Gearbox(MT)/Clutch - noise in second gear only
 

Hello,

does somebody experienced or knows what an "cutting wood with a circular saw" ONLY in second gear and ONLY at a certain rpm could cause it? Didnt find any info about this anywhere.

This only happens when the transmission/engine is at operating temperature (fully cold this doesnt happen). And only in second gear at EXACT 2600rpm.
If i accelerate slowly past that rpm the noise is quieter than when accelerating little bit faster trough.

Holding the rpm steady at that range results in no noise.
Revving the engine in neutral - no noise,
Revving with clutch in and in second gear - no noise
No modification to the drivetrain.
No unusual problems with the gearbox, shifts smooth (cold and warm)
Noise comes from the front/middle of the car
Only hear it audible enough with windows down

Could be the TOB? Squeaky and crunchy feel when pressing the clutch pedal. Car has about 35k miles on it.

I know, without any "soundfile" or "video" it will be hard to diagnose this. But the "cutting wood with a circular saw" nails it. And there's no point in recording it, my mic would rather pick up the exhaust.

Well, since the TOB is spinning all the time the engine is running, I doubt it just picks 2nd gear to act up.

Have you tried changing the transmission oil ... ??

That's where I'd start ...... you might get lucky.

ol @Ultramaroon will be along shortly, with some insight .....;)


humfrz

I have a feeling it whines in first gear too. You just get through it too quickly.

I also think it whines across a range of engine speed but you only actually hear the speed at which it resonates and really sings.

Listen for it carefully as you climb a steep hill. Am I correct in my thinking?

edit: Your TOB, squeaky crunchy as you operate? That is the feeling of it binding on the quill. It's bad but not exactly the same as failure of the rotating assembly. Try to get us a recording of the sound. I'll listen to it carefully.

I only hear it at that gear and rpm as said above. If i try to hold it at that rpm nothing happens. First gear also nothing between 1000-3000rpm when accelerating slowly.

Drove uphill and didnt heard anything unusual.
The only thing i notice is that my TOB makes lots of different noises.

Also i hear some veeeeery faint "whine" like a screw-type supercharger when lightly accelerating in lower rpm. Could be my winter-tyres.

Tried to record it, but it didnt pick the noise up. (it was rainy)

Edit: Somehow it sounds like this [ame="https://www.youtube.com/watch?v=M0hyQw491sY"]https://www.youtube.com/watch?v=M0hyQw491sY[/ame] @ 1:03 , 1:20 , 1:34, 1:42 - the faster (more throttle) i go past this specific rpm line, the louder/more noticeable it gets.

In that case I'll guess it has nothing to do with clutch/transmission and is actually a heat shield vibrating at resonance when the engine is tilted under just the right load and speed.

Hmmm, interesting.
The only heatshield that i'll have is the oem frontpipe and it looks pretty rusty to me when looking down from the engine bay.
Shouldnt it create that noise even in neutral?

Anyway i will change the TOB, new clutch disc, new pressure plate and an lw flywheel next month. Gonna investigate the heatshield and tap it a little to see if it is loose somehow.

Maybe the bolts on it came loose because my catback has such thick walls, you can feel the vibration of it even at idle.

Also do you know if the TOB can make a "grind" noise at idle? Clutch pedal pressed -> no noise, clutch pedal released -> noise. Sounds like when you "grind" two stones together. That one i could easily record.

Thanks for your help!

Well, it could be that when the engine is torqueing over when it is under load, the parts could hit each other. Maybe not so when the engine is torqueing over less in neutral (not under load).

A bad TOB can make a "bad" noise anytime the engine is running. It's an "active" TOB which means it's always in contact with the fingers of the pressure plate (it just doesn't push on them real hard until you push in on the clutch pedal).

A "bad" TOB can make all kinds of weird noises; whining, screaming, grinding, howling, crunching and a few others.

Before you go to the time and expense of replacing all that clutch related stuff, I'd suggest you get it up a rack and inspect the heat shields to see if they even come close to another body part ...... if so, bend them back.

While you have it up there, you might as well change the transmission oil to see if that settles it down.


humfrz

If the sound goes away by the time the pedal is pressed down only a third of the way, then yes, your TOB is shot.

If it only goes away because the clutch is disengaged, then it's @humfrz' favorite, neutral rollover.

@humfrz
I will change the oil for sure . Almost reached the 30k km mark since the last change.
The TOB was my only intention to change because of all that noise and typical symptoms (revised 2017 version), but why not the clutch disc and pressure plate too when the transmission needs to be dropped? Costs me maybe $250. (oem)

@Ultramaroon
The sound goes away if i push the clutch pedal about half the way in. (i lowered my pedal height very carefully, but i dont think it has to do anything about that, free-play etc is given all the time)

Thank you both for your advice!

NOT humfrz rollover, Ultramaroon invented this neutral/gear rollover thing. Like only HE can hear gears rolling over ........ or something in his head is rolling over ......:iono:

YIKES ....... maybe it's just the OP's second gear that is rolling over .....:eyebulge:


humfrz

Well, once you get it all apart, you will be able to see if the flywheel is scored, if the clutch disk is out of spec and whether or not the pressure plate fingers/springs are worn or weak.

Oh, heck, you might as well change the clutch and pressure plate along with the TOB. Maybe even throw one of them aftermarket billet clutch forks .....:thumbsup:


humfrz

You sound grumpy. Did you miss your early evening nap?

Well, yes, I had to take my two older granddaughters to their Krav Maga training session ....... and there ain't nutten to do there for an hour except watch the kids beat the heck out of padded things........:popcorn:

Then I stopped by the "taco bus" to pick up some Mexican food ...... that didn't taste too good ...... they must have been scraping the bottom of the barrel.

:mad0259:


humfrz

:(

Ah, well. It'll be better tomorrow. So will the taco bus. :cheers:

Yep, at least that cute little senorita was still at the taco bus ...... :drool:

And my granddaughters are getting well trained to protect me in my old age .... :thumbsup:


humfrz

The noise seems to be related from harmonics since its only occurring at certain RPM and load ranges. This could be causing a heat shield, unloaded gears in gear box or something else (bolted to the subframes or driveline) to make the noise you are hearing.

FYI...If you plan to install a LW flywheel then this will most likely increase the presence of any harmonic noise coming from the drivetrain. So your annoying noise may become more annoying, stay the same or may entirely go away(self correcting automotive repair SCAR :w00t:) SCARs are my favorite !!