jsnyder

iTrader: (1)

I have a 2004 GTO with a 6 speed manual transmission and recently it started making a horrible noise. There is a knocking noise coming from what sounds like the transmission area.
The noise only appears while driving the car and gets faster as the car goes faster. It is not present when the car is in neutral or when the clutch is depressed. It even appears to go away when I let off of the gas while driving.

Any ideas?

BlackScreaminMachine

iTrader: (17)

Sounds like a mount, IF internal there still should be some noise. It is worth getting it ona lift.

jsnyder

iTrader: (1)

A mount? Didn't think of this. Worth checking anyway.

jsnyder

iTrader: (1)

Any other ideas?

Gen414

iTrader: (38)

What kind of knocking? real fast, real slow, loud, metallic sounding, thumping, etc....?

When say you are driving @ 70 MPH, and you put it in neutral, sound still there? Go away?


What about sitting still, clutch in (or in neutral) and you rev the motor, sound there, or no?

Only at speed? How fast before you start noticing it?

jsnyder

iTrader: (1)

It is a pretty loud noise. It can be heard over the headers. It is kind of a thumping noise. Speed sensitive. The faster I go, the faster the knock/thump.

I haven't had the car up too fast since I heard the noise. The noise starts pretty much as soon I start moving. At 40 mph, if I put it in neutral the knocking goes away. It also goes away if I push in the clutch while driving. It even seems to go away if I let off the gas while driving.

It does not make the noise while sitting still, even if I rev it up.

I put the car on jack stands and ran it in first and second up to about 3000 rpms and didn't notice the noise then either. I was nervous to give it much gas though in fear that the torque may knock it off of the stands.

I am at a loss.

Throwout bearing?
Input shaft?

BlackScreaminMachine

iTrader: (17)

Get it on the lift.

I think it is suspension related and when the car has a load on the suspension, everything is compressed. On jackstands you do not get that same effect. A Dyno would be a safer place then jack stands.

calhoon

iTrader: (6)

A thumping that picks up with the vehicle speed and is not gear sensitive sounds like debis / chip in the headset gearing of the trans. Thats the input gear/ clustergear mesh.

jsnyder

iTrader: (1)

Not really what I wanted to hear. Any way of verifying this without pulling the transmission? Would I be able to see anything if I remove the shifter?

PewterScreaminMach

iTrader: (7)

I'll also throw it out there that there's a slight chance it could be a noise coming from the rear. Clunking and sounds that come from the rear sometimes travel up through the driveline and sound like they're coming from the transmission area.

jsnyder

iTrader: (1)

The rear end was one of my original suspicions, but I would think that if it was, it would still be making the sound even with the clutch pushed in if the car was in motion.

malott442

Not necessarily. My car had a slight knock that sounded like tranny.... Same indications as yours..... A few burnouts later and it turned out to be a twisted pinion shaft..... (on the POS 10bolt)

FWIW looking under car for a loose motor/tranny mount is good advice.

I hope its not internal.....


Good luck!

PewterScreaminMach

iTrader: (7)

Funny enough, my brother and I have the opposite issue as you. Going around corners and such, the 12-bolts both clunk very loudly when in neutral (or just having the clutch engaged) but when in gear, the clunking is much quieter. FWIW. Damn Mosers...

jsnyder

iTrader: (1)

It is definitely not the usual rear end clunk, but it could be something to do with the rear. I'll have to drain the fluid tonight and see what it looks like.