche are no longer interested in the enthusiast, but the wider market as a whole. That being the case, then the 991 GT3 can no longer be seen to be giving the driver a true visceral experience from behind the wheel. If I wanted to be molly coddled by driver aids I would buy a GTR and pocket the £20+k difference. Edited by Trev450 on Tuesday 8th April 15:00 Edited by Trev450 on Tuesday 8th April 15:03

I have not driven the 991 gt3 yet, so I can't really comment, other reputable mags have given it game changer status so the gt3 must be successfully playing on the senses to get out the required pistonhead emotions. I've just been out in my ultima with g96 porsche manual gearbox, no power steering, no abs and cold cut slicks. It's was a complete f king handful and I'd forgotten how easily it power slides I.e. Want to swap ends on cold tyres. However once I'd got over the lack of Pdk, electric steering and psm, I had a right old hoon, getting right back into toe and heeling compete with a dab of opposite lock on powering out of the corners. So unless I'm on the ring or in a race I personally don't need 4 wheel anything nor a milli sec gear change - I have enough sensory overload and fun handling cars without it. For mainly a road going car, I'm still not sure how 4ws adds to the enjoyment other more confidence going into high speed corners maybe? Pdk on the road with a fast and high revving engine is probably a good idea. Electric steering saves fuel. Would 4ws, electric steering, Pdk and gt3 weight put me off buying one for the road? No. The gt3 is now more useable more of the time and manages to thrill, according to the reviewers, to same level but in a different way. For me the 991 gt3 as package is coming close to being a very special daily.

tjlees said: For me the 991 gt3 as package is coming close to being a very special daily. And therein lies the problem imo. Surely the Carrera and Turbo very adequately meet this criteria. The GT3 on the other hand was always the more track-focused offering but could be used on the road as well. Love the sound of your Ultima by the way.

Trev450 said: Shooting from the hip here, but I'm with Neil (Fioran0)on this. The GT3 should embody the very essence of chassis feedback and that should translate to the seat of the pants of the driver, and not be masked by driver aids. In my opinion, RWS can be categorised in much the same manner as PDK (yes here we go again). It is another layer between the interaction of car and driver. And before the shouts of "its what the market demands" are repeated, the fact that it has not been offered as an option in the same way that PDK hasn't, suggests to me that Porsche are no longer interested in the enthusiast, but the wider market as a whole. That being the case, then the 991 GT3 can no longer be seen to be giving the driver a true visceral experience from behind the wheel. If I wanted to be molly coddled by driver aids I would buy a GTR and pocket the £20+k difference. Edited by Trev450 on Tuesday 8th April 15:00 Edited by Trev450 on Tuesday 8th April 15:03 I'd agree with this to some extent - however if one wants a new GT3 then it's this or nothing - and speaking as someone who bought one, the GTR never figured on the list of cars that were considered & I think that's true of pretty much every GT3 buyer.

You don't need an EDiff or rear wheel steer to rotate a car. It's a skill that can be learned and a rewarding one to get right. I'd prefer a car that rewarded the skill rather than thinking for me and excluding me from the process. On saying that, if you have no wish to learn it and enjoy travelling at the maximum speed with the minimum effort - nothing wrong with that - then I suppose it would be a good thing! Not for me though

Trev450 said: And therein lies the problem imo. Surely the Carrera and Turbo very adequately meet this criteria. The GT3 on the other hand was always the more track-focused offering but could be used on the road as well. Love the sound of your Ultima by the way. When I drove the 991 Carrera IMHO it was a game changer with Pdk and even the electric steering. I couldn't get over its useable performance, ride and handling. The 991 turbo will be something else. Maybe too fast, but still practical. I'm putting a roofbox on my 997.2, loading it up with the family (yes two teenage daughters do fit in the back) and heading towards the southwest coast this summer. I just have to control my right foot in the pyrenees The ultima is great for getting back to basics with a 7ltr V8 and 600+lb/ft, but even more extreme than a RS, so has to be trailered everywhere unless I want to arrive deaf with a knackered back and all my holiday money spent on super unleaded.

