Driving without Rear Driveline?

[Autoevo]

Ok , so my dumbass got a replacement transmission that has a different FD of 4.11. Since my rear diff is 3.90 i would like to run the car without the last half of my drive line until my other 4.11 diff shows up.

Has anyone tried driving without having their rear driveline connected?

[legacy98gt]

i think you can do it if you put that fuse in for fwd under the hood im not sure though havnt tried it

[Autoevo]

Didn't even know that there was a FWD fuse location.

[Grafton]

there is a fuse if you have an auto tranny, but it will be much safer for your tranny if you disconnected your driveshaft...

[Huffer]

Disconnect the driveshaft....

[Autoevo]

I was planning on disconnection the back half of the shaft. I just wanted to make sure that there would be no il-effect in doing so. Thanks everyone for the info.

[valkura]

What happens to that center diff if you disconnect the driveshaft? \postlongworkdayquestion

[Autoevo]

Well i disconnected the least half of the driveline today and went for a test drive. Wouldn't you know it we got 4 inches of snow today so it was an interesting test. The car seemed fine being 2WD but while i was spinning about i wondered if transmission was trying put more power to the back wheels. I don't know if a 95 was this advanced yet.

[mike-tracy]

I gotta say, if having tires greater than 2/32nd" different in height (per my owners manual) can destroy your center diff (over time) then having no rear load will definitely do it quicker! If your transmission is an auto then that's different, because Subaru put the aforementioned FWD fuse holder in the engine bay for being towed on two wheels (also as per my manual). So if you have an auto, just put in the fuse (15 amp) in the holder, and if you have a five speed, then please, for the sake of your center diff, stop driving it until you get the right rear diff.

-concerned subaru lover.

[Autoevo]

Thanks for the concern. I will probably just park it. Your last comment makes me think whether or not my tires are within the size threshold. And if not maybe that's why the tranny failed after a year with the rims i swapped from my last car. I had forgotten how sensitive AWD systems can be to tire size variation. It seems i may have learned an expensive lesson. :smt012

[B's Legacy Wagon]

currious about your statement with the tire size threashold and the AWD being sensitive to tire size variation. about to buy some new rims and tires so i am very concerned about getting something if it going to cause problems elsware, can you be more specific what you meen or size and what problems it causes?
thank you..

[ouch1011]

If you have an auto AND you put it in to FWD mode, it should be OK although I would drive it minimally.

If you have a manual, you will destroy the center differential. Open differentials send power to the path of least resistance. A limited slip differential (as the center differential is) will ATTEMPT to equalize the power between both sides of the differential (front and rear in the case of a center diff) but with such a huge difference as no load on the rear and the full load of the car on the front, there is no way the viscous limited slip in the center diff could cope, and it will destroy it very quickly. In fact, I'd be suprised if it were even strong enough to move the car a reasonable speed with no rear driveshaft. But it would destroy itself trying.

RE the last post, the difference in tire size on AWD, it is in regards to the difference in the individual tires on the car. i.e. if you have brand new tires on the front and very worn tires on the rear, or if you are running different tire sizes front and rear, you are causing a difference in tire speed front to rear which will damage the center diff. If all 4 tires are the same size, regardless of what that size is, you are OK.

[B's Legacy Wagon]

thank you exactly what i was wondering. totaly makes sence

[jewbaru]

i cant find that information anywhere in my manual. does anyone have a picture of where the fuse location can be found?

[TGX4776]

Has anyone done this (fuse on the auto) and seen an increase in MPG's?

[mike-tracy]

Jewbaru, look in your engine bay, passenger side around the strut tower.

TGX, the car drives like crap, like worse than a FWD vehicle, and since autos normally send 90% power to the front, theoretically driving in FWD will net you slightly better mileage. I didn't notice any difference in mpg.

[TGX4776]

i have a friend who is a big hyper miler and has an auto autback (98 or 99) and thought they would be interested if made a difference

[jewbaru]

Jewbaru, look in your engine bay, passenger side around the strut tower.

TGX, the car drives like crap, like worse than a FWD vehicle, and since autos normally send 90% power to the front, theoretically driving in FWD will net you slightly better mileage. I didn't notice any difference in mpg.


my fuse box is on the drivers side. is there another one on the passenger side that im missing? the duct work for the intake goes down the passenger side

[jewbaru]

https://sl-i.net/FORUM/images/imported/2010/08/sub1-1.jpg

am i still looking on the passenger side?

[green97gt]

Jewbaru, look in your engine bay, passenger side around the strut tower.

jewbaru(love the screenname BTW) your FWD fuse, is located in the main underhood fusebox on the drivers side

the 95-99s are on the pass side strut tower..

2000+ are in that fuse box near the battery, do you have the printout on the cover of the fuse box?

[jewbaru]

im sure i could get one.

and as for the name.. lol im not jewish. long story short, its more of an inside joke haha

ill get a picture up soon

[Sarra]

If you drive a Manual transmission car without the rear driveline in, you WILL DESTROY your center coupler. Be prepared to replace that if you do this... No FUSE or any other bullshit will save it.

If it's an Automatic, and you put the fuse in, you may be okay for a little while, but I seriously doubt you will be able to drive it that way for very long. It's hard on the Duty C solenoid and eventually it will overheat and you'll be replacing that.

[SPIT_FIRE89]

Hey guys i have some questions for all you legacy guys :), i got a 99 legacy gt 2.5 dohc stick and on my way to school the other day i got a flat on the right rear, with no time to spare i threw the donut on and hoped on the highway and about 50km later when i got of the highway i realized i had smoked my rear diff, the undercoating that was on the diff was putting on a smoke show and the rear was starting to lock up at very low speeds, i managed to make it to my school (another 2km off the highway) i repaired the damadged tire and changed the diff fluid (i put in lucas 75-90 synthetic) as the fluid that was in the diff got burned bad but no chunks of nothing came out, my cars been driving alright since then (this only happened about 300km ago) but its not the same and i think i melted the axle seals in the diff, now my question is how tough r these diff's, do you guys think a diff would b alright after something like that or do you think the lil limited slip clutch in there is fried ???