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Query: Switchable AWD/RWD Subaru?

19K views 14 replies 8 participants last post by  BAC5.2  
#1 ·
Hello.

A query, on behalf of a mate. He (and I, now) would like to know people's thoughts on the possibility/feasibility of modifying a Forester GT or XT or an Impreza WRX Wagon so that it can be switched between being AWD and being RWD. An important point: this is only concerned with manuals, so anything specific to automatics is not useful.
Also, note that we're looking at a switchable (preferably in-cabin) idea, so the notion of swapping front drive-shafts or similar isn't so useful.

We are aware that the current STIs have an electronically controllable centre diff, but that would be well beyond the desired budget. However, if an STI centre diff can be retro-fitted, that would be acceptable. (If it can, how far back? Could it go on a late 90s, early 2000s model?)

I've since done more research, and it seems that the STI diff, the DCCD thing, only goes so far as to vary the F/R bias from 65/35 to 50/50 anyway, so perhaps (in standard form at least), this wouldn't be so useful anyway. (Still open to ideas though).

Are there any other tricks that can be done with the centre diff?
Could locking hubs be fitted to the fronts? (In the manner of many part-time 4WDs).

We're definitely open to creative ideas, but really only things that have *some* chance of being feasible.

Not sure if it matters, but if this project was undertaken, it would be done in the UK.
If all else fails, is anyone aware of any non-tank vehicles that are or can be AWD/RWD switchable that have the space of a wagon? (The Forester or Impreza wagon is the rough size of vehicle sought, so no Patrol/Cuiser/Jeep/Range Rover/etcs.) Something that has road-performance potential too.

We are fully aware that there's every possibility that there's no chance in hell that this could be done (on a reasonable budget), but the idea is being thrown out for comments nonetheless.

Thank-you all in advance.
Des
 
#2 ·
Not really any way to do it, unfortunately. It's easy to leave it RWD or leave it AWD or leave it FWD, but being able to switch between the two is almost impossible without a lot of custom machining work (i.e. you would have to have a pretty substantial collar that can slide over the output shaft and the pinion shaft. Engage both for 50/50 perma 4wd, or slide it forward to have FWD only. But having it so that it's easy to slide would be nearly impossible.

If you have "unlocked" hubs up front (which would require a whole wheel bearing and knuckle assembly), it would simply have the center diff begin transferring ALL of the power to the front end (exactly where you won't want it to go).

You could TRICK the DCCD diff to transfer all power rearward, I think. But it's a really bad idea, and it will definately damage the diff. Espically since the retail on one of those diff's is $2400 USD.

Sorry mate, not a whole lot I can think of to get it to work. Maybe someone else will have an idea.
 
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#4 ·
The only real way its feasable would be to get a DCCD centre diff, gut out the epicylcic, weld up the rear drive to the input and use the clutch pack to pull in the front, but without a high tech controller your only AWD would then be locked centre diff (well no diff at all!) which isn't terribly nice...tbh its not worth it!

Simon
 
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#8 ·
I've seen some sti's with dccd doing smoke shows.

What they do is lift the handbrake a notch to disengage the center diff, thus making it almost completely rwd.

Install a switch to fake the handbrake being pulled. I think this will be the closest you can get without going crazy.
 
#10 ·
Unlocking the DCCD still gives you a centre diff with the stock torque bias (depending on which of the stock boases it has) it certainly doesn't make it RWD or FWD. However you can buy a centre diff replacement tube that makes a Subaru RWD only.

Simon
 
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#13 ·
The Skyline is that way too Funkymonkey. ATESSA is awesome. It's REALLY fast too. Hard launches barely chirp the rear tires. The FX35/45 use the same system. It's no joke. It's probably one of the best part-time awd systems in the world.

On the STi. If you crank up the e-brake, the center diff COMPLETELY unlocks. If you just pull it up one click and do a crazy launch, you'll spin the fronts like a high school kid in an integra.

It's all for the rally. Handbrake turns are common, and in a standard WRX, you need to keep your foot burried to the floor and abuse the crap out of the center diff or the engine will bog really badly. With the STi, pulling the e-brake disengages the center diff, so the engine doesn't bog and you can maintain speed. It doesn't make it front drive, but it makes it so it's possible for NO power to get to the rear, without really damaging anything.

We stock the 5-speed RWD spools, and can get the 6-speed spools for the DCCD and nonDCCD's.

I was rear-drive in my old car for a bit. Drifting is a lot of fun.
 
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