Some interesting and valid arguments. The question I see is, should a car be automatically fast or provide the potential to be fast. Thats it for me.

mollytherocker said: Some interesting and valid arguments. The question I see is, should a car be automatically fast or provide the potential to be fast. Thats it for me. How would say a Caterham 7 run by that rule? I've had three - all fairly lowly models but the greatest thing about them is that they FEEL fast without being all that fast. I'd really have liked a GT3 with lower gearing plus an overdrive - gives me 0-100mph in say 4 to 6 secs, plus a quiet gear for motorways - a top speed of say 140-160mph is more than adequate. Allows for greater opportunity for 'fun' with less risk of gaol-time when fun is only attainable at 100mph+

Just wondering and perhaps it's a dumb question but nevermind... Is the rws on the car a passive or active system? If it works on a passive system that is say simply a formula based on speed and steering angle, would have thought it wouldn't really be something that is a driver aid in the way traction control/e-diff are which would take away from the driver interaction with the car. If it's actively increasing or decreasing rear axle deflection as needed by the car's ECU based on what the sensors are telling it, that's different though.

0-100mph in 4 to 6 seconds? Are you nuts? That would involve putting a rocket on the roof. The Veyron takes 5 seconds and is utterly mad.

ORD said: 0-100mph in 4 to 6 seconds? Are you nuts? That would involve putting a rocket on the roof. The Veyron takes 5 seconds and is utterly mad. 991 GT3 takes 7.1......

For normal road use I quite like the rear wheel steer on the turbo S which I imagine is a similar system to the GT3. If there are maintenance problems I expect them to be covered by warranty while I own the car and thereafter will leave it to the subsequent owners to sort out. First PCGB track day at Castle Combe tomorrow. So I’ll be in the 968CS. Horses for courses I guess.

It will give stability at speed, that's the whole point. It's up to you if you like that kind of thing or not. It is hard to engineer stability into rear engined cars, rear wheel steering really helps.

By the arguments above, the GT3 should absolutely not have power steering or assisted brakes, as both systems dilute the purity of the control experience and both have the potential to go wrong.

bashful said: By the arguments above, the GT3 should absolutely not have power steering or assisted brakes, as both systems dilute the purity of the control experience and both have the potential to go wrong. that is a straw man argument. Edited by fioran0 on Wednesday 9th April 17:58

fioran0 said: bashful said: By the arguments above, the GT3 should absolutely not have power steering or assisted brakes, as both systems dilute the purity of the control experience and both have the potential to go wrong. that is a straw man argument. Edited by fioran0 on Wednesday 9th April 17:58 I agree. It is about drawing a line in the sand somewhere before they all become video machines with a seat. I want to feel the danger and get the satisfaction of getting it right on my own. I wonder how it will effect dealing with oversteer with all aids off (can they be turned completely off or into track mode - ????) and the same with the aids on. Pip

N24 said: mollytherocker said: Some interesting and valid arguments. The question I see is, should a car be automatically fast or provide the potential to be fast. Thats it for me. How would say a Caterham 7 run by that rule? I've had three - all fairly lowly models but the greatest thing about them is that they FEEL fast without being all that fast. I'd really have liked a GT3 with lower gearing plus an overdrive - gives me 0-100mph in say 4 to 6 secs, plus a quiet gear for motorways - a top speed of say 140-160mph is more than adequate. Allows for greater opportunity for 'fun' with less risk of gaol-time when fun is only attainable at 100mph+ A Caterham is an extreme example of 'potential to be fast'. The speed does not come easy, it takes skill, balance and effort to get one near its limits.

911's used to be like that.

