i was thinking, i have a friend that has an 02 outback sport and she complains about her gas mileage sometimes especially when she has to drive back and forth from albany to utica…
i know that when you get a flat and have to put a donut on a subie you are supposed to stick a fuse in the FWD “connector” under the hood, which disables the center differential so it doesnt destroy the AWD system…basically turns it into a FWD car…
what my question is…can one put a fuse in said connector for an extented period of time (basically til snow falls) without damaging the AWD system?
06+ have a center diff with a permanent mechanical engagement so even when power is fully dumped to the DCCD to the system isn’t completely unlocked, hence no fuse.
up to '04, the DCCD could be 100% unlocked by pulling power to the DCCD(that fuse activates a relay which open the DCCD main wiring, thus open circuit). Main reason why putting a six speed into a non DCCD car results in FWD unless you install an aftermarket DCCD controller, or send a 12volt 10amp load to the DCCD.
In my 98 Legacy, I ran with that fuse in all during the summer, then pulled it for winter. I have no idea if it was good or bad for the car, dont really care. But the gas mileage only went up by about 3 miles a gallon.
Ok, I understand the why. But now I would like to know how that works mechanically. If the entire AWD system is connected mechanically, how does a simple circuit allow you to stop sending power to the rear wheels?
I’m pretty sure, don’t quote me, the center diff in the 04 sti is controlled electronically. It will also open when the clutch is pushed in and the e-brake is pulled, so you don’t fry the center diff. Also helps with rally style e-brake initiated turns.
the >'05 cars had a diff that freewheels until power is applied to the electromagnet that locks the clutchpack inside the diff, thus connecting the front and rear for torque transfer. Inserting the fuse in the front on those cars applies power to a relay, which then OPENS the circuit to the DCCD in the transmission causing it to fully unlock and apply 100% torque to the front wheels.
'06+ the DCCD has a spider transfer section and cannot be completely unlocked even if power is cut to the electromagnet, thus no fuse and no FWD in those cars.
NOTE this is for the STi six speed though. I’m not 100% positive if the five speed from '06 on went with the spider DCCD or not. information that i’ve never needed myself. Thus the WRX/Legacy/etc/etc may indeed have that FWD fuse still
NO shit!?!?! i didnt know this. I have a 98 Legacy too and that shit only gets like 18mpg now thats is 200Kmi old! I am doing this and will see what it does since i drive highway all the time.
is it as simple as shorting the connection? if so you could just toggle switch it and have 4wd back at the flip of a switch.
Yes just fuse it, 10amp min/15 preferred. Closed circuit = FWD, open = AWD. Just run a harness to the fuse terminal… two male spade crimp connectors in the fuse socket, run wires from them into cabin to a switch with fuse inline.
Bam, insta FWD
I have my DCCD controller wired to cut power and unlock the center diff apon ebrake application so I can flick the car easier.
idk how this girls parents would like it if i started drilling holes and running wires and such in a car that was just purchased from a dealer a few monthes ago…lol