Outline · [ Standard ] · Linear+ Pt ce varianta de tractiune ati opta?

bine ma ... e mai buna supernova ... asta vroiai sa auzi???

bine ma ... e mai buna supernova ... asta vroiai sa auzi???

cea mai buna este dacia , da-i-as foc intr-o zi , ca imi mananca zilele ... viitoarea mea masina o sa fie subaru , fie ea si 1.6

Ia vedeti ceva mai on topic, please!

"Rear-wheel drive vs front-wheel drive

Why Front-Wheel Drive Sucks
And why rear-wheel drive is coming back
By Mickey Kaus
Friday, April 11, 2003

Car/sex metaphors are unavoidable, so let's get right to today's: Front-wheel drive cars are like bad sex. Rear-wheel drive cars are like good sex. Let me explain!

Sometime in the early 1980s, I asked my friend Paul why he drove a crass Chevy Camaro. He said he liked the "balance" of a rear-wheel drive car. I nodded but secretly sneered at him. Everyone knew that front-wheel drive cars were the efficient, sophisticated wave of the cenzuratre. Audis were front-wheel drive. Saabs were front-drive. GM, Ford, and Chrysler were about to embark on a massive shift to front-drive, resulting in the current Detroit product lineup, in which even the venerable Caddy DeVille is a front-drive car.

The advantages of front-wheel drive (FWD) seem self evident: By avoiding the need for a driveshaft connecting the engine in front with the rear wheels, front-drive cars save space. The entire drivetrain can be packed into a neat compartment in the front, leaving the rest of the car's volume for passengers and cargo. Plus, front-drive cars have better traction in slippery conditions (in part because the weight of the engine is on top of the wheels that are providing the power).

I should have realized the grim truth decades ago when I borrowed a friend's Audi 100 –- the first front-drive car I'd ever driven -- and took it out on Sunset Boulevard. In one of the curves leaving Beverly Hills, near the pink house that used to be owned by Jayne Mansfield, I mashed the throttle, expecting the satisfying "lock in" effect I got in my old rear-drive Volvo – the nose turning in, the car seeming to stop slipping, tightening its grip on the road even as it went around the corner faster. But that's not what happened. What happened is the front tires went all gooey and the car started to head for the living room of a nearby mansion. Only panicked braking calmed things down.

Naturally, my brain did what the human brain tends to do with a bit of aberrant data: I ignored it. All during the '80s and '90s the car magazines assured me, seemingly continually, that in sophisticated front-drive designs you couldn't even tell which set of tires was providing the power. Weren't front-drive Hondas the hippest cars around? Wasn't even Volvo switching, belatedly, to front drive? I also blamed the victim! I must just be a lousy or unsophisticated driver, I figured.

Then, a bit over a year ago, I conducted an abortive test drive of five convertibles. The idea was to sample cars that had at least a semblance of a rear seat. The entrants were Ford Mustang, Chevy Camaro, VW Cabriolet, Chrysler Sebring, and Toyota Solara. And that was the order of finishing (though the test was interrupted by 9/11 before I could drive a final production version of the Toyota). None of the cars was very good – you give up a lot in chassis stability when you chop off the roof, I discovered. But the old, junky, rear-drive Ford and Chevy pony cars were by far the most enjoyable – they rattled and guzzled, but at least they were a blast to drive around corners. The other three cars, all front-drive, were simply pleasant forms of transportation.

Why are rear-drive cars more fun? Every enthusiast may know the answer, but I didn't. So I called up a helpful GM suspension expert, Vehicle Chief Engineer Ed Zellner. There are, I learned, five basic reasons:

1) "Balance": The car rides on four patches of rubber, each about as big as your hand. An ideal car would distribute its weight evenly, so each tire had to bear the same load, and none would give way earlier than all the others. The ideal weight distribution, then, would be split about 50/50 between front and rear (actually, 48/52 to help with forward pitch during braking). "A rear-drive car can typically approach that," says Zellner. Engineers can move the front wheels forward, so that the engine – which doesn't have to be connected to those wheels -- sits behind the front axle. Meanwhile, the driveshaft and rear differential (necessary to send power to the rear tires) add weight in the rear. Front-drive cars, which must connect the engine and transmission to the front axle, typically have their engines mounted way forward and can't do much better than a 60/40 front/rear weight distribution.

