Engine rpm related vibration felt in shifter when changing gears

I've been suffering lately from some kind of vibration/whining mostly when the rpm drops while shifting gears. It is a vibration that can be felt in the shifter. It happens when changing any gear (e.g. 1 to 2, 2 to 3, and so on). Vibration is usually felt the most as the rpm drops and is around 2400 rpm.

It couldn't be the center diff right? Doesn't the center diff spin at a rate that is essentially engine rpm independent?

Any ideas?

fwiw, I currently have the transmission on my bench to install a new clutch.

no update really, since I am still in the process of changing the clutch (waiting for the flywheel to be delivered).

But yeah, I really have no clue what could cause this type of vibration when the engine rpm drops and trans is essentially in neutral. I guess what I am trying to figure out is which parts in the trans somewhat follow the engine rpm. Are there bearings in there that spin only when a gear is in?

Those are symptoms I'm not really familiar with. I would still be trying to figure out/isolate what major components could be causing the vibration: engine, clutch assembly, or transmission.

A little late to ask you this now (with the transmission on your bench), but do you know if you could reproduce the issue doing any of the following? Maybe some pattern would emerge in the answers...

-parked, but revving the engine, and letting it decel in gear with clutch pressed?

-parked, but revving the engine, and letting it decel in neutral with clutch pressed?

-parked, but revving the engine, and letting it decel in neutral without clutch pressed?

-driving, revving the engine, and letting it decel in gear with clutch pressed? (i think this is the one you describe in your OP)

-driving, revving the engine, and letting it decel in neutral with clutch pressed?

-driving, revving the engine, and letting it decel in neutral without clutch pressed?

Question: why are you replacing the clutch? Was it slipping? Other issues? What did the clutch disc look like? Was there a chunk of friction material missing? (this could cause an out-of-balance situation that would create vibrations). Any other oddities observed in there that could cause an out-of-balance situation?

While the transmission is out, perhaps replace the pilot bearing (a worn one could allow the input shaft/clutch disc to wobble/vibrate), and release bearing as well (normal wear item).

Was your flywheel the more desirable single-mass, or the more complicated dual mass unit? What unit are you getting delivered?

This idea is reaching a bit, but what shape are your transmission and motor mounts in? It's reaching because worn ones would normally cause more slop than vibrations, but still worth looking at I guess.

Are there bearings in there that spin only when a gear is in?

Forgot to answer this. If you're talking about when the clutch pedal is pressed, and moving down the road.

-Transmission in neutral: the "output side" of the transmission would be spinning (via the driveshaft), but nothing on the "input side" would be spinning (much)

-Transmission in a gear: the "output side" of the transmission would be spinning (via the driveshaft), as well as the "input side" (they would be connected via the selected gear)

Wow, you went all out heiche

Question: why are you replacing the clutch? Was it slipping? Other issues? What did the clutch disc look like?

I still have the dual mass flywheel on the 05 and it's been so annoying to drive with. Plus it started to make some funny noise each time the clutch disc was progressively making contact with the flywheel. Finally, I think it was slipping a bit at times. 90k miles on this whole thing...

What did the clutch disc look like? Was there a chunk of friction material missing? (this could cause an out-of-balance situation that would create vibrations). Any other oddities observed in there that could cause an out-of-balance situation?

I will post some pics of the condition of the stock clutch. It did not look too bad really but I think I was down to the rivets in some areas.

No apparent missing chunk of friction material.

BUT, the flywheel (which is made of two pieces) apparently started to have whatever is holding the two pieces fail: see my post here:

alright. Transmission is on my bench . About to loosen the flywheel bolts. Questions for those who had this kind of flywheel before: since it is a dual mass, I can see it is made of two pieces or something. And the strange thing is that the smaller piece of the flywheel was misaligned in a way that I could not access the torx bolts. I had to keep the largest piece of the flywheel in place, while hitting a flywheel pin with a hammer to realign the second flywheel piece, so I could acess the bolts. Hope I am making some sense... Is that normal?

and this:

[ame=http://www.youtube.com/watch?v=Y4v1MkZXPLs]dual mass flywheel obxt 05 misalignment - YouTube[/ame]

While the transmission is out, perhaps replace the pilot bearing (a worn one could allow the input shaft/clutch disc to wobble/vibrate), and release bearing as well (normal wear item).

