Start with WRX or Audi style transmission that has a longitudinal engine and front axles shooting out of the bellhousing and mount those axles to the rear wheels. Lock/weld the center diff(internal to the transmission). Adapt your choice of transfer case to the rear of that transmission and thread a driveshaft past your engine/transmission/axles to a front differential and you are in business. An early Astro transfer case has a nice rear bias so I would look into that. The whole assembly gets fairly long behind the rear axles so that presents a problem.
Edit-Hmmmmm..........your transfer case doesn't really bias the same way it would factory in that setup since nothing would be coming out of the rear of it. You need to transfer power forward like a transfer case but you also need to allow some slip.
MrJoshua wrote:
You need to transfer power forward like a transfer case but you also need to allow some slip.
That's why I was talking about something similar to what you described with the Subie-style gearbox, but leave the center differential operational and use a "dumb" transfer case (as light and simple as possible) to return the rear output toward the front...
In reply to MrJoshua:
Stick with the welded center diff Scooby transmission, but any transfer case that was a 1:1 high range and use an external viscous coupler somewhere between the front diff and transfer case. Viscous coupler from something like a Freelander or a few of the AWD Volvos would probably work.
Am I missing something with respect to why folks want to disable the Subaru's center diff and then try to add an external differential back in?
Unless the stock Subie center diff is RWD-biased, which would be FWD-biased when used like this, I can't see where the "win" is in welding it solid and having to reintroduce the differential functionality externally...
My idea would be to use a common transaxle that already splits F/R. Think taking an Eagle QuadraTrac system, plopping the AMC V8 in the middle of the car (with the Super T-10 behind it), QT after that with the rear output going to the Model 20/Ford 8.8 rear axle and the front output going past the engine like normal, having a second driveshaft (so basically a home-made center carrier-bearing setup) go to the nose to the other Model 20/ Ford 8.8 (or whatever an Exploder uses up front). With any luck the original rear driveshaft could be the new front shaft.
ransom wrote:
Am I missing something with respect to why folks want to disable the Subaru's center diff and then try to add an external differential back in?
Unless the stock Subie center diff is RWD-biased, which would be FWD-biased when used like this, I can't see where the "win" is in welding it solid and having to reintroduce the differential functionality externally...
I "Believe" the WRX is rear biased in stock form.
the Porsche/VW aircooled transaxles actually lubricate better when used in a mid-engined location. The ring gear throws the oil onto the pinion rather than dipping into it after passing it.
I had often wondered if you could use a Saab Classic 900 transaxle in a mid/awd configuation. The pinion is at the back end of the transaxle.. so making a cover to hold another pinion to the ring might work?
SVreX
MegaDork
8/28/12 8:48 p.m.
Toyota Previa All-Trac?
Isn't it already done for you?
In reply to ransom:
I assumed it was biased one way or the other, some google'n has me thinking they're 50/50 now, so may not need to weld the diff.
In reply to sverex:
believe it or not, that very drive train has gotten the gears turning in my head a time or two, but I never could find for sure if the AWD was available with a manual in the US, if so they must be like hens teeth.
I don't often have to explain myself and my random Craig's List searches to SWMBO anymore, but when she saw me looking for Previas once upon a time she exalted, with a hint of fear in her voice, something along the lines of "what the hell are WE going to do with that?!?!?"
SVreX wrote:
Toyota Previa All-Trac?
Isn't it already done for you?
What, what? 'Splain pleez... They come in a manual version?
^Was just starting to think the same thing, but it's not that simple, what about the gearbox? Eventually to have it mid-engined your transfer case would have to sit on top of the rear diff.
RossD wrote:
1. Take 'usual' four wheel drive setup and remove front and rear driveshafts.
2. Move engine, transmission and transfercase backwards.
3. Reinstall driveshafts in opposite positions.
4. Sit in front of engine, but between the axles, and start it up.
5. Hoon.
I LOL'd.
You could do that, make the rear driveshaft nothing more than a universal joint connecting the 2 yolks between the rear end and the transmission/transfer case. IRS and IFS would be a must. Solid mount the whole drivetrain for no movement.
Another option I just thought of...
Corvette transaxle from C5-C6 Corvette. Seperate the T56 from the diff and insert transfer case. Is that possible?
This type transfer case (#3 in the pic) is used on the Ford Escape, Mazda Tribute and the Dodge Journey. Maybe that's the answer, just turned around and pointed forward.
Good thinking, I was looking at one of those the other day. Problem is, once the engine's in the car, it's all facing the wrong way anyhow...
2GRX7
New Reader
9/17/16 8:14 p.m.
Suzuki Grand Vitara: there are plenty of these around in salvage yards. $40-$60 dollars and lighter than most transfer cases. Using Mr. Joshua's plan, it could work....
http://www.weberbrothersauto.com/product.aspx?t=3578866&gclid=Cj0KEQjw0_O-BRCfjsCw25CYzYoBEiQAqO9BDEL7b7MapYqia2wzdsY48GgUZLoBSa6bPe3aqW1qnm4aArJo8P8HAQ
what about using the Evo Drivetrain with an older 4g63t engine.. didn't they mount "backwards" from the more current Evo 8, 9 and 10?
I'm always surprised that no one makes a little box with a pair of quick change gears in it. A couple of shafts, a couple of bearing plates, and three different covers, one for a yoke on one side, one for two yokes on one side, and a cover. For the 4x4 crowd it could be a driveshaft drop for better angles and a gear change in one. In this case it would be a reverser for the front driveshaft. Seems easy enough, and all the hard work and parts are available off the shelf.
