Permanent FWD w/ no rear drive shaft - discussion and risks

[SbarroOutbackSteakhouse]

After a long hunt for a well-taken care of Subaru with low miles and devotion to regular maintenance, I bought a 1993 Legacy L Wagon. 4EAT, EJ22. This is my first car, so I tried to educate myself the best I could and took it into a shop so a mechanic could look for anything wrong before buying.

 

He gave the green light. But shortly after I found out the guy was way off: he didn't notice that the front struts were leaking oil, and steering bellows were completely separated. On top of that, he didn't notice that the rear drive shaft wasn't even present.

I talked to the old woman who owned the car for 22 years and got ahold of her regular mechanic, who told me that the transmission was replaced two years ago. Her mechanic said that when the transmission was replaced, the car was shuddering (torque bind?). It was supposed to be a compatible transmission (likely not the exact same model though) but something in the rear wasn't matching up right. Under the guidance of the Subaru dealer down the road, they decided to remove the rear drive shaft since it was an easy remedy, plus she had no need for AWD since she rarely drove.

This explained why the car seemed a bit sluggish, especially up hills, because a lot of the power was being diverted from the front wheels to the back, which couldn't even receive it. So I put in the FWD fuse the other day and there was an unmistakable increase in pep and power all across the board, especially on hills.

 

From what I understand, replacing just the rear drive shaft probably won't get the AWD working smooth, and replacing everything in the rear drive would potentially work to get the car AWD again... But I don't have much need for AWD and would be fine with this car being FWD permanently.

So my main question for the experts is: do I run any risks with keeping this car in FWD mode without the rear drive shaft? I know plenty of posters have done this temporarily when repairs were needed, and some folks on here drove like this for 35k or 40k miles as of 5 years ago, or alternate between seasons (some, even with the rear drive shaft in place). A lot of those threads are old though.. Are you guys still putting along fine? Did you have to do anything else to make this work? 

I've read many threads on use of the FWD fuse/removal of the rear drive shaft and understand that the duty solenoid C isn't designed to be in the circuit constantly. Is voltage still delivered when the car is off, say, overnight? I thought that the fuse only acts when the car is on (hence, why they shouldn't be towed even with the fuse in). Would removing the FWD fuse on occasion or installing a toggle switch serve as an acceptable remedy to this, to "give it a break," so to speak? If the solenoid goes bad, will FWD fail?

I've also read that the wire to the duty solenoid C can be cut, but puts undue stress on the clutch pack that it wasn't designed to handle. Is this the same as if there were a toggle switch?
 

 

I haven't yet been able to get ahold of the PO to ask if she always drove with the FWD fuse in, or just left it out and drove with the decreased power.

Sorry for the information and question overload. I've combed the web for similar situations and to learn as much as possible but this is all new to me. It would be great to hear from people with experience. This is a great car that was taken care of meticulously, and I don't want to subject it to unnecessary stress or damage, but I really need to know what to do since I don't have the money to just start replacing whole systems left and right and have a very big cross country trip planned for work.

Thanks for any help!

[CNY_Dave]

As long as the hole in the trans is plugged, no ATF out, no dirt in, zero risk.

[Dj7291993]

As Dave said, as long as the hole is plugged, you should be ok.  We have several people at our shop who have the fuse in all summer, with no problems.  All that solenoid does is bleed off pressure to the clutch disk for the rear driveshaft.  And, when the fuse is in, the trans will stop trying to send power back there, and hold that open all the time.  IT shouldn't really need a break, in fact, it's probably better having the fuse in then not if the driveshaft is out.  I wouldn't cut the wire, as the trans light will flash at you all the time, so you won't know when there is another problem.  Plus, there really isn't a need to have the rear locked in all the time.

[AdventureSubaru]

Good to go. And you may enjoy slightly better gas mileage than if it were running AWD.

[SbarroOutbackSteakhouse]

Thanks for the input. There's no ATF dripping, and it looked plugged when I got a look under there.

 

Today I did the diagnostic for existing problems with the Power light and it just flashed at quarter second intervals (can someone clarify that this means everything's normal? ), and now the car doesn't seem to do the 16 flashes on ignition... Doing the check for previous problems, resulted in a 24 code: duty solenoid C.

