A friend of mine owns a car almost identical to mine except for the paint and roof rack. She owns a 94 legacy automatic, and recently had a blowout. She took the tire to Discount Tire where is was origionally purchased, and in the course of their conversation the guy pointed out how having differing tire diameters can screw the viscous AWD system, and mentioned the FWD fuse. Now, Subie specialists have always told me not to use it for prolonged periods of time. I don't fully understand it personally, but I am sure that's the case. Now, this dude at Discount told her to put the spare on the back and use the FWD fuse to drive around on it till she gets a new set of four tires, but knowing my friend, she will likely drive a hundred miles before that happens. Any thoughts on potential damage?

the tire guy is right. you can drive with the FWD fuse in for an indefinate amount of time with no damage to the viscous coupling. under normal driving conditions, the car operates as FWD, only until slip is detected, then the AWD kicks in. she'll do no harm by driving for extended periods of time with the spare on the back and the FWD fuse installed. under no circumstances should the FWD fuse be removed until all of the tires are the same. just search the archive if you don't believe me!

Thanks for the feedback!

The automatics don't have a V-coupler. They have a clutch pack that can be deactivated with the fuse. The Manual transmission cars do have a V-coupler and do not have a fuse to deactivate the AWD. Correct me if I'm wrong.

 

 

Todd

that's right. the viscous coupler seems to be a little more tolerant of tire diameter differences, but the automatic can really get trashed by not installing the FWD fuse...it burns up the clutches fast!

Where is this fuse that I hear about? Which Fusebox? I don't see any info on "Front Wheel Drive" fuse in the manual or any slot in any of the fuseboxes on my 98 outback wagon.

any help is appreciated.

thanks.

It's close to the firewall on the passenger side of the engine bay.

Where is this fuse that I hear about? Which Fusebox? I don't see any info on "Front Wheel Drive" fuse in the manual or any slot in any of the fuseboxes on my 98 outback wagon.

any help is appreciated.

thanks.

It's buried at the tail end of the tire changing section. At least that was where I found it in the manual of my 97 OB. I "did" read my manual, but skimmed over the tire changing, since I'm pretty proficient at doing that. D'OH! You'd think something so important would be hi-lited more. In fact, there should be a placard right with, or on, the spare donut tire in my opinion. I didn't know about that FWD fuse (I had seen the fuse holder under the hood and wondered what it was about) until I got on this message board. Two years after buying the car (used).

 

Commuter

Putting the FWD fuse in causes duty solenoid C to go to 100% uh... duty. Driving like that for extended periods of time might cause the solenoid to wear out, I hear, which is an expensive fix.