Many thanks for posting the video. It also looks to be adjusting the wheel base of the car at the same time. From the road test reports it makes the steering feel far more responsive and the car changes direction quicker. I suppose I should not knock it until I have tried it. It is the Porsche way of moving the game on. But what is the game. What is the goal. To create a car that can be driven by most people without a thought being given to the mechanical processes involved. We will make is PDK only so nobody has to worry about messing up the gear change. Sixth to third can't be done so you cannot buzz the engine. With the 991GT3 that seems to be the least of their worries. I am not maligning the guys on here that have bought the new GT3 as we all like different things for different reasons. I'm sure it is an awesome weapon. But I am quite analytical. Much the same as I am certain Steve and Neil are and anyone out there with some real track day and race experience. Whilst in the car and out of the car at a race circuit you are constantly anaylising what is going on, what has gone on. What can you do or can be done to improve that lap time. The new breed of sportscar whilst being very efficient with huge amounts of mechanical grip and trick electronics numb that experience and for me there is far less skill envolved. From a sports car perspective I am only interested in something that really focuses the mind. Much like the Ultima I'm sure. Something that makes you think about what you are doing, why you are doing it and how you can do it better. I do not want to own something that removes 50% of the decision making from you and half the adrenalin rush. The decision making is what gives you the buzz.

Amen. Let us mourn the passing of an era.

NBTBRV8 said: It will be interesting to see if they cover this under extended warranty once the new car warranty runs out. Depends on whether a lot of them start to fail probably. If it looks potentially common and expensive then they will probably just retrospectively reclassify it as a consumable like the hub flange/central bolt, nut, upright, bearing and locator pins on the 997..... (Currently just the flange, bearing and nut on the 991 are consumables at the moment). I will be very impressed indeed if this system does not end up prone to failure or given a short service life within the next 3-4 years...

I fear that the car is under developed. Any big GT car producing that kind of performance puts huge loads on itself which do not bode well for anything under developed. FoR me GT3's were the ultimate 'old money' car in this respect. By that yardstick the 991 is very much 'new money'.. Only time - a long time - will tell..

Harris_I said: Amen. Let us mourn the passing of an era. Porsches have been developing and honing for 50 years. From a 2ltr air cooled 128hp to the screening 475hp 3.8ltr gt3. I'm looking forward to a 911 being mostly made of carbon with a kers system as standard and maybe active aero. 991 gt3 as a special daily road car and occasional trackday car, looks a very good choice. If I want the full blown race experience I'll go for the radical sr8 or rxc turbo - both can be road going as well with proper downforce. Even the 997.2 4.0 RS is not in the same league as these track weapons. If I believe half of the reviews in the mags, the 991 gt3 brings you onto a new level of sensory gratification - different from previous gt3s but nevertheless similar. Some of the challenge may have gone through the Pdk and 4ws which I may have a problem with on the track but probably not the road, since I cannot take the racing line and uk road surfaces are too unpredictable to have full on commitment into a corner. I would be very happy to live with that comprise to have more of a useable car given the state of the weather, roads and traffic in the uk. Use a 991 gt3 most of the time, hack round silverstone and go on my annual euro tour including the ring ( without ending up deaf, my left leg bigger than my right and a knackered back!)

tjlees said: Porsches have been developing and honing for 50 years. From a 2ltr air cooled 128hp to the screening 475hp 3.8ltr gt3. I'm looking forward to a 911 being mostly made of carbon with a kers system as standard and maybe active aero. At which point it will only be exploitable and enjoyable on track. tjlees said: 991 gt3 as a special daily road car and occasional trackday car, looks a very good choice. If I want the full blown race experience I'll go for the radical sr8 or rxc turbo - both can be road going as well with proper downforce. Even the 997.2 4.0 RS is not in the same league as these track weapons. Some people prefer the tintop experience. A 996 or 7 Cup car is close to the road going version (the 6 especially so) and require a high degree of skill. For some, that is the most satisfying part of owning a GT3. tjlees said: If I believe half of the reviews in the mags, the 991 gt3 brings you onto a new level of sensory gratification - different from previous gt3s but nevertheless similar. Journo reviews become less worthwhile the more specialist a car and the more skill it requires to extract a fast time. 911s traditionally needed a very particular skillset to extract a fast time. That is no longer the case. In which case the average buyer of a GT3 might also consider mid-engined alternatives like the 458 or 12C. Personally, I would not have considered these 2 manufacturers as direct rivals to a homologated 911 as their road cars bore little resemblance to their race cars. The 911 was absolutely unique. Now it is not. tjlees said: Some of the challenge may have gone through the Pdk and 4ws which I may have a problem with on the track but probably not the road, since I cannot take the racing line and uk road surfaces are too unpredictable to have full on commitment into a corner. I would be very happy to live with that comprise to have more of a useable car given the state of the weather, roads and traffic in the uk. Congestion, camera vans, speed limits and road surfaces in the UK have conspired to rob us of driving pleasure. The only way to take that pleasure back is to drive cars with lower limits and greater sensory feedback. For this reason I cannot see myself owning a modern supercar ever again. tjlees said: Use a 991 gt3 most of the time, hack round silverstone and go on my annual euro tour including the ring ( without ending up deaf, my left leg bigger than my right and a knackered back!) Sounds fantastic. But Porsche chose to apply a racing tag to the car which doesn't race. The recent engine issues only highlight how even Porsche have succumbed to the value of a brand (think M-Sport). Maybe they should have called it a GTS.