 

So it can't go bad when the rear drive is disconnected? What about the clutch parts?

[idosubaru]

no issues, drive it and don't worry about it.  no worries about the Duty C or clutches.  The clutches certainly shouldn't see any issues - they're not connected to nor is anything being driven by them, so they're not doing anything.

 

if you're that worried about it - install the matching rear differential and be done with it.

www.car-part.com

or someone on here will sell you a rear diff.

 

auto's usually have a 4.11 or 4.44 final drive ratio, maybe 3.9's were available too.  4.44's weren't available in 1995 or earlier Subarus.

[CNY_Dave]

Now if the shaft is removed, is the solenoid activated just to keep the stub in the trans from bouncing around?

 

It has a bearing at its front but uses the outside of the driveshaft on a bushing inside the rear of the tailsection for the rear support.

[SbarroOutbackSteakhouse]

no issues, drive it and don't worry about it.  no worries about the Duty C or clutches.  The clutches certainly shouldn't see any issues - they're not connected to nor is anything being driven by them, so they're not doing anything.

Thanks, I was actually hoping to hear from you and planning on writing a personal message at some point. I saw a lot of your posts from a few years back about your car and they were really helpful when first looking into what's going on with my car. Is yours still alive and kicking? 

 

 

 

Now if the shaft is removed, is the solenoid activated just to keep the stub in the trans from bouncing around?

 

It has a bearing at its front but uses the outside of the driveshaft on a bushing inside the rear of the tailsection for the rear support.

 

I'm not really sure what this means, since all of this is completely new to me and I'm just trying to learn as I go. On my car, I'm pretty sure that power was being directed towards the back in some way before I put the FWD fuse in, because there was a noticeable increase in acceleration and power afterwards, even on flat ground, but especially going up hills. I'm guessing that by putting the fuse in and completing the circuit with the solenoid, that's what's telling the car to keep all the power with the front wheels- and that's why I was worried about it potentially going bad, from being in the circuit constantly.

[CNY_Dave]

The front wheels are always connected by gears and metal to the engine, so if there is no drive shaft to the rear pickup should not change.

 

-But-

 

maybe the stub shaft is in the transmission still, and it can't turn, and without the fuse in the MPT clutch locks up a little and power gest wasted trying to turn it.

[Dj7291993]

 

maybe the stub shaft is in the transmission still, and it can't turn, and without the fuse in the MPT clutch locks up a little and power gest wasted trying to turn it.

 

That could be. In that case, it would be similar to trying to drive with the parking brake on.  Possible, but a lot of power would be wasted trying to overcome the added resistance.  If that is the case, then I would highly recommend putting the fuse in (if you haven't already), as if that clutch keeps trying to engage, but can't, you are going to rip up that clutch, cook your fluid, and cause a lot of unnecessary heat in the transmission.  Can you see anything sticking out of the back, or is it all covered?

[olepedersen]

Hi, I got my first Subaru yesterday a 2000 Outback with a bad RR bearing, and I am wanting to drive it 300 miles to my garage, the bearing noise when 

moving makes a strong ticking noise but not constantly, so I want to try Fw drive but I dont know where and witch fuse you are talking a bout , Can somebody help me Please Ole

[johnceggleston]

assuming it is an auto trans car,

and not the 3.0L engine

the FWD fuse should be located in the fuse box under the hood.

the fuse should be labeled,

but i'm pretty sure it is in the rear corner next to the washer fluid tank.

 

take it easy on your drive and you should be ok.

usually it takes a long time to actually fail, fall apart.

and i'm sure it will make a lot more noise before it does.

 

good luck.

[olepedersen]

  THANKS  I am on my way Ole

[olepedersen]

Well I was wrong it is the u joint in the center drive shaft,so for now can I remove the driveshaft and go in fw drive how would I seal the back of the tranny so it does not leak. there has to be a trick ??? Ole

[AdventureSubaru]

Temporarily I did just fine when the driveshaft went on my Impreza - A couple ziploc bags, a few layers of duct tape and either a big zip tie or hose clamp.

 

Anything that puts a seal on it should work fine so it doesn't leak. It's not really pressurized. Just needs to get you by until you get a new or junkyard driveshaft in there.

[olepedersen]

Beats pounding a golf ball in the hole. thanks again Ole