Cornering, handling and the 911
 

I know that this is kind of a general post...but after two days driving around in the 2004 Chevy Cavalier rental car... I felt like I had slipped behind the wheel of an F1 racer once I got my 911 back. The difference was like trying to balance on a slab of jello (Cavalier) to tap dancing on solid rock (Porsche).

More than anything, THIS is why I love this car. It simply handles better than any other car that I have driven....and I used to drive a lot of street cars back in the day, so I have a few to compare to.

Specifically, what is it that makes these cars so unique in their handling? How much is attributed to the weight distribution on the 911...? What suspension components set these aside from other road cars?

Does that mean (sorry, I've been away in Africa) that your 911 was repaired? What was done?

Every time I'm in a rantal car, either here or abroad, it is sooooooo nice to come home and drive home in my p-car.

Well, the 911 is unique in nearly all of automobiledom. The steering is probably the best of any mainstrean car. That's due to the weight distribution, the components utilized, and the geometry.

In terms of pure handling, I think there are plenty of better handling cars. The Miata comes to mind. On a track the Miata reads your mind. A little hot in the corner and its running a bit wide? Ease off the throttle for a split second and it tightens it's line nicely. A telepathic car.

The 911 has a few surprises up it's sleeve and isn't the best handling car relative to others.

I think that you are possibly referring to the overall 911 dynamic, which is the result of several factors, weight distribution among them. A short wheelbase makes it agile, but the great spring/shock package, coupled with the overall geometry, (roll centers, etc...) work together to make it one of the best drivers cars ever. As long as you know the dance, you can really make it fly.

I agree with everything Jake says, However, I do think the 911 is the best handling car not necessarily in predictability in the corner, but just plain following the road surface. There is somthing about the torsion bars and highly biased shocks designed for these cars that handle bumps better that anything I've driven. Why is it you can go over speed bumps in a Porsche or air cooled VW at twice the speed of any other car. I wizz over these things at 15 MPH while anything over 5 throws the tools out of my truck and into the street. The Boxster is somewhere in between. The fast compression and slow rebound is unique and I think it delivers an exceptional ride quality. That to me, is all part of handling

Good insight fellas. The day after I got my car back, I was crusing at about 80 in the left hand lane, started to get over into the center lane and lo and behold, a chunk of california metal freeway crap was directly in the path of my front passenger wheel.... I quickly jerked the wheel back hard to the left to avoid the chunk, the car bucked left hard, and then I made my cut back right over to the center lane...it was like Barry Sanders at 80 mph... no way a typical car could have handled that move as smoothly.

singpilot...I had the rear valance replaced and bumper repainted at Kevins shop in Van Nuys.

I think the lack of power steering probably is one reason the steering on a (pre-964 at least) 911 feels so direct.
-Chris

Well, if you think a Miata handles so perfectly ... throw away 1000+ lbs, then you have a '66 Lotus Elan, and REAL agility and handling!!! That's down in the 550 Spyder weight class, and no current production ricer even comes close!

You know Warren, I thought of using the Elan (and a few others) as my example, but thought better of it due to the Miatas huge infiltration. 1 American in 100 is familiar with the Elan, while ten in a hundred have probably driven the Miata!

Jake,

Well, when you are listing cars in the 1400 lb weight class ... it is a pretty short list, and the 550, 904, and Elan all make it! Up a couple of notches are the 356A Speedsters and Mini Coopers, both of which can eat most Miata lunches, too!

Never exactly production status ... but VW-based dune buggies fit in the Elan weight class, too, and I have seen a few that took FTOD at autocrosses regularly!

I got my car out of the garage yesterday & drove it for the first time in 4 months after changing the entire suspension. It needs an alignment & corner balance, so everthing is discombobulated. That being said, I feel absolutely conected to the road. I took a corner a little fast with cold tires & was able to catch it with a flick of the responsive steering wheel. Can't wait to get everything sorted out.

I think Jake has it right -- the 911 suspension is quite primitive by modern standards, but does feel alive. My Boxster could just wipe out both my early 70's 911s on a twisty and bumpy road and with little drama. I used this same "test track" over and over again, rotating thru the 3 cars (when I had all of them at the same time). Yet, as good as it was, the Boxster felt a little less exciting.

