4EAT Gurus, I need your wisdom. . (long, sorry)

[Gnuman]

OK, I'm comfortable with just about any other part of a Subaru, but I'm lagging a bit on the 4EAT, particularly in the area of the extension housing and how exactly the clutchpack works as well as how to correct torque bind.

 

As I understand it, the clutchpack is just like a motorcycle clutch, except that it is normally free moving, instead of bound. On a motorcycle you have a lever (either cable actuated, or hydaulicly activated) that releases the pressure on the clutch plates, disengaging it. If I understand correctly, the clutchpackis normally loose, but when the tranny is driving the car, the clutchpack engages the rear wheels, unless there is a voltage supplied to the Duty C solenoid to release the trans fluid pressure, and disengage the clutchpack. This is what the FWD fuse does, forces full voltage to the Duty C solenoid to lock out the rear diff. Without the fuse, the TCU engages oe disengages the clutchpack (by use of the DutyC solenoid) based on the readings of various sensors.

 

One problem I'm also having is where, exactly, does the tranny fluid push on the clutchpack rings to press them together? I took the extension housing off of a 90 4EAT and traced the workings of the Duty C solenoid and the clutchpack, but copuld not see where the rings were getting pressed together from. If someone could point this out it would greatly improve my understanding of this whole problem.

 

Am I correct so far?

 

As I further understand it there are two basic types of torque bind that happens to these trannies:

what we will call type 1 is where the Duty C solenoid fails, and putting the FWD fuse it causes the torque bind to go away (I have problems with this as we will diiscuss later)

 

What we will call type 2 is where the clutchpack has gotten all gummed up with burnt tranny fluid and has siezed together. Putting the FWD fuse in does not cure this and you need to replace the clutchpack(?) to cure this type.

 

Now I have a few problems with this. With Type1, if it is the Duty C solenoid, how does the FWD fuse engage it? Would it not be more likely that it is one of the sensors or the TCU that has failed, and the Duty C is in fact still good? If not, why does the FWD fuse (that engages the Duty C to full lockout) fix this, when the Duty C has failed?

 

With type 2, what part do you actually replace ( a friend went to a dealer and asked for a clutchpack and they did not know what he was talking about)?

 

are you still with me? I have a problem with a 96 4EAT that gives the following problems:

1) there is constant drag in the system that is causing the milage to drop horribly. (feels like a constant brake drag, that gets worse when you try to turn at all. . .)

 

2) Torque bind of Type 2 (FWD fuse does not help).

 

My suspicions (not fully checked out): The torque bind is obvious, but the cause of it is not. the tyres are all of the same type, and all seem to be new. Perhaps this was not always the case (the car was bought at a dealer, that did not want to deal with the torque bind problem), but it is now. Is it possable that the tranny was replaced in the past and the rear diff does not match it? wiould this cause the problems I'm experiencing? I'm sure that it is too late to save this clutchpack, unless I recondition it myself (which is possable). There is also the possability of swapping in a 4EAT from a 2001 into this car with the matching diff, or is this asking for trouble? is there a large difference between the '96 and the '01 4EAT? If I grab the trannym diff and TCU, would it plug and play, or are there major wiring problems that would need to be dealt with?

 

Those are the two solutions that I can see at the moment: recondition the cluthpack, or swap the tranny + diff + TCU. I will be checkign out the gear ratios on Monday, as well as checking out any other options that you bring to the table.

[Hondasucks]

From what I understand, if the transfer clutch solenoid receives 12V it RELEASES pressure from the clutch packs (what the FWD fuse does, and this is opposite the 4WD clutch in the older pushbutton autos, they engage when power is applied) and by controlling the duty cycle, it can regulate how much torque goes to the rear wheels. So if the solenoid goes bad, or otherwise it loses power, it engages the rear wheels as a 100% F/R lock, just like if you've put a M/T car in 4WD. (I'm sure those plates will slip if enough torque is applied..).

 

if they slipped long enough under pressure, the coating would wear off the plates, and generate enough heat to weld the plates together, which is one of the causes of torque bind (Like if the car is towed with only the front or rear wheels off the ground)

 

I've heard something about there beign steel sealing rings in the transfer assembly that ride in an aluminum housing (On the early models, they've since changed it, and the recall fix is installing a steel sleeve) and eventually leak, causing torque bind, but I don't know the details.

[Gnuman]

OK, I need help, seriously. I have the FSM for '96-'04 Outbacks, and I was reading it when I realised that I was finding it recreational. . . I'm sick, I tells ya!!

 

OK, the hole in the rear drive shaft shoots tranny fluid into the piston, compressing the driven plates into the drive plates, causing power to be transfered to the propeller shaft, and then to the rear diff, and the rear wheels. OK, now that I know that, I can go on with the diagnosis. Looks like the pressure is always there, but the Duty C solenoid bleeds it off, releasing the rear wheels as needed. This does not explain how a failing Duty C can be fixed by placing the fuse in the FWD fuse holder. . . Still working on that one.

 

OK, new info: the previous owner knew about the torque bind, situation, and the car was bought from him, not the dealer that serviced it. I also learned that the car had been stolen from him a while back. No mention of it being towed, but I suspect that now. There is no record of the tranny ever having been replaced. Parts to replace the clutchpack are on the order of $800, so refurbishing it is the order of the day. Ollks straightforward enough. I printed the salient parts of the manual out for reference. Should be good to go. Will post updates. . .

[Gnuman]

Thanks, Hondasucks. I'm bumping this so more of the 4EAT Gurus can see it.

Update: the "clutchpack" is not binding at all, so we are on to the elsctronics and function of the Duty C.