clutch noise

[idosubaru]

FT4WD XT6 manual. clutch and all components were replaced by previous owner.

 

sometimes makes a growling noise even just sitting still while idling. noise goes away if i press the clutch pedal down every time.

 

there's also a similar (i think it's the same) noise while driving in gear, a growling noise. grrrr....

 

i would think this could be adjustment related - like the throw out bearing is spinning when it's at idle......but that wouldn't explain a growl while driving at speed would it?

 

so if it *could* be clutch should i loosen the adjustment nut or tighten it? seems like loosen?

Edited December 16, 2010 by grossgary

[Caboobaroo]

Gary, if the entire clutch kit was replaced, it might not be a bad bearing... at least clutch bearing. My XT6 when I bought it, had a nasty bearing noise that I thought was clutch related. After I sold it to Rob, he replace the throwout bearing and the pilot bearing ang the noise was still there. Turns out it was inside the transmission.

 

It did exactly what you're describing though.

[idosubaru]

nice hit russ, maybe i should check the gear oil. it would still do it while sitting at idle though?

[Firespray401]

My non Subaru has a bad throw out bearing. Your description sounds like it could be that.

[zacyork]

does the sound increase from engine rpm? or does the sound increase from faster driving? that could clue you in if its throwout bearing or a transmission bearing.

[NorthWet]

One of our EA-series made an idle warbling-groan/squeal, and I think it also did it sometimes while at speed. I also seem to recall (hallucinate???) that it seemed worse in damp weather, which REALLY threw me. I never figured it out, but on the other hand nothing failed. I do not know the resolution. (Sold the car? Clutch replacement? "Orange smoke", aka magic?)

 

My feeling was that it was a harmonic condition where some bearing, for lack of a better word, "stuttered" at certain speeds. If the TO bearing was lightly touching the PP fingers it might be trying to turn, and different speeds might invoke a harmonic response.

 

If TO bearing, I would probably try loosening the clutch adjustment some (more freeplay) and see if it has any effect. (If the clips have slipped off TO or fork, this may not help.) If this doesn't change things, just for grins trying eliminating freeplay for a very short time and see if things change.

[Caboobaroo]

Input shaft bearings. Both the little one in the front of the case and the fat one on the back of the input/mainshaft inside the transmission.

 

It would do it at idle with the clutch out in neutral because the input shaft still spins in neutral with the clutch out. The counter shaft on the other hand, doesn't spin unless the vehicle is moving.

 

I wonder if the PO did not replace the pilot bearing. I've seen them fail and cause a noise like this. A lot of people don't tend to replace them as they can be a pain if you can't/lazy enough to take the flywheel off.

 

Just a couple of ideas:banana:

[lostinthe202]

Input shaft bearings. Both the little one in the front of the case and the fat one on the back of the input/mainshaft inside the transmission.

 

If the clutch bearings were replaced, my money is on this as well. The trans in my OBW did the same thing. When I tore into it, it was the giant double roller bearing at the back of the input shaft that was bad. If it's just growling some, you probably won't see anything in the gear oil, at least I didn't. Since I didn't see anything, I drove with it growling for about 70k miles before the sound got noticeably worse at which time I took the trans apart. It's really not that difficult thanks to Gloyale's write up,

 

http://www.ultimatesubaru.org/forum/showthread.php?t=90182

 

Good luck!

 

Will-

[GeneralDisorder]

Yeah - drain the gear oil and check for glitter. Sounds like input shaft bearings. You will likely find cage material in the gear oil.

 

GD

[idosubaru]

great thanks guys, this is my daily driver XT6. just to clarify since, while i've done a number of clutches and trans swaps i'm not well acquainted with them:

 

the only time it's perfectly QUIET is when i push the clutch pedal in.

 

if the clutch pedal is *not* being pressed it tends to make the noise.

 

seems like the fact that it's perfectly quiet 100% of the time when i press the clutch pedal in should point to something?

