Front Wheel Drive Vs Rear Wheel Drive vs All Wheel Drive

[ricksterrr]

I'm not really sure this is the place for this topic.

But what do you want to know specifically? They all have their advantages and disadvantages.

Given sufficient grip, RWD is the perfect setup - hence why every major motorsport in the world uses it. Even the most famous of 'AWD' cars (Nissan GTR for example) strip back to RWD for the race track. The rear wheels take care of acceleration and the front wheels take care of steering.
RWD cars tend to balance towards 'oversteer' which means the front of the car pulls to the inside of the corner (whilst the rear comes out), but as you know from 'drifting', some opposite lock combined with accelerator application fixes this

FWD is probably the worst of the bunch - especially in older designs. When you accelerate hard, weight shifts to the rear of the car which only lessens the grip to the front wheels (conversely, in RWD it provides more grip), and then to make matters worse, if you're turning at the same time, the wheels not only have to try accelerate, they then need to steer. This means they tend to 'understeer' or push towards the outside of the corner.
FWD are the most fuel efficient due to the lowest weight and highest drivetrain efficiency.
Having said that, the Golf GTI is a very well balanced FWD car. It has minimal 'weight shift' to the rear during acceleration, it has an awesomely balanced chassis that can literally corner on 3 wheels, and it has balanced 'drive shafts' so torque steer is all but elimated. It also has XDS which helps with the understeer issue during hard acceleration in corners.

AWD uses all 4 wheels to accelerate. Thus it's big advantage is that when acceleration exceeds the grip that two wheels can obtain, the other two wheels keep it accelerating hard. So on dry tarmac, this typically means on initial acceleration from a stand-still. In the wet this can mean even on rolling acceleration. On gravel or dirt, this means basically all the time.
Other than the advantage of superior acceleration, AWD then basically has negatives. It generally suffers the same understeer issues as FWD cars. The AWD system weighs more, meaning that they typically have lower peak cornering speeds as the added weight combined with lateral G means an identical car with AWD would need more lateral grip than the identical car with only FWD or RWD to maintain the same speed (and AWD gives more forward grip, not lateral grip). The added weight will also have a small disadvantage in braking distance, again for same reason. Also, the combination of that added weight and 'drivetrain loss' from being split to 4 wheels instead of 2 wheels means they're not as efficient as RWD or especially FWD cars.
So when it comes down to it, the power of the car needs to exceed the grip that two tyres will achieve for a 'significant-enough portion' of its 'intended use' for AWD to be an advantage, hence why AWD has never had wide adoption on closed tarmac racetracks where you're almost never at a standstill (apart from the start) and usually have wide slick tyres (F1, Indycar, Nascar, V8 Supercars, Japan-GT, 'Lemans' sports cars (LMP1/2, GT1/2/3 etc). Rallying (both 'WRC style) and 'Targa Tasmania' style is generally where AWD cars have an advantage. Plus, in countries with plenty of snow.


So this is all generalisations. Different cars do better or worse jobs at implementing each of these configurations.

Should you be worried about the GTI being FWD? No.
Will the R be better for having AWD? Yes.
Will a 300KW GTI be drivable with FWD? Yes, given some respect to the throttle application and a new LSD etc.
Will a 300KW R be easier to drive than the GTI? Yes. And much more forgiving.

Anyway - I hope that's a help

For experienced members... please don't come along and rip my post to shreds - I have a much more indepth understanding of these things, I'm just trying to be brief and not too complex or specific. Feel free to add things though - everyone has different experiences and opinions

Awesome explanation btw, Coreying ! Definitely learnt a few new things from it

[gregozedobe]

OK coreying, if you really want to nitpick I'm up for it (just remember that you started it) .......

AWD really does not allow you to acelerate around corners and better than FWD. They oversteer the same as FWD cars in that instance.

I don't know about your experiences, but my experiences with AWDs vs FWDs on wet roundabouts is that under acceleration FWD cars have a much stronger tendency towards UNDERsteer (not OVERsteer) than equivalent AWDs. My previous FWD (Laser TX3) basically gave you a choice - "Accelerate or Go around the corner (pick 1 only)". My Octavia is somewhat better at resisting understeer, but if provoked will do it too. I agree that some AWDs will understeer strongly if driven totally insensitively (and others will oversteer strongly if set up to mimic "RWD" characteristics), but given driving of at least average ability, then AWDs will generally understeer less than equivalent FWDs when accelerated on wet corners.

That said, AWD cars are not immune to the laws of physics, and cannot brake any better than an equivalent FWD, despite feeling "better" in slippery conditions. Many an over-enthusiastic AWD driver has been reminded of this fact to the detriment of the structural integrity of their car

All indications say that the R will be available in both manual and DSG here still.

