# Difference between 4XMotion on the Treg VS. 4Motion/Quattro on the Passat/Audi.



## spikeital (May 21, 2001)

*Difference between 4XMotion on the Treg VS. 4Motion/Quattro on the Passat/Audi?*

Was reading an article that my friend directed me to. Good for those ppl that do not understand the difference in 4 wheel drive systems. 
http://mozart.chat.net/~jeske/....html
Ok it doesn't mention how 4Xmotions works as I think the article is older. I did go to VW site to see what it said but under "engineering" it only mentions 4Motion not 4Xmotion. So what is the difference? The extra locking rear diff?

_Modified by spikeital at 2:59 PM 9-1-2004_


_Modified by spikeital at 3:00 PM 9-1-2004_


----------



## Pah-to (Apr 16, 2004)

*Re: Difference between 4XMotion on the Treg VS. 4Motion/Quattro on the Passat/Audi? (spikeital)*

Your Audi A4 has a Torsen Center Differential, and the front and rear differentials are open differentials. But the A4 also has EDL Electronic Differential Lock, which basically means that if the computer in the car senses a wheel spin it uses the four brakes individually to keep the wheel spin to a minimum. The A4 scores big points for having the Torsen Center Differential in my book.
The Touareg has an open center differential, and the front and rear differentials are open differentials. But you can lock the center differential, and optionally lock the rear differential too. The Touareg also has EDL. For the roughest of offroading, the Touareg scores big points for allowing the driver to lock at least the center differential, and don't forget that the Touareg also lets the driver switch to a low-range gear.
The only setup that would be superior to the Touareg would be to have three Torsen differentials, rather than two locking differentials and one open differential. But for reasons of expense, driveline drag, and fuel mileage, the setup that VW chose for the Touareg is really the best choice for it.
If you really enjoy this stuff, look to the following URL and download the PDF called "Chassis and Four-Wheel Drive Concept", on page 46 begins the discussion of the Touareg's drivetrain. The diagram on page 47 suffers from incomplete translation from German to English, but still you can figure it out.
http://www.ohiovw.com/files/touaregfiles/


----------



## cyberdog (Jun 1, 2000)

*Re: Difference between 4XMotion on the Treg VS. 4Motion/Quattro on the Passat/Audi? (Pah-to)*

hmmmmmmmm...... i always thought the 4XMotion was kinda a variant of the haldex system, but more sophisticated and completely controlled by another ecu whereas the 4motion/quattro on the passat/audi is all mechanical torsen system !


----------



## spikeital (May 21, 2001)

*Re: Difference between 4XMotion on the Treg VS. 4Motion/Quattro on the Passat/Audi? (Pah-to)*

Thanks for your insight. Just trying to figure out the exact differences. Never knew till now that the rear Disc Brakes also acted as rear drums for the Emergency Brakes and Parking. That is cool. Do most cars do this or is this unique to the Treg?


_Modified by spikeital at 9:06 AM 9-2-2004_


----------



## Pah-to (Apr 16, 2004)

*Re: Difference between 4XMotion on the Treg VS. 4Motion/Quattro on the Passat/Audi? (spikeital)*


_Quote, originally posted by *spikeital* »_Never knew till now that the rear Disc Brakes also acted as rear drums for the Emergency Brakes and Parking. That is cool. Do most cars do this or is this unique to the Treg?

It is not unique to the Touareg. I used to own a Toyota Previa Van and the parking brake setup was the same, with an internal drum brake in the rear.
The key thing with the parking brake is that manufacturers avoid having the system actuate through the normal brake hydraulics because it would be too easy to have a very slow leak by the seals in the brake master cylinder and thus have the brake release itself slowly. So every parking brake uses a steel cable to actuate the brake.
My Audi A4 uses a rear disc caliper that has hydraulic actuation for the normal braking action, and a steel cable to the same caliper to actuate the parking brake function. It is an interesting system, and it makes it difficult to change the disc brake pads unless you have a tool to reset the parking brake system since it self adjusts for pad wear.
I once owned a *vehicle* that used the normal brake master cylinders to also act as the parking brake. And the manual clearly stated not to rely on the parking brake for any more time than it took to get out and chock the wheels. That *vehicle* was a Cessna 150 airplane.


----------



## jgkptreg (Apr 7, 2004)

*Re: Difference between 4XMotion on the Treg VS. 4Motion/Quattro on the Passat/Audi? (Pah-to)*

Does having the parking brake drum integrated in the rear disk make replacement of the brake disks mucho dinero and a PITA?
Just wondering for future reference . . .


----------



## Pah-to (Apr 16, 2004)

*Re: Difference between 4XMotion on the Treg VS. 4Motion/Quattro on the Passat/Audi? (jgkptreg)*


_Quote, originally posted by *jgkptreg* »_Does having the parking brake drum integrated in the rear disk make replacement of the brake disks mucho dinero and a PITA?

No. The brake rotor is shaped like a hat, and it just slips off of the inner parking brake shoes. The inner parking brake shoes should not wear out in the life of the car unless you make a habit of driving aroud with the parking brake actuated. And to replace the disk brake pads is very simple too. This is the system on the Touareg.
On the other hand, the system that uses the same disk brake caliper for both normal braking and parking brake really requires that you have the right tool to reset the caliper piston before new disk brake pads (thicker than the worn ones you are taking off) will fit on the disk rotor. This is the system I said is on the Audi A4 for example.


_Modified by Pah-to at 4:48 PM 9-2-2004_


----------