Harris_I said: tjlees said: Porsches have been developing and honing for 50 years. From a 2ltr air cooled 128hp to the screening 475hp 3.8ltr gt3. I'm looking forward to a 911 being mostly made of carbon with a kers system as standard and maybe active aero. At which point it will only be exploitable and enjoyable on track. I'm pretty sure the 997 GT3 is really only fully exploitable on the track given second is good for 90+ but I understand your point - for me once my cars starting heading north of 200bhp/tonne, tracks were the only answer, otherwise I was likely to start having scenery interface/police/other roaduser problems, regardless of my talent (lack of) Harris_I said: tjlees said: 991 gt3 as a special daily road car and occasional trackday car, looks a very good choice. If I want the full blown race experience I'll go for the radical sr8 or rxc turbo - both can be road going as well with proper downforce. Even the 997.2 4.0 RS is not in the same league as these track weapons. Some people prefer the tintop experience. A 996 or 7 Cup car is close to the road going version (the 6 especially so) and require a high degree of skill. For some, that is the most satisfying part of owning a GT3. The radical rxc is a tintop (grp) and apparently not an intimidating drive. I'm with you on the requiring skills to drive. When I nail the Ultima/Atom on the track (in my own mind but probably not the instructors!) it's a brilliant feeling. On the road though, i'm fighting frustration with bad roads, other roadusers, cold tyres, cold brakes and race suspension that can't really cope. Harris_I said: tjlees said: If I believe half of the reviews in the mags, the 991 gt3 brings you onto a new level of sensory gratification - different from previous gt3s but nevertheless similar. Journo reviews become less worthwhile the more specialist a car and the more skill it requires to extract a fast time. 911s traditionally needed a very particular skillset to extract a fast time. That is no longer the case. In which case the average buyer of a GT3 might also consider mid-engined alternatives like the 458 or 12C. Personally, I would not have considered these 2 manufacturers as direct rivals to a homologated 911 as their road cars bore little resemblance to their race cars. The 911 was absolutely unique. Now it is not. Absolutely! As the 991 GT3 is now not race proven and has broadened its appeal, its racing characteristics have been diluted. I think people who liked thinly veiled race cars loved the 996/997 GT3/RS. However for me and probably others, when comparing 458, 12C and even the 991 Turbo, the 991 GT3 looks like a relatively good value, special and sensory overloaded daily driver. Harris_I said: tjlees said: Some of the challenge may have gone through the Pdk and 4ws which I may have a problem with on the track but probably not the road, since I cannot take the racing line and uk road surfaces are too unpredictable to have full on commitment into a corner. I would be very happy to live with that comprise to have more of a useable car given the state of the weather, roads and traffic in the uk. Congestion, camera vans, speed limits and road surfaces in the UK have conspired to rob us of driving pleasure. The only way to take that pleasure back is to drive cars with lower limits and greater sensory feedback. For this reason I cannot see myself owning a modern supercar ever again. There are some roads that you can still tickle all the senses to get the required emotions going. Even in a flappy paddled 4wd lambo, I managed have a great hoon at legalish speeds. Not the last in feel and handling but very enjoyable on uk roads. Harris_I said: tjlees said: Use a 991 gt3 most of the time, hack round silverstone and go on my annual euro tour including the ring ( without ending up deaf, my left leg bigger than my right and a knackered back!) Sounds fantastic. But Porsche chose to apply a racing tag to the car which doesn't race. The recent engine issues only highlight how even Porsche have succumbed to the value of a brand (think M-Sport). Maybe they should have called it a GTS. For some I think this is the biggest problem with the 991 GT3, its not race proven, it has reliability issues and it is effectively blurring the lines between the GTS and Turbo. For me, I can now get a Porsche that is special daily that IMHO looks wonderful and sounds unbelievable with apparently outstanding/confidence inducing handling, ride and performance especially on uk roads.

