Few questions about 2004 STI rear diff and a few other related concerns

[sonic03rex]

Hey everyone, I suspect my rear diff is toast from this insane kenne bell whine that I get in all gears once any throttle is applied while moving. I have all the seats out of the back and it sounds as if its coming from that area. Sometimes it sounds like it's coming from the front too but its hard to tell and I'm tired of speculating because it just makes me nuts, and the vision of dollars signs flying through my head worries me.

Anyway, when the rear wheels are off the ground in a 2004 STI, and you spin one wheel in or out of gear, is the other wheel supposed to spin opposite or in the same direction? Mine spins opposite in or out of gear. I have searched and searched and some posts lead me to believe I'm good, and others make me think I'm screwed.

I have read that the 2004 behaves differently than the 05/06 but wasn't sure what was normal or not.

Secondly, if im unlucky enough that it's in the tranny case, I'm going to have a local shop pull the tranny since I have a rotated mount and I don't want the dealership messing with my wastegate etc. Then I was planning on taking the case to the dealership because I was advised not to let anyone other than subaru mess with the 6mt.

Does anyone know how much the dealer would charge to open it and diagnose the problem, I'm thinking it could be the ring and pinion gears from what I have read so I'm trying to estimate what they would charge for that install just in labor, because I'll most likely take their part numbers and source the OEM parts from Jose's(pacobeagle1) dealership.

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[Sko]

I was under the impression that with an LSD both wheels spin the same direction and with an open diff they spun opposite directions.

But I'll have to wait til I do my exhaust to find out. I'm 90% sure they will spin the same direction but I could be wrong.

Nick

[sonic03rex]

ok yeah this is what I thought also. Our front diffs are open correct? Because those spin opposite as well when the rears are on the ground.

So if somone can confrim what me and Sko believe, then I guess my rear is messed up after all.

[scby rex]

I always thought the wheel spun oppisite on lsd? If I had my rear r front together I could tell you.

[sonic03rex]

see this is what confuses me also, i think the type of lsd makes a difference also, clutch vs something else. I've searched and searched and can't come up with a definitive answer, I pointed my buddy who is a subaru tech to this thread so hopefully we'll get an answer for me and future searchers haha.

[Pacobeagle]

Okay, if memory serves me right, you have a helical front lsd. This acts like an open differential whenever the wheels are off the ground. The best way to explain is to have you guys look at the internal gears of a Quaife LSD. I believe that their website is www.quaifeamerica.com

In any case, that front diff. does not have a clutch pack rather it uses worm gears to create the same effect. One reason that Subaru got rid of these is that they are rather noisey.

SO, to answer your question......When was the tranny serviced last? What fluid did you put in? When was the rear diff. serviced last? What fluid did you put in that? Was there any metal on the magnets other than the regular gray paste-like stuff?

Jose

[1/500yellowwrx]

Dylan if you have the time just put the car on jacks and drain the fluid to check for any metal specs. It may just be low on fluid or the fluid could be old. With that kind of power and if you are driving the car hard the fluid life will fade quickly.

Dave

[sonic03rex]

Originally Posted by Pacobeagle

Okay, if memory serves me right, you have a helical front lsd. This acts like an open differential whenever the wheels are off the ground. The best way to explain is to have you guys look at the internal gears of a Quaife LSD. I believe that their website is www.quaifeamerica.com

In any case, that front diff. does not have a clutch pack rather it uses worm gears to create the same effect. One reason that Subaru got rid of these is that they are rather noisey.

SO, to answer your question......When was the tranny serviced last? What fluid did you put in? When was the rear diff. serviced last? What fluid did you put in that? Was there any metal on the magnets other than the regular gray paste-like stuff?

Jose

Hey Jose thanks for the reply, I'm typing this from my phone so I'll make it as short as possible. Tranny has never had any work done other than fluid changes. I changed the trans fluid with hypoy c 75 90 because it was the only thing anyone had at the time and I just wanted to get something back in there after I drained the old stuff to look at the magnet.

Good bit of gray paste but nothing more.

Rear diff got the same treatment but I later found out I must have the correct subaru 90w. Fortunately the car has moved less than 2 miles after the fluid change. I will get the right stuff before it moves again.

As for the diff operation, what about the rears and how they behave on the 2004 Sti? Because mine wheels spin opposite and I'm under the impression this would indicate an open or malfunctioning 04 Sti rear? Or is this normal?

[swiftwrx06]

The sti has a clutch type rear diff. If the rear wheels are off the ground and the car is in NEUTRAL and you spin one of the rear wheels, the other rear wheel should spin the SAME direction. If the car is in gear and you spin one wheel it should be harder to turn as you have to overcome the force of the clutches to spin it and the other wheel would spin in the opposite direction.

The 04 sti has a suretrack diff in the front. I'm pretty sure that it acts like an open diff when off the ground as said above, ie when you spin one front wheel the other turns in the opposite direction.

[sonic03rex]

Bump for a 3rd and 4th opinion!