What is the difference in practical terms i.e owning/driving pleasure/stability etc in a front wheel and a rear wheel drive?Why are most cars front wheel drive whereas cars like BMW/MERCS (which keep getting top marks from all motoring journalists esp likes of 5 series BMW)rear wheel drive.And how do the likes of Audi quattro compare to the these rear wheel drives.Your thoughts on the subject will be very much appreciated.
yours sincerely
ravi
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Front wheel drives are more forgiving than rwd cars, inducing understeer which is more controlable than oversteer which can lead to losing the back end of the car if one is a bit premature on the gas through a bend. I would think it is also cheaper to produce fwd cars, without the need for a seperate back axle and a drive shaft running the length of the car.
Rwd gives better performance, which you can test by pushing the car and then trying to pull it and seeing which is easier. There are no fwd's in formula 1 for example.
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Only if you drive very quickly or make sudden emergency manoeuvres will the difference be noticed.
I would agree with Tom , FWD is safer for normal road driving for normal drivers.
The only downside with FWD is the difficulty of controlling the rear end of a car if it starts to slide.
But if you want the best handling RWD is the way to go just check out the supercars Ferrari/Porsche/MGB/Lotus/Beetle e.t.c
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Steve,
"just check out the supercars Ferrari/Porsche/MGB/Lotus/Beetle e.t.c"
The Ferrari and Porsche credentials are undeniable, the MGB's dubious but I'm feeling generous tonight, so I'll let you off - but where on earth did the Beetle make it in the Supercar ranks? I certainly wouldn't rate it's handling - I can only very charitably describe it as "entertaining".
Chad.R
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I think FWD was originally developed to give more room in small cars. No transmission hump or prop shaft tunnel. Space isn't so much of a problem in large cars. Each type has it's merits and drawbacks, but RWD cars have better weight distribution and don't have FWD problems such as torque steer and reduced traction.
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Steve seems to have put what could take an age to debate in a nutshell. I'm not totally convinced by BMWs ads that say rwd gives a stability advantage, the horse does not push the cart does it?
Mike
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Apart from the Citroen (I think), when the Mini came on the scene in the late fifties, it was highly unusual for "ordinary" cars to be FWD. It was marketed as the design of the future in terms of space saving and the majority of manufacturers followed suit. Now, fifty years later, it is the norm for the majority of small passenger vehicles.
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John,
In 1929, Cord (owned by the Auburn Automobile Company) made a model called the L-29. It was the first American production car to feature front-wheel drive...
Other models included the 810 & 812 (an 812 was driven by Ron Ely [of TV Tarzan fame] in the film "Doc Savage - Man of Bronze")
Nothing new under the sun...
CV
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Thanks Clare, yes, of course, there were a few but, as you might agree, they were not ordinary mass produced cars. I can even remember riding in a BSA 3 wheeler, which, I think, was front wheel drive but, it was no match for the rear wheel drive, 3 wheeled Morgan.
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Mike,
Actually, the horse does push the cart. Is just looks as though he is pulling.
He pushes via the collar around his neck. He pushes the collar, the cart follows.
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You could possibly be correct. Most of the power from a horse comes from its back legs, ie RWD or possibly a 4WD system with a bias to the rear......
The cart is the caravan and no car be it FWD, RWD or 4WD pushes a caravan
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CM wrote:
>
> You could possibly be correct. Most of the power from a horse
> comes from its back legs, ie RWD or possibly a 4WD system
> with a bias to the rear......
>
> The cart is the caravan and no car be it FWD, RWD or 4WD
> pushes a caravan
except when its reversing. ;-)
I know I know nobody loves a smartarse!
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From driving a few of each I would suggest a general rule of thumb would be, under 150 horse power, front drive is fine. Over, torque steer, inside wheel spinning out of slower corners, scrabbling for grip in the lower gears, etc will start to be a nuisance; Proton GTi is very good at 133 hp but these things are just starting to show.
Above 200, say, rear drive is almost a must but then most cars have it.
As to 4wd, sorry, no experience but in the case of the Audi and the Jag they started off with a fwd and improved it, it seems. The extra machinery must increase losses, and reduce economy.
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Tranmission power drain is the biggy here I should imagine - that is the loss between the flywheel and at the wheel. Most smaller cars are FWD mainly for space, costs and lack of power - a 30 or 50bhp power loss from a 90bhp engine would be noticed! That's why I cannot understand vehicles such as the Subaru Justy.
My estimates;
FWD - 15bhp
RWD - up to 30bhp
4WD - up to 50bhp
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Audi four wheel drive was banned from the btc some years ago because they were wiping the floor with the opposition winning all the racing , subaru/evo. Enough said.
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So, bottom line, does it really matter if you're living in the real world which it is?
BTW Thinking back on all the cars I've ever owned the Land Rover is the only rear wheel drive car amongst them!
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Rear wheel drive is better for towing as the drawbar weight is added to the driven wheels, rather than deducted from it as on front wheel drive, thereby giving better traction.
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Not according to the tests carried out by the caravan club
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Pete,
Do tell more. I regard FWD as poor for serious towing with the possible exception of the self-levelling Citroen's where the weight transfer from the front wheels doesn't seem too bad.
Of course much of my towing includes an element of off-road (track and field) so absolute traction can be important.
David
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I thought rear wheel would also be the best choice also but apparently some front wheel drive cars perform better in towing tests than front drive , article in the latest caravan club mag
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Brian,
Isn't the drawbar weight quite light? I am told that caravanners for instance should have no more than about 56lb noseweight on the bar.