Trev450 said: Showing my limited technical knowledge here, but carrying on from mrdemon's post, the suspension components that pivot when the rws is operating appear to be bushed as opposed to having a ball joint or rose joint. Surely this is likely to accelerate wear to these bushes. The rubber or urethane bushes on the RWS arms will be durability rated to around 100k miles, or rather less if used on track. The bush (or probably the whole arm) can then be changed. A rose joint on road car suspension isn't really suitable as the lifetime is low (we change them on rallycars after around 750 competitive miles), and they offer no compliance, so lots of vibration is transferred into the cabin. I have a 991 GT3, and have done around 2500 miles in it. You don't notice the RWS at all, but appreciate the car is very nimble bearing in mind its size. This became more apparent when I jumped into a 991 C2S loan car.....driving it on the same roads around here, it feels noticeably less nimble, but having said that there's obviously lots of other detail differences which affect the dynamics, not just RWS..!

Actually the limited slip diff of the early GT3's was very effective and stable platform under braking providing the driver had reasonable skills. It was very predictable. In later GT3's, Porsche attempted to provide an 'all things to all drivers' system that made things worse by adding a more rearward brake bias and an electronic safety net which interfered with the rear braking during a trial - ie just when it wasnt needed. This made things less predictable the closer the car/driver was to the limit. You can get round this by fitting competition based after market front discs, a more aggressive front brake pad, removing the electronic stability system and throwing it in the bin. A well set up chasis which allowed a driver to set the car up under braking all the way to the apex was the calling card of the original GT3 and what makes it an absolute delight to drive. It is very settled, easy to rotate and most rewarding PROVIDING the driver makes the effort to learn the relevant skills/technique. In providing Rear wheel steer, porsche have denied that pleasure to the driver who wishes to be more of a factor in the ultimate performance of the car but made it more accessible to the less talented driver or one who has no real wish to engage with his car.

graemel said: Many thanks for posting the video. It also looks to be adjusting the wheel base of the car at the same time. From the road test reports it makes the steering feel far more responsive and the car changes direction quicker. I suppose I should not knock it until I have tried it. It is the Porsche way of moving the game on. But what is the game. What is the goal. To create a car that can be driven by most people without a thought being given to the mechanical processes involved. We will make is PDK only so nobody has to worry about messing up the gear change. Sixth to third can't be done so you cannot buzz the engine. With the 991GT3 that seems to be the least of their worries. I am not maligning the guys on here that have bought the new GT3 as we all like different things for different reasons. I'm sure it is an awesome weapon. But I am quite analytical. Much the same as I am certain Steve and Neil are and anyone out there with some real track day and race experience. Whilst in the car and out of the car at a race circuit you are constantly anaylising what is going on, what has gone on. What can you do or can be done to improve that lap time. The new breed of sportscar whilst being very efficient with huge amounts of mechanical grip and trick electronics numb that experience and for me there is far less skill envolved. From a sports car perspective I am only interested in something that really focuses the mind. Much like the Ultima I'm sure. Something that makes you think about what you are doing, why you are doing it and how you can do it better. I do not want to own something that removes 50% of the decision making from you and half the adrenalin rush. The decision making is what gives you the buzz. No wheelbase adjustment. It gives agility at low speeeds by giving additional yaw to counter the lower response of a tyre(tyre response is connected to road speed), and it reduces yaw at speed..you don't have to wait for the body of the car to move to a big slip angle...which gives stability. Edited by Kawasicki on Saturday 12th April 09:23