how to tell if your diff is unhappy?

[gustavohuber]

hey everyone, so for a while now (i posted about it a while ago) I've had a sort of "NYYYYRT!" noise while the clutch is engaging as I start from a dead stop and go around a turn. Now here's where I start to crap myself -- I can almost swear I heard it yesterday while I was going around a corner perfectly engaged in 2nd.. no clutch action.. also, for sure it's started making the whine-grind even when I start off on a significant hill, even if I'm going straight ahead. The fact that the noise is happening more frequently has me totally spooked. I'm going to put in a new clutch when I do a longblock swap soon, but if my diff is what's moaning, I need to take care of that while the engine is out.. any ideas?

[skid542]

Can you tell where the noise is coming from? Is the noise dependant on how tight you turn or RPM dependant? Is it a steady noise until you get out of the turn or is it like something is slipping and then finally enganges? I'm only FWD so diffs aren't my fortie but can you eliminate the possibility of bad ball joints or CV joints?

[gustavohuber]

well, I just did the front halfshafts a few months ago, and they still look fine. The noise is a sort of engagement noise.. it goes in time with the clutch. A spicy tidbit that I just noticed now is actually that I'm running one THICK FWD halfshaft (on the front right, and one less thick, AWD halfshaft on the driver's side front).. I'll post another note to see if that's cause trouble for anyone else. I also checked the transaxle dipstick, and it seems full.. or overfull if anything. The oil looks clear, but somehow just doesn't seem like gear oil.. it feels like motor oil to me. I might try swapping it out for some new 90w tomorrow.

[skid542]

I wouldn't be inclined to think that the different half shafts would be cause for any trouble. You aren't pushing high power outputs that would cause significant differences in twisting, if anything though that'd show up as torque steer I'd think. A gear oil change would be the first step and sometimes those intuitions are right. Keep us posted.

[gustavohuber]

Well, I put in new 80w90 yesterday, and it changed the noise noticably, but didn't do away with it. I kinda sorta maybe fixed a power steering leak, and at any rate, I refilled that to a respectable level.. so the only thing left is that it, in fact, is the diff. I peeked in the tranny drain while the oil was out, and the gears looked allright.. actually, the few i could see looked fine and freshly-milled. I couldn't see into the diff itself, but when the oil came out, it was dirty, but not phenomenally so, and there was a little mud on the magnet of the plug, but not a whole lot.. say half a dime worth of metal dust, or probably less. No chunks, no big red flags that I could see.. but still when I kinda launch it around a hard turn (getting out of parking spaces in San Francisco, getting onto the freeway from a stoplight, etc) NYYYRT! It's still there, but maybe quieter, and for sure less frequent. I don't get it!

[gustavohuber]

oh, also for the life of me I couldn't loosen my rear diff plugs.. so that oil stayed as-is.. I made both of my arms sore tugging on a breaker bar while on my back under the car but NOTHING.. not a tiny amount of give. SOMEONE must have done this with an impact wrench. Oh, and is there any way to tell whether my rear diff is limited slip or open? (so I know what kind of oil to put in when I get around to it)

[vrg3]

Those plugs are often really tight. Just always make sure you remove the upper one before trying to remove the lower one.

All AWD first-generation Legacies use the same type of fluid in the rear differential; the limited-slip devices are completely sealed and not exposed to the fluid.

But, in any case, there should be a metallic sticker on the back of the differential (it may be buried under dirt, grease, and grime) stating the part number and final drive ratio. That sticker will also say "VISCOUS LSD" if it's a limited slip.

[gustavohuber]

whee! the diff is fine! it was the power steering whining all the time!