Bah! Elans are overweight pigs compared to a Lotus 7.

I remember the Elan very well, but don't recall the power unit and output?

Elan's were powered by the Lotus tuned Ford Twink. They are a pricey little jewel much like the boxter to rebuild. They were impressive for their time much like the Alfa's 4, but pail compared to VTec's or Duratec's of today. They can be tuned to about 200hp for vintage racing and they will make a many of a car look down right piggish in a corner. It is a beautiful thing watching a little Elan go outside in a corner and pass a much more powerful car. Love watching Elans race! Would hate to get hit on the street in an Elan so I came back to steel cars.

Another significant factor is an exceptionally low center of gravity.

Good topic.

When you think about it, the pre-964 911 is a pretty elemental car compared to >95% of the street cars out there (and certainly any rental fleet car). Relatively light. Good power, for the weight. Great traction (to a point), with all that rear bias pressing the rear tires into the pavement. Low center of gravity. Short wheelbase. Manual steering and a light, responsive front end. Suspension tuned more for than a plush ride. Upright fenders that visually place the car on the road. No-distractions interior. Plenty of engine, gearbox and road sound for feedback. And, of course, refined for 20+ years by obsessive German engineers to excel in almost every form of auto racing as well as the curvy roads, bumpy surfaces, and no-limit autobahns of Europe. So, hey, it had better handle better at 7/10s than anything most of us have driven.

I love the way my 911 feels too. Now, I think I'd enjoy driving a Caterham Super 7 as much or more. But I can buy the 911 for a reasonable price, use it in all weather and all traffic, carry the family, and after 150K miles and 15 years that high-quality German construction still looks great. Boy, we are lucky.

YOUALL haen't driven a BMW have you? Especially an M6, M5, or M3. Even the big 7 series handles exceptionally well, how well, well with the BMW you can drink a cup of coffie in one hand while doing 1 G corners, try that with a Porsche.

And I have 3 Porsches, 2 BMWs, an MB, and even a GMC Denali pickup.

"exceptionally low center of gravity"

How low is it? I've never seen any data. We might expect it to be low (dry sump, boxer engine) but the numbers tell the truth.

I will agree that the BMW is a great car, I own one (the wife’s actually) but I’ll take the 911 any day. The BMW has good power, great handling, brakes, even road feel, but my 20+ year older 911 spanks its ass in the fun category. In the performance category it would be close if I had the stock engine, but in my experience (3 series) the 20 year old 911 still wins out.

After having the car down for 3 months for the engine conversion, I felt like I was in a go-cart just driving it down the street at 10 mph. It still feels that way, even at 100+ mph.

Well My M6, and even the 633 I used to have is an E ticket ride, no comparason to a 3 series. And the 7 series, big, huge, comfort for 5 plus people, with AC going, Fully loaded with 5 people, ON THE RACE TRACK, felt like a 911 with one person aboard. I LOVE Porsches, but BMW KICKS BUTT, is TOTALLY AWSOME, at least in their higher end cars. I mean, think about this, you take a basic 4 door, car, with 5 passengers in it, and its capable of beating a 911, on the race track!! JUST DOWNRIGHT AWESOME! And thats with the AC turned ON. We arn't talking about a typical Cadillac sled, we are talking about a Street car, with 5 people, that can CRUSE at 150MPH ALL DAY LONG. JUST AWESOME!!

True, the M cars are different animals, but I'd still miss my 911. :p

I'm trying to talk my wife into taking her A8 to the track. She evidently has done a few high speed runs down the 110 fwy (below Pasadena...the fun part) at rather high rates of speed. 300hp and quaatro good...

I have to disagree somewhat though. I've driven a few M3 coupes, and they didn't feel as visceral as the 911. The M Coupe was closer, but even that felt more disconnected than my SC.

Yeh, they are still 3 series. Entry level stuff

thats the difference for me with a 911 - the speed is effortless. i just had a friend drive alongside me on the m/way to check the accuracy of my speedo. it had been reading 80mph, but it felt more like 50-60mph - it checked out ok.

