[strongdeo]

What do you reckon? What is the difference between traction vs grip?

My thoughts are that A4 Quattro has more traction due to the 4wd but the E90 has more lateral grip due to the chassis etc.

Therefore does that mean going round a bend (in the dry) the BMW will be quicker than the Audi?

[dxb335d]

so many variations to consider.

not as easy to just pinpoint one thing. Some cars have very good mechanical grip. 4WD helps also. But a well set up RWD car will be quicker than a 4wd car around a tarmac track.

Rally cars are 4wd because of the many loose surfaces they run on. They need that amount of traction from four wheels otherwise they would crash quite quickly.

A race car built for race tracks needs grip but does not need excess weight of 4wd and transmission losses which come with it.

They need as much power down to the wheels as possible. RWD is a better set-up for track and fwd is just for cost and simplivity on cheap road cars.

[NFS]

Originally Posted by strongdeo

What do you reckon? What is the difference between traction vs grip?

My thoughts are that A4 Quattro has more traction due to the 4wd but the E90 has more lateral grip due to the chassis etc.

Therefore does that mean going round a bend (in the dry) the BMW will be quicker than the Audi?

In literal terms 'traction' is 'grip'. It's the 'adhesive friction between the wheel and the road'.

The difference in this context is the ability to use 'grip' to turn wheel torque into forward momentum.

A 4wd car will (in theory) always have an advantage because the wheel torque is transferred through 4 contact patches rather than 2. However, the chassis still comes into play because a bigger contact patch is no use if the tyre isn't kept in contact with the road.

In terms of lateral grip 4wd and 2wd cars have the same amount of contact, so the chassis is more important. The car that maintains grip at the right wheels at the right time will corner faster.

Quick 4wd cars generally function as RWD cars when cornering to maximise the limit of grip by balancing the forces front and rear.

My experience is that the e90 can typically 'punch above it's weight' in terms of handling because:

a. Weight distribution is very even
b. Front and rear grip are well balanced
c. Handling is neutral (neither over or understeer)
d. The limits of adhesion are approached gradually, with plenty of feedback.

My experience of fast 4wd cars is that the trick diffs balance the torque at the wheels very very well.

They can corner amazingly quickly, but they don't 'stand on their tiptoes' like a really well balanced RWD car.

[misterS3]

Originally Posted by dxb335d

so many variations to consider.

But a well set up RWD car will be quicker than a 4wd car around a tarmac track.

Rally cars are 4wd because of the many loose surfaces they run on. They need that amount of traction from four wheels otherwise they would crash quite quickly.

A race car built for race tracks needs grip but does not need excess weight of 4wd and transmission losses which come with it.

They need as much power down to the wheels as possible. RWD is a better set-up for track and fwd is just for cost and simplivity on cheap road cars.

All else being equal.....i.e power to weight ratio, tyres, set up. etc.
I was under the impression a 4wd would be faster than a RWD round a track.
I'd have imagined that 4WD would be able to put power down earlier than RWD coming out of every corner for one?


In real life...... Anybody who had driven towards Prestwick airport from the north, will know the 2nd roundabout before the airport and the road leading from that to the roundabout right outside the airport.

I can do that section of road much faster in a 4WD car, because 4Wd can get the power down . Admittedly its on a usually wet road. But there is no way i can get my Beemer down that stretch as fast as my S3, and there 335D is much much faster in a straight line.

To be honest, it's not a bad thing that i drive more conservatively, but i can't wait to get the GTR and have all the reassurance of 4WD.
I realise this makes me a heathen or some sort of gay boy because real men drive RWD

[M3-FAST]

Originally Posted by strongdeo

What do you reckon? What is the difference between traction vs grip?

My thoughts are that A4 Quattro has more traction due to the 4wd but the E90 has more lateral grip due to the chassis etc.

Therefore does that mean going round a bend (in the dry) the BMW will be quicker than the Audi?

I came from an Audi A4 2.0T quattro into my BMW 325i

There are pro's and con's to each setup IMO. The Audi had immense grip and rarely put a foot wrong. Actually it NEVER put a foot wrong

It was however not as much fun to drive around the twisty stuff than the BMW where the RWD and the front wheels doing the steering only, does a good job at providing some feedback.

The ESP on the Audi was incredible - you could enter large roundabouts at silly speeds, keep the throttle floored and the computer would adjust power to the engine and to each wheel meaning that you just could not get it into trouble. The downside is that if your a driver that DOES like to have fun, the car won't let you! Even turning the ESP off, only reduced it's input. It was NEVER actually off.

It was a car that gave you confidence in it's abilities, and a car you would happily pass to the missus in the snow (knowing she was driving to work safer than she would in her E46 compact at the time!).

I even blasted it round an empty car park in the snow once. Foot to the floor in 1st gear, the engine would just feed in small amounts of power leaving the car completely controllable and more importantly steerable. An amazing feat of engineering.......if slightly dull

Even with these small frosts we have been having, my 3 series has been scrambling for grip on our estate where we live.

