I sometimes read about how Subaru uses "true" all wheel drive, while other automakers don't. What did they mean by this?

I sometimes read about how Subaru uses "true" all wheel drive, while other automakers don't. What did they mean by this?

Other urls found in this thread:

thetruthaboutcars.com/2013/06/alphabet-soup-4x4-vs-4wd-vs-awd-wheres-the-differential/
en.wikipedia.org/wiki/Citroën_Xsara#Xsara_WRC
youtube.com/watch?v=4XYX2cC1dnY
twitter.com/SFWRedditVideos

Some companies use an electric clutch to sometimes drive the rear wheels when the need arises
>I think Volvo does this

well marketing terms can mean anything but they probably mean "not haldex"

all wheel drive all the time as opposed to

Power is constantly being sent to all 4 wheels. Most 'all wheel drive' cars send power to only the front wheels during normal driving, and only send power to the wheels when the car is losing grip and starting to slide.

Because Subarus give power to all the wheels all the time.

AWD is a meme anyway

Less weight with FWD or RWD

If you have AWD, why not use all of it all the time?

fuel economy lmao

>muh 90 degree turns

Is there any difference in drivetrain power loss between Scoobydoo AWD and the rest?

Is this official subaru literature or the work of some idiot fanboy?

Several reasons:

Subaru AWD systems are "on" 100% of the time, which means they'll always be sending power to both the front and rear wheels. This hurts fuel economy, but helps handling. Haldex systems with electronic diffs will often only send power to the front wheels, and then route power when the computer senses slippage. However, sometimes you want more power sent to the rear wheels, even when there isn't slippage (like when you're accelerating out of a corner). This all means you can accelerate earlier out of a corner.

Subarus also have longitudinally mounted engines, which means that they have equal-length shafts which totally eliminates torque steer. AWD systems adapted from transverse FWD systems will sometimes still suffer from minor torque-steer. This longitudinal setup with equal-length shafts is the "Symmetric" part of their marketing. The downside to having a longitudinal setup is that the engine will stick out a bit more over the front wheels, increasing understeer.

Both of these reasons are why, when you're driving fast through corners, a Subaru can tend to understeer into a corner and oversteer out. Still, though, most people will agree that Subarus will have the best AWD systems at their price point.

>sending power to the rear transaxle to send back forward to the front
disgusting

Anyways, here's source
thetruthaboutcars.com/2013/06/alphabet-soup-4x4-vs-4wd-vs-awd-wheres-the-differential/

I sometimes read about how BMW doesn't have front wheel drives. What did they mean by this?

Because the front wheels don't need power going to them 90% of the time, it just causes understeer and bad fuel economy.

Ideally you want a RWD bias with power going to the front only when shit gets hairy.

thanks but it doesn't really answer my question lol

>disgusting
I can see how it might cause someone's autism to flare but muh weight distribution

>"Our symmetrical all-wheel drive is distinguished by how it constantly proportions power to the wheels..."
>our

I don't know myself but judging by the severe marketing bias and use of the word "our," there could be a sad chance it's a legit scoobydoo diagram.

>muh weight distribution
53/47

It's bullshit, because quattro is superior in every way.

"quattro" doesn't mean shit now that audi have started using transverse fwd haldex setups branded as "quattro" now

now you need to go for the s and rs models to get the real deal

Quattro/4motion is the only thing comparable to subarus AWD back in 06-07, can't say much about newer cars though.
Test drove a audi TTs, that was a fun machine, it felt really smooth.

The real deal is still the best, though

It means power to the rear wheels is better hence the picture of a hare with hind legs in the front.

Not really, the good Quattro setups are pretty much the same as the Subaro ones.

very informative post, thanks dude

>Subaro
u*

They do now
X1s are FWD now

For the most part, yes, but Quattro systems use some combination of Torsen mechanical diffs and traditional locking diffs depending on the year, while manual Subarus use viscous diffs and automatic Subarus use electronic ones.

Torsens can transfer power in real time as the wheels slip, while viscous diffs only transfer power after the wheel is slipping. Both will get keep you from getting stuck, but the Torsen system will do it faster and smoother.

