9000RPM

Many 4WD owners rave on about the benifits of 4WD. But is the benifits more percieved than actual?

I like Imprezas, and am considering buying one now that I need 4oors. I do a lot of snowboarding so the 4WD is also appealing. The thing is, in 7 years of dragging myself up the mountains,(in some fairly horrendous conditions), I've never been stuck because of 2WD.(other than having to be dug out the car park due to drifts).

I also enjoy driving in the wet. Appart from very occasional wheelspinthe grip is good.(the torsion diff on the ITR is 1st class).

So my point is: For the majority of owners ie the non boarders and city dwellers, does 4WD matter a damn? or does it just make you feel better on that one day a year when the snow lies?

drumsterphil

iTrader: (1)

Prior to my scoob, which I've had for a month now, I've had 12 years driving front-wheel drive cars (last car being a Rover 220 Coupe Turbo - don't scoff, they are fast, trust me!).

My observations at this early stage are that the level of traction that I get irrespective of road conditions is something that no 2wd car can get closed to. (I'm sure people will argue about traction control etc - but 4wd really is the dogs).

However, the difficulty for me has been to learn the correct style for driving a Scooby. Imprezas are constrained by the laws of physics and 4wd does not allow you to circumvent this. After reading various threads I have adopted a slow in-fast out style and it works. One thing I have found is that stability when accelerating or braking is amazing - nothing (2wd) I've driven comes close to it . 4wd isn't just about traction but the inherent stability that comes from sharing the power through two axles rather than one, IMHO of course

DP.

AJbaseBloke

The other thing that is forgotten about Subies is the simple brilliance of the Subaru AWD drivetrain.

Equal length drive shafts, low COG = good balance and predictability.

No rocket science there - just very solid basics!

I also go to the snow regularly, and in combo with some good snow tyres my car is pretty unstoppable (a B4) - I even pulled 2 large AWD wagons out of a ditch last snow season (makers will remain nameless ).

Cheers.

RT

YES, its definitely better.

In the rain, on the painted lines, powering out of a tight corner are some situations when a FWD will surely spin a wheel (perhaps so for a RWD). But the 4WD gives almost complete confidence that when you drop the clutch or floor the throttle, the car will go and not just spin a wheel. I've had 2 scooby's, a RWD and a FWD in the last couple of years so this is a fact. You don't need snow or ice to reap the benefits.

Don't forget the std rex puts out almost 300Nm (and the STI 370+Nm). Surely you don't want all that torque to go thru just 2 wheels?

SDB

The traction benefits of the scoob AWD are substantial from an out and out performance point of view.. but I accept that the majority of situations (particularly on the road) will not require this.

I would then say that the inherrant simplicity (in terms of the driving) of the handling are a benefit in emergency situations, but the 'tegra chassis is also fabulous, and probably even easier to drive for most.

If you are going up and down snowy mountains though, I think you would be very surprised at the added confidence and poise the scoob would give.

Cheers

Simon

EvilBevel

Simon,

At the risk of becoming the laughing stock of Scoobynet ... I DISAGREE with you LOL. Oh dear, and this on Xmas day

OK, 9000 RPM, all "torsion diff" and "ulcer jokes" aside ...

The standard UK Scooby has got one nasty bit ... it's got an open diff at the front, actually making it 3 wheel drive in a lot of cases.

I have seen far too many UK scoobs being stuck in mud/snow to not know this for sure.

Simon is probably talking from an STi4 owner POV ( )... they have an LSD front diff ... UK scoobs don't.

The ITR is an amazing car, and I would bet it's the underestimated car of the decade to be honest ... all things equal, an ITR will be faster in most conditions when we talk average drivers.

When we talk about accomplished drivers ... the Scoob would still be ahead. The extra traction can be used, if you know how to.

If not, in my book AWD holds a few surprises. Yes, traction is great, and chuckability (if that is a word) also, but I don't really want to know how many people got surprised by either lift off oversteer or ... overconfidence the extra traction gives you.

Best advice is to try one (for more than an hour) and see if it makes you feel happier than your ITR.

My bet is (and I'm a *big* Scooby fan) you won't. You really need to learn to drive these cars.

