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Noisy Cricket said:
Which Subaru? Subaru has used every possible layout.

They had manual transmissions that were FWD until you splined the rear driveshaft to the trans. (Some, but not all, of these were dual-range.) They had automatic transmissions that were FWD until an internal clutch pack was engaged to have the same effect. (These are the ones with the underhood fuse you pulled so you could tow it rear wheels down)

Then they had transmissions with center diffs that you could manually lock. Some, but not all, were dual-range - close ratio dual range at that, changed effective final drive from 3.70 to 4.30 or thereabouts. (The 3-door RX Turbo trans)

The common Impreza/Legacy transmissions had VLSDs, not viscous couplings. They were normal bevel diffs that had a viscous limited slip section on the back. These are the diffs were people swap in 12kg or 16kg or 20kg viscous sections. A 20kg is basically just enough slip that you don't break axles - you can drive them with an axle out.

Some automatics (and IIRC some STIs that we didn't get here) had cam and pawl differentials. Look them up, they're a neat concept. The cars with this had a 45/55 torque split.

Some STIs had epicyclic diffs with a computer controlled clutch pack to lock the diff. The cars with these had the differential dial where you could dial in manual lock vs. computer control. Again note that drive was always through gears, the clutch pack is only there as a limited slip device.

IIRC the only Subarus that DID use viscous couplings were Rexes, which we didn't get here because it was a Kei car. IIRC it was no center diff, no rear diff, just a viscous coupling on EACH rear axle. Neat idea (IIRC it was licensed from Ferguson) and you don't need much in a super tiny car with a 660cc engine.
Not totally correct:

I used to be a Subaru mechanic at an independent shop in PDX and got to mess with Subaru's sub-standard drive trains on a daily basis.

I'll give you the basic rundown:

Most EA series cars had part time 4wd, either single ratio or dual range. Even the 3AT auto cars had the same part time system as the manuals.

Some of those came AWD, using basically the same system as the later EJ cars...in fact the 4EAT trans used in the EA cars is the same as the EJ with a different bell housing. This trans uses a clutch type center diff that is controlled by a solenoid (specifically the duty C solenoid...the one that causes torque bind) that also allows the AWD to be disabled by use of a fuse in the engine compartment.

The RX (both 3 door and rare sedan) used a dual range, awd trans with a switchable locking center diff...which is probably the closest thing to an 016 Audi trans with a 2 range transfer case. I've never seen the center locker in a non dual range car.

None of these are particularly strong...basically can handle EJ22 power but not much more

The early EJ series manual trans are similar to an 016 without any lockers. Just straight differentials.

Around about the OBDII time the manuals "gained" a viscous center diff...which likes to fail.

Autos were still the 4EAT...a generally boring unit that actually holds a decent amount of power.

Some STi models had AP Suretrac front diffs...which is a quasi-helical (torsen) unit...most others were straight torsen.

The DCCD in the 5 and 6 speed STi trannies are a planetary unit that uses a clutch pack to vary the power distribution between front and rear.

STi had a torsen rear...all the other LSDs were viscous with the exception of the 3.70 unit used in the EA cars (clutch type)

My opinion after looking at Audi and Subaru drivetrain components was that Subaru recognized the good ideas Audi had and decided to use their technology and just make it shittier. (my theory)
 

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Noisy Cricket said:
rallynz said:
The RX (both 3 door and rare sedan) used a dual range, awd trans with a switchable locking center diff...which is probably the closest thing to an 016 Audi trans with a 2 range transfer case. I've never seen the center locker in a non dual range car.
The GL-10 Turbo supposedly had a single range center/locker. I haven't seen one though.

The RX Turbo sedan did not have a center diff, it was FWD/4WD. That is what mine had. It was the same transmission as my GL wagon except it was a close ratio dual range instead of wide ratio. Also it had the turbo EA82 which was the most fragile Japanese turbo engine ever, which is why I did not own that car for very long. (And I still kick myself for unloading it because it was a RUST FREE RX TURBO)
So if the RX Sedan only came with a FWD/4WD, then why did we have a dual range, full time awd, center diff lock car at the shop? Explain that to me...and no it was not swapped.

I can understand why the 20kg center diff sucked on the road...it's usually the choice for gravel rally cars.

I always thought the 2.5RS drove like a bag of dicks...not a well balanced car and the power band sucks. My Legacy Turbo felt far more balanced and easy to control...but the noodle-ish nature of the Subaru chassis ruins it all. I think my 4kq is easier to drive in corners...when it lets go I just have to lift throttle and it generally comes back into shape.

I spun my Legacy out a number of times but haven't ever spun an Audi (without trying to :D )
 

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The Oregon rally cross champ until a few years ago was a stock 84 4kq with rally tires...no Subaru could even touch his times...even stage cars.

I think Subaru's AWD system is set up more for idiotic soccer moms who can't drive in the snow than competition...I've ridden in a lot of different stage cars and all the Noobarus needed $$$$$$ to make them properly handle in gravel...whereas the 20v Ur quattro I rode in just had locked stock diffs and turned great with left foot braking.
 

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123quattro said:
Friend of mine owns a local tuning shop that does a lot of Toyota/Lotus work. He has a RAV4 with a turbo AWD powertrain from pieced together JDM Toyota parts. No one can touch him in rally cross or ice racing. It's about 300awhp. The Subaroo guys get so angry when their caged cars get beat by his daily driver.

Now that is cool!

Rally cross and especially gravel performance rally is very much about driver and tire vs. car...I've seen guys take class wins in 100hp cars and beat 300hp Subarus...But...rally is also about endurance...and I've never seen an Audi retire from a rally because of broken gearbox...whereas I've seen more Subarus do it than I can count on my hands and toes.
 
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