what is variable-wheel-drive as opposed to a-w-d?
Discussion
Torque on demand I think you'll find.
There was a post on a few weeks back with similar questions. This is a cheaper way to make an AWD car.
If the Torque is only supplied to some wheels occasionaly then the system can be lightweight, cheap, compact & normally unstressed.
A few cars are using it, some Audi's, the BMW X5 & Merc'c amongst others. Usually it's a front drive system with occasional assistance from the rear when required, especially on suedo 4x4's.
There was a post on a few weeks back with similar questions. This is a cheaper way to make an AWD car.
If the Torque is only supplied to some wheels occasionaly then the system can be lightweight, cheap, compact & normally unstressed.
A few cars are using it, some Audi's, the BMW X5 & Merc'c amongst others. Usually it's a front drive system with occasional assistance from the rear when required, especially on suedo 4x4's.
cptsideways said:
A few cars are using it, some Audi's, the BMW X5 & Merc'c amongst others. Usually it's a front drive system with occasional assistance from the rear when required, especially on suedo 4x4's.
Mmmm. Most VAG stuff is front wheel drive most of the time.
Mine, of course, is 50/50 until the going gets rough. Then 3 diffs work out which end I'm going to crash.....
vlc said:
If the Torque is only supplied to some wheels occasionally then the system can be lightweight, cheap, compact & normally unstressed.
So would say that if you wanted to build a sporty 4x4 car you'd use vwd over 4wd as to save weight???
No - you would do that to save cost. Weight would be secondary.
Variable drive saves the cost of a differential and some heavily machined shafts. It does add a controller and harness though.
You can call it awd but engineer it to do a tenth of normal duty cycle and save a ton of cash. Given average customer usage, good tuning etc you can make the car AWD 5% of the time but sell the feature as a big deal. That's huge profit potential.
The Haldex system used on Volvos and VWs is at least honest, though I feel it is not optimal for dry high speed aggressive handling it enables drivers in nasty weather to get from A to B safely.
GavinPearson said:
So would you say that if you wanted to build a sporty 4x4 car you'd use vwd over awd as to save weight???
No - you would do that to save cost. Weight would be secondary.
Ah - but i'm looking at from a performance view, in that would a vwd car be quicker than an awd version as its lighter as said earlier?
vlc said:
vlc said:
So would you say that if you wanted to build a sporty 4x4 car you'd use vwd over awd as to save weight???
No - you would do that to save cost. Weight would be secondary.
Ah - but i'm looking at from a performance view, in that would a vwd car be quicker than an awd version as its lighter as said earlier?
If you want performance you need AWD not VWD because the AWD inherently lets all tyres work to the limit, VWD works to the limit of two and then channels the power to the others to give more margin.
Bottom line is you'd feel the understeer sooner in VWD - hardly good for performance.
AWD - Impreza, EVO 8, Ford Sierra & Escort Cosworth, Audi A4, A6, A8 quattro
VWD - Volvo and anything using Haldex system.
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