My car has nice, cool air conditioning. You wanna race your 6 against my 911? ;)

The bigger BMW's are great Autobahn cruisers, but they're not really ideal for a track. Too much weight.

The M3 is a very decent track car, though -- in my opinion.

I don't know about Bimmers our Audis, but I do know that every time I drive my P-car, I'm grinning the whole way, no matter where I'm going. I always come back from a drive exhiliarated. Is it the raw driving feel, the "visceral" nature of the car? Is it the weight distribution and suspension design? Beats me. I just enjoy driving the darn thing. :)


Dan

Talk about tail happy. I had an M6 and it was a pig! My 911 would smoke it in any contest except fall asleep ho hum boredom while driving. If you want comfort and high speed prowess get a 928. I use my S4 for the long drives and the 911 for urban assault missions.

Cheers,

Geoff

http://forums.pelicanparts.com/ultim...ons/icon14.gif

I'm always amazed that this is lost on so many 911 owners.

If there is one theme of the 911 (pre 89) it is low C.G.

(Anti) swaybars on a sedan are no substitute for a low C.G. (it's a tire loading thang)

Shrup: Great news! Where are you taking the car to have it aligned?

What I notice most about the Pcar is the need to keep both hands on the steering wheel when negotiating a corner. My car, at least, wants to come back to center (I guess this is understeer?). This is a Momo steering wheel, smaller than the stock SC three-spoker, and I have the advantage of a new suspension and fresh alignment. I love it!

John

John,

The 'return-to-center feeling' is the direct resultant of the 6°+ caster angle Porsche chose to use on the 911 front suspension. Mercedes also has used 'high-caster' to great effect for 40 years or so ... a little secret GM didn't learn about until the engineering for the 1972 Monte Carlo was being done ... GM bought several Mercedes sedans and set their engineers about dissecting their suspensions to find out why they handled so well, and 'high-caster' was the 'discovery!'

BTW, I was told that corporate secret by an Air Force mechanical engineer, who had as a grad. student, interned at Chevrolet Engineering in '69 - '70. Lots of interesting work went on back then at GM's 'Black Lake' ... the worlds largest skid pad, where Paul van Valkenberg [co-author of Donohue's <b><i>Unfair Advantage</b></i>] worked in instrumentation and testing during the Jim Hall Chaparral road racing days!

We keep saying "low center of gravity," but I've never actually seen a real comparison. I won't disagree -- logically, the reason it's silly to try and make a car like a Civic fast is because of the vertically mounted engine with a high CoG. Logically, the 911 has an impossibly low CoG -- but how low? How does it compare with other cars?

But then, it occurs to me that there's probably a reason these numbers aren't posted anywhere. It's probably very difficult to determine the actual number. You'd either have to weigh all the components and determine their exact placement in the car, or do some psycho kinematics experiment, or something.

Hmmm,

Dan

Comparing older 911s to newer BMWs is hard to do and not really fair. My E39 M5 would easily take out a stock 80s and earlier 911 at the track if driven by 2 equally competent drivers. It is hard to compete with 400 NA HP, even if the car weighs in at 3600 lbs. The key here is "stock." When you start using a car like Jack's for comparison everything changes. Porsche never introduced a production car like that and certainly had no where near the knowledge to do so 30 years ago.

For example, I just added adjustable sway bars to my 930, and even on the street the difference in handling is very noticeable. The car feels lighter and way more balanced. In fact, it reminds me a lot of my M5.

The older 911s defintely have a connected to the road feel though that no other car I have driven matches.

Try a Toyota MR2 and you'll get some of the same road reel as an older light 911. A few summers ago, I rented one a year ago and chased a friend in his Gruppe B 3.2 liter 911t . He's a better driver than I am and has an faster car, but we still had a blast.

This is great stuff, but there is a wrench that can be thrown into the works. Why does the Cayenne seemingly break the conventional rules and handle nearly as well as a 996? Heavy, high c.g. (even in it's hunkered down stance), etc., and this is even with the PSM turned off.

