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Faster on track GT3 or TT?

 
Old 05-22-2013, 11:22 PM
  #136  
Petevb
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Originally Posted by utkinpol View Post
do you realize what actual pressure it takes to bend that piece of solid metal? and now look at size and design of RWS assembly and where it sits. do you all really do not see what I see? assembly size is hardly bigger than couple inches wide where motor part is, so it is mostly 1 inch gear inside with tiny teeth that moves that link now.
No, I do not see what you see, and yes, I have a better feel than most for what it takes to bend one of those links. Notice how far forward and aft of the wheel centerline the toe control links are now located? This increases the moment arm for the new links, decreasing axial loads on them in proportion. Based on racing rules to thumb I'd expect the engineers would use a factor of safety of around 7 for that part over worst-case loads likely encountered in steady state cornering to deal with hitting a bump/ curb during maximum cornering. Achieving that factor of safety, or a higher one for that matter, can be accomplished many ways and is relatively trivial compared to the challenge of making them move fast enough under the loads they see. Take, for example, the steering rack, where you have "tiny little teeth" from both the power steering and steering wheel moving the steering rack. Plenty of proven ways to protect those teeth, including some not available on the front end, such as a slip clutch with hard stops.

I can only hope the body of that assembly is at least half as strong as my ERP solid steel joints and whole thing will not simply pop out of it after a decent hit at a curb.
All respect to ERP (and I know those guys), but I can pretty much guarantee that this component, to be used across the Porsche model range (including the 918, probably) was subject to more FEA than ERP has done across all their suspension parts put together. Pretty sure they figured out how to avoid it "popping out". You're welcome to be skeptical, but there are plenty of other things I'd worry about more (ie ice mode, etc) if I were you.
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Old 05-22-2013, 11:25 PM
  #137  
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IMO, since the rear angle change is only a small fraction of the front, RWS is best viewed as a means to dynamically adjust the wheelbase of the car rather than steer it, and the concept does have merit.

Also, I don't think the comments about rear toe have much application to RWS. With rear toe in, the rear wheels are pointed in opposite directions, whereas with RWS its in the same direction.
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Old 05-23-2013, 12:01 AM
  #138  
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yawn...
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Old 05-23-2013, 02:46 AM
  #139  
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Originally Posted by Petevb View Post
I find the criticism of the RWS amusing, and at it's root I see a general fear of change and the unknown. The concerns over reliability are not compelling to me- the number of system that can fail and take a car out are innumerable, and many of them are completely new or redesigned with each generation. The PDK could fail and select two gears at once, locking the transmission. Any one of the power steering, ABS or ESP systems could have a bug, the motor could seize, etc. Solid engineering is required to prevent any of these failures, and while there is always a chance of getting something wrong Porsche engineering is generally near the best. They will have followed a long and through failure modes and effects analysis, and they will have put more engineering resources into this single component than many race and kit car manufactures can afford to spend on their entire cars. I see the chances of an issue on this particular system, despite the fact that it's new, as low.

What's amusing to me is that while I wouldn't want 99% of the crap on a modern car, I see the RWS system as one of the few things I'd consider. Stability control, power steering, ABS and sequential shifters are just some of the complicated toys on newer cars that make them faster but heavier, more complex and get between the driver and the car. RWS, however, promises to truly broaden the car's performance envelope in a way that addresses its worst vices, simultaneously improving both stability and agility without adding a nanny. That's the type of improvement that nearly impossible to get any other way.

We'll all see if reliability is an issue, but I predict that once this ceases to be the scary new thing and becomes par for the course (as ABS, water cooling, power steering, etc have before it) this will be a non-issue, and this debate will be forgotten. Or looked back on with amusement, for some of us.

How about the unknown as it relates to parts tested in racing and brought down to the cars that homologate it. Porsche had many years with CL's and we see how that turned out. They didn't even bother putting the RWS on the lesser models first. If you think that is enough emprical data to make it acceptable to every discerning non koolaid drinking Porschephile, well you are mistaken.

With Porsche's recent struggles in reliability with the GT3's anyone who would take anything they are adding new at face value is foolish, let alone a ton of systems added all at once.

