Quattro explained

[titanium3.2]

there are alot of very knowledgeable individuals in this model forum so I wanted to also ask this question here too.

http://www.audizine.com/forum/showth...40#post7737640

TIA

[Adub-Drew]

Okay I'm no expert on the topic but i do know a little bit. Here's the breakdown Quattro has two different Quattro setups. One is called Haldex, and another is Torsen. Torsen is the one we have in b7's and is a mechanical system, it always works and has power being fed to all four wheels at any given time. However it can send more power to any which wheel with the aid of electronics i believe. Haldex found on the TT, a3, and any other Audi that has a motor latitudally (not sure if thats a word, or what to call it) mounted, More or less the same way a fwd car's motor generally is. It permanently sends power to the front wheels and there is a viscous coupling that engages the rear wheels when it senses that the two front wheels are spinning at different speeds via electronics. However after some wear of engaging and disengaging it starts to fail. This is why haldex is a inferior system, and in my opinion should not hold the same "quattro" badge.

Haldex Explained, nevermind the whole saab thing.. More or less the same stuff..



Here's an example of quattro..

[titanium3.2]

^ that was informative. If I was understanding the English properly then the system uses the brakes while cornering to change the crown gear distribution? Not the greatest design I would think.

According to some quick searching the torsen in our cars I bolted to the end of the gear box. Then the question is how does the power get to the front wheels? A propshaft inside the transmission housing ?

[Tcass]

Awesome videos bro! I love my Quattro!!!

[JPT]

^ that was informative. If I was understanding the English properly then the system uses the brakes while cornering to change the crown gear distribution? Not the greatest design I would think.

It is actually a good design to use brakes. You have a couple of options (like any differential) clutches (wear out over time), gear driven (also a good design), or brakes. Gear driven, is great for off roading, and has proven to be strong and last a long time (based on the strength of materials). Using the brakes, is not ideal if YOU are the one applying the brakes, but with highly advanced traction control systems, they can control front to back and side to side. We only have pedals that apply brakes evenly to all 4 wheels, but the computer in a traction control system, can apply brake force to each wheel individually as needed, many times per second. Allowing power to be diverted to one wheel.

[Adub-Drew]

Awesome videos bro! I love my Quattro!!!

Thanks, i love quattro. My dad has a 328xi and although its awd system is sadly faster to react than quattro to shifting power to the right wheel. The bmw solely relies on electronics, whereas the quattro is more mechanical and will work non-stop at the end of the day. Quattro is a great awd system.

[alpinevr]

The nice thing about the haldex system is you can get a controller to alter the characteristics.

http://www.hpamotorsport.com/haldex.htm

[Charles.waite]

Also it's transverse mounted not latitudinally. Haha.

The Torsten system the longitudinal audis use is the most durable system out there. The electronic systems' achilles heel is that it relies on electronics to work whereas torsen systems work through pure mechanical physics. You might think it's a weak point but the brakes are generally on of the most dependable systems on our cars. Therefore having them in charge of distributing torque in adverse conditions is much preferable to a computer controlled diff.

[Adub-Drew]

Also it's transverse mounted not latitudinally. Haha.

The Torsten system the longitudinal audis use is the most durable system out there. The electronic systems' achilles heel is that it relies on electronics to work whereas torsen systems work through pure mechanical physics. You might think it's a weak point but the brakes are generally on of the most dependable systems on our cars. Therefore having them in charge of distributing torque in adverse conditions is much preferable to a computer controlled diff.

Transverse, thats the word I was looking for haha..

[airbornerifleman]

The nice thing about the haldex system is you can get a controller to alter the characteristics.

http://www.hpamotorsport.com/haldex.htm

That’s pretty cool

[Acme]

^ that was informative. If I was understanding the English properly then the system uses the brakes while cornering to change the crown gear distribution? Not the greatest design I would think.

BTW, the system in our B7 isn't the last generation with the crown gear... The ratio is 50:50 and EDL is used to control wheel spin on one axle, using ABS sensors and brakes.

The last iteration with 60:40 ratio was introduced in the B7 RS4 and is used in the B8. The crown gear was introduced later I think...

[Adub-Drew]

BTW, the system in our B7 isn't the last generation with the crown gear... The ratio is 50:50 and EDL is used to control wheel spin on one axle, using ABS sensors and brakes.

The last iteration with 60:40 ratio was introduced in the B7 RS4 and is used in the B8. The crown gear was introduced later I think...

That's correct, we only have a 50:50 spilt! But that is better for when we have bad weather!

[Jay-Bee]

That's correct, we only have a 50:50 spilt! But that is better for when we have bad weather!

It's a 50:50 default split but can apply up to 75% of torque transfer to either front or rear axle.

quattro generation IV

[citation needed]

Starting from 1995 on Audi A4/S4/RS4 (B5 platform), Audi A6/S6/allroad/RS6, Audi A8/S8 with both manual and automatic transmissions. Also on VW Passat B5, where it was initially referred to as syncro, but by the time it reached US soil, it had been re-christened 4motion. Also used on the Volkswagen Phaeton and Volkswagen Group D platform sister vehicles. The Volkswagen Touareg used 4Xmotion with a separate transmission, PTUs and front axles.

The manually locking rear differential from the earlier generations was replaced with a conventional open differential, with Electronic Differential Lock (EDL) (which detects wheelspin via ABS road wheel speed sensors, and applies brakes to one spinning wheel, thus transferring torque via open differential to the opposite wheel which has more traction). EDL works at speeds up to 80 km/h (50 mph) on all quattro models (on non-quattro models: up to 40 km/h (25 mph).

System type: Permanent four-wheel drive.

Torsen type 1 or 2 centre differential, 50:50 'default' split, automatically apportioning up to 75% of torque transfer to either front or rear axle.

Open rear differential, Electronic Differential Lock (EDL).[4]

Open front differential, Electronic Differential Lock (EDL).[4]

[Acme]

The nice thing about the haldex system is you can get a controller to alter the characteristics.

http://www.hpamotorsport.com/haldex.htm

And you should have a look at the Haldex system in the Golf R. I used to think that a Torsen system was better, but I'm not so sure anymore...

[funky_snowman]

torsen used to be considerably better. personally, i think it still is. however, haldex has come a long way. the newer versions can actually transfer more power to the rear than 50%, which is a huge deal for haldex imo.

a lot of people see "electronics" as being a bad word, and there certainly are benefits to mechanical systems. However, when you look at cars like the EVO X and GTR, it's pretty clear that you can do some cool stuff with electronics that just aren't possible without them.

[Salt n Peppa]

Interesting thread! Way to break it all down.