Hmm... No VDC for 5mt EVER?

I just realized somthing.... Subaru's AWD system makes it nearly impossible to implement any type of Vehicle dynamics control system as it stands.

 

The concept of a VDC system is individual braking to each of the 4 wheels to bring the car under control. This requires each wheel to be truely independent or to at least become truely independent of each other when VDC is engaged.

 

Subaru's use a of a center and rear viscous coupling Locking Differentials makes it impossible because all the wheels are mechanically linked.

 

A correction to the right rear wheel will induce a lock in the left rear wheel which will also induce a lock in the center diff locking your front wheels.

 

Correct me if I am wrong but I beleive this is the logistics of not offering VDC on 5mt vehicles.

 

Of course the AWD system is awesome for performing drifts and rallycrossing and generally imparts a better overall level of performance. But 99.999999999999999999999 percent of drivers including myself suck. And will only be advantegous if you are in the elite 0.00000000000000000001 percent that actually knows what they are doing.

Yep. The question is whetehr the simplicity, low cost and effectiveness is worth the trade off of having an electronic system. You can get VDC all day on a Haldex type ssytem, but I would rather have the Viscous system any day.

I second that... rather have a limited slip anyday.

That statement is true, but the 5MT does have 4-channel ABS which also comes against the same problem. I've read that the viscous coupling on the 5MT vehicles is tuned to not react too quickly in order to minimize conflict with the ABS system. The same probably applies to the rear LSD.

 

I'm not sure how the level of independent wheel braking differs between an ABS and ESP system, but it seems as though Subaru should be able to use a basic braking only ESP system on all their vehicles instead of a more integrated VDC system. Doesn't Audi Quattro with a Torsen center diffy also come against the same problem when applying ESP?

 

Ken

Well the Audi does not have LSD in either the front or rear axles, they use the brakes for (poorly) simulated LSD at low speeds and it sucks.

 

The lock up of the LSD can be different upon acceleration and deceleration and that can help with making ABS work. ABS in an awd drive car is very difficult to make work properly.

But the traction gained with AWD and proper engine breaking, Outweighs VDC, To me. Especially in snow, or slick surface, having a LSdiff is the difference between stuck and not stuck! Also, I love the way this car locks and pounces out of sharp turns... That is more immpressive than is straight line torq>