I am pretty sure I have this [18 - 24 mos now] but meantime many other things have gone bad. I would like to disconnect the rear drive partly to confirm diagnosis but also to accept 2WD at least until the winter, instead of costly repair. I cannot sensibly put any more money in until I have a few months of no repair costs! Is there a description of how to do this somewhere [for long term use]?

 

Nomention of viscous coupling in Haynes up to 1998. Do I need real 1999 onward edition?

 

thanks

 

John

make model trans miles of car???

make model trans miles of car???

 

Manual Trans, 160K.

best solution:

cut power to duty C - this will lock the 4WD for sure (until you want to fix it, then just splice that wire back together). it's only one wire (did it last year).

 

then remove the rear half of the drive shaft.

 

free fix. you'll have 2WD then. if you need winter traction occasionally, just get snow tires. FWD and high quality snow tires is better than 4WD with low quality street tires anyway. if you do significant and scarry winter driving then fixing the 4WD might be warranted. but there are a great deal of people using 2WD in severe winter duty - they just use high quality snow tires. even studded, that's top notch.

best solution:

cut power to duty C -

 

it's a manual, no duty c...... ooops.

 

 

 

then remove the rear half of the drive shaft.

 

will this work on a manual?? seems like it would.

It should. Only one way to find out,

 

 

I am pretty sure I have this [18 - 24 mos now] but meantime many other things have gone bad. I would like to disconnect the rear drive partly to confirm diagnosis but also to accept 2WD at least until the winter, instead of costly repair.

 

You could remove the driveshaft as a diagnostic tool. However, I would not drive it like that for any extended time at all. If you're center diff is OK now, it won't be after running with only FWD. You'll be asking the viscous coupler to transfer power through it all the time. You'll be absolutely cooking it even going to the grocery store.

 

Nomention of viscous coupling in Haynes up to 1998. Do I need real 1999 onward edition?

 

 

Yeah, being an internal transmission part, Haynes doesn't cover it. Anything beyond a clutch change, Haynes(and chilton) say something like "due to the complexity of transmissions, repair by the home mechanic is not possible. Take it to a dealer or transmission shop"

 

What you really need is a Subaru FSM.

Which i know someone has .....

 

 

 

nipper

If you're center diff is OK now, it won't be after running with only FWD. You'll be asking the viscous coupler to transfer power through it all the time. You'll be absolutely cooking it even going to the grocery store.

 

could you explain this a little more. my understanding was that the speed differential causes the viscous fluid to heat up and thicken? then causing the rear to engage. with no load on the rear it seems it would be less wear than with the drive shaft in.

 

but i don't know that much about manual trans.

Since there will be minimal drag on the center diff, the visous coupling really wont be doing anything. Also since your VC may already be shot, the point is moot.

 

Now if the halfshaft was locked somehow, then you would fry the viscous coupling.

could you explain this a little more. my understanding was that the speed differential causes the viscous fluid to heat up and thicken? then causing the rear to engage. with no load on the rear it seems it would be less wear than with the drive shaft in.

 

but i don't know that much about manual trans.

 

 

It's an open diff with a viscous locker.

 

Example: like any open diff, the power will go to the axle with the least resistance, say a front wheel in mud. When that wheel spins (with the rears sitting still) there will be a speed difference. The Fluid heats,expands, and locks, sending power to the rear wheel and getting you out of the mud.

 

 

Now apply that to our situation:

 

No rear axle means that all the power will first go through the rear output, spinning the shaft in the air. Front axles will not get any power till the fluid heats, expands, and locks. Only then will the fronts get power and ALL of that power will be coming through the viscous pack.

 

Normally, the viscous unit is only called on momentarily to transfer during wheel slip in snow,mud, etc. (the spider gears in the diff take all the force as long as all 4 wheels are on the ground) But in this case, you'd be asking it to transfer ALL you're driving force ALL the time. Not good for it. Plus, the viscous pack can't transfer all the force created by the engine either, so you would also end up with a tremendous power and efficiency loss.

It's an open diff with a viscous locker.