I await Simons spanking

HO HO HO LOL

Theo

john banks

Theo I think you are talking ****. Happy Xmas!

john banks

Only joking I've driven an ITR briefly and the traction is very impressive so that even in the wet you would not believe it is FWD a lot of the time. But there are not Scooby amounts of torque suddenly dumped through the wheels to contend with. In my hands it certainly wasn't as quick as even an unmodded UK Scooby. Having driven/owned some fast(ish) FWD Fords and Peugeots which are said to have very good chassis, I can say confidently that they have very little traction compared with the Scooby in all conditions. Now I know we don't do snow like you do, but we have some impressive stuff in Scotland. Earlier in the year in the bad snow, the Scooby was the only thing in our street that could get out, most other folk couldn't get off their drives never mind up the hill. One guy in an Audi AllRoad thingie got stuck and he had an easier run. At sane speeds the Scooby has very inert handling, but of course there are obvious limits.

Is it just the STi IV that has a front LSD? Most of them don't IIRC?

Surely stability under breaking is nothing to do with AWD, neither is steady speed cornering where you are not trying to put power down.

Says he that handling expert who can't even drive (me)

http://www.fortunecity.com/silversto...action_4wd.htm is an interesting link as well as Simon's http://www.drivingtechniques.co.uk/

[Edited by john banks - 12/25/2001 7:21:11 PM]

SDB

hehe

Theo.. thanks for the email warning.. prepare to be spanked!!

No, actually I agree with most of what you said (I normally do), but the the traction front diff thing is not the problem you suggest..

firstly... ()

when accelerating weight shifts rearward (as you know).. so in theory, rwd will have more accelerating traction than FWD. So AWD (even if it's only acting as 3WD) will have more traction again.

I also mentioned going up and down snowy hills..

on the way down, the weight is moved forward reducing the desire for a tight front diff as you need as much directional control as possible.

have I missed the bit you were arguing with? (just in-case... that was a genuine question, not a cocky retort!! LOL)

All the best

Simon

EvilBevel

Oh lol ...

Considering I had 3 whiskies, 4 glasses of champes, and 4 glasses of wine, I will try to reply

As always, we are talking about different things, but actually saying the same ...

John: re: only STi IV ... no, all STi's (AFAIK) have front LSD's, so does the P1 etc. Only the UK/Euro model doesn't.

As an aside: the *big* difference between the EVO and a Scoob is the quality of the diffs BTW (personal opinion)

>>Surely stability under breaking is nothing to do with AWD

You are absolutely right. The traction in breaking is the same for any car, 1, 2, 3 or AWD. Well, erm... no, the transition from AWD to braking can be even more "sudden, with more effects" than from 2WD, but this is over my head, still studying this ...

>>, neither is steady speed cornering where you are not trying to put power down.

No discussion there ... this is down to contact patches, weight transfers, weight, etc, but not to traction. The big plus in AWD is accelerating out of corners IMHO (and gravel/muddy surfaces, and from a standstill if you know how)

>>drivingtechniques.co.uk

LOL, I think I know that from somewhere

What I was trying to say is that AWD inspires you (means: go fast). Your neighbour was stuck, you weren't, so there you go. Brooaat. Until ... you need to corner or slow down: your AWD car suddenly has to obey the laws of physics and becomes your average car... you may not have been prepared for that though

>>on the way down, the weight is moved forward reducing the desire for a tight front diff as you need as much directional control as possible.

A front Torsen or ATB diff doesn't interfere with this, as it only locks when there is a) torque and b) a rotational difference. Without a) or b) it acts as an open diff In tight corners, it *does* make a big difference though (IMHO again)

>>have I missed the bit you were arguing with? (just in-case... that was a genuine question, not a cocky retort!! LOL)

I was arguing with the idea that AWD is your big friend in buckets of snow (not your words). It isn't, because the 3WD (UK scoob) could also mean you loose all your torque on 1 wheel, just like a no diff FWD car ... the center diff is rather lame on the UK model, allowing you to really get stuck if one front wheel is spinning (I have pictures if you want) I think this is what 9000 RPM was talking about ? ("I do a lot of snowboarding so the 4WD is also appealing"). It's not a Landrover Defender if you know what I mean.

