Controllability of the vehicle is an important promotional factor for All-Wheel-Drive. AWD provides enhanced road handling and is safer in all driving conditions.
Meeting these requirements, the Haldex LSC offers fully controllable torque transfer characteristics and extremely rapid activation and deactivation - automatically.
Maximum performance and safety is achieved in all driving situations, as shown here:

Parking
Low or zero torque transfer enables easy and comfortable manoeuvring in parking situations.

Acceleration
High torque transfer for maximum traction, instantly, on all four wheels.

Driving on slippery wet roads
Swift activation of the coupling for maximum traction and safety depending on the slip of the wheels. The coupling communicates on-line with other safety systems in the vehicle.

Different tyre wear and pressure conditions
An algorithm in the ECU detects differences in the diameters of the tyres and compensates the characteristics accordingly.

Braking/ABS
ABS braking overrules the coupling to ensure full function of the ABS system.

Brake testing
Coupling is not activated until a preset engine speed is exceeded. This means that the coupling is not activated, even if the ignition is on.

Towing
Coupling is not activated until a preset engine speed is exceeded. The ignition can be on for lights etc. Towing with one axle lifted is not a problem.

ESP
Immediate deactivation on ESP signal to ensure full function of the ESP system. An alternative is to communicate with the ESP system to add the control possibility of the Haldex LSC to the ESP system.

Run-flat-tyre
Maintained traction capability and secured against damage.

Off-road
Instant activation with high torque transfer for maximum traction. Alternative, separate off-road mode (switch) to lock the coupling.

The ECU controls a valve which directs the torque transfer characteristics, ranging from fully open to fully closed.
The open position is used during ABS operation and when Stability Control Systems are activated. The valve opens in less the 60 ms. The closed position is used when accelerating and driving on soft ground


Haldex LSC is fast! With instant activation independant on differential speed, Haldex LSC with PreX provides high torque transfer from stationery independant of any wheel rotation.

The Haldex LSC with PreX do not need any difference rpm to generate high torque transfer.

Haldex LSC is activated regardless of whether the input shaft is rotating faster or slower than the output shaft. This is a major advantage for the dynamic stability of the vehicle in acceleration or deceleration in combination with cornering or manoeuvring.

The torque transfer characteristics are controlled by the ECU, using the vehicle management information to adjust oil pressure via the throttle valve. With the controllable torque transfer characteristics of Haldex LSC, the vehicle performance does not need to be a compromise between traction, demanding high torque transfer, and manoeuvrability, demanding low torque transfer. The torque transfer is optimised for each driving situation - ensuring maximum safety and performance.

Torque transfer characteristics of the Haldex LSC. In normal driving conditions, the torque over the unit is controlled by the ECU. When a wheel start to spin, the coupling automatically and instantly stops the spinning. The maximum torque is set by the overload protection valve according to the vehicle manufacturer's specification.


The application software communicates with other active systems in the vehicle via a data bus. It determines the vehicle state with the help of the read signals. Examples of received signals are: engine torque, engine revs and wheel speeds. From this estimated vehicle state, the optimum torque distribution is determined in each condition.
If the input signals are lost due to a failure in another ECU, the Haldex LSC enters a limp home mode, maintaining AWD.


Fully integrated into the control management system of the vehicle, Haldex LSC offers advanced and attractive features to the new generation of All-Wheel-Drive (AWD) vehicles:

Enhanced Vehicle Traction
- Torque transfer up to 2.400 Nm on prop shaft.
- Built-in torque transfer limitation.
- Full function in reverse.
- Instant activation independant of differential speed.

Enhanced Vehicle Dynamics
- Improved vehicle dynamics control during acceleration
- and deceleration.
- Rapid activation and deactivation.
- Fully controllable torque transfer characteristics.

Enhanced Safety
- Full integration with brake systems (like ABS) and stability
- systems (like ESP). On demand, the system can be
- deactivated in less than 60 ms.
- Limited/full AWD function with Run-flat-tyres.

Enhanced Vehicle System Compatibility
- Fully compatible with ABS, ESP and TCS without freewheel
- or additional clutch.
- On-line communication with the CAN system.
- No extra sensors needed. All required information obtained
- from the CAN system.

Enhanced Vehicle Driving Comfort and Transparency
- No wind-up during tight cornering and parking.
- Optimal traction during acceleration.
- No functional problems with tyres having uneven wear,
- pressure or size (mini spare).
- No functional problems when towing with one axle lifted.
- Transparent actuation.