It's symmetrical all wheel drive. It's a 50/50 split now then in the past it was 51 to 49 or 52 to 48

It is a constant awd, others engage the rear wheels only when traction is lost at the front.

What does Mitsu S-AWC count as?

You're correct for most Subarus, though WRX STis came with Torsens in past generations, and current-gen STi models use a helical differential that is essentially a Torsen in everything but name.

>Almost have enough to buy one.
Now saving up for the options I want on it.

It doesn't help handling when going into a corner you understeer because of excessive torque sent to the front. On corner exit it does better because more power is sent to the front but for motorsport use systems like Porsche and Nissan's rear-biased AWD systems are a lot faster.

When was the last time a a RWD or FWD kicked ass in the WRC ... Lmao get out of here user

Yes, but AWD Porsches and GT-Rs cost a fuckton more than a WRX. Porsche gets more out of an NA flat six than Subaru, too, but I wouldn't really call them competitors.

The only reason why Subaru sticks with the front-biased system is because it's "rally-inspired" so it's tuned for dirt roads and other low-traction surfaces.

wait, subaru used vlsd?
i heard these disintegrate after some time, and it's impossible to fix them, you have to replace the whole unit

if i recall correctly miata also had it for 3 years then mazda switched to torsen

"True AWD" = not Haldex

AWD infinitis use the same system.

Literally only base models and the tt have haldex/fwd. And at that point you're just buying the badge

I'm on my second AWD BMW, and while it does pretty well in the snow, it certainly doesn't feel like true AWD. Had a 2001 Quattro that was a beast though.

Would true all wheel drive just be 4wheel drive?

Not quite the GT-R system as the rear transaxle would absolutely trash rear seat room in the Q50 sedan but it's very much an RWD-biased system that can apportion 50/50 torque front and rear. I don't believe it actually has an LSD either for some models and the ECU just selectively brakes wheels so it's not going to last as long in track conditions.

you are implying a distinction between AWD and 4WD that doesn't exist

Thats the point. just call it 4wd you fucking fucks. Fuck you eurotrash, fuck you asians. Fuck you soccer moms.

well its not often you hear 4x6 or 8x4

why so angry? no sex?

if you are reading anger into that post then maybe you should go get some sleep, son

>engine in front of the front axle
True AWD my ass. Even Audi does that crap.

>yfw FWD naturally aspirated Citroen managed to beat the shit out of the most advanced WRC machines
en.wikipedia.org/wiki/Citroën_Xsara#Xsara_WRC

Good explanation, thanks man.

classic/blob/bug aren't front biased though...

Well, not really. When I dont need the traction, on the highway for exemple, 90% of the power is sent to my front wheel.

Haldex transmish

Subaru has equal length front driveshafts to eliminate torque steer. Unfortunately, their solution involves mounting the entire length of the engine in front of the axle, which is a huge no-no for handling.

It's just another of the derpy ways Subaru does everything wrong and then claims to be better, like making a flat engine in order to lower the center of gravity, and then being forced to raise the entire engine to clear the oil pan and manifolds, raising the center of gravity higher than an inline engine.

That's why Nissan and porshe are killing it in rally these last few years eh?

Frogs know how to FWD.

Torsens don't function in low traction conditions. If one tire ever completely loses traction, it becomes and open diff and that tire spins up. If it suddenly regains traction while still spinning quickly, the diff will explode when the worm drive binds.

Got any sources or proof for those claims

They work quite well as center differentials when performance isn't the goal (ie base model subies). They are a terrible replacement for a Torsen rear lsd on the track though.

Sure, just look at Subaru's marketing material. They show the entire engine in front of the axle line.

You're reading that wrong. The Xsara entered in the earlier kit car class was NA and FWD. The Xsara WRC was turbocharged and AWD.

Can i just say that these threads are much better than the other kinds of threads and I hope we have more of them

The Cayenne is doing a hell of a lot better than the WRX right now.

Huge no no? it's nothing to do with the engine position, it's to do with weight distribution which moving the engine forward and backwards has the most affect on.

