How does AWD works in other than 50/50 torque distro...

BMW xdrive
either 50/50 or FWD/RWD until loss of traction

Since becoming US legal Skylines tripled in price. Fuck everything.

So now that even the old Audi Quattro system was using electronic computers to handle the dynamic power delivery, anyone knows where i can learn the basics of computers and solenoids to know how those things work?

they are over rated and dont have enough spare parts to go around

I wish everyone would just collectively forget about that R35 pigfat slug and put the R32-34 back into production

Lets not go nostalgiafag here. The R35 its literally better than any previous GTR in every sense. I personally just like the R31, R32 and R34 due to the autistic JDM culture of the early 2000's.

Besides, even if they were re added into production they would still get with the same issues of smog and crash tests and would not be allowed into the states.

>automatic
>3900 lbs
>ugly
Three strikes.

>where i can learn the basics of computers and solenoids
You can learn the basics of computers by getting a TI-83 and writing some programs for it. Once you do that's you'll have a surface-level understanding of what a program is. Then get an arduino and make more interactive things, and it will soon make sense how the computers in cars operate.

Computers in cars are really quite simple once you get down to it. They are devices that respond to inputs, and give a corresponding output. You can write very complex directions for them to follow, and they follow them really fast.
So when the computer sees the front wheels turning faster than the rear wheels, it activates hydraulic clutches to send more power to the rear wheels, and once they're all turning the same speed, transfers the power back to the front wheels.

I'll teach you how solenoids work:
>electric current applied
>makes magnetic field
>moves piece of metal
This can actuate a hydraulic valve, act as a big switch (this is called a relay), or physically move something.

There's still a centre differential split. The way you've described it, said Celica would have a locked centre, which it doesn't.
Yep, a viscous coupling achieves that reasonably well.
As above, you can indeed have a mechanical AWD that isn't locked.

>automatic

I dont like it, but DCT has proven to be more efficient than manual for quick shifting. If there were DCT back in the 90's and 80's i have no doubt older GTRs would use it

>3900 lbs
Good point, but the GTR isn't exactly a miata. Its not about light weight handling but rather on compensating with power, and being 500 lbs more than the R34 and having 200 to almost 300 hp more gives better power to weight ratio

>ugly
Objective opinion.

Every nissan skyline has been an improvement over the previous generation. R32 has a classier look and is very much more widely available than the R34, but other than that there is no reason to pick an R32 when you can get a more modern edition since its always an improvement. Same with the R35. It contains better aerodynamics, better power, better electronics and better AWD system.

I know how solenoids works, thanks. I didn't mean that i wanted to know how basic coding works. I am still getting a grasp at how the ABS system communicates using magnetic signals. What i really meant i wanted to know was how the computer is set to react when it detects the different magnetic currents in between driveshafts. Then again, that would mean that the ATTESA is pretty much same in sensors to an ABS, but it only uses solenoids to activate or disengage the clutch that works to give power to the front.

Yes. The celica 3 diff system would still have a locked centre, however a 2 diff system wouldn't be so much different since the power would still go to the rear wheels (remember, the power of the driveshaft would be coming out from the gear that power the entire differential, not one of the side gears that go to the wheels)

>Yep, a viscous coupling achieves that reasonably well.

But wouldn't that still create a 50/50? or would the torque split depend on the actual liquid itself? and wouldn't that mean that the gearbox would have to first directly send power to one of the axles and then let the liquid send some power to the other axle?

Oftentimes AWD systems share sensors with ABS.
The computer measures each wheel speed, and does it's best through the clutch system to try and keep the wheels all spinning at the same speed. Some systems even can apply the brake on a specific wheel to keep both wheels on an open diff spinning.

So wouldn't all of this also share sensors with TCS since its basically an ABS for the lose of grip during acceleration?

