AWD->FWD - Debate with friend, need answers.

[hfxdesign]

Alright, me and my friend are getting in a heated debate about whether or not running my car on just the front wheels is gonna trash the transmission. The back story is this: The duty C solenoid in my car fizzled out, and I don't have the time to replace it, instead I removed the rear section of the driveshaft (4EAT transmission), leaving the rear differential / axle shafts in place.

I'm not really seeing where there could be much of an issue, aside from extra stress on the front CV shafts. Anyone have some input on this to clear it up?

[Bhatman]

There is a fusible link labeled "FWD" which when you put the fuse in it will disable the AWD (only for 4AT transmissions). You can leave the rear running, but just moving excess weight of the diff and half-shafts.

I dont know how long you can run in FWD mode...but I do not think its for long periods of time.

[Felipe]

My car has that fwd fuse option, but i thought that was for towing purpose only?

[hfxdesign]

I'm not using the fuse, I have the rear section of the driveshaft physically removed. He thinks it's going to destroy the transmission since there's no power to the rear tires.

[Huffer]

I'd like to see a picture of what you removed. If you disconnected the driveshaft from the middle u-joint, the remaining part will be unbalanced and wobble... and eventually will destroy your transmission completely.

You'd have been better off putting the FWD fuse in, until you can afford to swap the transmission out.

[Felipe]

I dont know how long you can run in FWD mode...but I do not think its for long periods of time.

How long is too long with the fuse? Just curious.

[Bhatman]

I dont know how long you can run in FWD mode...but I do not think its for long periods of time.

How long is too long with the fuse? Just curious.

When you plug in the FWD fuse, that kills the duty cycle on the Duty C Solenoid to 0. Technically the solenoid with that fuse wont cause any damage, but before the solenoid could go out, the transmission as Huffer said would wobble due to being out of balance.

[Felipe]

I wonder if you can do the same and make it RWD? lol

[Muse]

You can't.

And I've been running FWD unless it's snowing since I crashed in October with no discernable ill effects.

[Felipe]

If running on just FWD does it get 100% to both front wheels 50/50?

[Muse]

Well, not really. If you have the fuse in, you'll get 100% to one or the other front wheels, unless you have a limited slip front differential..

[Grimmrican]

Or just weld it so it posse lol but that'll be dumb. But yea my dads BG ran with the fuse on his car for about 3 months until I did a transmission drain and fill. Ran perfect after that. AWD awesomeness was resurrected to his BG

[Felipe]

Is there such thing as a lsd for awd trans for front or back?

And sorry for the....

http://www.xdtalk.com/forums/xdtalk-chatter-box/175907-hijack-thread.html

[Grimmrican]

Aww the pic is broken on my phone :(

I think there's a VCD for the car and a LSD and u can make the rear posse at like 80% torque on the rears 20% in the front

[Huffer]

There's plenty of LSD options for the rear diff - just depends on your gearing and what you want to do.
I don't recommend it if you're not proficient at skid-recovery though.

[Felipe]

80% to the rears.... Interestiningnig

Proficient Skid recovery... Does it count if my last car was 240SX with a vlsd :0)

[Grimmrican]

Yea iirc u can go up to 90% rear but not full 100%

[Felipe]

RWD legacy waggon

https://www.youtube.com/watch?v=URuHcXeGGX8&feature=youtube_gdata_player

And says.... " removed front axle, kept the end to hold the wheel bearing together. welded center diff? to send all power to rear wheels only, replaced rear diff with factory lsd from legacy outback."

[Felipe]

https://sl-i.net/FORUM/images/imported/2013/04/threadjack-1.jpg

:grin:

[Grimmrican]

https://sl-i.net/FORUM/images/imported/2013/04/threadjack-1.jpg

:grin:lol true

And not too long ago on my FBI news page I saw someone with a rwd wrx who did something similar

[Felipe]

Stock Lsd from an outback? So only outback came with lsd or was it an option of some sort.... I mean why get an lsd when the car is already awd?

[Grimmrican]

It's a little more complexed than being an AWD ill just let the next fellow under me explain how it really works.....

[Felipe]

Fine ill google\wiki it lol

[Muse]

Far as I can tell, with an open diff, a car is esentially one wheel drive, in the sense that there is only one actually getting the power at any given time. With AWD or an LSD you bring that up to two wheel drive (both drive wheels in a FWD/RWD or one front/one rear in an AWD.) With a rear LSD-equipped Outback, you have both rears and one front getting the power.