2) Center of Gravity: This is the point the car wants to "rotate around" in a turn. On a rear-drive car, it's "about where the driver sits," says Zellner. In a turn, in other words, the car seems to be rotating around you – you're at the center. It's a natural pleasant effect, suggesting you're in control, the way you're in control when you're walking or running around a corner and your weight is centered inside you. (Analogy No. 2: It's like wearing stereo headphones and having the sound centered between your ears!) A front-drive car, in contrast, with its massive front weight bias, wants to rotate around a point in front of the driver. So in a corner, the driver isn't just rotating around his spine. He's moving sideways, as if he were a tether ball on the end of a rope, or Linus being dragged when Snoopy gets hold of his blanket. Not such a pleasant feeling, or a feeling that gives you a sense of natural control.

3) "Torque Steer": One of the most annoying habits of many powerful front-drive cars is that they don't go straight when you step on the accelerator! Instead, they pull to one side, requiring you to steer in the other direction to compensate, like on a damn boat. This "torque steer" usually happens because the drive shafts that connect the engine to the front wheels aren't the same length. Under power, the shafts wind up like springs. The longer shaft -- typically on the right -- winds up a bit more, while the shorter left shaft winds up less and transmits its power to the ground more quickly, which has the effect of pulling the car to the left. (This winding-up phenomenon occurs the moment you step on the pedal. After that, the wind-up relaxes, but "torque steer" can still be produced by the angles of the joints in the drive axles as the whole drivetrain twists on its rubber mounts.)

Engineers try various strategies to control this veering tendency, but even designing shafts of equal length (as in all Cadillacs) doesn't completely solve the problem because the engine still twists a bit in its mounts and alters the angles of the drive shafts. True, some manufacturers -- Audi, for example -- are said to do a particularly good job of repressing torque steer . But even a top-rank company such as Nissan has problems -- its otherwise appealing new front-drive Maxima is said to be plagued by big-time, uninhibited torque steer. Rear-drive cars, meanwhile, don't really have a torque-steer problem that needs repressing. Their power goes to the rear through one driveshaft to a center differential that can a) have equal-length shafts coming out from it and be more firmly mounted.

4) Weight Shift: Suppose you just want to go in a straight line. What's the best way to get traction? Answer: Have as much weight over the driving wheels as possible. Front-drive cars start with an advantage -- but when any car accelerates, the front end tips up, and the rear end squats down. This transfers weight to the rear wheels -- away from the driving wheels in a FWD car but toward the driving wheels in a rear-drive car, where it adds to available traction. In effect, the laws of physics conspire to give RWD cars a bit more grip where they need it when they need it. (This salutary effect is more than canceled out in slippery, wet conditions, where you aren't going to stomp on the accelerator. Then, FWD cars have the edge, in part, because they start out with so much more of their weight over both the driving and the turning wheels. Also, it's simply more stable to pull a heavy wheeled object than to push it -- as any hotel bellhop steering a loaded luggage cart knows. In snow, FWD cars have a third advantage in that they pull the car through the path the front tires create, instead of turning the front tires into mini-snowplows.)

5) "Oversteer" and the Semi-Orgasmic Lock-In Effect: In a rear-drive car, there's a division of labor -- the front tires basically steer the car, and the rear tires push the car down the road. In a FWD car, the front tires do all the work – both steering and applying the power to the road – while the rears are largely along for the ride. That, it turns out, is asking a lot of the front tires. Since the driving wheels tend to lose traction first, the front tires of front-drive cars invariably start slipping in a corner before the lightly loaded rear tires do -- a phenomenon known as "understeer." If you go too fast into a curve -- I mean really too fast -- the car will plow off the road front end first. In rear-drive cars, the rear wheels tend to lose traction first, and the rear of the car threatens to swing around and pass the front end -- "oversteer." If you go too fast into a corner in an oversteering car, the car will tend to spin and fly off the road rear end first.

What's the best way to fly off the road? Safety types prefer frontwards -- understeer. Why? To control an oversteering skid, where the rear wheels are heading for the weeds, you have to both slow down and counterintuitively turn the wheel in the opposite of the direction you're turning. In a front-drive car, with the front wheels slipping, you slow down and keep turning the way you'd been turning to get around the corner in the first place -- a more natural maneuver, since you're pointing the car in the direction you want to go. This is why, for safety reasons, even rear-drive cars sold to average consumers tend to have their springs and other suspension bits set up to make them understeer -- to make the front tires slip first, despite the car's innate oversteering tendency. Only by applying lots of power in a corner can you actually break the rear end of a bread-and-butter rear-drive car like the Mustang loose -- a maneuver favored by sports car freaks, but one you try at your own peril.