Second point I was trying to make is that you can get over-confident in a Scoob. Which is a baaad idea

A good point was made though that AWD distributes the traction between 4 wheels ... less torque per wheel, so in theory more sideways grip (grip circle comes to mind). Is that true BTW ?

Theo

john banks

I thought STi and P1 did NOT have a front LSD. New STi does I believe. Is that one of the reasons we understeer more than Evos?

[Edited by john banks - 12/26/2001 10:31:32 AM]

RT

My MY01 STI RA has a front "suretrac" diff, as with the rear. The center diff is a heavy duty viscous type. My previous MY00 220hp Rex only had center and rear viscous diffs. Yes, I did spin the front inside wheel in tight corners on wet days, but that was really provoking it.

I have to add that differentials do help the braking effort! Assuming you're braking very hard in a straight line, if one tyre hits oil or paint etc, it will lock - triggering the ABS. What the LSD does is to postpone this lockup as there is a rotational difference between it and its twin.

Of course, it has to be set up right, if not - to quote MRTRally - it will "understeer like a dog"!

jamesa

Interesting stuff lads but........I`ll admit to not being a technical whizz so I tend to go by `feel` and driving satisfaction which has been rather different in my last few cars. Namely; ITR - standard Impreza MY00 - P1 with brake and back box options.

ITR - superbly rewarding, more so than either Subaru (yet!) as I felt I could use more of it`s performance and get closer to it`s limit in relative safety. Excellent as a daily driver; long distance tourer - for two !

MY00 - initially disappointed as was not so involving and perhaps was too easy to go too fast. Grew to appreciate it`smoothness and effortless response at motorway speeds but in low down, multi-gearchanging driving it was not a patch on the ITR. This really is where I get the most satisfaction from my driving. Did not appreciate the AWD grip level even on those RE010`s until we ventured out marshalling one night and traversed sections where others with FWD were struggling in the wet.

P1 - even smoother, especially the gearchange and engine management plus an improved level of feel from being lower and stiffer. Fantastic buzz from acceleration in a straight line but a handful when you arrive at that next bend `that` fast. Am really still learning but agree with the slow in fast out approach - not so rewarding as FWD I find.

Anyway, thanks for all the useful tips and enjoy whatever you drive.

Cheers

john banks

Some people prefer 2WD as they can reach the limits. I only use my Scooby on the road and am not a particularly skilled driver. I appreciate that I will (hopefully) never seriously see the limits of adhesion here, but realise that if you like to be able to explore your car in this way it could seem very dull.

DavidRB

If you have (for the sake of argument) an engine that can generate 400 Nm of torque and tyres that can only transmit 100 Nm of torque to the road, then the best a 2WD car can do (even with traction control) is to apply 2 x 100 Nm of torque to the road, whereas a 4WD car can deliver 4 x 100 Nm of torque and hence accelerate more quickly. You don't gain any more sideways grip as this is limited by the tyres and not the drivetrain. What you do get is the ability to apply more acceleration when cornering below the absolute limit because you can apply torque to all four wheels and not just two. That's why the best place to show off to a 2WD car is accelerating out of a corner. Apparently.

4WD is not so necessary these days because most normal cars have very grippy tyres and drive on good quality roads. The extra weight & transmission losses are only worth suffering when you have a car with Scooby power and you want to apply maximum power on a slippery road surface.

Over confidence in 4WD isn't as big a problem as over confidence in 2WD. You'll find far more 2WD cars leave the road in slippy conditions than 4WD ones. Just possibly at slower speeds, that's all. Dealing with lift-off oversteer is just learning to drive the car. It's no different from learning any other driving technique, apart from possibly being a little un-intuitive. Any car with 200+ bhp requires a little respect, whether FWD, RWD or 4WD.

Having an LSD can help, but it can make things worse if it's not set up properly. For example, go piling into a corner on the brakes and the inner wheel needs to turn more slowly than the outer one. A viscous diff might lock up under these conditions, dragging the inner wheel along at a higher speed, causing understeer. From the STi 7 reviews, it looks like this isn't a problem and the car's ability to accelerate out of the corners (where an open diff might just spin the inside wheel) is apparently very impressive.

