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RWDboy
Forums Junkie

Location:
South Australia
Registered:
July 2002

Re: Front wheel drives

Wed, 25 August 2004 02:45

Well as a matter of fact that was my last post - but I'll give you the satisfaction of one more unconstructive post coming from me.

ST184_sillyboy on Wed 23rd June

An equivelant RWD or 4WD car is faster everywhere, with the exception of Rally - where FWD can be driven at 8/10ths quickly without having to commit to corners. The extra weight over the driven wheels also helps traction on low-grip surfaces.
(Note: The Lancia Stratos and 037 Rally cars proved that Mid-engined RWD can work on the dirt, if driven with commitment)

-Notice how Ferrari and BMW have never waivered from RWD ?

That sorted, I have a FWD '90 Celica that OVERSTEERS

That's right - it only ever understeers on 100% throttle, over smooth, banked corners!!

Okay so far so good, nothing majorly wrong with anything yet...the Stratos was a diabolical snap-oversteerer and the 037 had problems of it's own but granted they were both awesome rally cars. However a FWD car will not beat them on 99% of rallies Razz

ST184_sillyboy on Thurs 24th June

mick on Wed 23rd June

thats were you are wrong because in a case of cars having less then 100kw the front wheel drive will usally come off best off the mark due to having the least amount of traction and will also usally have the highest top speed as well

What the shit???? In what universe is LESS traction an ADVANTAGE in a drag-race???
-It's conceivable that of a FWD and RWD car, each with identical engines, weights, etc the FWD will have maybe 0.5% higher top speed, due to the drivetrain loss at the diff's crownwheel+pinion in the RWD.

Well I'm not going to mention this one much yet, but suffice to say that you arguments later down the track regarding AWD may be contrary to the picture you are painting here

ST184_sillyboy on Thurs 24th June

RWD cars typically have a more even weight distribution, due to the mechanical components being spread more evenly around the car. They also enjoy the benefits of steering from the front, and driving from the rear. This allows the driver the luxury of balancing the car between the throttle and steering while exiting a corner, allowing front AND rear tyres to reach their full grip potential together.

I'm not claiming to be some kind of handling/mechanical-layout overlord, but it's simple physics that FWD can't make use of it's available grip beyond a corner's apex, like a RWD car can. Since cars transfer their weight towards the rear under acceleration, this just magnifies RWD's advantage over FWD both out of corners, and on the drag-strip.

RWD cars have a typically more even weight distribution ey? Okay, possible, but they also have larger polar momentum BECAUSE the weight is distributed about a greater area - if you've ever read a decent vehicle dynamics text, then perhaps you wouldn't be so keen to argue that point - low polar momentum, low center of gravity are also important aspects. Gee, I wonder why Subaru are always pushing the nice, low, flat four AWD technology? I dunno.

ST184_sillyboy on Fri 25th June

The reason that having so much weight over the front tyres when braking is bad, is that you're using ALL FOUR tyres to brake. It's more effecient to have the load shared equally to maximise grip. Most FWD's will over-work their front tyres & brakes, leaving the rear tyres dragging around doing not much. Transferring weight rearward in a RWD while accelerating is ACE, 'coz it lets you get WAY more power to the ground.

As for the "losing more front end grip and hence start to steer wide" in a RWD" - yeah, totally agree with you. There's many RWD cars renowned for understeering horrificly under light-moderate throttle. Just hope that if you're in one of these, it's got enough power to kick the rear-out 2->5 degrees under heavy throttle, and keep on turning!! -At least this is possible in a RWD. In a FWD car, you've got to just grin and accept the understeer post-Apex.

Your first point was perfect, and I was definitely way off with my post (think before post is a good motto that I should probably adhere to more often). But I do want to get something off my chest...having the tail hanging out is not necessarily oversteer, and it is definitely NOT a fast way of driving. The arse end of the car could be hanging out but the fronts could still be sliding at a big slip angle, thus although the car is slowly pivoting inwards, it's actual turning arc as measured from the cars centre of gravity, could be WELL under the optimum for that car, and give an indication that the car is actually understeering. Thus - when a RWD gets too much power down and starts pushing the fronts wide, then you are consigned to understeer regardless of the balls the car has. In fact, in any RWD car this can happen to a certain degree (slight understeer is the optimum cornering technique so this isn't all bad news).