Adding more parts that move (an are computerized) is adding more parts prone to failure, period. How does this system, and car overall look in 10 years when guys buy them as a track toy? Or will this turn into the E60 M5 to be avoided like the plague after warranty?


Originally Posted by Macca View Post
Its good some intelligent comments like this finally prevail.

Ive driven RWS in a Prelude I once had and more recently in a Nissan GTR. I never had any issues with 4WS reliability and a number of colleagues with 4WS in the GTR (albiet a different system) have not had reliability issues since they purchased their cars new in 2009 on road or track (which is the primary use for their GTRs).


..

Homework bub, no RWS in the R35 GTR.
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Old 05-23-2013, 02:56 AM
  #140  
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Originally Posted by Manifold View Post

Also, I don't think the comments about rear toe have much application to RWS. With rear toe in, the rear wheels are pointed in opposite directions, whereas with RWS its in the same direction.
Correct, but let's be honest, under load the rear inside wheel is not shouldering much of the load, at least not nearly as much as the outside wheel, so it's direction in relation to the outside wheel is less of a factor than the direction of the outside wheel to begin with. We are talking about changing the whole direction of the rear wheel altogether which has got to affect camber as well.

Stock it will work fine, but what happens when you go for a serious track alignment? Seems like adding negative camber with this system is bound to cause excess tire wear on the outer edge. I wouldn't want to be the first to try this on slicks.
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Old 05-23-2013, 04:01 AM
  #141  
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Originally Posted by wanna911 View Post
How about the unknown as it relates to parts tested in racing and brought down to the cars that homologate it. Porsche had many years with CL's and we see how that turned out. They didn't even bother putting the RWS on the lesser models first. If you think that is enough emprical data to make it acceptable to every discerning non koolaid drinking Porschephile, well you are mistaken.

With Porsche's recent struggles in reliability with the GT3's anyone who would take anything they are adding new at face value is foolish, let alone a ton of systems added all at once.

Adding more parts that move (an are computerized) is adding more parts prone to failure, period. How does this system, and car overall look in 10 years when guys buy them as a track toy? Or will this turn into the E60 M5 to be avoided like the plague after warranty?





Homework bub, no RWS in the R35 GTR.
Hey champ. Check out wkipedia.

http://en.wikipedia.org/wiki/Nissan_Skyline_GT-R

"The car also had computer-controlled all wheel steering system referred to as HICAS. The HICAS system activated when the vehicle exceeded 80 km/h (50 mph) and controlled the steering of the rear wheels in the same direction as the front to improve turn in on entry to corners" R34

Hey Pete. You must be mistaken. Having been one of the few people on the planet to shoe horn a water cooled cup car engine into a long hood 911 (huge engineering challenge Id imagine) and being the owner of WEVO everything you say obviously gets translated via babble fish when Champ hears what you say....
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Old 05-23-2013, 04:11 AM
  #142  
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This car really needs to get delivered already and driven for a few months, and the 20' fitment tires need to be released and so on. And the aftermarket goodies developed. And the chance for those who can afford the car to buy it and those who can't to not. There have been a dozen or so threads about why this car is crap or why its amazing or why its fast but boring or slower but boring or whatever.

My vote is going to the 991RS. Thats where my money is going too.
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Old 05-23-2013, 05:09 AM
  #143  
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Originally Posted by BBMGT3 View Post
This car really needs to get delivered already and driven for a few months, and the 20' fitment tires need to be released and so on. And the aftermarket goodies developed. And the chance for those who can afford the car to buy it and those who can't to not. There have been a dozen or so threads about why this car is crap or why its amazing or why its fast but boring or slower but boring or whatever.

