New C4S - Understeer....

Hi Im a newbie to the forum but have just put an order in for a C4S for delivery in March/April- Seal Grey, Met Blue leather, Sports exhaust, Bi-xenons, Small Alu pack and PCM - never thought Id ever have the chance to own a 911 and i am so excited about it I couldnt resist posting about it <img src="graemlins/a_smil17.gif" border="0" alt="[blabla]" /> . I do have one question though.... Its the first time Ive driven a 911 <img src="graemlins/jumper.gif" border="0" alt="[jumper]" /> (or a 4WD at anything over 10MPH , albeit that was in the mud) but Ive had two Boxters before, latest an S, and when I test drove the C4S was completely blown away by the performance <img src="graemlins/burnout.gif" border="0" alt="[burnout]" /> and the way it looks. However, it did seem to understeer more than the Boxster, not vicious or in any way uncontrollable but definitely there- difficult to really tell on a fairly short test drive on cold damp UK roads but is this typical of all 996's or just the C4's? Or did I read it wrong? Does anyone have any advice regards mods or suspension adjustments to make to dial in the handling? Very Happy New Year and safe quick driving to all... Tom 03 - C4S Boxter S Suzuki GSXR750

Tom, Read my post about understeer it might help you a lot, though the C4S will behave much different, am sure the guys will help you out. Waz

Tom, As Tiff Needel was quoted during a 996Turbo test video, the predominant handling characteristic of the 996AWD platform is "understeer, understeer, understeer"; so what you experienced is normal for the stock setup of the car. It is also the safest right out of the box for most people (at least in Porsche's mind). If you prefer a more C2, older 911 oversteer feel, please search the 996Turbo boards. There have been numerous postings on making the car more neutral to leaning towards oversteer. Happy Holidays

Tomsk, Congrats! a C4S! you won't be disappointed Why would you want to dial out the suttle understeer of a C4S?, its there for a reason. The C4S and TT do quite well in everyday performance with its set-up. I've tried the Boxer on a wet skipad making it slide to get the feel of the oversteer and underster and the 996 4WD's definately behaves different in that respect, but its not a bad thing. Give it some time since you are used to the Boxer and you will get used to it, it just feels weird initially. Then, if you still don't like it or if you plan on using your C4S primarily for track purpose, there is always time to change the tire-suspension setup. I came home from work today in the pouring rain in the highway and I was grateful of that understeer tendency

That type of understeer is quite normal as all mentioned, however due to the 11" rear tires and above average power from the engine it is quite easy to give some throttle when you feel the understeer and the car will go in-line right away. Congrats on the order <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

The easiest way to dial out the understeer (and I agree that it's there and I prefer neutral to oversteer) is to get yourself adjustable sway bars. Steve W. at Rennsport can probably help you out there. Congratulations on your order. You'll be thrilled, but don't be shy about making a few well chosen mods (like the sways) to make it closer to your tastes. Porsche gave you ABS, AWD, and PSM for your C4S. Giving you understeer also is overkill, IMHO. But don't worry, you can banish it easily enough...

Maybe if you're going real slow, and have lots of room for a mistake, you can erase understeer with a huge dose of throttle in a four wheel drive car. In general, however, you'll make the understeer worse. So, about the only place to try that is in a parking lot. At fast street speeds, the best way to tighten up the line (reduce the tendency of the car to push wide) is to lift slightly off the throttle. Obviously, the higher the rpm of the engine at the time you lift, the higher the engine braking, and the higher rear to front weight transfer, so more understeer will go away. Experimenting in second gear will illustrate the scenario best. I found the Boxter to be a very significant understeerer at the track, unless you use the above technique, in which case you can make it do anything. My ttX50 doesn't convert to oversteer as easily as the Boxter. AS

I haven't been able to correct understeer with opening the throttle even at slow speeds in a wet surface ever, it only made the understeer worse in my C4 (PSM off of course). I agree with Alexander. Once I lost the front end on the C4, any throttle input would keep the front further away from traction and closing the steering angle did't help induce oversteer because the front end did't have any grip to turn the car in. But thats my personal expierience and with a 4WD 996 (M030/18") and maybe others are able to do it.

What impact does changing tire pressures make? I wonder how sensitive the C4S is to pressure changes front to rear? Anyone tried it and if so what were the results? MTIA Le Chef

Thanks for all the responses -I am hoping to get the car in March, maybe April so Ill wait till then and see what i think...Ill let you know. Tom

Tom I agree with Chef. Try playing with the tire pressure. I don't know about a C-4, but it's made a huge difference on my C-2, especially when autocrossing. Try an archive search on this board and on 993 board. Congrats on the purchase. M in C

I hate the understeer feeling. When purchasing a 996 I contemplated going for a C4, but after driving one, I said NO WAY. The understeer can be lessened with tire pressure manipulation, changing of the factory springs, or adding anti-sway bars(as mentioned above). I think a C4 (or Turbo) would be great with the understeer dialed out completely!! My preference is still a C2.... Good Luck.

I agree with John Murray's comments.