If anyone finds themself stuck with only one front wheel spinning this winter, the solution is simple. Put the car in gear, lift off the clutch and keep your right foot on the gas to get the wheel spinning, then press the brake pedal with your left foot at the same time. This is a very crude way of locking the diffs and will transmit torque away from the spinning wheel and back to the other wheels. The car might clunk a little bit and should then start moving forwards. Once underway, keep your momentum up and don't lift off the brake too soon or you'll just bog down again.

Some more stuff on diffs & 4WD:
http://web2.iadfw.net/oldwolf/how_di...tials_work.htm
http://www.eskimo.com/~eliot/awd.html

Chris L

Conversation with three guys at work last week: All three of them own Boxsters - very nice cars, however, two told stories of the cars swapping ends on greasy roads. Both incidents occurred within the last month. I am very happy having AWD on my car, it is certainly a lot more secure in conditions that could be described as being less than perfect (i.e. a fair percentage of the time in this country).

I did 'rib' them a little about this (2 of these guys are serious drivers, who do their fair share of track drives and one has a 360 on order, so they know what they're doing) - they did challenge me to a little 'race', so I suggested Nurburgring in the wet

Under good conditions with a good driver, then ultimately, RWD is probably the ultimate in performance. For the rest of us mere mortals, I'll stick to AWD thanks.

Cheers
Chris

BTW for any Porsche owner's looking - this isn't a dig at Porsche or me wishing to start a debate on the pros and cons of Scoobies v Porsches - simply a conversation with a couple of colleagues in the office - Chris

SDB

Great thread guys!

I have to agree with chris

the Boxsters have great chassis (what's the plural of chassis???) and suspension, and are probably one of the more forgiving of true RWD sports cars, but they are never going to be a forgiving as a scoob in the majority of situations..

One of the reasons why RWD is so powerful in the right hands is that you have independant control over the front and rear of the car. In addition, it allows the front tyres to deal solely with cornering allowing slightly more flexibility on the set-up. The only time this is not true is under braking, but there is more load on the fronts under braking so front end grip is rarely a problem.

The reason they are less forgiving (on the whole) the same reason that they are so powerful.. the right foot has a huge effect on the cornering ability of the rears alone (OK that's not *quite* true but you know what I mean), where as AWD effects all 4 tyres.

So lots of power in rwd takes lots of cornering grip away from the rears, and leaves the fronts alone (apart from a reduction in load).

Cheers

Simon

9000RPM

Very informative boys! Cheers.

I didn't realise that the UK scoob had an open front diff. This would explain why my mate couldn't get out of the car park at the Lecht last year and I could. I thought he just had crap technique! He was probably loosing his power through the one wheel.

As for over confidence in 4WD, it reminded me of a friend of a friend, who pranged his Legacy in the snow 2 years ago. He kept saying "but it's 4WD, this shouldn't have happenned", "I was'nt going that fast" etc, etc. The fact was he felt the car slide and he hit the brakes! 4WD becomes 0WD!

drumsterphil

iTrader: (1)

Seen as I started the braking aspect of this thread ....

I was chatting to a friend and he stated that rear-wheel drive offers the ultimate in braking stability compared to any other configuration. I cannot remember exactly his explanation but was wondering if he was correct. (Aandy if you're reading this I do not doubt you!!)

I would have thought that 4wd with diffs being able to counteract the effects of lock-up would provide the best solution, but is this not the case?

What about engine placement? Porsche Boxter's being mid-engined will inherently suffer from sudden oversteer whereas front-engined cars are more benign in such circumstances so whether 2wd or 4wd will not have such an impact as configuration.

Insight or opinion would be appreciated.

DP.

eyeMAJIC

Hmmmm.... This is very interesting about the "open front diff" thing.

I'm currently staying with my folks in the remote West Highlands. They have a 1:4 steep dirt track which is currently coated with 6 inches of snow.

My UK MY01 WRX wagon cruised up 3 times today, without the slightest hint of lost traction: it was unladen too.

My work car (BMW 330D) cannot even ascend this slope in the dry; it gets halfway, then the spinning starts!!

So how come my MY01 WRX can cruise up in the snow as easily as my Mum's Discovery if it has an open front diff??...... *puzzled*

eyeMAJIC

CORN......

ooops, sorry, wrong forum...