 

Example: like any open diff, the power will go to the axle with the least resistance, say a front wheel in mud. When that wheel spins (with the rears sitting still) there will be a speed difference. The Fluid heats,expands, and locks, sending power to the rear wheel and getting you out of the mud.

 

 

Now apply that to our situation:

 

No rear axle means that all the power will first go through the rear output, spinning the shaft in the air. Front axles will not get any power till the fluid heats, expands, and locks. Only then will the fronts get power and ALL of that power will be coming through the viscous pack.

 

Normally, the viscous unit is only called on momentarily to transfer during wheel slip in snow,mud, etc. (the spider gears in the diff take all the force as long as all 4 wheels are on the ground) But in this case, you'd be asking it to transfer ALL you're driving force ALL the time. Not good for it. Plus, the viscous pack can't transfer all the force created by the engine either, so you would also end up with a tremendous power and efficiency loss.

 

No your asking it to drive nothing more then a hloow shaft that has no resistance to rotation.

 

The viscous coupling needs a resistance to start heating up and operating. If one side is free spinning ( a disconnected ddriveshaft) he is doing it no harm. And the VC only transfers power to the rear. Subarus are FWD by default.

 

nipper

No your asking it to drive nothing more then a hloow shaft that has no resistance to rotation.

Excactly, there is no resistance. An open diff needs resistance from both axles to transsfer power. When there is no resistance from one axle, the Viscous coupler is the only thing that keeps power going to the other shaft.

 

The viscous coupling needs a resistance to start heating up and operating. If one side is free spinning ( a disconnected ddriveshaft) he is doing it no harm. And the VC only transfers power to the rear. Subarus are FWD by default.

 

nipper

 

This is wrong. Firtst off, only the automatics are FWD by default, and they have no "differnetial" it's a computer controlled hydraulic clutch pack. These can safely be driven with the rear output disconnected.

 

MANUAL TRANSMISSION SUBARUS ARE TRUE AWD! Not FWD. There is a true "differential" with bevel and spider gears. Power goes equally front to back the in the same manner as it goes side to side through the differentials at the axles. What happens when one wheel is on ice or mud spinning with an open diff? The other wheel just sits there not getting any power. Unless there is a LSD. Imagine removing one side axle on a FWD car. Would the car drive??? NO. Not without an LSD, and if it had one the LSD would be the ONLY thing transfering power.

 

So now imagine instead of a wheel at each end of the diff, we have a whole axle. That is what we are dealing with here. If the rear output is disconnected, it's just the same as if the rear wheels were spinning free on ice. What happens in that situation? The car would go nowhere if it was just an open diff (ask anyone with an old *fulltime* xt or RX) But for the newer cars, there is THE VISCOUS PACK (LSD). It is the only reason the diff TRANSFERS POWER in that situation!

 

Nipper, sorry, but you clearly don't understand how the VC works. To the Original poster. DO NOT drive with the rear shaft disconnected for anything but a short test to see if the Torque bind goes away.

 

You WILL damage you're center diff if you drive without the rear output for any length of time.

so, there's no choice about fixing the TB.

 

can anyone direct me to a description of the job? The part is about $500 so evidently there's over $500 of labor in R & R, judgine by the numebrs I see on the board. I might be able to get a part-time mechanic to help me, if there are no special tricks to the set up, simple remove and replace?

 

Excactly, there is no resistance. An open diff needs resistance from both axles to transsfer power. When there is no resistance from one axle, the Viscous coupler is the only thing that keeps power going to the other shaft.

 

 

 

This is wrong. Firtst off, only the automatics are FWD by default, and they have no "differnetial" it's a computer controlled hydraulic clutch pack. These can safely be driven with the rear output disconnected.

 

MANUAL TRANSMISSION SUBARUS ARE TRUE AWD! Not FWD. There is a true "differential" with bevel and spider gears. Power goes equally front to back the in the same manner as it goes side to side through the differentials at the axles. What happens when one wheel is on ice or mud spinning with an open diff? The other wheel just sits there not getting any power. Unless there is a LSD. Imagine removing one side axle on a FWD car. Would the car drive??? NO. Not without an LSD, and if it had one the LSD would be the ONLY thing transfering power.