The pilot bearing will be changed. I am also installing an FF502 flywheel (single mass light weight), with a stage 1 organic exedy clutch kit. That's what I have on the 06 and I love it.

'release bearing': which one is this?

This idea is reaching a bit, but what shape are your transmission and motor mounts in? It's reaching because worn ones would normally cause more slop than vibrations, but still worth looking at I guess.

They are a bit flimsy. They don't show cracks though. In any case, I should probably change these too.

yes, "too much power"

It's very likely that changing out your worn clutch and worn dual mass flywheel will correct this problem. But I get what you're saying... since you have it all apart, IF the problem is something else now is the time to address it.

When I changed my dmfw, it was misaligned as well, but it was easy to shift the 2 pieces of the fw. fyi,

btw, when I said release bearing, i meant the same thing as throwout bearing.

yes, "too much power"

 

It's very likely that changing out your worn clutch and worn dual mass flywheel will correct this problem. But I get what you're saying... since you have it all apart, IF the problem is something else now is the time to address it.

 

When I changed my dmfw, it was misaligned as well, but it was easy to shift the 2 pieces of the fw. fyi,

(not mine) shows the innards of the dmfw. Again, I could see this piece as being the issue, although can't say 100% for sure.

 

btw, when I said release bearing, i meant the same thing as throwout bearing.

I hope that is it too. So even though the trans is starring at me, I will most likely leave it alone except perhaps change that shift rod seal. I recall you did that too. I think you posted somewhere in one of your threads how you did it no? In any case, I will probably follow the FSM on how to change it.

Thanks for the video link. Will definitely have a look.

And yeah, the throw out bearing will be changed (TSK3). The current one was fine though (tsk3 as well--35k on it).

I think I know which seal you guys are talking about, I thought about replacing that when I did my center differential, but decided not to. The tail end of the transmission has to come off. It was a little difficult to break the seal, but nothing too bad. Mostly nervewracking since I used a chisel and a hammer to break it loose after the bolts were removed.

*Granted, I did this with the transmission in the car. There might be an easier way to remove the tail with the transmission out of the car.

He removes the seal starting at 1:08 below

You can also see the center differential in the video above when the tail is removed, and the transfer driven gear.

Found it in this other video at the 50 second mark

[ame=http://www.youtube.com/watch?v=CBR4F6pGWEw]Subaru wrx sti legacy forester outback 5 sp 6 sp transmission shift rod seal replacement - YouTube[/ame]

For 5MT: 1 qt Motul Gear 300, ~3 qts Redline Lightweight ShockProof

For rear diff: < 1qt Motul Gear 300

Interesting mix. So this one?

http://www.ebay.com/itm/Red-Line-Oil-58404-Synthetic-ShockProof-Gear-Oil-Lightweight-ShockProof-R-/253056957102?epid=657337024&hash=item3aeb5ebaae:g:KGIAAOSwnDxUnhbB&vxp=mtr

Edit: yeah I can see that is the one. https://www.rallysportdirect.com/part/transmission-fluid/rdl-58404-red-line-lightweight-shockproof-gear-oil-1qt

thanks man.

Uh oh

I really have no idea. I had to stop working on the car and take care of my family..

I am just trying to think... Do you think gear pieces could end up in the transfer case?

Strange things is that all gears work just fine. But I've been suffering lately of this whirring during decel (without any gear engaged).

In any case, looks like I am going to play lego soon and take this whole thing apart. sigh.

Interesting.. I want to say they might have come from the center differential, but if you say the gears inside look ok, then I'm not sure..

http://subaruidiots.com/subaru-wrx-five-speed-manual-tips-and-tricks/2/

I carefully looked at the center diff. I really don't think it comes from there. Could be wrong though.

So, took the transfer case 'cover' off tonight. Found lots more pieces, but nothing looks obviously broken. So, still baffled at this point. However, I am seeing something loose (see video below). Is this normal?

[ame=http://www.youtube.com/watch?v=dmpOH7gGjuk]transfer case off--further inspection - YouTube[/ame]