[Grimmrican]

Yea but I thought the AWD only turns off one wheel when turning to prevent binding....

[Huffer]

You guys are getting totally mixed up with AWD and LSDs.

Even a RWD car can have an LSD. It's not limited to AWD or FWD.

Read this for info on STOCK transmissions and setups. Once you get that, then you can move onto "what do I think I want to replace":
http://www.cars101.com/subaru_terms.html#awd

[Felipe]

It Talks about the split to front/rear, but it dont say if it sends power to both right/left or just one

And my 240SX was rwd with an open diff (power to one wheel) until i installed a VLSD.

[Neatfellen]

well then, I can certainly say that the thread def is off of the orignal question haha, but still fun to read the back and forth. As far as my manual said when I read through it, the Fuse option is only a temporary fix, does not say how long temporary is though, but would not recommend anything else to make your car FWD unless it was to use the switch per what was already brought up by Huffer. (btw mine is a 5 MT and I have the same fuse option to make it FWD so not to sure about it being only on the 4AT, maybe it changed on the 3rd gen that i have)

[Huffer]

It Talks about the split to front/rear, but it dont say if it sends power to both right/left or just one

And my 240SX was rwd with an open diff (power to one wheel) until i installed a VLSD.

Your 240SX is only confusing the issue - we're talking about Subaru's here.

The Subaru AWD system doesn't allow (at least in the pre-2005 models) for a left-right (yaw) control of sending torque. The only system that does is the VDC system which is typically only found in the Outback models.


well then, I can certainly say that the thread def is off of the orignal question haha, but still fun to read the back and forth. As far as my manual said when I read through it, the Fuse option is only a temporary fix, does not say how long temporary is though, but would not recommend anything else to make your car FWD unless it was to use the switch per what was already brought up by Huffer. (btw mine is a 5 MT and I have the same fuse option to make it FWD so not to sure about it being only on the 4AT, maybe it changed on the 3rd gen that i have)

A 5MT does NOT have a fuse to make it FWD. It's only on the ATs. I'd check under your hood again.

[Neatfellen]

It Talks about the split to front/rear, but it dont say if it sends power to both right/left or just one

And my 240SX was rwd with an open diff (power to one wheel) until i installed a VLSD.

Your 240SX is only confusing the issue - we're talking about Subaru's here.

The Subaru AWD system doesn't allow (at least in the pre-2005 models) for a left-right (yaw) control of sending torque. The only system that does is the VDC system which is typically only found in the Outback models.


well then, I can certainly say that the thread def is off of the orignal question haha, but still fun to read the back and forth. As far as my manual said when I read through it, the Fuse option is only a temporary fix, does not say how long temporary is though, but would not recommend anything else to make your car FWD unless it was to use the switch per what was already brought up by Huffer. (btw mine is a 5 MT and I have the same fuse option to make it FWD so not to sure about it being only on the 4AT, maybe it changed on the 3rd gen that i have)

A 5MT does NOT have a fuse to make it FWD. It's only on the ATs. I'd check under your hood again.
hmm, I didn't look overly close so its possible that its just a blank slot but still labeled as that but with no connectors in it.

[Muse]

I didn't think the 3rd gens had that at all.

[Felipe]

The Subaru AWD system doesn't allow (at least in the pre-2005 models) for a left-right (yaw) control of sending torque. The only system that does is the VDC system which is typically only found in the Outback models.

So only pre 05 models only get power to the right?
:smt017

[Muse]

No, they do. there's just no system to control it.power will go to the wheel with less resistance.

[Felipe]

Hope you guys dont think i am being a jack ass -.-

Im just trying understand and feed my brian with awd system and what is possible under certain situations or what isnt.

[Grimmrican]

Hope you guys dont think i am being a jack ass -.-

Im just trying understand and feed my brian with awd system and what is possible under certain situations or what isnt.feed ur brian? Lmao u mean brain

[Neatfellen]

I didn't think the 3rd gens had that at all.
3rd gens definitely have it, just only the AT's (my car has the fuse spot but its a blank on the MT)

[Grimmrican]

For the 2nd gen it should be just behind the passengers strut housing. 3rd gen should be up in the left hand corner of the fuse box under the hood. ATs only!!

[Felipe]

I seen it... Now im just curious to try it lol

[Neatfellen]

I seen it... Now im just curious to try it lol
I'm not, lol. No offense but I bought a subie cuz I was sick of FWD so I am not curious to see how it is, I love my AWD, took me 4 years since I could drive to be able to get one and I'm not giving it up!