 

So now imagine instead of a wheel at each end of the diff, we have a whole axle. That is what we are dealing with here. If the rear output is disconnected, it's just the same as if the rear wheels were spinning free on ice. What happens in that situation? The car would go nowhere if it was just an open diff (ask anyone with an old *fulltime* xt or RX) But for the newer cars, there is THE VISCOUS PACK (LSD). It is the only reason the diff TRANSFERS POWER in that situation!

 

Nipper, sorry, but you clearly don't understand how the VC works. To the Original poster. DO NOT drive with the rear shaft disconnected for anything but a short test to see if the Torque bind goes away.

 

You WILL damage you're center diff if you drive without the rear output for any length of time.

on a auto trans thje parts are only 200$ vor so, and you can do from under the car in the driveway. the shop i used charged about 300$ to swap the extention housing.

 

i don't know about manual trans, but before i spent 500$ on a new part for a old trans, i'd look for a good used trans. swapping them is a job, but very straight forward. (i paid about 500$ for a swap.) when was the last time you did your clutch? is it due?

Manual trans.

 

I don't know about manual trans, but before I spent 500$ on a new part for a old trans, i'd look for a good used trans. swapping them is a job, but very straight forward. (i paid about 500$ for a swap.) when was the last time you did your clutch? is it due?

 

mechanic says thrust bearing is bad and while I agree it doesn't feel so good, no sounds to my ear, so priority lowered. He quoted $500 to do that [half parts, half labor]. Not sure if anything else is included.

 

how to trust a used transmission, if i were to consider doing it with my friend? I had this done on a Trooper 10 years ago [~ $900, i think], and the shop warranted it at least for a while to be sure it was working when installed, as found, I think. If fact, it wasn't so good and they took it back for rebuilding, if I remember rightly, at no further cost. It then was good for 8 years to my knowledge. Maybe i should try them again!

John, the steps for the job are:

 

1) put the car up on 4 jackstands

2)remove the exaust (all of it)

3)drain the transmission

4)remove the propeller shaft (driveshaft that goes to the rear)

(you may have a heat shield that you need to remove to get to it)

5) remove shifter linkage with a drift punch at teh input to the transmission

(you need to do this in order to get the extension housing off)

6)support the transmission with a jack and remove the rear transmission mount.

7) remove rear extension housing

8)remove and replace visious coupling in rear extension housing.

9) assembly is the reverse of disassembly. . .

 

So about ten steps roughly. Yes I have done this at least once. . .

John, the steps for the job are:

 

1) put the car up on 4 jackstands

2)remove the exaust (all of it)

3)drain the transmission

4)remove the propeller shaft (driveshaft that goes to the rear)

(you may have a heat shield that you need to remove to get to it)

5) remove shifter linkage with a drift punch at teh input to the transmission

(you need to do this in order to get the extension housing off)

6)support the transmission with a jack and remove the rear transmission mount.

7) remove rear extension housing

8)remove and replace visious coupling in rear extension housing.

9) assembly is the reverse of disassembly. . .

 

So about ten steps roughly. Yes I have done this at least once. . .

 

Actually, it doesn't need to be driven out. If you simply unbolt the linkage, you can still seperate the rear extension.

 

The key is to remove the bolt that holds the reverse lockout arm to the shifter input rod. You have to remove the cover with 4 bolts on the rear/top of trans. If you remove that 10mm bolt, then you can simply turn the input rod couterclockwise and pull the tailsection off.

Is the extension housing on an automatic the same as on a manual transmission? any changes in 1997-1998-1999??

 

thanks!

Is the extension housing on an automatic the same as on a manual transmission? any changes in 1997-1998-1999??

 

thanks!

 

Two completly differnt AWD systems. Two completly different transmissions and extension housings.

 

nipper

Is the extension housing on an automatic the same as on a manual transmission?

not even close...might not even be called an "extension housing" on a manual transmission.

 

swapping transmissions is a fine option, particularly with a manual transmission. they don't fail all that often so getting a good used one is typically easy and cheap. the shop i bought mine from offers 3 warranty on transmissions. didn't have to use it and the trans was only $150. yours being a 99 will be significantly more expensive to replace though probably....unless you're resourceful.