Great~taste~Bloke

percieved benfits of awd..... more stickers on the boot!
oh and a more sound motor.traction grip like **** on a blanket
Matthew

9000RPM

eyeMAGIC

I think the point is: Once traction breaks, power is then lost through the spinning wheel. Up to that point you will have more traction(assuming same tyres/torque/power) than a 2WD car.

Feel free to slag me off if you think I'm talking crap.

I find it hard to believe that you're BM has such crap traction in the dry!

matt d

Simon - with a RWD car where it is easy to measure out power and tell how much grip is left at the rear, wouldn't that negate the "unforgiving" aspect of things (at least in terms of power oversteer)?

IMO another potential problem is that performance RWD cars often have excellent turn-in, which if you utilise it to the full will loosen the rear & cause oversteer. In a scoob if you tried the same, it would just start to understeer and you'd back off a touch and stay on course. And I think this is down more to the setup of the cars than which wheels deliver the power (although this has an effect). I'm not convinced that power oversteer is the main cause of spins in RWD cars (although I'm not totally sure if this is what you're saying!).

NBW

Interesting thread...

Scooby is my first AWD car, after a string of FWD's. I recently changed from Bridgestone RE010's to Toyo's, and now in the winter weather, am really feeling the benefit of these with AWD, but there are lessons to be learnt:

Last winter I spun my car, fortunetly at very low speed, because I had a big lift-off on an icy bend. As mentoned, AWD is no benefit when you do this - in fact it's even worse because the driver has a false sense of security because 'I have AWD and I am therefore invincible'.

Again last winter, turning into our road - which has a short but steep hill at the start - see man at side of road frantically waving arms for me to stop. Why? Because he couldn't get up this icy slope in his FWD car, and had slid backwards back down the hill. I drove straight up, it might as well have been dry tarmac.

Yesterday, having got used to new tyres, I am driving round elongated roundabout, where I am turning right (and indicating my intention to do so). Brake and turn in slow, feed power in. Car settles and grips, grips, grips. So far so good. Plonker approaching roundabout too fast CANNOT BELIEVE that I am going to carry my momentum through the 'bend' of the roundabout and goes to come straight on to the roundabout in front/side/back of me. He panic brakes way, way to late, his ABS kicks in immediately. I boot it and the Scoob just corners faster than it was, but still corners, no under/over steer, just does it, and I am safely out of danger (I would add, I wasn't speeding, just 'making progress').

Those are the benefits and pitfalls that I have found of driving a AWD car for a year and a half. I wouldn't preclude buying a 2wd car in the future, but my shortlist will mainly be AWD cars.

One final point - not a great fan of traction control. IMHO it seems pointless to put a powerful engine in a car, and then put some electronics into reduce the power when accelerating hard in the lower gears. When this happens, your GTi suddenly becomes a 1.4GL !!! Personally I think it's a cop out - Peugeot managed to engineer the front suspension on the 306 GTi6 properly to get the power down. Other manufacturers don't seem able to achieve this and so resort to electronics to throttle back the power.

Just my pennies' worth.

Tim

[Edited by NBW - 12/28/2001 12:31:55 PM]

golfturbo

It depends how good the electronics are I have racelogic traction control with variable slip..
If I boot it out of a slippy corner it has the effect of making it tuck in better as the power is reduced when the electronics kick in......i think standard T/C on most cars just has one setting which is probably the same as my wet setting only to used when its pissing down....having said that I have just bought the whole rear driveline of an S3 Haldex diff, drive shafts, hubs, calipers, prop shaft - the whole lot £345.00 including delivery - 330 bhp 5 door golf sleeper....

Richard Askew

....do I know you Golf Turbo?? ...

golfturbo

You probably know Gary Handa......I have a couple of bits on mine that he has....we both use AMD, alas i don't have the TT 225 engine with AMD remap....just a normal 1.8t with a K04 upgrade & FMIC

Been in Gary's car - BAD idea, felt way faster, more than I expected, must have been the 310 lbs torque :-) the equal length drive shafts seem to make a big differnce as well, combined with the racelogic they work really well - its at AMD at the moment having some big f&"$ off turbo put on......i think he's looking for 350-400 bhp

Richard Askew

yup I know Gary - thought it was u.. melikes Gary's car

NBW

'as the power is reduced when the electronics kick in'

My point exactly.....