How does an AWD car achieve torque split without any wheel spin

>what's a differential

>>16679138
>expecting an educated response
don't think you get it...

>>16679111
Usually a combo of >>16679138 and tapping of the brakes.

I still need more clarification...

Let's say I'm a car with 33:67 torque split front:rear and I don't have a fluid coupling connecting the front an rear. If I use some gear set to rotate the rears faster (which is actually what some of the Focus RS people used to say say) to get more torque to the rear, then won't the fucking tires always be chirping? It sounds like there might be clutch packs that connect the front and rear, but wouldn't those wear very fast if they are always in use? Simply putting an open differential between front and rear would make the torque split 50:50, no?

>>16679630
From my understanding of how Subaru does this is with Autos they use the viscous coupling and can transfer as much as 50% torque to the rear but it is primarily FWD. The manual versions have a LSD in the center to keep the split close to 50:50.

So your example would probably be a RWD car with a viscous coupling to drive the fronts as needed.

mitsubishi, subaru and nissan all use viscous coupling.

>>16679828
No Subaru on the road today regardless of transmission operates primarily in front wheel drive.

>>16680271
The autos are FWD based but send at level ground around 30% to the rear, this is ramped up to 50% as needed. The manuals are 50:50 regardless.

>>16679111
It is all a lie.

>>16679924
don't think mitsu's use viscous coupling. They have 50:50 differential with clutches that can lock the center diff up. it's 50:50 until wheels slip, then it locks up, which will send more torque to the wheel with more traction just like a standard locking diff.

>>16680271
he may be referring to wrx's of years past that only sent torque to the rear when front slip was detected (either with clutches or viscous unit)

>>16680280
But how!?

>>16680282
I mean... it's the best explanation yet. I've heard that it's all badly worded marketing and that non-Haldex awd systems are all 50:50 until traction is lost.

>>16680338
>But how!?
As the front slips it causes the center viscous coupling to slip making it heat up. As it heats up it sends more power to the rear. It's a fluid that gets thicker as it heats up.

>>16680280
What years are you referring too? They are all 50-50 split across the board. Since 2006 if I recall they all became symmetrical all wheel drive auto or manual with the exception of the STI which you can adjust the cent diff to send up to 70% of power to the rear wheels for that dorito

>>16680387
'05 and earlier. Yes, they did change the split to 50:50 in '06 but earlier versions did not have that yet.

>>16680402
Oh well then yeah I agree. The forester had a 60-40 split and the forester S in manual has the viscous limited slip. I think the S model in general from those years had the viscous one.

>>16679630
The split isn't referring to wheel speed it's referring to torque. Wheel can spin at the same rate while receiving different torque values.
This is why even with a clutch pack centre diff you can have more torque going to each end of the car. Everything rotating at the same speed but receiving different amounts of torque so there is no wear on the clutches.

>>16680310

youre thinking about a torsen as used in the audi quattro or the rear diff of a j200.
Mitsubishi's most hi-tech awd system uses asymmetrical planetary gears and viscous coupling.
If you're talking about the evo it has clutch packs in the center and rear plus a torsen knockoff up front.

>>16679630
Lol 33-67 awd is not what you think it is. The rear axle has a limited slip differential, the front axle is open diff. This means under power, 33% power is being sent to each of the rear wheels, and that remaining third is being sent to ONE of the front wheels. This system is already technically a 50:50 split because the power will balance across both axles if all 4 wheels are allowed to free spin.

For true 50:50 like an evo you need a centre lsd or torque vectoring. It cannot be done using gear ratios, because then one axle will want to spin faster than the other

>>16680489
I was thinking about Evos and just assumed Mitsubishi did the same with the rest of their cars.

>>16680355
The premise was how to accomplish this WITHOUT a viscous coupling

>>16680387
How is 70% at the rears achieved? Do they have a viscous coupling?

>>16680421
I am wanting the nitty gritty of how this is achieved. I am completely unsatisfied with the responses I get from Google and here (so far), where people are saying it's achieved with a gear ratio (planetary gear), as shown here
>>16680315
When a gear ratio multiplies torque, it also affects the speed.

File: IMAG0019.jpg (2MB, 1836x3264px) Image search: [Google]

2MB, 1836x3264px

>>16680934

The WRX STI uses a limited-slip, planetary gear-type center differential, augmented by an electronically controlled center limited-slip differential. This provides for a performance-oriented 41:59 torque split. This allows the mechanically limited slip differential to have a quicker response and activates just prior to the electronic limited-slip differential.
The 2015 WRX STI DCCD AWD System has three automatic modes: “Auto” provides optimal performance for all conditions. The “Auto” (-) Active Sport setting shifts the torque bias to the rear and also opens the center limited-slip differential (no locking factor), which improves steering feel for performance driving on the track.
Reminder that Subaru has 4 DIFFERENT TYPES OF SYMETRICAL ALL WHEEL DRIVE SYSTEM VARIANTS

Picture unrelated

>>16680271
Except for the FWD ones.

>>16679924
ATTESA is a wet multiplate clutch.

>>16679111
bump because this is a good thread
also checc da trips

>>16680970
>SYMETRICAL
>%50 of the time

nice meme

>>16679630
In a Focus RS the clutches slip to equalise wheel speed, the gearing is asymmetric which helps to send more torque to the rear wheels by spinning them faster when the clutch pack engages.

>>16680934
>When a gear ratio multiplies torque, it also affects the speed.
Not how you think.