My relative weighs his with a bathroom scales under the jockey wheel.
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Alwyn
Depends on the towcar or towbar or caravan limits. My towcar will take up to 140kg, towbar is type-approved up to 120kg and caravan limit is given as 100kg - so I aim for the lowest of these. General rule of thumb is 7% of caravan gross laden weight (MTPLW for the purists) but that's all it is - a rule of thumb.
Noseweight gauges aren't expensive and they do save a lot of ruined bathroom scales!
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If the yanks are/were the grand-masters of vehicular innovation then why are they still driving around in Dodge Vipers and the like with their V-10 8ltr lorry engines putting out as much power as a 3 litre Euro supercar or even a 2ltr rally supercar (Lancer Evo/Scooby/etc).
Cars with bhp/cc in the same league as the Lotus Esprit Turbo and such like are indicators of true innovation.
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All I know is that I can get wheelspin on starting off when towing (in a not particularly powerful car) with front wheel drive if I let the clutch in too quickly.
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To paraphrase Brian,
All I know is that I can get wheelspin on starting off also when *not* towing (in a not particularly powerful car and a diesel too boot) with front wheel drive, and the clutch does not have to be let in all that quickly either.
Also reckon Tomo and Steve G (partly in the latter case) sum it up quite nicely.
The predominant way a fwd slides is understeer, ie front wheels run wide. Can be many causes of this but the normal driver reaction which is to simply lift off the gas is usually the safest method of restoring sanity.
Where it all gets tricky with fwd, is as Steve says, if when lifting off you get lift off oversteer, ie the back end slides. This needs rapid steering input and/or getting back on the gas, the latter is perhaps not the most natural reaction to an inexperienced driver who is maybe in their first real life skid. The reason that fwd is the most acceptable option to the majority is that the average driver will have to be pushing very hard (no pun intended) in order to get into such a situation.
However the reason fwd is most common, apart from all the perfectly valid engineering reasons mentioned by others, is due to cost, packaging and marketing reasons.
For rwd either the front or the rear could let go dependant upon a whole host of circumstances, speed, steering input, power input, brake input etc, and generally you will require to alter both steering and throttle inputs dependant. Generally rwd is inherently less stable, but more fun which is why journos like them as I guess they get the opportunity to play off public roads more than most..
As Mike Harvey says I?m not too convinced by the BMW arguments, I remember only too well the 2002ti and early 3 series which were decidedly unstable and regularly disappeared backwards through hedges at the behest of the road warrior behind the wheel.
Oh yes, Guy Lacey aka GG, Well said sir!
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Yes, it is quite light, although when packing on site the weight distribution has to be guessed and it may sometimes be a little more than 56 lb.
On the other hand it is at the extreme end of the vehicle so exerts the maximum leverage.
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Is this a myth?
Possibly the two FWD cars I used to drive with the greatest enthusiasm were an Alfasud and Saab 99 2dr Turbo (oh yes plus a 1.8i company Cavalier).
Despite some wickedly nippy driving neither ever suffered this problem, just a reassuring tightening of the cornering line on lift-off.
David
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David,
No its not a myth, apart from the car, it depends upon how hard or how silly you push it and the slipperiness of the surface.
Seen someone have the car equivelant of a real tank slapper, and it carried on until he gunned it.
Plus remember my S60 comments in that email the other day? Ok so it was slippery, the ESP was switched off, and I was deliberately playing, but it was possible to get to the point where it needed a smart dose of opposite followed by a bit of welly to pull it straight. But it did need driver behaviour beyond the point one is normally prepared to go on public roads if that is any comfort.
So I can understand your comment, and just to be inconsistent I would guess that is the situation I get on UK highway, just enough tightening of the line to be comfortable. Hope that explains that it is possible.
regds,
S
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Stuart,
OK, you're the boss on this one with your comp' experience. Perhaps my feel for the car and throttle was sufficient to allow a progressive lift-off to keep it balanced.
I'll creep away somewhere else, extreme trailer towing anyone?
David
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"Perhaps my feel for the car and throttle was sufficient to allow a progressive lift-off to keep it balanced."
I think you've hit the nail fair and squarely right on the head there. What we think we do and what we actually do without realising it are two different things I guess. The latter is probably the more sophisticated in all reality, wonderful thing the human brain isn't it?
Computers...... pah!
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And I suppose I was weaned on the all time lift-off oversteer kings....Triumph Herald and VW 1500 Variant.
After those any FWD was tame.
David
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It's called flying by the seat of your pants.
Your body reacts to G forces, the feedback from the steering wheel, wheelspin or skid, sound, etc. without conciously registering the fact and you react instinctively.
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>>Re:
just check out the supercars Ferrari/Porsche/MGB/Lotus/Beetle e.t.c
This was tongue in cheek ;-) ... but in a strange way points out just how many variations there are when it comes to drivetrains.
Tomo made a very good point about the power output.I would say modern FWD chassis can handle 200bhp (Gti-6,Type-R)but once you go over this torque steer will become a nuisance.
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Too many answers to read.... but 'lift-off oversteer' sounds like 4WD Audi to me. I personaly prefer this to RWD, but it can get out of hand in the earlier large 4WD Audis (100, 200), in the same way that RWD can get out of hand if throttle is applied too liberally.
Martin.
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A good compromise might be a torque tube transmission. The rear wheels push against the engine mountings, and the mountings pull the car along.
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