My old Subaru had a viscous coupling, and it worked like this:
>power normally applied to front wheels
>back wheels should spin at the same speed
>speed mismatch due to slippage, the 2 sides of the center diff would spin at different speeds
>viscous fluid acted like corn starch, and the generated friction would cause the fluid to harden and lock the diff together
>all wheels would then spin together

>remember, the power of the driveshaft would be coming out from the gear that power the entire differential, not one of the side gears that go to the wheels
It doesn't work like this, as again this would be a locked setup which Celicas don't have. That does not work with a road car.
>But wouldn't that still create a 50/50? or would the torque split depend on the actual liquid itself? and wouldn't that mean that the gearbox would have to first directly send power to one of the axles and then let the liquid send some power to the other axle?
Basically, yes. One axle has a fixed mechanical connection where the other axle is coupled by a glorified torque converter. You'll find a lot of early AWD Toyotas and SuperSelect Mitsubishi offroaders have such a system.

Got it. So basically the main power delivery was into the front but it used Visc coupling diff in the center to equalize the power delivery. Wouldn't add heavier liquid also provide better rear wheel torque too?

Probably, if your vehicle has it. All the computer needs is a way to know how fast each wheel is spinning.

>It doesn't work like this, as again this would be a locked setup which Celicas don't have. That does not work with a road car.
But why? i am not stating that celicas had them. But i cant think of any way that having a driveshaft leave the front diff and power a rear diff would fail. It would not be locked but it would not lose traction if the front wheel slipped.

Yes. Welcome to modern cars, and the horror of trying to make a production-based race car out of something with CANBUS.

I'm not sure that heavier liquid would increase torque, but it would probably increase parasitic loss on the drive-line and "lock" the front/rear together more.

Here's a picture of what a viscous coupling looks like so you can visualize it for yourself. They're really quite neat solutions for AWD, but ultimately computers are more efficient.

>But why? i am not stating that celicas had them. But i cant think of any way that having a driveshaft leave the front diff and power a rear diff would fail. It would not be locked.
Ah, it would be locked as you described here >remember, the power of the driveshaft would be coming out from the gear that power the entire differential, not one of the side gears that go to the wheels
Not sure how you expect that gear to slip.

Yes, ok. I get your point. With the front and rear getting the same amount of power delivery it would act more to a 4WD than an AWD. But wouldn't the extra torque that might break the system by forcing the rear to go at the same speed as the front axle be cancelled by the rear diff then? because i am sure i have seen some companies make 2 diff AWD work.

>But wouldn't the extra torque that might break the system by forcing the rear to go at the same speed as the front axle be cancelled by the rear diff then?
What? No. The rear diff splits drive at the rear diff. It doesn't magically make drive disappear to suit a shorter radius than the front end.

I actually meant what i said considering that the front axle spins faster than the rear one while cornering. But now that i think about it, it would make no sense for there to be a lot of issues if it would be the same power to the rear axle if the car was a RWD to begin with. Honestly i kinda lost myself thinking about how the power delivery of a 2 diff car while cornering would be moving.

But if you didn't meant that, why did you said that a 2 diff AWD would not work in real life application?

That is what I meant. There has to be some sort of differential split between the front and rear axle.
Also, an equal torque split does not equal a locked centre. You CAN have different output speeds with a constant torque between them, which is the job of a centre differential (specifically a centre differential in a 50-50 split).

But this goes all the way back to the very same issue. Wouldn't the differential split between the speeds of the front and rear axle be taken care of by the rear diff?

Jesus fuck i would really like to be able to make some kind of mock model to try that.

>Wouldn't the differential split between the speeds of the front and rear axle be taken care of by the rear diff?
No, once again it doesn't. If the input drive at a differential is constant, then at least one or both output axles will be spinning at the same speed (divided by the drive ratio... Which is the same at either end). I think you need to do a lot more homework on differentials, because they sure as hell don't work the way you think they do.

Well other than your wrong assumption you are right. I thought that having a 2 diff AWD would be the same as a 1 diff RWD but then i realized that the front axle would always be spinning at a higher speed than the rear axle. So i do guess than 2 diff AWD is truly impossible then.

No.
Lets say in a turn, the front axle spins a total of 40 revolutions, and the rear one spins 25. The front axle is going to be sending all that extra distance back to the rear axle, and what is the rear axle going to do with it?