Having a balanced weight distribution from the position of transmission and engine allowed by a longitudinal flat 4 is an advantage for CoG and body roll. The engine is also balanced as a result too, all positives.

The problem isn't weight bias, it's polar MOI.

The layout is appalling from a weight distribution perspective, whether cog, or moi or bias.

but the tranny and other weight are planted further back as a result

The ideal would be mid engined-all wheel drive but like all things in reality putting a concept into practice is a lot harder than making the statement. All car designs are trade-offs unless you have a blank cheque as your budget.

What you're basically saying is that a car that is a mass production car isn't totally ideal therefore its bad, it's a bit of a dichotomy.

Impreza has better weight distribution than a Lan Evo

maybe standard, but as rally cars the impreza's layout was its achille's heel

Some of that may be true, but the 2015 WRX's CoG is lower than a good number of other cars - i.e. it's over an inch lower than a GTI's

Where do you think the Evo's engine is mounted

don't get cunty lad

And it had the tranny in a worse place, so whats the difference?

Imma be completely honest... subaru engine bays are hideous

is it because everything isn't covered by plastic and you feel intimidated by wires and lines you do not understand?

Probably because no visible valve covers.

truth
here's a pretty bad one too

Who said it was good for rally cars? Look at the success of the R32 GT-R in touring car competitions. AWD with a strong rear bias is going to feel very foreign in low traction and tend towards a lot of oversteer.

Nissan MID4.

nah the system was clever enough to allow up to 50% of torque to the front if needed, and i'm guessing it would be doing that a lot on low traction surfaces

There's a non-trivial amount of FWD on corner entry. This inherently increases understeer because the available traction is being split between longitudinal and lateral forces. On corner entry you want to keep as much power to the rear wheels especially when trail braking to help the car rotate around the corner but this has to be controlled to avoid snap oversteer.

Strong FWD only makes sense on corner exit where RWD will make you spin. Subaru's AWD system has rear bias, but it spends a lot of time with a non-ideal torque distribution. On corner entry it has too much FWD so you start understeering at which point you've already lost time.

For road-going AWD initial RWD with a system to divert torque to the front wheels is a lot more effective. The same system is not great in rally because you can't endlessly practice on the course until you have the perfect line so the oversteering nature of something like ATTESA is a lot more dangerous. You want something closer to a 35/65 torque split initially like the Porsche 959 which was very successful in group B.

It's fairly common to see remapped ATTESA controllers that engage FWD much more often on the road too, especially under hard braking and much more aggressively on corner exit to reduce oversteer characteristics.

The COG doesn't really matter when you got the full weight of the engine hanging over the front axle. Hence why Subaru's are understeering pigs.

>For road-going AWD initial RWD with a system to divert torque to the front wheels is a lot more effective. The same system is not great in rally because you can't endlessly practice on the course until you have the perfect line so the oversteering nature of something like ATTESA is a lot more dangerous. You want something closer to a 35/65 torque split initially like the Porsche 959 which was very successful in group B.


good post apart from this nonsense.

>corner entry
>power going to the wheels

pick uno, sport

Are you in neutral as you enter the corner or completely off throttle? If you aren't, torque distribution absolutely matters. FF doesn't just understeer on corner exit unless set up to snap oversteer.

The 959 dominated the Dakar Rally and its AWD system was 40/60 initial torque. I don't really see how this is nonsense.

I guess you can argue that the R33 and R32 GT-R performed well at Pikes Peak, but the R35 has a dedicated snow mode that is almost always 50/50 initial torque rather than 2/98 in normal mode. I don't really think they would do this if it didn't help.

youtube.com/watch?v=4XYX2cC1dnY

Bonus footage of the Nismo 400R at Pikes Peak.

honda did that with the crv too right?
it says awd on it but it only kicks in when the computer tells it to, otherwise its just fwd?

What he means is that some Quattro systems are the good kind, and others are not. In the US market, the previous-gen A3 was the only Audi with an AWD system that was part-time (the lame kind). So the term has become diluted.

Haldex systems aren't all that bad. They do help prevent the front wheels from spinning if you get on the throttle too hard or you're on a slippery surface. But they usually have a low limit on how much power they can send to the rear wheels. It's fine on a family car, not useful in hard driving.