VWA chose to only import the Pirelli edition with DSGs, no manuals were available. Time will tell whether they repeat that decision with the R or not. I note that VW NZ only offers the R with a DSG.

As for tuning, the Stage III GTI kit gives you 276KW/521NM. The Stage III R kit gives you 298KW/501NM - so much of a muchness as far as ability to tune either engine without having to replace internals etc.

Note that I said "Golf R can be more easily tuned to give much more power. I don't regard a Stage III kit on a GTI as easy tuning as it involves a complete new turbo and other stuff. To me an easy tune is a simple remap.

I wouldn't be comfortable driving a Golf GTI that had it's power bumped from 155Kw/280Mn to 276KW/521NM too hard (eg track work) without upgrading some of the internals (of course you may have a higher risk tolerance than me and the VAG engineers who design engines). And at those sort of power levels you can kiss your engine and drive train warranty goodbye, unless you have a VERY accomodating dealer who is willing to take a big risk.

[Corey_R]

AWD traditionally understeer. As the front wheels are both accelerating and turning, understeer is the 'generalised' characteristic of AWD (from many sources, wikipedia being the most basic). Sure particular models of cars handle different from the 'generalised characteristic of a configuration', but the typical cornering charactistic of an AWD is understeer.

What VWA did with the Pirelli is not relevant since VWA have already announced they're bringing the Golf R in both DSG and Manual. Source Carsales.com and others sites who are quoting VW Australia.

As for upgrading the power, the GTI can be upgraded by 22% power and 44% torque with the APR Stage I ECU. The Golf R can be upgraded by 21% power and 24% torque using the APR Stage I ECU. So really both cars can just as easily be upgraded. (although granted, since VW Australia is detuning the power for the R in Australia, for us that'll be a 28% power upgrade).
And just because you're not comfortable with 276KW/521NM from a GTI without changing internals doesn't mean that Volkswagen aren't comfortable as well. In fact, it was Volkswagen that commissioned APR to develop the Stage III kit for the GTI. It was first displayed as GTI-R at SEMA in 2006, and later as the famous APR 'Black and White' GTI (a year later?). Though, even APR acknowledge that the full potential of their GTI Stage III kit cannot be made without upgrading the internals. At this point 300KW (and more?) is possible.

[G-rig]

Golf R is better just like R32 is better. Wheelspin and axel tramp sucks and although I love the GTI is still isn't as good or well balanced as an integra type R.. Couldn't feel that was a fwd.

As mentioned though theres not too much to worry about with the GTI. Just have to be sensible with the right foot (moreso when modding for more power).

[Timbo]

Timbo, alot of members here are talking up RWD.. I think FWD in this case GTI has good enough technology to replicate rear wheel drive and i think it can be as fun. As far as understeer goes, GTI has XDL to counter understeer and it would perform exactly with vehicle that has RWD. I was very negative about FWD at first, but after seeing what the FWD especially the GTI can do in corners, i would say it match up with RWD cars or even better. More fun to i must add.

Nothing wrong with FWD; I wasn't criticising it at all, just explaining the different characteristics.

I've had (and still have) a number of FWD cars and they're great fun to drive. As you point out, the XDL on the new MkVI GTI gets good reviews in controlling understeer.

Personally, I would prefer to drive any model in the current Golf range as a daily drive relative to, say, a Falcadore for the same money. Golfs are a much better driving experience IMO.

Also, I've done enough track work in FWDs to know they can hold their end up when pushed.

[AdamD]

I don't know about your experiences, but my experiences with AWDs vs FWDs on wet roundabouts is that under acceleration FWD cars have a much stronger tendency towards UNDERsteer (not OVERsteer) than equivalent AWDs.

I don't think you can really generalise either way about the handling characteristics of a car based solely on the drive configuration. I'd suggest there are three major factors at play that determine a AWD car's understeer or oversteer tendency in a particular situation:

1. The AWD setup: Not all AWD setups are equal by any means. Some use a fixed torque split between axles (such as most Subarus). Others transfer torque between front and rear (and sometimes side to side) by means of active diffs, and have a default drive behaviour that only changes as required when the car determines that more or less grip is required at a certain wheel or axle. For example, past and present Nissan GTRs are effectively 100% RWD until the car decides to send torque to the front wheels for added traction; as a result it is, more or less, reactive AWD. The latest models (V35 GTR, Mitsubishi Evo X, etc) use sophisticated algorithms to predict vehicle movement and driver responses based on sensor readings, and so therefore are much more bulletproof in typical situations, but this hasn't always been the case.

From what little reading I've done on the newer VW and Audi AWD systems, they're reactive, FWD-biased setups, that transfer drive rearwards when required for accelerative traction, but rarely otherwise. So, all things being equal, they're likely to behave more like an equivalent FWD car unless the car is wheelspinning under power. (But please feel free to correct me here if I'm wrong.)