ST184_sillyboy on Sat 26th June

It's not like every RWD car ever made is a superbly balanced track-beast. Just like not every FWD is a gutless, boring, eternally understeering shitbox! I said as much in one of my previous posts here. When I said that RWD is fundamentally better, I meant just that - F U N D A M E N T A L L Y better. The fine-tuning is another matter, but RWD is quicker than a FWD car with same weight + power. Hence the ballast for RWD's in SuperTouring, and the eventual ban of non-FWD cars.

Physics aside, I personally think that to deny one's self the challenge of balancing the rear of the car on-throttle, and the front with your hands through the steering is well; wrong, boring, annoying, FRUSTRATING - when you know that RWD's can be worked-hard into, and OUT of a corner.

Okay - RWD is fundamentally better - better at what? Quicker you say? Okay if we were all building go-karts here then I'd be making a RWD one, but we aren't. This is one thing you never budge on, the fact that you are narrowing your criteria of what a car is so that you can come to the one conclusion about what platform is better. I'm a BIG supporter of an open mind to what a car is and can be, so I think that we will have a disagreement here for a while. As for 'the challenge' of getting a RWD balanced out of a corner - well, I say that if you can slide the car big time out of the corner, then you didn't go into the corner quite hard enough. Optimum driving is always *slight* understeer, if you under commit on entry, then you will be sliding big on the exit as the car attempts to get more power down around the same curve that a less under-used car would follow.

ST184_sillyboy on Thurs 1 July

Actually, I do realise how advanced the EVO's AYC system is. I've seen it referred to as the "hand of God" by journalist test-drivers. That won't magically conjure up extra tyre grip though. It can only put the power-down using the grip not maximised by cornering too. i.e. if you're using all of the tyre's grip to corner, you can't accelerate or brake without breaking traction and sliding/skidding. Read up on the "traction circle" to see what I mean.

Well there's a weak statement. Tyres work in mysterious and fun ways - a tyre doesn't have a linear relationship in how it can split it's work - ie if you do 'x' less cornering 'g's then you can do 'x' more accerating 'g's. There are so many dynamic forces at work that it is very hard to quantify what the heck is going on. I wouldn't argue too much about this kind of stuff without some serious back up hardcoredata.

ST184_sillyboy on Wed 18th August

I think it's unfair to try and boil this whole argument down to understeer Vs. oversteer: are you talking turn-in balance? mid-corner? corner-exit? etc. etc. . . 99.9% of RWD's understeer, whether you're talking circuit or road cars. The difference between RWD and FWD, is the freedom that RWD allows the driver - to balance the car post-apex between the steeering and the throttle. Given a similar weight, chassis, weight distribution etc, both rwd and fwd cars can be set-up to behave in the same fashion under braking, turn-in and near-limit, static radius+speed cornering.

The difference, and why I love RWD, is that once you start looking towards the next straight bit of road/circuit, you can pick your line and slip-angle with the throttle. This to me, is much more gratifying than waiting helplessly for the corner to end, while the front-end tries to wash wide, in a FWD and most 4WD's.

Well, whaddya know another statement that is pretty good. Seems contrary to your previous stuff going on about how good RWD is because of the oversteer...and how your FWD oversteers and how if god drove, he would oversteer. I guess there's a difference in our idea of driving. You want to be challenged to 'balance' the car and to drift out of the corner. I try and drive any car really fast, and adapt my style to get the most out of the car. Maybe I've got it wrong, afterall you seem to love the idea of a ridiculously active diff 4WD even though they won't oversteer. Maybe that's because you know they are going really quick - i dunno.

Then there is your argument about AWD not being any good unless you have 300 computer sensors attached to it and they are more active than a ho-house on saturday night. Then of course, suddenly an overly complex AWD system will lose tonnes of power to the ground and hence be slower, even though you stated a FWD system will gain sweet-fa over a RWD system earlier (okay there is a magnitude of difference between comparing FWD-RWD power loss and 2WD-4WD power loss - but you are being too selective with yer argument there).

In between all these moments of constructive argumentative posts - I can count a billion and one times that the same rhetoric was stated by you over and over again - that FWD is worse because of weight distr./dynamic weight/traction/blah blah and that 'an equivalent rwd is faster'. Whatever 'equivalent' means - which no one seems to be able to nail down quite yet. And for each time that same crap came up I'd spout the same 'why can't we all just get along' message. I'm not right, you're not wrong, and no one here is better than the other.

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