Enhanced Optimisation of Weight and Fuel Consumption
- The built in overload protection valve, in combination with
- the fully controllable torque transfer characteristics,
- decreases the design requirements of the complete
- AWD drive line, resulting in reduced weight and
- reduced fuel consumption.

f1anatic frate acu te iei de audi....? maine o sa spui ca subaru e mai bun ca navele spatiale de la nasa

quattro is a superior drive system. Very superior. In touring car motorsport, in fact, quattro is so superior that officials had no choice but to consider whether quattro should be burdened by handicaps or even banned! And in this order, this is precisely what major motorsport organisations did – and without undue delay.

After all, they did not want Audi quattro to “do its own thing”, and leave all the others trailing in its wake. Rather, they wanted a genuine “show” keeping fans and television excited. And keeping sponsors interested in the sport. They wanted close races for the lead – door to door, wheel to wheel, with just split-seconds in it. One car or brand dominating the others, however, has no place in the “show”. Especially as battles further down the field are not shown on TV anyway.

in the following year Audi’s race-proven quattros ran into hard times in the DTM German Touring Masters. The difficulty they experienced was not on the track, however, but rather at the conference table when the OMS Motorsport Authority claimed that the new crankshaft in Audi’s eight-cylinder was not in line with regulations, although two preceding tests had confirmed that the crankshaft was perfectly legal. As a result, Audi pulled out of national racing and concentrated on racing series outside of Germany.

Racing the Audi A4 Supertouring, the Company once again achieved a unique story of success in 1996, winning not only the prestigious D1 ADAC Super Touring Car Cup, but also, with the help of the respective importers, six national championships – in Italy, Great Britain, Belgium, Spain, South Africa, and Australia.

Once again, the sports authorities responded, burdening racing cars with four-wheel drive by additional weight of up to 95 kg in order to prevent further victories of this kind. And just one year later the FIA Motorsport Authority put an end to quattro technology in motor racing once and for all. Meaning that from now on Audi quattro has been able to show its merits “only” in road traffic – but all year round!

One of the most significant rally cars of all time made its introduction to the world in 1980, with the unveiling of Audi's rally contender, the Quattro. The Quattro was the first rally car to take advantage of the new rules permitting four-wheel-drive for rally competition, but there were some initial doubts about four-wheel-drive's suitability to rallying. Some thought it would be too complex and heavy to be competitive. The critics were quickly proven wrong.

The Quattro won its first rally on its first outing, the Austrian round of the European championship in 1981: the four-wheel-drive experiment was an instant success. The Quattro went on to win a couple rounds of the world rally championship, and Audi gained additional exposure when Michèle Mouton won the 1981 San Remo rally, the first woman to win at the international level. The 1982 season looked set to be an Audi tour de force.

While the Audi was clearly the fastest and one of the most revolutionary rally cars in some time, it did have a number of shortcomings. The Quattro was rather heavy, its front-engine, monocoque chassis gave the car clumsy and unwieldy handling characteristics, and the car had problems with mechanical reliability. The car did win the 1982 championship for constructors, but Walter Röhrl took his first win of the year and the championship on the final event, the Ivory Coast rally, after Michèle Mouton's Quattro suffered a broken transmission.

The 1983 season was another bittersweet season for Audi; the introduction of the Lancia 037 promised fiercer competition (despite the 037 still being rear-wheel-drive), and the 037 delivered. Audi's #1 driver, Hannu Mikkola, won the 1983 driver's championship, but Lancia pilots Markku Alen and Walter Röhrl finished in the points frequently enough to give Lancia the constructor's title. The 1984 season was Audi's most successful year in rallying. Stig Blomqvist's sideways driving style plus the introduction of the short-wheelbase, more powerful (450+ hp) and more advanced (six-speed transmission, kevlar bodiwork) Sport Quattro combined to take both titles for the 1984 season.

However, the 1984 season saw a new challenger to Audi's crown: Peugeot launched their brand new 205 T16 in Corsica for the 1984 Tour de Corse rally. The new 205 differed from the Quattro in several key respects: it was rear-engined, it had a space frame, and it was a generally smaller car with less weight. Peugeot driver Ari Vatanen nearly won the 205's first rally, except a crash prematurely ended his rally. The Peugeot caused enough concern that the Audi team managers sent messages back to the engineers in Ingolstadt, reminding the engineers to keep up development, and not to be complacent with the current success.

The title of "king of the hill" was transferred to Peugeot at the start of the 1985 season. The Sport Quattro was simply unable to keep up; its handling and reliability was poor compared with the 205 T16. Audi never ceased development despite losing its crown, and the radical Sport Quattro S1, introduced at the 1000 Lakes rally in 1985, proved to the rally community that Audi was very serious in its attempt to regain its previous form. The S1 had more power than any other rally car in history, reaching over 600 horsepower in 1986, and it had huge wings to aid with traction on faster stages. Faced with ever-increasing competition, the S1 only managed a single victory, on the San Remo rally in 1985.

