4EAT no make RWD

I guess it's my turn for a little assistance.

My 'new' (used) '94 Touring (turbo) Wagon is all 'fixed up now- I installed the new brakes, new KYB struts, new front axles, changed all the lube fluids for synthetic and treated the car to a 15 qt. 'backyard' ATF flush. It runs pretty smooth now, except for one flaw........

While I was doing the flush, with the car up on 4 jack stands, I happened to notice that only the front wheels were turning. I know some times there might be some binding due to brakes or other that might prevent the rears from initally spinning, but only with a moderate applicaton of throttle could I get the back tires to turn at all. This is also supported by the significant torque steer (under harder throttle) and spinning of the inside wheels with any loose surface (i.e. sand) during a tight turn while driving.

It looks like I might have a 'Duty C' solenoid 'issue' or other. Considering the '94 Legacy 4EAT is essentially the same as our SVX's, what assistance can you guys offer for a fairly reliable and/or simple testing procedure to isolate the faulty component?

I'm all ears....

Thanks in advance for any and all help.

-Mark

[UberRoo]

Find a quiet place and turn the ignition key on until your dash looks like a Christmas tree, but don't start the car. If you bend down and put your head under the car, you should hear a faint clicking/buzzing noise coming from the rear of your transmission. This noise is duty solenoid C cycling. If you don't hear anything, check for trouble codes on the TCU. This should pretty much verify if the electronics are working. If you have a trouble code for solenoid C, or don't hear any noise, stop right here. You've got an electrical problem.

If the electronics looks good, you're gonna have to get dirty. On the rear of the transmission is wheel speed sensor number two. The sensor contains a magnet. If you pull it out and it has lots of metal shavings on it, you might have a broken transfer clutch.

Pictures of the sensor and location on the tranny. More pictures in my locker.

Proviso: This is all based off what I know about the SVX. I'm pretty sure it applies to other 4EAT transmissions, but don't quote me on that.

[Mr. Pockets]

I only started my SVX and engaged 'D' while it was on stands once. Only the front wheels turned, yet I can assure you that my AWD was working just fine.

I think pretty much every person who has had their SVX (with the 4EAT) on a lift or jackstands and put it in 'D' has seen the same thing. I don't think that this indacates a problem at all. My guess is that, at zero throttle with the transmission in gear, there is pretty much no pressure applied to the transfer clutch. I think the only real rest of the AWD is to take it out on a variety of surfaces and see how it drives.

If you note significant slippage of the front wheels before the rears engage, or binding in tight turns, then we can talk about what the problem might be. I assure you I've had plenty of hands-on experience repairing the Legacy transfer clutch recently.

Originally posted by Mr. Pockets
I only started my SVX and engaged 'D' while it was on stands once. Only the front wheels turned, yet I can assure you that my AWD was working just fine.

I think pretty much every person who has had their SVX (with the 4EAT) on a lift or jackstands and put it in 'D' has seen the same thing. I don't think that this indacates a problem at all. My guess is that, at zero throttle with the transmission in gear, there is pretty much no pressure applied to the transfer clutch. I think the only real rest of the AWD is to take it out on a variety of surfaces and see how it drives.

If you note significant slippage of the front wheels before the rears engage, or binding in tight turns, then we can talk about what the problem might be. I assure you I've had plenty of hands-on experience repairing the Legacy transfer clutch recently.

Agreed

Thanks for the feedback thus far. I know the transfer clutch isn't working in any kind of fashion, because I can easily spin the front tires upon launching, get a lot of torque steer, and can spin an inner wheel upon a 'powered' tight turn. I've driven enough Subaru's to know what the symptoms are- and these aren't the 'correct' conditions.

There is no 'check engine' light or other indicator that I've been able to spot. I believe this engine/trans should have the same generation of controls (TCU/ECU) as our SVX's. Is there a similar set of 'blue wires/connector' under the kick panel (or elsewhere) that should be able to transmit an error code?

From what I've gathered, if the Duty C solenoid were 'out', I'd get a 'locked' unit (the 'default'/limp-home mode) and I'd be complaining instead about 'binding' in turns. So, apparently either the Duty C solenoid is stuck 'on' or something is trashed in the clutch assembly.

Any further thoughts?

-Mark

[oab_au]

Originally posted by mark10t
Thanks for the feedback thus far. I know the transfer clutch isn't working in any kind of fashion, because I can easily spin the front tires upon launching, get a lot of torque steer, and can spin an inner wheel upon a 'powered' tight turn. I've driven enough Subaru's to know what the symptoms are- and these aren't the 'correct' conditions.

There is no 'check engine' light or other indicator that I've been able to spot. I believe this engine/trans should have the same generation of controls (TCU/ECU) as our SVX's. Is there a similar set of 'blue wires/connector' under the kick panel (or elsewhere) that should be able to transmit an error code?

From what I've gathered, if the Duty C solenoid were 'out', I'd get a 'locked' unit (the 'default'/limp-home mode) and I'd be complaining instead about 'binding' in turns. So, apparently either the Duty C solenoid is stuck 'on' or something is trashed in the clutch assembly.

Any further thoughts?

-Mark

Hi Mark, spinning the front wheels, means the clutch is not working. If you do find that there is a code for C solenoid, then it may be electrical, if so it will fail in the FWD mode, not locked.

No code points to either the , C solenoid, pilot valve or transfer valve, could be stuck. If it is stuck in the on position then the clutch will bind. If stuck in the off position, the clutch will not engage, your problem.