Remember too, the driving wheels really only have an impact on vehicle handling when power is applied, or when using engine/compression braking (ignoring the weight issues of an AWD setup).

2. The suspension geometry and tune: Any car can be made to have an understeer or oversteer tendency regardless of the driven wheels, even under power (within reason of course). Just look at the Honda Integra Type R DC2 - tuned to virtually eliminate understeer despite being FWD. Older Peugeot FWD cars were tuned with very stiff rear suspension and had a real oversteery tendency - especially when lifting off. Scary. The car's ability to deal with road imperfections is also a big issue with suspension tune - sudden changes in the road surface or available grip to an individual wheel can throw some (many) cars right off if the suspension can't cope adequately.

3. Weight distribution and transfer: Weight transfer when accelerating, braking or cornering plays a huge role in handling balance. If a car transfers a lot of weight forwards when braking, the rear end can become unloaded and the available grip will reduce to the point that oversteer is inevitable. If, however, weight transfer is well controlled, then the car is less likely to be unsettled by an excess or lack of weight over a wheel or axle.

So, I guess I'd say that if we're talking about a specific model of car, with a particular suspension tune, then it's easy to generalise about handling tendencies. But the drive configuration alone (the sticker-on-the-bootlid factor) isn't going to suffice. Just my 2c.

[gregozedobe]

Oh, you want more "discussion" ? OK then ...........

AWD traditionally understeer. As the front wheels are both accelerating and turning, understeer is the 'generalised' characteristic of AWD (from many sources, wikipedia being the most basic).

If you want to keep disagreeing with me you should at least read what I actually wrote and try to respond to that - I didn't make a blanket statement that most AWD's oversteer most of the time, I said that FWD's tend to understeer more than similar AWDs when accelerating around a wet roundabout.

In the case of what the OP was asking about (ie staying on topic), I believe that a Mk 6 Golf GTI will understeer MORE than a Golf R will if both are driven at the same speed into a wet roundabout, then the driver accelerates as much as they can while going around a roundabout (assuming same driver, same tyres, sane entry speed, staying in own lane, wet hotmix surface). If you want to believe that the FWD Golf will understeer LESS than the AWD Golf R in these conditions then I guess that is your perogative It might be worth your while checking with S3 and R32 drivers before making further statements on this subject.

What VWA did with the Pirelli is not relevant since VWA have already announced they're bringing the Golf R in both DSG and Manual. Source Carsales.com and others sites who are quoting VW Australia.

I had a look at that site. It appears to be mainly a rehash of previous overseas press releases on the Golf R, mixed in with a short statement by a VWA spokesman talking about release dates in Oz and planned pricing. I still think that the Golf R will (intially at least) only be available with the DSG. As you are so confident a MT will also be available at release time I suggest a bet of $10, with the loser paying up actual $$$ and also publicly acknowledging they were wrong (in this thread). Are you willing to put a small amount of money where your mouth is ?

As for upgrading the power, the GTI can be upgraded by 22% power and 44% torque with the APR Stage I ECU. The Golf R can be upgraded by 21% power and 24% torque using the APR Stage I ECU. So really both cars can just as easily be upgraded. (although granted, since VW Australia is detuning the power for the R in Australia, for us that'll be a 28% power upgrade).

Again, you might want to go back and read what I actually said - "Golf R can be more easily tuned to give much more power." According to the APR site, a Stage 1 Golf GTI has 254bhp, while a stage 1 Audi S3 (same engine as Golf R) has 322bhp. That is 68bhp more, which would make a noticeable difference.

And just because you're not comfortable with 276KW/521NM from a GTI without changing internals doesn't mean that Volkswagen aren't comfortable as well. In fact, it was Volkswagen that commissioned APR to develop the Stage III kit for the GTI. It was first displayed as GTI-R at SEMA in 2006, and later as the famous APR 'Black and White' GTI (a year later?).

Any car importer can get someone to build a "show special" for them, but until VW head office (ie Germany) release a GTI engine with std internals AND more than 200Kw for sale to the general public with a full factory warranty I think that VW's actions speak louder than your words

I note that VW still haven't released (for general sale) a hi-po version of the new cam chain engine (EA888 family) - all the current "hot" 2.0 turbo petrol VAG cars are running the old rubber cam belt engine still, and this is over 18 months since they started making GTIs with the new engine.

I enjoy a lively discussion, but please try to stay on topic, otherwise the mods may close this thread down

[Corey_R]

I think we should just agree to disagree, some of it is just semantics, some it's just my opinion is different - and since it takes too to keep a thread off topic, your last comment is humourous but true, so I'll stop