The curtain call for Audi's Group B program came with the death of Henri Toivonen on the Tour de Corse 1986; following Toivonen's death, Audi, along with Ford, immediately pulled the plug on its Group B rally program. The Quattro in its various iterations competed for four and a half years, winning four championships, and changing the face of rallying forever.

retragerea din competitie nu este solutia... cred ca reintegrarea VAG si Porsche in circuitul automobilistic de performanta este necesara in primul rand lor.

iar povestea Quattro in grupa B nu pare fi asa de invincibila precum spui tu

As in most Acura products, the steering is deliciously slick and direct, and the car handles with aplomb at speed. We discovered a spooky tank-slapping boogie in the emergency lane change with the vehicle stability assist switched off, but we achieved a faster run (and far less dramatic oscillations) with the system on, the way most owners would likely leave it. The RL demonstrated its user-friendly calibrations to great effect in the mountains, where the SH-AWD offers up predictable understeer while the readable brake pedal delivers strong, stable retardation.

Daca Subaru ar pune ESP pe STi - atunci ar fi fara discutzie cel mai bun sistem awd.
Daca AUDI ar pune LSD-uri pe cele doua puntzi sistemul lor quattro (renuntzind la EDL) atunci ar fi cei mai tari.
PINA ATUNCI, LUPTA CONTINUA !
Cind e vorba de cutie manuala...
Audi are avantajul ESP-ului si dezavantaj cu EDL.
Subaru are avantajul LSD-urilor si dezavantajul incompatibilitatzii ESP.

90% omul...

si omul a ales un Subaru ca partener de dans!

am putea sa facem un clasament awd si dupa rezultatele WRC, nu? in fond acolo are cea mai mare importanta :angel:

1983 - Michelin and 4WD
Lancia proved that the days of rear-wheel drive machinery at world level were not yet over by securing the Manufacturers' title, two points clear of Audi who had switched to Michelin tyres.

Apoi daca citeam tot ce ai spus tu...am fi intzeles ca au fost invincibili in Raliu. Mai tirziu ai editat si ai oferit explicatzii...cum ca e vorba de anii 1990 si DTM nu raliu. Una peste alta...AUDI nu a fost acea fortza in lumea raliurilor...care a taiat si a spinzurat.

Campionatul Mondial de Raliuri. ... Cind e vorba strict de AUDI vs. Subaru... Cred ca NU.

pot sa trag o concluzie si poate sa ne mai calmam un pic ?

the Torsen is superior to the viscous coupling because it transfers torque to the stable wheels before the actual slipping occurs

(Da...ma voi afunda...sau voi iesi din cacatul alb...dar stiu ca am o sansa...sa ies...comparat cu un vehicul caruia i se frineaza rotzile)

practic un Subaru e f. greu sa ramana blocat din lipsa de tractiune. de regula rotile care se invart in gol "dig for traction" si asta e cazul si pe zapada si pe nisip sau mai stiu eu ce...

An interesting thing about friction is that it usually takes more force to break an object loose than to keep it sliding. There is a coefficient of static friction, where the two surfaces in contact are not sliding relative to each other. If the two surfaces are sliding relative to each other, the amount of force is determined by the coefficient of dynamic friction, which is usually less than the coefficient of static friction.
For a car tire, the coefficient of dynamic friction is much less than the coefficient of static friction. The car tire provides the greatest traction when the contact patch is not sliding relative to the road. When it is sliding (like during a skid or a burnout), traction is greatly reduced.

ESP-ul e fara indoiala util mai ales in situatii limita dinamice. la plecatul de pe loc nu sunt convins ca teoria ( faptul ca un quattro poate pleca si cu tractiunea pe o roata) este la fel de valabila si in practica pt. ca franarea rotilor impiedica acest " dig for traction phenomenon". daca ramai impotmolit cu un quattro/4 motion ai mai multe sanse sa iesi din necaz decupland ESP-ul si sa lasi rotile sa patineze pana isi sapa tractiunea...

He he he. Ce smecher esti... citesti doar ce-ti convine. Ia citeste mai jos in acel link. Ai sa vezi ca scrie ca functioneaza perfect cu torsen si nu exista nici o sansa ca torsen sa piarda tractiunea. Lasa-ma q0 minute, te rog. Sa pun ce-am scris...