[Huffer]

I didn't think the 3rd gens had that at all.

*sigh* EVERY subaru with a 4EAT system has the FWD fuse slot to bypass Duty C solenoid in the transmission that turns the rear wheels. Every single one.


"The Subaru AWD system doesn't allow (at least in the pre-2005 models) for a left-right (yaw) control of sending torque. The only system that does is the VDC system which is typically only found in the Outback models."

So only pre 05 models only get power to the [rear] right?
:smt017

No no no.
For the Subaru AWD system for AUTOMATICS, the D gear selection allows for 90% front, 10% rear torque split. In D3 gear selection, the power is split 50/50 front/rear.
The AWD system is NOT the same as a Traction Control System - which is what VDC etc do - they sense which wheels are slipping and remove power from that wheel until it regains traction, and conversely send the power to the wheels that DO have traction. The mechanics of sending the power to individual wheels varies - some systems allow yaw (left-right) and front-back. Some only allow front-back only, in the case of open differentials. Limited Slip Differentials allow the wheels on either side to spin at differing rates depending on the rate of slippage, which is why you will see some people upgrading from "open" differentials to "LSD" ones.

It gets a lot more complicated from there on out.

Just remember what your car does (stock) and in what gear (D = 90/10 torque split, D3, D2, D1 = 50/50 torque split).

[Felipe]

I get the split part and and i know the lsd job.... So stock legacys are equiped with open diff...front and back. How would you tell if an outback has a lsd in it?

[Huffer]

I get the split part and and i know the lsd job.... So stock legacys are equiped with open diff...front and back. How would you tell if an outback has a lsd in it?

Typically, if you jack the rear end up, and turn one of the rear wheels, the other side should turn also.

[Grimmrican]

^ in the same direction (LSD) in the opposite direction (open diff) I never tested it in a AWD but u may still stand corrected sir lol

[Felipe]

Similar to rwd, But backwards... when one turns foward the other tire will spin in reverse = lsd... But with an open diff you turn one wheel and the other dont spin at all.

[Grimmrican]

Similar to rwd, But backwards... when one turns foward the other tire will spin in reverse = lsd... But with an open diff you turn one wheel and the other dont spin at all.thats prolly what I was thinking just flub it all up. Sorry

[Felipe]

Im guessing the front is the same way

[Neatfellen]

so I understand that only 4EAT has the option of FWD only. And this is prolly a dumb question, but why cant the 5MT have the option? Or is it just not equipped but would be able to if Subaru so choose to put the option on a 5MT?

[Huffer]

so I understand that only 4EAT has the option of FWD only. And this is prolly a dumb question, but why cant the 5MT have the option? Or is it just not equipped but would be able to if Subaru so choose to put the option on a 5MT?

The 5MT is very mechanical. You shift, it changes gears. The 4EAT (nay, all the AT's) have the ability to transfer power via a series of clutch packs and the Duty C Solenoid. When these clutch packs go bad, or duty c solenoid burns out, it locks the rear wheels into a state called torque bind.

Think about this - unless you are traveling in a straight line, NONE of your wheels are turning at the same speed. If this happened, every time you cornered you'd leave tire marks and broken axles. The OUTSIDE line of a turning circle is wider (and thus the wheel rotates slower) than the INSIDE line of a turning circle. It's like a running track. The outside lane, all the way around, is longer than the inside lane. That's why in track meets the runners in the inside lanes start way behind the outside lane runner, so that the distance they run is equal.

Back to your question - the reason the 5MT doesn't have this "FWD only" mode is because it's mechanical and it doesn't have an ability to disengage the rear driveline via an electrical actuator (duty c solenoid). Sure, they could put it in... but the point of a 5MT AWD is...AWD. Not some bizarre bastardization of a "sometime AWD" system.

[Muse]

Is the 5mt always a 50/50 split then?

[Huffer]

Yep.
If you take a 4EAT into the snow, and hit the gas, the front tires will lose traction before the rears do, because those at the main drive wheels. Shift it into D3 and all of a sudden you have snap oversteer at your disposal. a 5MT car (in the snow) can do that in 1st gear without hesitation.

