When I was starting the car up today there was a knocking sound coming from the transmission only while the clutch pedal is released. Also if the car is in gear it doesn't knock/rattle either.

Once you press it in it goes away, its not a quiet rattle or anything of that nature it is a pretty loud, we actualy thought it was rod knock at first that's how loud it is.

Could this be throw out bearing rattle or is it possible the throw out bearing came apart or anything?

Let me know what you think.

 

Is your clutch engaging differently? Cause if it sounds like a loud GONK GONK GONK GONK or an extremely fast vibration while driving, almost like dense metal rattling/buzzing quickly, that would be your flywheel bolts having let go and the flywheel is buzzing against the crank. Ask me how I know lol.


TOB failure usually sounds like high pitched whine/squeal almost. Do you have a vid?

 

Does the rattle get louder when you turn your a/c on? I have the same issue and have searched for hours on this subject. Doesn't seem like anyone's figured it out :/. I read someone was saying it was clutch chatter.

 

I do not have a video of it right now, I suppose I can go take one. the only thing that would throw me off on flywheel bolts is if the clutch pedal is in no sound.

No engagement difference on the clutch, altho I only have 5 miles on the new build. So I suppose it could be just about anything.

 

My a/c doesn't work so I can try when I make the video to atleast turn the blower on to see if it goes away or not.

 

If you press your clutch in the chatter should go away if it was flywheel bolts because then the clutch unit and flywheel would be pressed firmly against the crank. When there is less/no load on the clutch, ie, when the clutch pedal is out, there would be chatter.

 

Got it, makes sense. Now to get some things ordered up

 

I have the same issue and have searched for hours on this subject.

 

Are you sure its not clutch chatter? What clutch setup are you currently running?

This is what a worn out tob sounds like. At least in my mind.

 

It is a loud knocking sound, no wooshing anything of that nature. It sounds like rod knock when you hear it. The flywheel bolt makes sense though and would make the sounds I am hearing... also you can feel vibrations through the clutch pedal as you press down on it.

 

Although you don't want to rule out something as serious as flywheel bolts too quickly, my bet is on gear rattle. Gear rattle which often sounds like rod knock, will increase with a lighter flywheel, aftermarket clutch disc (especially solid center), etc. If the noise goes away as soon as you pass the point of clutch disengagement (roughly 1/2 way down) you can probably rule out everything except gear rattle or transmission issues, because the only thing that is changing is that the clutch disc and everything downstream is no longer spinning with the motor.

 

I've been having this same issue. Sounds more like a thud than a rattle. Its especially bad in the morning when car is warming up with clutch disengaged and not in gear. Going to change out the clutch very soon.

Btw, i have an act hdss, gruppe-s lightened flywheel with about 40K on it. I have about 6-7 drag launches from a few years ago.

 

Just to clarify, disengaged meaning clutch disengaged (pedal down) or clutch pedal disengaged? Thud, as in one occurrence? FYI, usually gear idle rattle noise will get worse when the transmission oil is hot and possibly when the air conditioning is on.

 

Clutch pedal out (engaged?) and its multiple thuds every few seconds until i push clutch in. I can feel and hear the thuds thru the floor and cabin. I hope its not the the flywheel bolts loosening up. Regardless, looks like I'll be buying a new clutch soon.

 

I've had this same noise ever since I got my car 30k miles, I thought it was either TOB or input shaft bearings. Well when I replaced the clutch I checked the input shaft bearings and they looked fantastic. So replaced clutch and throwout bearing. Noise went away after clutch install for about 5k miles and slowly reappeared. I'm either thinking its either gear noise as ACTman says, or the clutchfork/throwout bearing rattling. I greased up the clutchfork really well when I replaced the clutch so it would kinda make since as the grease worked its way out i started rattling again.