If the drive-line is strong, or you're on dirt, you'll spin your tires. This isn't really bad at slow speeds, just wears your tires a bit.

If the drive-line isn't strong, or you have particularly sticky tires, the gears in the diff are going to oppose each other to the point where either they slip over each other (very bad), or they break (catastrophic).

Transfer cases deal with this by assuming that the owner will only put the vehicle in 4wd when the tires can spin to relieve that difference. 2wd mode disengages one axle, and your vehicle acts like a RWD vehicle.

AWD handles this through either a viscous coupling, which allows for small relative difference between the axles, or computers that monitor the wheels and only apply when needed, and can act very quickly to prevent binding.

Basically, the front diff equalizes between the front two tires, and the rear diff equalizes between the rear two. Something has to be in between, or it can only be used off-road.

I think you're getting it.
But what wrong assumption exactly?

The one that i didn't knew about differentials.

Yep. Came to that realization. Regardless of how i thought about the issue the front would always spin faster. However i do know that some AWD 3 diff systems use open diff in the center, and it wouldn't surprise me if some one made a clutch-pack center diff.

>it wouldn't surprise me if some one made a clutch-pack center diff
I'm 90% sure that's what Ford did on their explorers, at least on the 2nd gen. You could put it in 2wd, 4wd auto, or 4x4 low, the latter of which locked the center.

>The one that i didn't knew about differentials
Ah, considering you didn't actually know what a differential did, I think that's a pretty safe assumption.
I'll give you the benefit of the doubt and assume you're picking up on it.

Pretty certain the Ford setup is similar to the Mitsubishi arrangement. Fixed drive to the rear with a viscous coupled front.

I did knew what a differential did. I just actually never thought about the front axle going faster than the rear.

I actually meant a clutch center diff in the sense that a rear diff works, but considering that those diffs work on G forces to lock they wouldn't be the most efficient as a permanent AWD center diff. They wouldn't be a bad idea as an AWD drag car or something of the like.

You are a fucking retard, OP

This desu

why? :(

>How does AWD works in other than 50/50 torque distro?
awdwiki.com/en/home/

>superior 2 differential setup
Whoawhoawhoawhoa. Back the fuck up.

A 2 diff setup still has a power split, it usually just happens to do left front/right front/rear at once instead of doing front/rear and front left/front right seperately (or the inverse, in midengined setups like the Audi R8).
This is just a way of how the power is routed, NOT how it is distributed. Even a car without a center diff usually has a transaxle that simply does the function of the center and front (or center and rear) diffs at once.

A 2 diff setup is usually not superior, because it puts the engine ahead of the front axle (e.g. Audi, Subaru), which causes loads of understeer. The only solution with a 2-diff setup is to put the engine between the axles, which means a major compromise in passenger space: you'll only see that in supercars. The only other 2-diff setup would be an AWD 911, and the only reason those aren't oversteery as fuck is because of the half century of chassis development that's gone on there - they had to tune the tendency to oversteer out of the RR versions, after all, and adding front drive helps, too.

You can use (computer controlled) clutches and viscous couplings to split the power differently. Quattro usually goes from a 50/50 either way (30/70 or 70/30 depending on conditions), Attessa is a 0/100 system that can go up to 50/50, and Haldex is the inverse, 100/0 untill it detects slip, and then it can go up to something like 50/50 iirc.

>Most transverse engines with AWD will only send power to the rear when the front wheels slip
FTFY.

Most longitudinal setups are RWD biased.

>but DCT has proven to be more efficient than manual for quick shifting.
Only modern ones - and that 6 speed is almost a decade old by now.

>power to weight
Doesn't matter if weight is excessive. Power can't solve everything.

>Only modern ones - and that 6 speed is almost a decade old by now.
And its still faster than most people with a manual
>Doesn't matter if weight is excessive. Power can't solve everything.

Of course it cant. But power to weight ratio is the actual important factor, more than raw power or raw weight. As long as the new GTR has better P/W ratio and has better aerodynamics (it does) then it will be faster than the R34 no matter what.