[hfxdesign]

MMMM...The part I disconnected wasn't a U joint. The drive shaft is split into 2 parts on the A/T suabrus, the rear section is held on by 4 bolts connected to the diff, and halfway through there's another 4 bolts and a carrier bushing. My friend's concern is that it'll destroy the transmission due to excess power to the front tires. But I've heard of converting subarus from AWD to FWD using this exact method (with a few extras, removing the diff and the rear axles, keeping the stubs in place on the wheels.)

For reference: I disconnected the shaft because the FWD fuse wouldn't keep the car in FWD mode, and I had burned the last differential out; thus, to avoid tearing up another differential, I just disconnected the rear half.

[EJ22D]

Okay.
Everyone aside from Huffer (got his info right) read VERY CAREFULLY.

1. Our 4EATs in the 2nd gens have a normal 90/10 split that varies while the car is in motion & the load on the engine from that variance can be up to 25%. That 90/10 can vary all the way up to 50/50, where the car essentially becomes 4WD.

2. My 4EAT locks the transmission into the 50/50 split in 1st & 2nd gear ONLY. I have a 98 GT Limited. I can't speak for other 4EATs though. My last 4EAT, which was a 97 L, locked the transmission into 50/50 in 1st, 2nd, & 3rd gear.

3. It is said that leaving the FWD fuse in will mess up the transmission. My current GT is just fine. I re-wired the FWD fuse so that it is inline with the constant power feed to the switch, serving as a "breaking point" rather than being the switch itself.

4. There is no need to remove any part of the driveline when in FWD. The reason it is said that you shouldn't drive aggressively or at high speeds is because when the car is in FWD mode, it diverts ALL of it's power to the front wheels. The CV joints in the front are slimmer than those in the actual FWD version & are said to not be capable of withstanding that much torque for very long, which makes sense. Towing in FWD also makes sense because more torque is usable/produced by the engine to move the car & whatever it's towing but using slim CV joints to tow a load was a slip up on the R&D's end.

5. FWD makes the car respond & handle ENTIRELY different under extreme conditions & the grip that AWD initiates during a corner or during acceleration is completely lost. The car WILL be far more prone to understeer but on the flipside, there will be no parasitic drain from the AWD. The car's full power/tq will be released, resulting in more mpgs. The extra driveline hardware will not be as much of a drag as people make it out to be with the extra power released. Engine load only goes as high as 13% during normal operation.

6. I use my FWD switch very often, especially when I'm moseying around town & driving at street speeds & all with no ill effects. When I switch from FWD to AWD, I do it ALWAYS when the transmission is in park, even if I have to switch to park at a light. I use it, NOT abuse it as I am not yet certain what kind of effect that switching in motion will have on the Duty C.

[Felipe]

I would like to see that fwd switch... Very interstingning idea.

[Neatfellen]

so I understand that only 4EAT has the option of FWD only. And this is prolly a dumb question, but why cant the 5MT have the option? Or is it just not equipped but would be able to if Subaru so choose to put the option on a 5MT?

The 5MT is very mechanical. You shift, it changes gears. The 4EAT (nay, all the AT's) have the ability to transfer power via a series of clutch packs and the Duty C Solenoid. When these clutch packs go bad, or duty c solenoid burns out, it locks the rear wheels into a state called torque bind.

Think about this - unless you are traveling in a straight line, NONE of your wheels are turning at the same speed. If this happened, every time you cornered you'd leave tire marks and broken axles. The OUTSIDE line of a turning circle is wider (and thus the wheel rotates slower) than the INSIDE line of a turning circle. It's like a running track. The outside lane, all the way around, is longer than the inside lane. That's why in track meets the runners in the inside lanes start way behind the outside lane runner, so that the distance they run is equal.

Back to your question - the reason the 5MT doesn't have this "FWD only" mode is because it's mechanical and it doesn't have an ability to disengage the rear driveline via an electrical actuator (duty c solenoid). Sure, they could put it in... but the point of a 5MT AWD is...AWD. Not some bizarre bastardization of a "sometime AWD" system.
Ty for the explanation, that answered my question completely, just wanted to learn a little for knowledge sake. it makes a lot of sense. N I agree completely, that's exactly why I got the 5MT lol.

[hfxdesign]

Is it odd I'm still getting a flashing AT OIL light even with the rear tires disconnected?

[Grimmrican]

Uhm I'm pretty sure any kind of flashing lights in it cluster is bad news with the exception of ur hazards and blinkers lol

[EJ22D]

Is it odd I'm still getting a flashing AT OIL light even with the rear tires disconnected?

