I'm in the middle of a clutch job, and the tranny is out. But I discovered that I have a leaky front pinion seal at the rear differential. The Factory Service Manual says I need the Subaru special tool to hold flange while breaking the nut loose.

 

Could I use a pipe wrench on the flange and/or have someone stomp on the brakes while I yank on it?

 

I do have an electric impact wrench but doubt the it has enough juice for this one.

Edited October 17, 201114 yr by hohieu
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are you sure it's leaking and not just blow back from some other leak/fluid up front?

 

i think you're on the right track. that does look like a beasty nut, though i've yet to need to remove one. i wouldn't think i'd have any problem trying some things to get it off. the flange has the 4 bolt holes in it too for the driveshaft i think, those could be used to hold it in place.

 

a friend of mine uses his elec impact for cam pulley bolts which can be quite tight, might be worth a shot to put it on there for a minute and see what happens.

The oil is definitely coming through the pinion seal back there. It's getting past the seal and some collected between the flanges and dripped out when I separated the flanges to remove the drive shaft. Besides, the car is otherwise clean -- doesn't leak a drop of anything else. I had a Subaru differential protector back there and wasn't sure of the source and thought maybe it was coming out of the breather because from what I've heard, the front pinion seal back there so rarely fails .

 

Yep, there are 4 holes for the M8 flange bolts. I'm afraid I might snap one of these little bolts if I use it for leverage against the pinion nut. The special tool has four protruding studs that slide into these holes with a cutout in the middle to accommodate a socket for the pinion nut.

 

BTW, I've periodically checked the rear differential oil and it's never been low so it's a very slow, albeit nasty, leak -- gear oil is some funky stuff. I figured that while I had things apart, I'd replace that seal if it's not too much trouble. I've replaced these pinion seals on my other car, but the yokes are rectangular so it's easy to put a pipe wrench on there while I break the nuts loose.

nice, a square for holding on the other ones! got a pipe wrench big enough to just fit on the entire flange?

 

oh right, i wouldn't use the nut either. if you rig something up to hold it in place, it won't snap those driveshaft bolts. though you could just use different bolts and throw them away when you're done for the holding process in case you're worried about fatigue, stressing, etc, but it won't be an issue - they will hold.

 

i would not hold one nut to counter against the pinion, but rather somehow bolt a piece of metal or wood or to a vice or something like that to hold it in place and use the bolt holes to hold it that way.

it will help if the wheels are on the ground and the hand brake is on.

 

put the impact on it and have at it .

 

do you think the impact is going to move the car??

Take a angle iron about a 1' long and drill 2 holes in it that match the drive shaft bolts off on one side. That will allow you to lock up the rear diff input and then you can brake the nut loose.

 

I have one dripping also, I have to get to it sometime.

I'll be back at it again today and will let you know how things go.

That's a good suggestion Imdew. I have sections of some industrial shelving frames that should work, but this will have to wait. I zipped everything back up after replacing the clutch, ball joints, and the front right CV half shaft.

 

There's too much flex in the rear driveline to do it by engaging the brakes.

Impact wrench wont get it loose?

The nut is tight but it's steel, once it cracks loose it will fly right off.

I'd thrown in the towel after putting everything else back together. It was late into the night, and cold. Besides, it's pretty easy to drop the propeller shaft when I'm ready to get back into the ring with this thing. Round 1 goes to the pinion nut.

 

The electric Dewalt impact wrench, which barely fit into the recess of the front member, didn't budge the nut. Maybe I'll try it it again at some point (with some ear protection!) but I think I'll need to crack it loose with a breaker bar. Without a lift, though, getting a long breaker bar on that nut will be a challenge because the front member restricts rotation between 5 o'clock and 7 o'clock.

Edited October 27, 201114 yr by hohieu

make sure you know the torquing procedure before you pull it apart. there is a part about measuring the torque it takse to rotate the pinion / input shaft. because when you put the nudt back on, you can over torque it making it too tight which will lead to wearing out the bearings? in the diff.

 

this may be standard for rear diffs, but it was news to me when i look into doing mine.

Thanks, John. I have an in-lb. torque wrench for checking the preload on the bearing, though I'll also mark the pinion with and the nut with a chisel beforehand.