Maybe there isn't a formal distinction, but in the US you usually see 4WD used to describe transfer case systems used for low-speed driving in manly-man trucks. Those have always been common here and AWD cars were not. When the latter started becoming popular, there was a need to not confuse them with those trucky systems so they become known as AWD instead of 4WD.

Forward-mounted engines will always be common in 4- or 5-seaters, because it maximizes interior space and crumple zones. That’s a lot more important to most buyers than polar moment of inertia. BMW ignores it and suffers an interior space penalty relative to the car’s length. Easier to get away with that in the luxury market.

RWD cars performed very well on tarmac, it wasn't a hindrance at all. Something like the RS200 would run in RWD mode on tar.
ATTESA wasn't ever considered "dangerous" that was HICAS.
The 959 never competed at Group B level.

>go to Subaru dealership at night to see if they have an STI to test drive
>look around
>1 WRX, 0 STI, 0 BRZ's, over 100 SUV's and Crossovers
>the 1 WRX isn't even in the showroom, just tucked into a random spot at the corner of the dealership

Jesus Christ, is it really that bad?

>Buy 2005 Outback for $400 because head gaskets
>About to spend a week drinking to psyche myself up to pull the engine and do it

How fucked am I?

RWD is great for tarmac but for gravel and dirt it's slow compared to a proper AWD system. ATTESA isn't dangerous, but in the R32 it didn't have a lot of FWD. It was strongly emphasized that if the rear breaks loose that you have to stay on the throttle and wait for the ATTESA system to transfer torque to the front to pull you out of the slide or else the system would go back to RWD as soon as you let off the throttle and you would either spin or get a tank slapper.

Such a system would absolutely be slower in low-traction courses. You want more torque to the front initially for low traction courses to improve stability.

Group B that actually won the series needed AWD to be fast, and they usually didn't use initial torque splits that approached RWD.

AWD aside there are a lot more variables to a car that affect handling. The R35 understeers fairly heavily out of the box because the front tires are not as wide as the rear. The front-mounted engine is also mounted high up compared to the R32-R34 which increases the moment of inertia. Changing the anti-roll bars out will also balance out the car.

The Nismo variant has properly tuned suspension out of the box.

Similarly, the R32 understeered horribly in high speed corners despite the strong RWD bias. Multiple engineers in charge detailed how bad the aero and weight distribution were. Things got a lot better with the R33 but the RB26 was heavy and they barely got to 55:45 and much less front lift but it was still there. With the R34 the engineers pushed hard to move to an aluminum block V6 along with new brakes and other changes to seriously resolve these issues in the Skyline GT-R but Nissan was basically bankrupt at the time.

Putting the engine further forward forces the engineers to put other things further backward in order to balance it out. This means that you have a lot of weight located far away from the center of the car.

Evo engine and transmission are directly over the axle line. Subaru engine is in front of the axle line and transmission is more or less centered on the axle.

That's how it is everywhere. The WRXs aren't just gonna be laying around like American cars

CR-V, Pilot, and Frontline I think all had the same layout, actually kinda nice for MPG and general handling, since AWD always feels laggy like you're driving a tank.

MOI with regards to weight or the spinning of the engine/transmission/axles?

>AWD traction meme
I always considered this to be dangerous thing for car marketers to push as AWD doesn't really improve traction. It is only purposeful if you are stuck and need a little extra push when two wheels can't get the job done. I only have an AWD car so I don't have to shovel my way out of my parking spot in winter, I live in Green Bay they always seem to plow the lot in the middle of the day which forms these big snow and ice dams behind the cars.

Weight. The engine placed at the extremes of the vehicle means you have a 300+ pound mass at the extreme front of the vehicle when the CG is closer to where the driver is. Angular acceleration will decrease for the same torque produced by the wheels.

Ignoring this issue is inevitable in Subaru marketing materials, and most people will never noticed because they don't give a shit about how fast the car turns in but they do give a shit if the car is gigantic relative to interior room like a Nissan GT-R or anything that approaches front midship.