Something in the transmission has failed. You should stop driving it at this point.

[hfxdesign]

Read the first post here. My duty C solenoid failed, I'm just saying I'm still getting a flashing light despite having the driveshaft pulled. I'm beginning to wonder if it's the TCU and not the solenoid itself. I've already pulled the code, and the only one I get is for a failed duty C. The transmission still shifts just fine, no problems whatsoever.

[Felipe]

Just remember what your car does (stock) and in what gear (D = 90/10 torque split, D3, D2, D1 = 50/50 torque split).

What about in Reverse?

[Neatfellen]

I believe reverse would be like 1, 2, 3 and is 50-50. That would make sense.

[EJ22D]

Read the first post here. My duty C solenoid failed, I'm just saying I'm still getting a flashing light despite having the driveshaft pulled. I'm beginning to wonder if it's the TCU and not the solenoid itself. I've already pulled the code, and the only one I get is for a failed duty C. The transmission still shifts just fine, no problems whatsoever.

The TCU is throwing the code for a failed Duty C but you can still drive it. It's just going to constantly remind you in that annoying way. I have never heard of a TCU "lying" or being messed up that badly. Not to say that it doesn't happen but if it says you have a failed Duty C, it is so. Just because you have it in FWD doesn't mean that the flashing will stop since the TCU isn't picking up an electrical signal from the Duty C.

[Huffer]

Just remember what your car does (stock) and in what gear (D = 90/10 torque split, D3, D2, D1 = 50/50 torque split).

What about in Reverse?

Reverse... that would different. Besides the fact that your speed is severely limited by the gearing (R I think is as short as 1st gear) the "rear" wheels while moving in reverse have much greater turning capability. As far as torque split goes, you'd probably be the same as D4 - Rear wheels will still only 10% while the fronts get 90%. I guess you could say that while in reverse, you now have a mostly RWD car... LOL


Read the first post here. My duty C solenoid failed, I'm just saying I'm still getting a flashing light despite having the driveshaft pulled. I'm beginning to wonder if it's the TCU and not the solenoid itself. I've already pulled the code, and the only one I get is for a failed duty C. The transmission still shifts just fine, no problems whatsoever.

And you'll get a code because your failed duty C solenoid isn't part of the rear driveshaft. It's a sensor/switch inside the trans and it's failed. It's like unplugging your antenna and then saying your stereo still isn't picking up FM even though your CD player is still working.
The trans will shift fine - because shifting has no bearing on how the rear wheels are turning. The rear diff isn't dependent on how the trans shifts - it's dependent on how the fast the driveshaft is turning based on the rear clutch packs. Because you've physically disconnected the driveshaft (which means under your car you now have a spinning pipe that's not anchored on both ends, which is really dangerous), you won't "feel" any difference in the transmissions shifting or how the rear wheels are turning.

Oddly, you'd have achieved the exact same result just by inserting the FWD fuse in the engine bay. Much less work and far less dangerous overall.



6. I use my FWD switch very often, especially when I'm moseying around town & driving at street speeds & all with no ill effects. When I switch from FWD to AWD, I do it ALWAYS when the transmission is in park, even if I have to switch to park at a light. I use it, NOT abuse it as I am not yet certain what kind of effect that switching in motion will have on the Duty C.

That's really interesting about your 4EAT in your 98 only locking into 50/50 in 1st and 2nd gear. I've had 2 98 GTs (sedan and wagon) and they locked into 50/50 in 3rd gear (on the freeway, doing 60mph in snow, based on RPMs). Granted I pay more attention to the engine speed and wheel speed more than I did gearing so I could be wrong - but all the literature I've read says 50/50 from D3 to D1.

I'd really avoid switching the Duty C "off" mid-roll... I imagine the driveline shock might be a bit much over time, a bit like when someone jumps a gear or stalls out on a hill too many times.

[Dead91silvia]

Alright, me and my friend are getting in a heated debate about whether or not running my car on just the front wheels is gonna trash the transmission. The back story is this: The duty C solenoid in my car fizzled out, and I don't have the time to replace it, instead I removed the rear section of the driveshaft (4EAT transmission), leaving the rear differential / axle shafts in place.

I'm not really seeing where there could be much of an issue, aside from extra stress on the front CV shafts. Anyone have some input on this to clear it up?

So much BS in this thread (other post's)....