Wait a second...one person says lift off the throttle, another says give it throttle to control the understeer. Ah, someone is wrong. Undesteer has been controlled by giving it throttle during understeer since the 1950s. The person that says to correct understeer by lifting off....please explain your reasoning in more detail... thanks, Kent

Hi Kent, Maybe both are right? depending on the way throttle is applied and when it is applied. But you sure have to be a brave and confident one to come in too fast and spin it around with throttle oversteer. I do this with my SportQuad in the dirt but not with my 996... <img border="0" title="" alt="[Eek!]" src="eek.gif" /> This article excert my shed some light: </font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva"> "The more tractive force we apply, the larger slip angle is created in the driving wheel. Therefore, for the RWD cars, we can use the throttle to control the degree of oversteer. When the car is entering a corner too fast and seems likely to run wide, we can correct its direction by increasing the throttle (not to do this before reaching the mid corner !), then the car oversteers. If we find the correction is too much, we can ease the throttle and let the car returns to neutral steer or even mild understeer, depends on the suspension design and weight distribution. Only RWD cars or rear-biased 4WD cars can do this ! In the same situation, the driver in a FWD car has nothing to do other than easing the throttle, slow down the car thus reduce the centrifugal force, and hope the car can overcome the corner." </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">I deduct from this that if you do it before mid-corner you can apply the gas and oversteer so as not to run wide (understeer), but after that you can only use lift off. The reason why you decrease understeer when you lift off the gas (both before or at mid corner) is because when you lift off the gas not only you decrease speed to gain more grip but you transfer more weight from the rear wheels to the front wheels hence reducing undesteer and if excesive inducing now oversteer (I've done that in the rain too) especially on a rear weight biased car such as a 911.

John, I have read in the, now famous, Panorama article on the M030 vs ROWM030 suspension that the RoWM030 significantly reduces understeer on the 996. And personally I don't find my 996 ROWM030 with 18" wheels tends to understeer much and is very neutral, but since I think you have tried quite a bit of standard suspension C2's and C4's to compare with, I would also be interested in your impresion if you ever try a ROWM030 996 (not US M030) on its steering tendenciescompared to a standard C2.

Why is the understeer considered a benefit...in any fashion? Being there for a reason? That's kinda puzzling as I've only had cars that understeer and once you go beyond a certain point, you DO only have prayer to rely upon. Surely Porsche isn't just trying to get as far from oversteer as possible. What do you guys think?

Its easier for the "average" driver to regain control from going into understeer than oversteer. So the trend in most car manufactures to designing their cars with an understeer setup is for safety reasons.

Kent, It's a common misconception that more throttle erases understeer. It can in certain cases when there is enough power to break the rear tires loose, before the fronts have given up-eg. a very low speed entry with a sudden burst of throttle. Otherwise, Carlos has it right. When you lift off the throttle in a fast corner, weight transfers forward, decreasing the grip of the rears. The car will transition toward oversteer. The more engine-braking, the more transfer, and the greater the effect. Thats why people say don't brake a Porsche in a corner. It exaggerates this effect very dramatically. Rally drivers take advantage of this in a unique way by starting at the INSIDE of an upcoming corner, turning AWAY from the corner with engine AND foot braking (starting a tail-wag the wrong way), then turning into the corner which starts the tail sliding the other way, which is coincidently the desired tail-out attitude desired for the actual corner being taken. Then they control the oversteer by dialing IN understeer with MORE throttle. On snow, you can even make a 4wd truck oversteer with this technique. It was taught at the Ice racing School at Steamboat Springs, Colo. Carlos, I couldn't make my 91C4 oversteer with just throttle in slow corners, but I can in my A6 Audi, and a low speeds on the road so will my tt. even with PSM on. AS

Tomsk, Is it true that you can order a C4S now for March/April? I was looking for a targa in October and the wait then for a C4S was a year (more for a turbo). I bought a 3000 mile targa with a view to sitting on it for year while waiting. Are you getting your choice of spec?

Alex, I have found the same thing, I could induce oversteer with throttle in my previous M3, but not in the 996C4. I think its a combination of understeer-neutral setup, tons of grip (18" & S03's) for the available power, an the transfer of available torque from the rears to the front by the viscous differential in the AWD 996. The only way I personally have been able to induce oversteer is by Trailing throttle oversteer. But with the TT's torque you can do anything... <img border="0" title="" alt="[Wink]" src="wink.gif" /> Vic Elford describes the rally technique you mentioned in his book "Porsche High-Performance Driving" for gravel, snow and ice surfaces that he learnt from the Scandinavians back in the 60's in the Monte Carlo Rallyes. He mentioned that the 911 (of that time) was the best handling car in the world in slippery surfaces due to its fowarded pivot point due to the rear-engine, and RWD.

Gents This board is amazingly active, thanks for all the responses... Ian Mcg, re order date... I went into the dealer in December and they quoted me a year for delivery of a C4S - I went for a test drive a week later and was told they had had a cancellation from someone with a March build date when they asked them to spec it out and up the deposit. I took the build date and specced it myself. I have bought a couple of Boxsters from them in the last four years or so and they regard me as a 'good' customer but the showroom is as quiet as a morgue and they dont give the impression of being busy selling much at the moment - not sure i would have ordered it if Id had to wait the full year given the 997 is due ...(2005?) Others re understeer... Am i right to assume that if its understeering already and you put more power down to try and force oversteer to adjust for it, the transmission in C4 will sense slippage at the rear and transfer more power to the front so negating the oversteer at which point I guess things may get quite exciting with the little orange PSM light starting to light up? (or am I just confusing things even further?) Are 'sway-bars' the same as what we call 'anti roll bars' in the UK? <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" />

Carlos, I once spent a day with Vic Elford (and Derek Bell)He's an amazingly nice guy, a genuine enthusiast, and a great driver. He had a few tricks that probably weren't in the book (like blipping the throttle while downshifting a tip under braking) AS

Really? with "Vic Elford"? <img border="0" alt="[king]" title="" src="graemlins/r.gif" /> ...ahh those were the good days of Porsche Motorsport... 911 at Morte Carlo, 917 at Le Mans...