Big American manufacturers (all heavily invested in front drive) like to say that for 99 percent of drivers, driving at normal speeds, FWD's inherent understeer and better traction in the wet makes it preferable -- both safer and easier to drive quickly. It's only the 1 percent of speed freaks who enjoy breaking the rear end loose and then catching it with a bit of "reverse lock." Here's where I emphatically dissent.

It's pretty clear to me, after driving hundreds of different vehicles over several decades, that rear drive offers a big aesthetic advantage to ordinary drivers at ordinary speeds in ordinary conditions. Why? The lock-in effect I mentioned earlier. Suppose you go into a corner in a rear-drive car at a reasonable, safe, legal speed. Nothing's about to skid. But you can still feel the front end starting to plow wide a bit. What to do? Step on the gas! Don't stomp on it -- but add a bit of power, and a miraculous thing happens. The front end swings back in, the car tightens its line. Cornering traction seems to increase. And the car feels locked into a groove, balanced between the motive power from the rear and the turning power in the front.

You don't have to be a race driver to feel this. You can be a defensive driver and feel it. You can be driving a 1973 Ford Maverick with leaking shocks and you'll feel it. Accountants feel it on the way to the office and housewives feel it on the way to the Safeway. Even Ralph Nader probably feels it. It's a good part of what makes driving a car a sensual act. (What's happening, technically? None of the tires is at its limit of adhesion. But the added speed is making the front tires --which [since they are undriven] have plenty of surplus traction -- apply more force to the road surface to change direction. Meanwhile, the rear of the car is shifting outward, ever so slightly -- not a Bullitt-style power slide, but a subtle attitude adjustment that cancels the plowing effect. The power "helps you through the corner," as Zellner puts it.)

This doesn't happen in a front-drive car. The best an ordinary driver can hope for in a FWD car is that it "corners as if on rails" -- no slippage at all. No plowing -- but also no semi-orgasmic "lock in." More typically, if you hit the accelerator in a fast corner, things get mushy up front (as they did that evening near Jayne Mansfield's house). The lesson the FWD car seems to be teaching is: Try to go faster, and you're punished. Front-drive cars are Puritans! In a rear-drive car, you hit the accelerator and things get better! Rear-drive cars are hedonists. (This is assuming you don't hit the accelerator too hard.)

I'm not saying there aren't sophisticated techniques that allow FWD cars to do better. A recent issue of Grassroots Motorsports tested a humble FWD Acura RSX against a classy rear-drive BMW. The Acura actually turned laps a bit more quickly. How'd that happen? The Grassroots people realized that by stepping on the brake hard enough on entering a turn, the rear of the Acura could be made to swing wide, canceling out its inherent understeer. (This is the same effect you get by stepping on the gas in a rear-drive car.) But normal drivers aren't going to mash the brakes and go sliding through turns like a rally champion. Nor does braking to achieve "lock-in" seem as satisfying as accelerating to achieve lock in. I suppose I shouldn't knock it until I've tried it -- but I'm not going to try it! That's the point. Housewives heading to the Safeway aren't going to try it either. The joys of rear-drive are accessible to them -- it's the joys of FWD that are reserved for the skilled Grassroots Motorsport elite.

Explaining SUVs: Now that the goo-goo bien pensant scales have fallen from my eyes, and I recognize the front-drive-for-the-masses movement as the Carter-era energy crisis con it is, several previously inexplicable things become explicable. Why did truck-based SUVs suddenly become popular just as Detroit shifted to front-wheel drive for its passenger cars? Was it (as anti-SUV activists claim) because the SUVs were exempt from various safety and economy standards -- or because the SUVs still had rear-wheel drive, with all its subtle satisfactions? Why do all BMWs (and virtually all Mercedes-Benzes) persist in using rear-wheel drive? Why do my friends, who aren't fast drivers, say that BMWs just feel better?

It's also now clear to me why Acura is in trouble (it only offers FWD sedans), why GM is busy working on a new "Tubular" rear-drive chassis, why the Infiniti G-35 and Lexus IS-300 (both rear drive) are so popular, and why the RWD Cadillac CTS and Lincoln LS are so refreshing to drive.