Yes, you can run with the FWD fuse in.
Yes, it may damage the trans
Yes, it can be converted to FWD

Removing the rear half of the driveline is not the best idea, but it can be done. If you are doing it to save MPG, it's pointless since you still have both rear axles installed as complete units. You might save a little. That trans is meant to run ALL 4 WHEELS!

The FWD fuse is for towing and if you are using a spear tire. Thats the reason for it. Not because your trans is having problems.

[rkrenicki]

...The FWD fuse is for towing ...

Here is a question in regards to this. Is it for towing something with the car, or the car being towed?

My understanding was to put the car into FWD for an unavoidable front-wheel tow (as in, not a flatbed tow) so as to not destroy the transmission, but if you are using the car to tow a trailer or whatever to leave it in AWD as you would be putting a larger load on the front axles than normal.

[hfxdesign]

Alright, well I'm planning on replacing the Duty C, anyone know where I can get one for a decent price?

[hfxdesign]

@rkrenicki That's what 1, 2, and 3 are used for, as stated, most 4EATs lock into 50/50 in the numbered gears, and yes you want it full time AWD when towing a trailer, on the AWD subarus the front CV shafts are slimmer than the ones on the FWD versions, so they're not as sturdy.

[Grimmrican]

Not to stray away from this convo any further than it has lol. But is it ok to drive in 3 thru city like areas? Obviously not highway. So lets say under 50mph.

[EJ22D]

That's really interesting about your 4EAT in your 98 only locking into 50/50 in 1st and 2nd gear. I've had 2 98 GTs (sedan and wagon) and they locked into 50/50 in 3rd gear (on the freeway, doing 60mph in snow, based on RPMs). Granted I pay more attention to the engine speed and wheel speed more than I did gearing so I could be wrong - but all the literature I've read says 50/50 from D3 to D1.

I'd really avoid switching the Duty C "off" mid-roll... I imagine the driveline shock might be a bit much over time, a bit like when someone jumps a gear or stalls out on a hill too many times.

I only switch on/off at complete stops & in P, never during a roll. I don't have the courage to test that out & I don't want to gain it! :D But yes, my 4EAT doesn't not lock into 50/50 in 3rd gear, only 1st/2nd. There is no bind when I put it into 3rd but it immediately comes up when 1st/2nd is selected. My old L did it in 1st, 2nd, & 3rd. I have had this transmission checked & it is in great shape for its age.

To the OP,
1. You can run with the FWD fuse in & it is recommended for you to do so should you have any problems with the transmission.
2. You're likely to break a C/V joint long before you'd ever hurt the transmission due to them not being as strong as those in the FWD version.
3. The transmission is a FWD based transmission, so it is good to use if you have to do it.
4. Even if you drive in FWD mode, you will save gasoline. 3mpg at best but its still a gain over being in AWD. I don't know about you but 15k+ feet is quite the distance.
5. The 4EAT is a FWD based transmission that has AWD as a "secondary response", so to speak. Most times when you're driving at lower speeds, the transmission has a 90/10 split, essentially making it a FWD car.
6. It is true that you are to use FWD when you're towing a load or when you have a flat but when that flat happens, the wheel speed sensors sense the difference in tire speed & will cause the transmission to bind, much like what will happen with a failed Duty C, hence why the FWD fuse is there to use.


Not to stray away from this convo any further than it has lol. But is it ok to drive in 3 thru city like areas? Obviously not highway. So lets say under 50mph.

Any time you have the transmission out of Drive & if its binding, you are essentially in 4WD (50/50) & the stress of all 4 wheels turning at the exact same time causes extra heat/stress on the transmission itself, which tears up the fluid much faster & will leave you with a blown Duty C & very damaged clutch packs. I hope this answers your question.

[Grimmrican]

Ok so it depends really if 3rd binds or not which I don't feel when it does only in 2nd. But ok good to know ill avoid it unless I desperately need to use it

[hfxdesign]

Duty C was destroyed due to 4 different tires being on the car, which also destroyed the rear diff. New tires put on today, rear driveshaft will stay disconnected as the Duty C is so far gone the FWD fuse no longer works anyway. Still deciding whether to replace the solenoid, or get a plug for the front / center diff, remove the whole driveshaft and rear diff, and stub off the rear hubs (essentially convert it to FWD completely).

[EJ22D]

Duty C was destroyed due to 4 different tires being on the car, which also destroyed the rear diff. New tires put on today, rear driveshaft will stay disconnected as the Duty C is so far gone the FWD fuse no longer works anyway. Still deciding whether to replace the solenoid, or get a plug for the front / center diff, remove the whole driveshaft and rear diff, and stub off the rear hubs (essentially convert it to FWD completely).

