4EAT: no 4th gear?

[davew833]

This question relates to my '92 Legacy turbo AWD auto, not my SVX, but I'm not getting much action on this topic over at legacycentral or usmb so any ideas are welcome! All Subaru phase 1 4EATS are basically the same, right?

The problem is the car never shifts into 4th gear, ever, or even tries. I can get up to 4500 rpm and 75 mph on the freeway and no shift out of 3rd. Doesn't matter if it's cold or warmed up. Seems to shift through the other gears just fine. It doesn't seem to slip or flare in other gears. No torque bind.
I did a stall test and it seemed to be in normal range. It had a previously stored code for VSS1 which I replaced with one from my spare SVX trans. That didn't fix the 4th gear problem. Do you have to clear stored codes before the TCU realizes the problem's been fixed?

I've only had this car for 2 months. There's evidence it's been parked for about 10 years previous to that. It's got about 137k miles.

About a month ago, the trans started slipping badly in any gear so I dropped the pan and found the filter clogged with brownish gunk. I didn't find an abnormal amount of metal particles in the pan, but the filter was so clogged I had to replace it. I drained and filled the fluid twice during that process. That seemed to restore normal driving in the lower gears. I had never driven the car on the freeway previous to that so I don't know if 4th gear has ever worked since I've had it.

Any suggestions as to why it won't shift into 4th, and are there any easy fixes I can try before I start pulling and swapping trannies?

Someone suggested brake band adjustment, but I've got no 2-3 shift flare. Someone else suggested TPS, but they are a PITA to adjust on a Legacy compared to the SVX, and I get no codes for that.

Also, I have a chance to get a low-mileage 4EAT out of a non-turbo '92 Legacy from the Pick-N-Pull for cheap. Does anyone know how the gearing compares? My research says the final drive is the same at 3.90 but I don't know how the other gears compare.

[1986nate]

The non turbo legacy auto you found is a 4.11, not a 3.90. The legacy Turbo received the only 3.90 AWD auto phase 1 4eat in the states. so you'd also have to change the rear. Also, you're going to run into the problem of swapping weaker transmissions into an SVX as the non turbo legacy trans is not as strong as the legacy turbo. It will last longer in the t-leg since it doesn't have quite the power and torque of the EG33, but it won't get you too far more than likely unless it is very low miles.

As to your current issue, if it doesn't flare up trying to shift out of 4th that only leaves a few possibilities. 1 being linkage (if the trans is actually in "3" regardless of what the indicater says) and 2, being electronics-either a solenoid isn't functioning properly or a servo is completely clogged, or a lack of communication somewhere. This more than likely is not related to the friction materials inside the transmission since it does not even attempt to change gear as it would flare up out of 3rd gear until you reach a high enough RPM that it gets to a point where it would normally shift back to third anyway. (that may only make sense in my own head)

[gbianchi]

The non turbo legacy auto you found is a 4.11, not a 3.90. The legacy Turbo received the only 3.90 AWD auto phase 1 4eat in the states......not true, no disrespect Nate, but I just swapped a tranny from a 90 legy into a 92 legy and then had to swap the rear diff because it was a 3.90 and the 90 is a 4.11 so there was a little fighting going on. I think the 92 nonturbo has the only 3.90 of any legacy??? Not 100% but thats what I dealt with.........G

[oab_au]

Originally Posted by 1986nate

As to your current issue, if it doesn't flare up trying to shift out of 4th that only leaves a few possibilities. 1 being linkage (if the trans is actually in "3" regardless of what the indicater says) and 2, being electronics-either a solenoid isn't functioning properly or a servo is completely clogged, or a lack of communication somewhere. This more than likely is not related to the friction materials inside the transmission since it does not even attempt to change gear as it would flare up out of 3rd gear until you reach a high enough RPM that it gets to a point where it would normally shift back to third anyway. (that may only make sense in my own head)

No I don't think it has problems with the friction materials, as 2nd and 3rd are OK. To goto 3rd the high clutch comes on, to go to 4th, the high clutch stays on, and the band is applied over the top of 3rd. If the band is not applying for 4th, the box stays in 3rd, no flaring or reving, just stays in 3rd.

The band uses two different servos to apply it in 2nd, and for 4th. There could be a problem with this compound servo, but there are other reasons for it, like the VS1, that says when it should change to 4th. Also the temp of the ATF that has to reach a set temp before it will go to 4th.

As the box has stood for some time unused, and you found 'goo' in the filter, it may also have 'goo' in the valve body.
So I would check the temp sensor in the box first.
Ensure that the VS1 is OK, then remove the valve body, and get it cleaned.

Harvey.