I'm not saying that any rear-wheel-drive car is better than any front-wheel-drive car, the way, say, any car with plain black tires looks better than any car with whitewalls. But it's close! Front-drive cars can be fun. Even bad sex is fun. But why choose it? "
Materialul e copiat de la urmatoarea adresa:
http://www.autoshow.ro/forum/viewthread.php?tid=2351
daca vreti cititi si parerile de acolo...nu ca ati cistiga ceva...

bai nu stiu ce scrie asta aici in aricolu lui ca e prea lung si imi da abort okiu la atata scris in engleza dar ca posesor de 3 masini cu tractiune pe spate (mercedes, ford si opel) pot sa va spun ca e najpa rau sa conduci o astfel de masina (cu tractziune pe spate) pe toate tipurile de vreme. Mi-am luat tzeapa si pe uscat, si pe nisip, si pe ploaie, si pe zapada/gheatza nu mai zic. E nasol de tot mai ales iarna. tin minte mai ales o faza care m-a speriat rau de tot: Eram aku 3 ierni cu opelu si mergeam si io pe zapada pe la ora 10 dimineatza la capu lu 6 si 331 (in damaroaia) akolo pe un coltz de strada e un petrom mic cu 2 pompe una de premium si una de diesel. aveam cca 30km la ora si rotzile bracate maxim la stanga in lok sa virez mergeam direkt spre pompele alea. Daca aveam trctziune pe fatza acceleram un pic si o lua in directia aia. dar cu tractziunea pe spate :? am bagat frana de motor si m-am rugat sa ma opresc la timp. am oprit cu rotzile la 15 cm de pompa deoarece akolo curatzasera aia zapada altfel rupeam pompa si dracu ma lua.

Tractiunea spate necesita deprinderi mai stranii decit tractiunea fata si ca sa iesi din situatii limita trebuie sa aplici proceduri ceva mai complicate decit la tractiune fata...dar unora le place mersul pe sirma...

tractziunea 4x4 permanenta la masini care nu sunt de teren mi se pare o chestie nu prea necesara / eficienta decat la masini cu motoare de top care nu reusesc sa imprime tractziunea doar pe o singura punte. (prsche etc....) io am condus o bora diesel 4x4 si nu era nici o shmecherie cu ea. nici pe zapada nu se simtzea cine stie ce. In plus ganditzi-va ca masiana are 4 planetare si mult mai multe componente care se pot strica cel mai des se duce la alea cu tractziune pe spate cuplajul elastic care amortizeaza shocurile dintre cutie si cardan. daca nu e schimbat periodic poate sa se sfasie si sa cada cardanu pe jos!!! (am patit-o si a fost ingrozitor a cazut cardanu si s-a infipt intr-o groapa asa ca o super frana - masina facand cum fac aia care practica saritura cu prajina :? )

Okey, okey! eu am condus doar o amarita de Lada 1500 cu puntea motoare mai mult decit primitiva si un Fiat 600 cu motor/punte motoare spate si pur si simplu mi-a placut senzatia, atita tot, fie vara, fie iarna, uscat, ud, namol etc.
4x4 la masini de strada s-a bagat in special din motive de securitate, in conditii grele de drum n-o scapi asa usor in decor, ca sa nu mai vorbim de electronica...

Decat pe spate mai bine pe fata, oricum eu prefer 4x4:)

La cata caterinca e pe topicul asta imi permit si eu
La bani foarte multi clar pe spate ...
La bani multi clar pe patru roate ...
La banii moderati clar pe fata ...
La banii nostrii cateodata pe fata (DSN) ...
La banii altora clar impinsa (Traby) ...
La altii 8x4 ...

io inca visez la un DSN AWD... :shock: chiar, cum ar fi ?

Cica roti motoare fata=tractiune shi roti motoare spate=propulsie.
Asha ca va doresc tractiune cu propulsie 2x2 la bicicleta.
Sa va feriti de 5x3 pt ca a 5-a e roata de rezerva care e antrenata in miscare de 2x4 a hotului care fuge de rupe pamantul cu rezerva in mana ...mai !

papucul e FWD, RWD, AWD... deci sunt sanse...
din pacate la papuc e longitudinal motoru, deci o sa aiba ceva de lucru..

Apropo de tractiune, in conditiile din Romania o masina de teren ar fi buna, dar in lipsa ei macar o masina de oras cu tractiune integrala.
Papucul 4x4 are un mare dejavantaj comparativ cu tractiunea fata: poate merge cu fata cuplata pana la 40 km/h, in rest e doar cu tractiune spate; deci ideala e o masina 4x4 permanet.
Si se scrie 4x2, nu 2x4.