That will do it.
All tires on our AWD systems must be of the same type, size, tread, & psi.
It would be better if you restored the car's AWD system piece by piece as it being non-functional will affect the resale value of the car.
Also, it would also be great to have that extra control when you need it but if you're going to go through all of that extra effort, you may as well swap in a FWD transmission so you don't have the dead weight of the inert AWD parts stopping your car from being as efficient as can be.

[hfxdesign]

Well the only piece it needs is the solenoid...It's just a very time consuming process to replace it, not to mention finding the part I need. I've already replaced the rear differential, disconnected the driveshaft to avoid damaging it. Taking it to a dealer to have them do it would cost more than what I paid for the car ($700) Swapping for a FWD transmission would probably cost about the same, and if I was going to do a transmission swap I'd just get a known good AWD 4EAT (4.11FD) transmission. So you can see my dilemma.

[Huffer]

...The FWD fuse is for towing ...

Here is a question in regards to this. Is it for towing something with the car, or the car being towed?

My understanding was to put the car into FWD for an unavoidable front-wheel tow (as in, not a flatbed tow) so as to not destroy the transmission, but if you are using the car to tow a trailer or whatever to leave it in AWD as you would be putting a larger load on the front axles than normal.

Yep.

The only time it is recommended to use the FWD fuse slot is:
1. for an emergency tow where you would have the front wheels off the ground, but the rear wheels on the ground. This allows the rear wheels to free-roll without damage.
2. For diagnosing a torque bind situation that usually results in duty c solenoid going/gone bad or burnt transfer clutch packs inside the trans.

[Lojasmo]

I'm not using the fuse, I have the rear section of the driveshaft physically removed. He thinks it's going to destroy the transmission since there's no power to the rear tires.

I drove mine for several hundred miles with the rear drive shaft removed. No damage to the transmission, but if you get ANY snow, it will be a zero wheel drive vehicle.

Edit. Mine was 5MT so nevermind.

[Wiscon_Mark]

An open differential will only send power to one front wheel if there is slippage, which results in the wheel with the least traction spinning while the other wheel sits there helplessly. Open diffs are designed with turning in mind - the wheels can be driven while still rotating at different speeds (around corners) so you don't end up with "wheel hop" when you drive around a corner.

LSDs help send power to both wheels in a slipping condition while retaining the ability for each wheel to turn at a different speed, like around corners. Many upper model Subarus have rear LSDs (Legacy GT, Outback, Forester XS/XT, WRX, STi) while very few have front LSDs (STi, possibly others that I'm not aware of).

On newer Subarus with VDC, the car has the ability to brake the spinning wheel on one side to allow the wheel on the other side with more traction to regain power. It's kind of a compromise with LSDs & locking diffs, but a system that works pretty well in slippery conditions.

You could have 50/50 power split across the front/rear wheels if you locked the diffs (a feature not available on modern Subarus), but that would cause the wheels to turn at the same speed, even around corners which causes wheel hop & other annoying side effects. That's why locking diffs are only used in slow, off roading conditions, generally.

From what I've read about the DutyC on autos, you can burn it out by locking it 50/50 with a resistor mod, and possibly by using the FWD fuse too long (only in theory though) but to the OP that doesn't matter as it's wrecked anyways. Of course, the FWD fuse might not work with the duty C ruined.

[hfxdesign]

Sorry to resurrect this post. I just got new tires on the car and re-connected the driveshaft. Still getting torque bind, but far less severe than it was, still have the 16 flashes of AT oil temp, and FWD fuse does nothing. Pretty much 99.8% sure the duty C is shot. Would driving it like this risk further damage? If so, what kind of damage? I'm not exactly made of money and don't have alot of time to work on it. My only A-B vehicle ATM so I can't have it 'in the shop' per se.

[hfxdesign]

Bump

[86bratman]

you run the risk of snapping the transfer shaft if you let it continue to run with torque bind

[hfxdesign]

So pretty much back to square 1: fwd

[86bratman]

That would be our safest bet. At least until you have the money to fix it right.

[hfxdesign]

I meant if the transfer shaft broke.

[86bratman]

yeah, that would be the end of the transmission's awd ability without a decent bit of work/money.

[hfxdesign]

Oh well, New transmission incoming anyway