Mike in CA

Just to clarify, the maximum articulation for the Porsche "rear turn system" is 1.5 deg, which is only slightly more than the passive deflection for a normal Weissach rear axle. (By contrast previous RWS systems from Honda and Mazda deflected up to 5 deg).

The point is, even if the threaded RWS linkage rod were to break, which is no more likely than your normal steering linkage or any other suspension part breaking, your rear wheels won't "rotate sideways" at 120MPH, or any other speed.

MaxLTV

Mike, it seems that when people hear "rear wheel steering", some imagine this, except with a computer controlling the rear steering wheel:

Mike in CA

I think you're right Max!

TRAKCAR

LOL

NJ-GT

Rear toe-in for a 996/997 is typically set at 0.25 degrees or less per wheel. I have driven a 996 GT3 setup at 0 rear toe and it was horrible.

Set a 996/997 to 0.25 degrees rear toe-out, drive at a racetrack at 8/10th or faster, and the car will surely hit the wall.

1.5 degrees of angle on the rear wheels is a gigantic deal, especially if they are turning in opposite direction to the front wheels.

The RWS hardware is installed ahead of the axle, as long as VW is not racing on this technology, I won't believe it is track-abuse approved or Trakcar-Nation approved. No idea on what has been built into the electronics in case one actuator fails (mechanically or electronically).

Hopefully, the RWS hardware allows the fitment of 19" wheels, or some people won't be too happy of being forced to run MPSC2/SportMaxx on track days, while the real GT3s are running on R6/R1 or even slicks.

utkinpol

lateral forces there are strong enough to move that stock toe arm out of its position so we all replace it with much stronger racing parts and bolts.
if they left overall design there to be exact same with comparable amount of compression force to the toe arm mount but introduced some sort of a moving mechanism there I do not know what good will it be on a track.

all in all, it is a very simple deal about a 'perfect' ratio between level of performance and level of complexity. you can improve performance by raising complexity but it reduces reliability. for a street car higher complexity is fine. for a track car higher reliability is way more important.
997 cup car and its 'simplified' versions as rs, gt3, etc. were damn close to that 'perfect' ratio in my opinion. I never had a car that is so damn easy to work on and with such a little number of critical spots where anything critical can actually brake off. 997 was a very well designed car. I hope 991 will be somewhere close to it but I doubt it.

ps. I just look at this picture above and I do not like it any single bit. think about hitting right curb at WGI bus stop at 80-100mph with this gizmo. will it be able to take it well? here is what I like - it will take a nuclear blast to brake off any of those solid steel joints:

neanicu

Just to be correct,the rear wheels turn the opposite direction of the front wheels only at low speed,30 MPH or less. Above 30 MPH they turn the same direction as the front wheels,putting less stress on the system I assume.
I don't think there're many turns that you take at 30 MPH or less at the track.
How reliable the whole system will be remains to be seen...

utkinpol

how reliable? first thing I did think about when I heard of 'dynamic' sway bars system in the 991 street car was a bended in half stock sway bar rear drop link from my car.
here you got some sort of an electric motor with most likely some worm gear design to apply that movement to a toe link, well, good luck hitting curbs with all that.

wanna911

This should not be compared to deflection under load as your car toes out under load. RWS is causing a toe in on that wheel that would normally toe out slightly to maybe zero toe if aligned with some toe to account for this deflection.

The more it's talked about, the dumber it sounds to add a complete system which adds a lot of weight. Now your racing derived car has a system on it of which the primary function parameters are below 30 mph (meaning NEVER will see on a track) and above that turns into a glorified weight transfer dynamic.

This is some real Cars N Coffee type stuff.

utkinpol

well, all that stuff is too much worry about nothing. we got to wait for real 991 cup car to come out and IF they will keep geometry and most body mounts locations same then perhaps it will be possible to do same thing with moving cup parts into our cars so all that wonderful inventive crap will be ditched and replaced with something that was actually designed for racing applications. life will tell.

just looked up that new 991 RSR video, so, can anybody tell what is actually used in that suspension?

neanicu

I think the system will be well worth it if it proves to be reliable and not another CL shenanigan. It will matter most for people that buy the new GT3 for faster lap times. Just like PDK,it supposedly shaving a few seconds a lap.

FastLaneTurbo

With 50 years of 911 development, much of it in racing and track testing, I fail to see how we can presume
to criticize the engineering, performance and long term reliability of a car that we have neither driven nor even seen. I would think intelligent criticism of its perceived track behavior, let alone its long term reliability, would at least await independent and comprehensive published reviews by those that have at least driven it.

utkinpol

you presume internals of that electronic toe link gizmo are capable to sustain same level of shock stress as my ERP dogbones? I do not think so.... u do not have to be a specialized automotive industry engineer to be able to see potential points of failure. it is all I speak about - I see no need for additional points of failure in a car that did not have them before.

and as I read about 991 cup car it looks like they actually did exactly that in front suspension now using wishbones there so they actually improved old weak spot and I see not a single notice about anything like active rear axle steering in the 991 cup.

it`s like you can presume that is 991 street car came up again with no 3rd radiator by default - it must overheat. despite of anything what was written about it before and now you go and read about it on track forum - indeed, it overheats at 55deg ambient temp. and no 50 years of engineering got anything to do with that, just same old crap they do to reduce costs. so this 991 pdk gt3 car better also have 3rd radiator and tranny intercooler for those who intend to track it.

zanwar

Looking at the components of the current cars that are prone to failure, it doesn't seem to be the more sophisticated electronic stuff that breaks. Coolent fittings, clutches, diffs and CLs are the simple mechanical things. Systems like PASM, DEM and now PDK and EPAS seem to be holding up.

P_collector

according to your 50 years logic, there should have been no problems with 996/boxster engines, there should have been no problems with 997 GT3 CL and so on...

Humans makes mistake..and so does Porsche. I agree that the discussion on the real wheel steering is a bit too much...- but we will get the answer in a few months after the 991 GT3 has been tracked..then we will see.

Fact is however that neither 991 CUP or 991 RSR use this system - for the latter its forbidden. Simple as that.