 

it's loud under load - up hills or accelerating - when going down hill it's noticeably quiet(er), not sure if it goes away or not. it's perfectly quiet like it should be when the cltuch pedal is in.

Edited December 17, 2010 by grossgary

[GeneralDisorder]

The input shaft bearings are "floating" when the clutch is disengaged - once you release the clutch the input shaft is loaded with engine torque - it gets quieter when you go down hill and would probably be it's quietest when everything is just coasting - slightly downhill, no throttle pressure, but not fully closed either..... you know what I mean.

 

Sounds like classic input shaft bearings to me. This is usually an AWD transmission problem but being the XT6 is the FT4WD without the D/R it would have the same bearing setup as the AWD tranny's.

 

GD

[idosubaru]

well crack head.

 

how long will it keep rolling like this? can i drive it until summer, i've got way too much other stuff to do this now?

 

should i avoid long highway trips or driving altogether?

[Caboobaroo]

You should be able to drive it for a bit but its like a timing belt thats over the recommended replacement mileage, just a ticking timebomb.

 

 

Wait, would a hella boosted EA82T be more equivelant?

[idosubaru]

Wait, would a hella boosted EA82T be more equivelant?

oh no, i hope it's not that bad.

[GeneralDisorder]

Just depends - but I've heard of them lasting 20k to 40k making noise. Depends on where the failure is and how rapidly its progressing. Could also damage other bearings or gears if allowed to progress too far - remember these are shaft bearings and play in the shaft will affect gear tooth alignments, etc.

 

GD

[lostinthe202]

I'm kind of arm-chair engineering here, but...

 

the non-4wd transmissions all have the same design as far as the input shaft goes in that the first bearing (working from the engine back) is quite a distance from the pilot bearing leaving lots of unsupported input shaft. The first bearing in line is a needle bearing with some sizable needles, like 3 or 4mm in OD by like 10 or 15mm long. All the bearings for the gears are also needle bearings which all have lots of surface area. While I'm not quite sure how that compares with the contact surface area inside the large double roller bearing at the back of the shaft, I can say that when I tore mine apart, all the bearings on the input shaft were in perfect shape except for the the double roller bearing which was hurting really bad.....

 

 

Perhaps a resonance gets setup that puts more strain on that bearing?

 

As I stated before, I noticed the noise at a bit under 120k and drove it to a bit over 180k before I fixed it. During that time, the noise stayed consistent (same behavior you described) and only started to get worse near the end.

 

When the sound did get worse, I checked the gear oil again and found that glittery paste that GD mentioned in spades. When I got the bearing out, the cages on both sides had turned to powder. All the balls were present and accounted for and really didn't look too beat up, though they are hardened. The races didn't fare so well, they were pretty hammered and I'm sure I was really close to something really bad happening.

 

But, I never had difficulty shifting, the trans never once popped out of gear or exhibited any odd behavior beyond the funny noises and when I put it back together it still worked just as well as it did before.

 

Not advocating this as a rule of thumb or anything, but if the noise is relatively new, I bet you could wait 'till summer at least to tackle it.

 

Will-

Edited December 18, 2010 by lostinthe202

[idosubaru]

thanks guys, good to see and hear from you Will.

 

i'll use it some but have a few vehicles so i can easily just not drive it too.

 

i just got the car, so don't know how long it's been like this. i'll ask the PO how long it was making the noise as it was never mentioned during purchase and i bought it sight-unseen from a board member here and another forum.

[GeneralDisorder]

Yep - that's the ugly mother right there.

 

I've also seen some other wacky failures on the 5MT's - you might rememember my post about the '96 Legacy where 2nd gear stripped out completely, and then I've also seen the center diff/VC eat itself (but that was a '99 tranny with a different design for the VC I guess)...... would want you to let it go too far and end up with a secondary failure like a chewed gear set, etc.

 

Gear oil is real good at suspending particulate I've noticed - even after draining silver gear oil out with large chunks in it - an ATF flush later and it's good to go. That stuff doesn't usually seem to cause any big issues.

 

GD