Is AWD over-rated?

[GT-Driver]

Hi,

All whel Drive s a huge advantage on gravel, sand and wet / slippy surfaces. But on a dry tarmac, what the hell of an advantage does it give??

Yes it can put the power just a little earlier than a rear or front wheel drive and it can take a little bit more roughness.

I still prefer either front wheel or rear wheel drive. Front wheel is easy to push hard and the rear whel drive can use its ability to drift (controlably) to turn in the nose of the car in the right angel to hit the apex and they can trail break nicely too.

Also not to mention the added weight and power loss of the AWD. So does an AWD help the car corner better generally?

[auroan]

Watch the 2012 Italian superstars series. You'll see the answer in how the 4wd RS5s walked all over the competition wet or dry.... until they got a 100kg!! Weight penalty.

[Al Weyman]

The Nissan GTR's are untouchable in series like the former DTM and Classic Thunder closely followed by 4 x 4 Escort Cossies, the GTR's broke the back of Aussie Touring cars didn't they even dumping the mighty Cosworth hence why they went over to V8's.

[Notso Swift]

Not to mention the 2litre BTCC where cars were all the same power and the 4WD Audi's had to carry 50kg over RWD and 100 on FWD (4% and 9% or so on a relatively low power class) yet were still reasonably comfortable on tight circuits, winning a championship then getting nobbled, eventually banned in about 98 (or so?)

[Al Weyman]

I have never driven a 4x4 on a circuit but plenty of RWD's and I dont whether its just me or whether you are going that much faster but it always seems the race track is slipperer than the normal road surface, maybe its rubber, maybe oil dropped I don't know but I have always felt 4x4 must be an advantage and a big one.

[VIVA GT]

I suppose it's all about power vs grip really.
If the car has sufficient grip to transmit all of the engine power through just two wheels, then four-wheel drive would b e no advantage. (In fact, bearing in mind the extra weight and transmission frictional losses, it would be a disadvantage).
As power levels rise however, the added traction of twice as many wheels can be advantageous.
Four wheel drive can also help under braking as, if all four wheels are effectively tied together by the transmission, the braking forces are equally distributed too...

[auroan]

Originally Posted by VIVA GT

Four wheel drive can also help under braking as, if all four wheels are effectively tied together by the transmission, the braking forces are equally distributed too...

Erm, yes, but not the way you're thinking. Things like diffs prevent all 4 wheels locking up and having the same braking force all at the same time.

What 4wd does give you, is the engine braking effect on all four wheels rather than just two when off the gas. But that's only to say if the 4WD is permanent. There are some systems that only engage the rear axle when slip is detected at the front (not sure if any such system is ever used in circuit racing though).

[dtype38]

Originally Posted by GT-Driver

Hi,

All wheel Drive s a huge advantage on gravel, sand and wet / slippy surfaces. But on a dry tarmac, what the hell of an advantage does it give??

Yes it can put the power just a little earlier than a rear or front wheel drive and it can take a little bit more roughness.

Well I think you just gave two answers to your own question! But fundamentally, with four contact patches driving the car instead of two, any time the patches are not on the absolute limit of their breaking or lateral grip you have more capacity to push the car forwards.

Originally Posted by GT-Driver

I still prefer either front wheel or rear wheel drive. Front wheel is easy to push hard and the rear wheel drive can use its ability to drift (controllably) to turn in the nose of the car in the right angel to hit the apex and they can trail break nicely too.

I agree in as much as I also prefer two wheel drive cars - I just find them easier to control. My limited experience of four wheel drive on track just showed that I struggled to think about traction both ends of the car at the same time. Whether that was lack of experience or just lack of brain power is open to debate. What I could see, though, is that 4wd is as different to 2wd, as fwd is to rwd. You have to get your brain round it before you can be quick.

Originally Posted by GT-Driver

Also not to mention the added weight and power loss of the AWD. So does an AWD help the car corner better generally?

Regardless of what happens mid corner it would seem from various race series' experience that, in the right hands, the benefits outweigh the drawbacks.