My vote is going to the 991RS. Thats where my money is going too.
Agree. I cant wait for the RS so the GT3 will be a good gap filler....
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Old 05-23-2013, 06:35 AM
  #144  
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Originally Posted by Macca View Post
Hey champ. Check out wkipedia.

http://en.wikipedia.org/wiki/Nissan_Skyline_GT-R

"The car also had computer-controlled all wheel steering system referred to as HICAS. The HICAS system activated when the vehicle exceeded 80 km/h (50 mph) and controlled the steering of the rear wheels in the same direction as the front to improve turn in on entry to corners" R34

Hey Pete. You must be mistaken. Having been one of the few people on the planet to shoe horn a water cooled cup car engine into a long hood 911 (huge engineering challenge Id imagine) and being the owner of WEVO everything you say obviously gets translated via babble fish when Champ hears what you say....
I don't believe HICAS is a feature of the current R35s...
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Old 05-23-2013, 08:39 AM
  #145  
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Chris you are correct. They were 2007/8 GTR (R34) not the current model (R35) from 2009/10+. My bad. Im not very GTR learned...
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Old 05-23-2013, 10:03 AM
  #146  
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Originally Posted by Macca View Post
Hey champ. Check out wkipedia.

http://en.wikipedia.org/wiki/Nissan_Skyline_GT-R

"The car also had computer-controlled all wheel steering system referred to as HICAS. The HICAS system activated when the vehicle exceeded 80 km/h (50 mph) and controlled the steering of the rear wheels in the same direction as the front to improve turn in on entry to corners" R34

Hey Pete. You must be mistaken. Having been one of the few people on the planet to shoe horn a water cooled cup car engine into a long hood 911 (huge engineering challenge Id imagine) and being the owner of WEVO everything you say obviously gets translated via babble fish when Champ hears what you say....
Do you know the difference between and R34 and an R35? The 2009 is not an R34. You clearly were not referring to R34's as you said 2009's, which is the R35, which does not have Hicas. The R34 wasn't even sold in the states. So I highly doubt you drove it, or your friends have not had any problems with it since buying in 2009, considering the R34 ended production in the late 90's early 00's.

It's ok to admit you don't know what you are talking about. We are aware of that already.
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Old 05-23-2013, 10:29 AM
  #147  
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brutal
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Old 05-23-2013, 10:47 AM
  #148  
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c'mon. no matter what who says here, we`re all friendlies here.
old HICAS was crap. if you were not around cars, google it a bit. it was not reliable at all and it did fail plenty of times. to what degree new RWS will be sustainable to track induced stress is yet to be seen.
I agree to Peter`s comment btw - indeed new arms configuration should help reducing the load, still, it all depends of what they`ve done there.
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Old 05-23-2013, 12:45 PM
  #149  
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Originally Posted by wanna911 View Post
The R34 wasn't even sold in the states. So I highly doubt you drove it, or your friends have not had any problems with it since buying in 2009, considering the R34 ended production in the late 90's early 00's.

It's ok to admit you don't know what you are talking about. We are aware of that already.
ahh..you can accuse Macca of being a Kiwi.....which would be legitimate....but he ain't a Seppo (Septic Tank...Yank..American for a bit of rhyming slang)....hence quite possible he could have driven an R34...or even a R32 ....which as we're on the subject of rear wheel steer in racing....there's the little matter of Godzilla

to wit:

"In the case of the R32 Skyline, that meant six cylinders, twin turbos, all-wheel drive with computer-controlled torque split and all-wheel steer. Looking back, this was the racing equivalent of arriving at a knife fight with a machine gun, but there’s no question it made for spectacular racing, both in Japan and abroad. In Europe the Group A R32 Skyline creamed the opposition in the 1991 Spa 24 Hours, while in Australia the GT-Rs kicked seven shades out of the V8 Fords and Holdens and used E30 M3s as toothpicks with which to prize out the gristle left from chewing up RS500 Cosworths. Between them Nissan drivers Jim Richards and Mark Skaife won the 1990, 1991 and 1992 Group A championships (the forerunner to V8 Supercars), plus the ’91 and ’92 Bathurst 1000 races. Their exploits prompted the Australian press to come up with that immortal nickname for the GT-R: ‘Godzilla’."

cf: http://www.evo.co.uk/features/featur..._race_car.html

(the world is sometimes rather larger than the 48 contiguous)....
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Old 05-23-2013, 01:29 PM
  #150  
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If we were scoring, Macca would consistently rate higher than most for accuracy and bias free posting, and he says what he thinks without being a jerk about it. We all get a fact wrong once in a while, and when we do we shouldn't expect more than a friendly jab from our forum mates. Save the personal insults and putdowns for lesser venues. My $.02.
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