It doesn't matter which valve is stuck, or if the clutch plates are worn, as the transfer case has to come off to fix it, and you would be well advised to replace the complete C solenoid valve assemble and clutch plates to be sure.

In the mean time, don't spin the front wheels, as the resultant shock loading can break the front diff gears.

Harvey.

[Mr. Pockets]

I agree with Harvey. I'd replace the transfer clutch plates and, while I was in there, duty solenoid C.

I just did this for my Legacy in my own garage, and I'll warn that it's not something most people should attempt. I didn't put the transmission back together correctly and ended up replacing the reduction drive gear and park pawl return spring.

[svx_commuter]

A check on the transfer pressure will tell you if it's the clutch plates or duty "C". It was the "C" on my SVX.

i've found that if you're able to break traction with the front wheels, it means your AWD is not functioning properly. a 2.2l motor operating in FWD mode should be able to break traction at the front wheels even before the turbo spools up, especially if you're on dirt or something slick. so find a dirt road, hammer the gas from a stop, and if you don't break traction, i'd say you're doing fine

-adam

Originally posted by oab_au


In the mean time, don't spin the front wheels, as the resultant shock loading can break the front diff gears.

Harvey.

Just because I can break the fronts loose, doesn't mean I'm doing that regularly. I realize the strain on the axles, etc. (I've been TRYING to avoid it, but the turbo makes it difficult- if you know what I mean.... )

Astralbody (Victoria) is going to donate or sell at low cost the 'old' trans/traction clutch assy. from her SVX that she's swapping to a 5MT. Her trans had a bad front diff, so hopefully, the trans and/or the traction clutch assy. are OK. I'm probably looking at swapping out the traction clutch assy. as-is.

I believe a '94 SVX and a '94 Legacy Turbo should have the same assembly--- Anyone confirm?

Any precautions on doing this swap on the car?

Thanks!

-Mark

Originally posted by oab_au


In the mean time, don't spin the front wheels, as the resultant shock loading can break the front diff gears.

Harvey.

Just because I can break the fronts loose, doesn't mean I'm doing that regularly. I realize the strain on the axles, etc. (I've been TRYING to avoid it, but the turbo makes it difficult- if you know what I mean.... )

Astralbody (Victoria) is going to donate or sell at low cost the 'old' trans/traction clutch assy. from her SVX that she's swapping to a 5MT. Her trans had a bad front diff, so hopefully, the trans and/or the traction clutch assy. are OK. I'm probably looking at swapping out the traction clutch assy. as-is.

I believe a '94 SVX and a '94 Legacy Turbo should have the same assembly--- Anyone confirm?

Any precautions on doing this swap on the car?

Thanks!

-Mark

[Mr. Pockets]

Originally posted by mark10t
Any precautions on doing this swap on the car?

Yes, a few.

Different cars have different part number transfer clutch sets. I haven't yet received a satisfactory explanation for it, but here are the details.

The first pressure plate behind the snap ring in the clutch assembly can be one of four different thicknesses between 3.3 and 4.5 millimeters. I don't know whether it'd be best to just swap out the entire clutch drum assembly or put the new clutch set in your old clutch drum with your old pressure plate. As I said, I haven't yet received a great explanation for why that plate was manufactured in four different sizes.

Also, if Victoria has to ship these parts to you, I recommend making sure they're tightly wrapped in plastic. They have to remain clean.

[Sonar]

At least the euro version of the Legacy 4EAT works in a diffrent way than explained by oab_au.

I for sure know that, because I have modified mine 4EAT in my Legacy to have a 4WD "lock" switch

If you cut the wire to the 4WD transfer soleniod, it locks up the clutch, by not being able to "bleed" out the pressure from it, but if you put in the FWD fuse, then you give the same soleniod "all time" open condition, thus no pressure can build up and lock the clutch.

My vote is either the soleniod has jammed open, or the clutch is worn out


/Sonny

[oab_au]

Originally posted by Sonar
At least the euro version of the Legacy 4EAT works in a diffrent way than explained by oab_au.

I for sure know that, because I have modified mine 4EAT in my Legacy to have a 4WD "lock" switch

If you cut the wire to the 4WD transfer soleniod, it locks up the clutch, by not being able to "bleed" out the pressure from it, but if you put in the FWD fuse, then you give the same soleniod "all time" open condition, thus no pressure can build up and lock the clutch.

My vote is either the soleniod has jammed open, or the clutch is worn out


/Sonny

Gid'ay Sonny, Yes that looks like it is the case, it works the oppersit way to the SVX transfer assemble. I have a SVX assemble on the desk here from the Euro model, and the C solenoid is in the by pass position, with no current applied. In this positon it bleeds off the pilot pressure, that would move the transfer valve, to apply the clutch.

Does the US SVX model work the same way? If some body could check the US manual, to see if the C solenoid fails in the FWD or AWD position? The Euro model fails in the clutch off position.

edit. A bit more. If it is different, then the C solenoid would be different. The part no. on the Euro solenoid is; CDA19. What is the no. on a transfer clutch C solenoid?

Harvey.

[lee]

Originally posted by oab_au


Does the US SVX model work the same way? If some body could check the US manual, to see if the C solenoid fails in the FWD or AWD position? The Euro model fails in the clutch off position.


Harvey.

When the C solenoid fails the US model goes to maximum AWD engagement, per Subaru's EndWrench site.