There are plenty of cars that will out handle a 911, but as someone already mentioned there is a serious danger that the pilot will fall asleep with boredom before the race ends!.
For me a BMW is a car I will drive 'when I am old' :)

As for the low centre of gravity, I imagine that the engineers use a similar calculation to a maritime calculation for transverse stability where they calculate the centre of gravity GM (or Meta centric height) and then calculate the amount of effort taken to heel the vessel to a certain angle before it becomes unstable.
I would imagine there must be some similar calculation made to figure at what height the bulk mass of weight is (GM) , raising that height and weight upwards increases roll and eventually lifts a wheel or the car slides.
With a vessel we lower the GM to increase stability by ballasting (filling completely)fuel or water tanks.
Likewise with cars we reduce the sprung height increasing the weight below the GM of the car.
If our fuel tanks were baffled this would also help the 'free surface effect' which is basically reducing the 'slop' of fuel in the tank and help reduce body roll!.
I believe race tank cells are honey combed for fire reasons but this would also help stability!.
.... hmmm rambling here, perhaps no one is interested in boat stuff :D
Ben

Ben,
I was actually thinking of the metacenter calculations when I asked the question. Ironic. I haven't taken naval science in quite some time, but it seems to me that the free surface effect of the gas in the tank, or the oil, for that matter, probably contribute only negligibly to handling stability. <shrug> Neat thought, though. But back to the point, it seems like actually measuring the metacenter with any degree of accuracy would be pretty painful. What do you do, rock the car up on it's side and see where it balances? Can we do that with somebody else's Porsche, but not mine? Hmmm...

Dan

Actually, you can measure both longitudinal and lateral CG of any car rather simply with platform scales, a jack, 2' tall blocks, and some trigonometry.

TT

to get the CG, you put the car on a frame and balance it out. I think there is a description in Race Car Vehicle Dynamics or some other tome.

But.... what is the CG??

vis·cer·al ( P ) Pronunciation Key (vsr-l)
adj.
Relating to, situated in, or affecting the viscera.
Perceived in or as if in the viscera; profound: “The scientific approach to life is not really appropriate to states of visceral anguish” (Anthony Burgess).
Instinctive: visceral needs. See Synonyms at instinctive.

I think we should define "Handling"

To me, handling is how well behaved the car is during cornering, transient manouvers, as well as combinations of braking, cornering and throttle application, on different surface profiles.

IT is not how many Gs it can pull on a skidpad. (BTW, I'm sure the author was making a point but no 6 series car pulls over a G in a corner without some chassis changes and some serious stick (aka Race rubber))

Nor is it a fast slalom, or a fast road course time. Good handling cars may post good numbers, but they are not, IMHO, the only measure of handling.

911s, at least many of them are not known to be among the top eschelon of the great handling cars. Why? Well, they can bite. There was a statistic, which has now become urban legend, that of all the first year 911 turbos sold in the states, nearly half were sold in CA, and nearly half were wrecked in the first year, backwards into walls, etc.

Now, I know that is a great (bit sad) story, but I doubt the numbers. I do think there is some truth in it. Trailing throttle oversteer was a known 911 issue, and was worsened by the addition of more weight (turbos, etc) high US spec ride height, newfound power, and so on. (not to mention the demograpic profile of the buyer) Cars that snap spin when you jump off the throttle are not driver friendly, and can't be considered among the worlds best handlers. And yes, some TTO is a good thing, if it's kept in check. The Miata and BMWs have a good amount.

The Cayenne may be a safe handler, but I doubt its an enjoyable handler! Too numb, and while its weight and traction may be well managed, it will prove to be a terminal undresteerer at the limit. In my book, thats not a great handler. Not neutral. Another good handling trait, neutrality..

The M3 is one of the best, and has an engine to match the chassis. The M3 is responsive, communacative, balanced, with great transient behavior, as well as high limits. BMW has acheived this through solid engineering, great chassis geometry, good wheel and tire choice, great shock and spring setup, and a good stiff platform.

The 911 starts with a deficit...the rear engine weight bias, with a large mass outside the wheelbase. Porsche has done an awesome job to overcome the physical limitations the package presents (and has also maintained the packages inherent dynamic strenghts, such as high R/F weght transfer which aids braking). But, while it is a great ride with great dynamics, and can be driven around it's weaknesses, it is not a car that is at the top of the list handling wise.