Ask me to choose between the two.....mmmmm, I would have to think about that one

[Dave_3]

Originally Posted by misterS3

In real life...... Anybody who had driven towards Prestwick airport from the north, will know the 2nd roundabout before the airport and the road leading from that to the roundabout right outside the airport.

Just passed by it Tuesday and yesterday ... and there are tyre marks across the tarmac and into the roundabout grass, must have ducked under the keep left sign from the Ayr end

It is a really bad design - too abrubt, I remember when it was just a junction.

Turn in speed is the killer there.

D.

[DaveC]

Originally Posted by strongdeo

What do you reckon? What is the difference between traction vs grip?

My thoughts are that A4 Quattro has more traction due to the 4wd but the E90 has more lateral grip due to the chassis etc.

Therefore does that mean going round a bend (in the dry) the BMW will be quicker than the Audi?

Actually the biggest determining factor on corner speed between two fairly well sorted chasis (maybe the E90 is better sorted than the A4 Quattro, who knows but the Quattro is by no means rubbish) comes down to one simple thing - contact patch size or tyre width in relation to vehicle weight.

[MOB]

Can I bring in FWD as well.

Best car I ever drove in terms of grip was a Clio 182 Cup - seemingly endless grip from the front end - why is this??

Best handling car I ever drove was my old Cayman S - telepathic steering - nothing else has come close since.

[NFS]

Originally Posted by MOB

Can I bring in FWD as well.

Best car I ever drove in terms of grip was a Clio 182 Cup - seemingly endless grip from the front end - why is this??

Best handling car I ever drove was my old Cayman S - telepathic steering - nothing else has come close since.

Wikipedia is great !:

http://en.wikipedia.org/wiki/Automobile_layout

Rear engine rear wheel drive (porka 911) is ideal for acceleration because the weight transfer under power pushes the back end down onto the road maximising grip. You can feel this happening when you drive one.

With front wheel drive, you have 2 problems; the contact patch has to steer as well as provide forward traction and the weight transfer works against you by lightening the front of the car under power.

That's why FWD cars have traditionally been unable to handle lots of horsepower.

You are right about the clio though it's a grippy pointy little thing. I think this is because it's balance is so good.

When cornering, you want to transfer some weight to the front wheels, e.g. by trailbraking, to help you turn. If you use too much you break traction and understeer.

FWD are prone to understeer because they already have a lot of weight at the front and it's easy to overload things.

The clios though have lots and lots of mechanical grip because the tyres are kept in contact with the road. They also have a fantastically mobile and controllable rear end which allows you to turn the car using lift off oversteer, then take advantage of the mechanical grip to pull hard out of the corner in a straight line.

Strangely enough, my bestest ever powerslide was in a race spec renault clio cup at Palmersport, where I managed a good 100ft of sideways action!

Clever chaps at renault.

[strongdeo]

I find the Audi provided more safety and perhaps more traction too - as you went round the bend it would cling on for dear life and not let go. However the deedback was not so great it was a little numb. You didnt know how close to the edge you were. In my BM 6 series you know where you are and how close to the edge of adhesion you are, it's more fun to drive.

I think the 330i that I will get at the weekend will be more telegraphic with the information it provides and will be better balanced and lighter than the quattro (and for that matter lighter than the 645).

[strongdeo]

About five years ago Autocar Magazine did a test in the wet of the E46 M3 with the previous RS4. Now the latter is a sensational drivers car. The normal genereal consensus of opinion was that the M3 was the better fun to drive but the RS4 provides more grip/traction.

In the wet they tested it and found gthe M3 with its LSD could actually give you more grip and go faster round the bends (and give you better feedback).

LSD = huge benefit.

[encee]

There is definitely more traction with RWD than FWD (although I know that this is not in dispute).

I have owned quite a few of the latest hot-hatches in recent years, all front-drivers of course, and certainly, in this sort of weather, with the roads still lacking in grip even when dry, my E92 copes much better than any of them did.........in spite of the fact that it`s also chucking out miles more torque than any of them too !

[Irnbrukid]

Originally Posted by misterS3

In real life...... Anybody who had driven towards Prestwick airport from the north, will know the 2nd roundabout before the airport and the road leading from that to the roundabout right outside the airport.

I can do that section of road much faster in a 4WD car, because 4Wd can get the power down . Admittedly its on a usually wet road. But there is no way i can get my Beemer down that stretch as fast as my S3, and there 335D is much much faster in a straight line.

What that isnt that bad a bit of road just melt it and hold on.

That used to be a great stretch of road before they put those roundabouts in that was a killer bend sorted the men from the boys or the brave from the braver...

[dxb335d]

Originally Posted by misterS3

All else being equal.....i.e power to weight ratio, tyres, set up. etc.
I was under the impression a 4wd would be faster than a RWD round a track.
I'd have imagined that 4WD would be able to put power down earlier than RWD coming out of every corner for one?


In real life...... Anybody who had driven towards Prestwick airport from the north, will know the 2nd roundabout before the airport and the road leading from that to the roundabout right outside the airport.

I can do that section of road much faster in a 4WD car, because 4Wd can get the power down . Admittedly its on a usually wet road. But there is no way i can get my Beemer down that stretch as fast as my S3, and there 335D is much much faster in a straight line.