In Concluzie, dupa o anumita viteza de cca. 25 mph/40 kph sistemul EDL nu mai functzioneaza

Daca AUDI ar veni cu Torsen (~LSD central) iar quattro asta al lor ar veni cu LSD-uri pe ambele puntzi - sau macar pe spate, ar fi absolut un produs net superior. Dar NU ofera asa ceva...ci doar LSD pe centru si EDL pe cele 2 puntzi. Masinile nu sint facute sa mearga si in cazuri mai "extreme" cind nu mai ai tractziune la nici o roata. Da...o fi mai iute...da...permite ESP. Dar cind e vorba de mers la munte iarna pe zapada...parca am o ezitare.

2006 LEGACY GT vs AUDI A4 QUATTRO vs BMW 330 xi
http://www2.uic.edu/~bcatal1/etcetera/suba...AUDI.SUBARU.pdf
LSD centru AUDI, SUBARU
LSD spate SUBARU

valentin , pana acum ai dat dovada de maturitate . cum te contrazice careva in schimb sari in sus si treci la atacuri . nu mi se pare normal . te rog sa te controlezi si sa pastram discutia intr-un ton normal si informativ.
multumesc .

si inca ceva : eu prefer un sistem mecanic unuia electronic oricand .

pe scurt: prefer mecanica AWD ului cu diferentiale deschise unui quattro . punct . de ce ? pentru ca ce e mecanic are sanse mult mai mici sa se strice decat ceva mecanic + electronic

WRX STI AWD System Revised

The 300-horsepower Impreza WRX STI gains a further edge in all-wheel drive performance for 2006. The power distribution ratio in its advanced Driver Controlled Center Differential (DCCD) version of Symmetrical All-Wheel Drive has been changed from 35:65 to 41:59 and uses a new mechanical limited slip center differential in place of the previous hydraulically controlled unit. The addition of a steering sensor to the differential’s control inputs further enhances torque transfer and overall performance of the AWD system.

Also note, it does not try to prevent wheelspin! If both sides lose traction at the same time and spin at the same speed then EDL has no idea anything is wrong. A more advanced system measures the difference between the speeds of all 4 wheels during acceleration and assumes that anything spinning faster than the slowest rotating wheel is slipping. A cheap system will apply the brakes. An expensive system will reduce the throttle until the problem goes away. BMW's and new VW's use this method to prevent wheelspin.

The problem with the way EDL works is that it's pretty harsh. The pulsing of the ABS isn't progressive. If the ABS is on, it applies full braking power followed by zero braking power.. full, zero, full, zero.. The torque from the engine that's being transferred repeatedly all the way across the drivetrain from wheel to wheel a dozen times a second, puts stress on everything. Brakes, rotors, axles, U joints, output shafts, and the differential itself. The left and right halves of the differential in the VW 02A transmission are held together with rivets which if forced to take this pounding too long will eventually fail. Neat huh?
Did I mention EDL uses the brakes? Perhaps "uses up the brakes" would be more appropriate. It's really designed for emergency low traction situations and not drag racing or rallying or other long duration, low traction situations.
So why use EDL if it's so bad?
Well, the torque transfer is only really bad if the input torque is high and the resistance at the side where it's being transferred to is high. Such as.. When you're spinning one tire on the pavement and the engine is cranking out 175 ft/lbs of torque. When it kicks that torque across from one side to the other, it finds that the other side (also on pavement) initially has lots of traction and therefore a lot of resistance which means that the drivetrain takes the brunt of the stress all at once. Worse case, is when the side that is slowed, slows enough to regain full traction, while the other side starts spinning. Then the EDL compensates and brakes that side.. and the whole process repeats back and forth many times.. Solution.. take your foot off the gas.

On the other hand, if one tire is on snow, and the other is spinning on ice and the EDL has you accelerating slowly, the engine is producing little torque and if you tried to gas it hard, the torque transfer from the EDL meets up with little resistance on the snow so the torque "escapes" as wheelspin on the snow side. If it's ice and pavement then yes, you want to avoid mashing on the gas, but pulling away smoothly shouldn't present a problem as each pulse of the ABS transfers into a small bit more acceleration of the car.

Electronic differential lock, or EDS (german acronym for same), is not a differential lock as per usual. It uses the ABS sensors at driven wheels (i.e. left/right front on FWD, left/right front and left/right rear on quattro), to determine if one of the two wheels is spinning faster than the other. At some speed differential (approximately 25 mph / 40 km/h), the highly sophisticated fifth-generation ABS/EBV actually pulsates the brake momentarily at the spinning wheel, effectively transferring the torque through the open differential to the wheel with more traction. This system is effective, but due to the stress that it would create on the braking system, it is only used up to speeds of about 25 mph / 40km/h.
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Aha, probabil ca tu esti unul care nu poate ramane inzapezit cu 2WD. Ce nevoie mai avem de AWD daca ne descurcam cu 2WD, doar "dig for traction", nu?