Subaru Impreza WRX STI 2.0, 265 CP

visul meu

AWD subaru
_________________

Da.........plus mini cooper<one> varianta S,peugeot 206 <preferabil cc>, Opel corsa<modelul nou>, Yaris de la toyota> , Hyundai coupe FX, Shi cam atat

4x4 daca as avea alta masina (nu Dacie)
Tractiune fata la Dacie!!!

4X4 rules !!!! Dar nu pe Dacie ca se blocheaza intr-o veselie.

hai sa actualizam topicu (,) ca pare interesant...
de ce ati votat oameni buni doar fata sau doar spate? e ca si cum ati avea 2 hartii de 10 lei si ati avea variantele: o luati pe prina, o luati pe a doua sau le luati pe amandoua

Am vazut la tv un test cu masini 4x4... Un Golf cu tractiune integrala si ESP, n-au reusit sa-l faca sa derapeze pe zapada... Ce mi-as mai lua o Octavia II Combi cu nebunia asta montata pe ea, chit ca-i vreo 18.000 Euro CIP in varianta standard.

Eu votez PROPULSIE. Sa schimbe cineva ca este gresit "tractiune spate". Exista TRACTIUNE si PROPULSIE.

This post has been edited by ironickSQUAD: 26 Aug 2005, 16:31

Squad,asta e discutabil. si eu sunt de acord ca ii zice propulsie, dar in talon scrie clar TRACTIUNE SPATE, desi tractiune vine de la "a trage"

TRACŢIÚNE, tracţiuni, s.f. Acţiune de deplasare a unui vehicul, a unui sistem tehnic etc. prin tragere cu ajutorul unei forţe exterioare (animale sau mecanice); forţă care pune în mişcare un vehicul, un sistem tehnic etc. – Din fr. traction.


PROPÚLSIE, propulsii, s.f. Forţă care se exercită asupra unui obiect (de obicei asupra unui vehicul), provocând înaintarea lui. ♦ Sistem tehnic prin care se realizează propulsarea unui vehicul. [Var.: propulsiúne s.f.] – Din fr. propulsion, lat. propulsio, -onis.

pai daca asa zice DEX-ul, atunci nici aia din fata nu e tractiune ca si aia e tot propulsie....

Sistem 4x4 permanent cu diferentiale cu vascocuplaj, autoblocante.
Fiecare diferential (adica 3 la numar) cu reglaj in interior.
Asta numesc eu tractiunea ideala din punctul meu de vedere.

Am votat tractiune spate. Si am votat pe baza experientei proprii, nu pe ce am vazut la tv sau am auzit. Am avut un pipi de bmw 318 cu 113 CP, greutate cam 1300 kg parca (E36). Era o placere sa il calci de la 160 in sus. Abia atunci parca incepea motorul sa traiasca. Si aia chiar era pipi de masina, dar tractiunea pe spate cred ca facea diferenta aia mare. Mers la viteze de 160-170 pe ploaie destul de puternica, nu am simtit sa o ia masina in vreo parte "de capu' ei". Si iarna nici o problema cu derapaje, cu toate ca multi spun ca bmw-ul e nasol iarna. Daca stii sa conduci si ai anvelope de iarna nu vad cum poti derapa, decit daca asta vrei neaparat. Si inca ceva, daimler si bmw sint considerate cele mai bune masini de serie, si culmea amindoua au tractiune pe spate. De ce oare?

spate clar ,+ costuri mai mici de intretinere.
cat despre mersu iarna (alte pericole)

4X4 nepermanent,tractiune pe spate permanent ,fata cu reductor cu 3 trepte.....

Sunt un impatimit 4x4 (chiar am vrut sa imi cumpar un ARO 10 din acest motiv. Bine ca am renuntat).
La noi in tara daca nu ai 4x4 trebuie sa cam ai tractiune nu propulsie pt. ca iarna... nu e ca vara (vorba lu' Basescu)

Am votat 4x4 , ... of bora bora

pai daca asa zice DEX-ul, atunci nici aia din fata nu e tractiune ca si aia e tot propulsie....

Nu prea.

Pana si Dacia s-a prins . . .
Image1s.jpg ( Size: 73.66k ) Number of downloads: 126

4 x 4