To be honest, it's not a bad thing that i drive more conservatively, but i can't wait to get the GTR and have all the reassurance of 4WD.
I realise this makes me a heathen or some sort of gay boy because real men drive RWD

Round a track mate, rwd is quicker. Most race cars are rwd. Think of any series, single seaters, GT cars etc. (road going designed race cars, Ultima Radical etc)

Dont see a 4wd ferrari do you. (Lambo do, but due to being owned by Audi)

Rally cars are 4wd for reasons i mentioned earlier.

Now on the road there is even more variences.

Several High profile mags and TV series tested RS4 and M3 on track.

Both similar weight, same power but the m3 was quicker.

The reason 4wd is quicker on the road because its easier to access the performance compared to rwd. A ok driver can be quick in a 4wd car.

[misterS3]

Originally Posted by dxb335d

Round a track mate, rwd is quicker. Most race cars are rwd. Think of any series, single seaters, GT cars etc. (road going designed race cars, Ultima Radical etc)

Erm....do your remember when Audi entered Touring Cars with their 4Wd cars what happened? They destroyed the field and had to be weighted down to even things up.

The reason for any series not having 4wd is not because it's not faster. It will most likely be because it's cheaper to develop a rwd car

Originally Posted by dxb335d

Dont see a 4wd ferrari do you. (Lambo do, but due to being owned by Audi)

I'm sure this makes sense to you, but whether Ferrari do or don't have a 4wd car, doesn't mean that definitely RWD is faster that 4WD.

I guess there was a reason for the Veyron being 4WD - maybe even that it means it can get more of it power down more of the time and hence be quicker? I don't know. But would seem to make sense to me.

Originally Posted by dxb335d

Rally cars are 4wd for reasons i mentioned earlier.

To get more power down more of the time and hence be quicker? Doesn't that apply on tarmac too?

Originally Posted by dxb335d

Now on the road there is even more variences.

Which is exactly why 4wd would be faster on the road - it can cope better with these variances.

Originally Posted by dxb335d

Several High profile mags and TV series tested RS4 and M3 on track.

Both similar weight, same power but the m3 was quicker.

But you're not taking into account the different chassis' of those 2 cars etc.
Also the different bhp and torque.

I said above "all other things being equal" for a reason.

Originally Posted by dxb335d

The reason 4wd is quicker on the road because its easier to access the performance compared to rwd. A ok driver can be quick in a 4wd car.

So that wouldn't apply to the track? Because.......

Please dont tell me this has anything to do with the fact the GTR is 4WD

[M3-FAST]

[misterS3]

Originally Posted by redE93cab

Have you checked with Will that it's okay to be eating 2 boxes of his popcorn?

[M3-FAST]

Originally Posted by misterS3

Have you checked with Will that it's okay to be eating 2 boxes of his popcorn?

It's OK, Will gave me them to look after

[willhollin]

Originally Posted by redE93cab

[NFS]

For once I totally agree with Carl.

RWD is generally better for track cars than 4WD.

All genuinely fast 4WD cars have trick diffs and when cornering they are effectively RWD.

[misterS3]

Originally Posted by NFS

For once I totally agree with Carl.

RWD is generally better for track cars than 4WD.

All genuinely fast 4WD cars have trick diffs and when cornering they are effectively RWD.

??? Confused.com

So genuinely fast 4wd can't be considered because they have trick diffs to shift the power around as required.
But it's okay for RWD cars in this comparison to have LSD's?

Sounds to me a bit one sided.

[dxb335d]

Originally Posted by misterS3

Erm....do your remember when Audi entered Touring Cars with their 4Wd cars what happened? They destroyed the field and had to be weighted down to even things up.

The reason for any series not having 4wd is not because it's not faster. It will most likely be because it's cheaper to develop a rwd car


I'm sure this makes sense to you, but whether Ferrari do or don't have a 4wd car, doesn't mean that definitely RWD is faster that 4WD.

I guess there was a reason for the Veyron being 4WD - maybe even that it means it can get more of it power down more of the time and hence be quicker? I don't know. But would seem to make sense to me.



To get more power down more of the time and hence be quicker? Doesn't that apply on tarmac too?


Which is exactly why 4wd would be faster on the road - it can cope better with these variances.



But you're not taking into account the different chassis' of those 2 cars etc.
Also the different bhp and torque.

I said above "all other things being equal" for a reason.



So that wouldn't apply to the track? Because.......

Please dont tell me this has anything to do with the fact the GTR is 4WD

GT-R is a street car. I couldnt give a f**k about it.


Look at porsche's GT2, took out the front driveshafts then homologated it for racing.


Mate, go watch top gear when they had the M3 and rs4.

4wd aint quicker. Its more weight up front which induces understeer.

The 4wd audis had more power as well as 4wd


veyron once again a road car, and with 1000bhp. It needs 4wd. And is actually slower around a track than a car with a mere 600bhp which is rwd.

Im talking race vehicles.

The pinnacle of motor racing is formula one, if 4wd was the way to go. They would have had it 20 years ago in f1.

Rallying, right, they soon found out 4wd is quicker for loose surfaces... its developed that way and there great.