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Discussion Starter #1
I posted this on I-club, but to no avail. I want to know if the "clunk" I hear when power goes rearward due to spinning tires is a bad clunk. does this sudden power transfer hurt the rear diff significantly? is it enough of a stress that I shouold really try to avoid it, or is it not that big a deal? I like playing in snow but I don't want to go tearing up my diffs. BTW, I have a 4EAT.
 

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hmmm, in the 5MT, that clunk is the locking on the center differential. I don't know if the new 4AT's have a mechanical center diff or not...but I heard they don't.

so in retrospect...I don't know for sure :)
 

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Discussion Starter #3
the 4EATs have a clutch pack that can lock up to go from the normal 90/10 split to a 50/50 split if the fronts are spinning. When the clutch locks up, there's a clunk from the rear diff, and lurch forward as you get traction back.

The 4EAT clutch pack is a little nicer than the Viscous center diff the RS (GC8 and 02) 5MTs have. there's no lag. it knows when the slip is going to happen and compensates preemtively. the WRXs have a snazzy Torsen center diff that's even better. the only problem is that proloinged wheelspin on all 4 at once will tear it apart. The clutch pack can take more abuse, and has the super-sweet FWD mode for all kinds o winter fun!!
 

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This happened to me about the 3rd week I had the car. It was raining heavily, and the roads around here are heavily traveled and greasy. I went over a crest and heard a... shhhhhhhhhhhhhTHUNK! I thought I broke something but, aparently like Jgard said, it's the center diff locking. That was the only time I had that happen though.

So I guess I can't answer either as I'm 5MT. :D
 

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According to FHI, the clunk is normal and doesn't hurt anything... according to my experience as a mechanic, any loud noise that you can feel as much as you hear can't be good... try to avoid it when possible. You go almost as fast by engaging the clutch a little smoother, and if it shortens the clutch life, well it's cheaper than a tranny or center diff rebuild.
 
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