I have an 04 G35 Coupe 6 speed manual
I bought the car at the end of Nov 2015, today is March 25, 2015


The clutch was acting worn out when I bought the car so I bought a clutch and flywheel. The clutch and flywheel that was already in the car was a new Nissan setup with a broken flywheel. The damper between the two masses was broken, weird.
The new clutch and flywheel was installed in late December.


On March 14, I noticed the Throw out bearing problem starting.. While the clutch is pressed in it starts grinding and when I put it in neutral and release the clutch it stops grinding. I also have a light grinding that sounds like the same bearing, when the clutch is pressed and just before it goes into gear it grinds, and then again as I release the clutch during normal acceleration. This grinding is a lot more quiet than gears grinding.


I had a new Throw out bearing installed on March 20 and it started back up the next day. The problem seemed to be solved on the 30 mile drive home, operating smooth and quietly.


I am waiting for any ideas before I start a trial and error process, each time dropping and reinstalling the transmission.


I am thinking about replacing the pressure plate, since it shows discoloration on the finger tips where it got hot against the bearing installed in December. I also plan to replace the pilot bushing and the throw out bearing. If that doesn't fix it, I will be deciding wether to repair or replace the transmission. I'm not made of money so it will be a used replacement, which might have it's own set of problems. I sure hope it doesn't come to the replacement.

In the Bell Housing photo, you see the bearing that got replaced on March 20. You can see how the bearing was discolored. The brake dust got cleaned up and the shaft and clutch lever were lubed with bearing grease. The Pressure plate photo shows how the finger tips have been discolored due to getting hot.

 

i glanced. so sorry if i missed something. but you are saying you have had 3 go out on you total? and two you changed? i would have a mechanic that has done this work before do it. sounds like something else is wrong or its not aligned properly.

but you have throw out bearings keep going bad its obvious its not the throw out bearing.

 

I failed to mention that the mechanic is a close friend of mine, so I get to watch or help, and he's got over 20 years experience. We did the work at the car dealer shop where he works. He's been building cars from the ground up for these 20 years, as before then he was pulling parts in the family junk business before age 10, by 12 he was building them up. He also worked at a Nissan dealer for the past 2 years. I know for certain that the problem is not from me doing the work on my own.

I also don't know if the throwout bearing on the very first clutch was bad because the flywheel was broken and we just knew it was messed up really bad and needed to be replaced. I had also never driven the car with a good working clutch because I bought the car like that in late November.

I am hoping for some credible information like "you have to change the _____ with the throwout bearing to prevent this from happening again.

We are waiting on a Nissan Master Tech Guru that my friend knows to get back to us with some information.. IF he contacts us.

 

Here's something a little awkward. The newest bearing that is in there doesn't make the noise every time I press the clutch down, and it's taking longer to progress than the one before now. The one I just replaced March 20 was fine from the December install until March 14 and the grinding progressed in 2 days. Is there a connection between the Pilot bushing and the throw out bearing?

So, the noise when pushing the clutch in is still rarely occurring on the new bearing. The small grinding while pushing the gear shifter into the gear, and again when pulling the clutch out during normal acceleration, is consistent. Maybe the Pilot bushing is making the small grinds during shifting, and the Throw out bearing is not even fully damaged yet. Maybe the Pilot bushing trouble is making the throw out bearing go out of whack.

All I can do is kick ideas around and every attempt at fixing the solution requires dropping the tranny again.

 

A friend of mine suggests that it could be the Pilot bushing, which was not replaced. Saying if it's worn, everything will be out of whack. It grinds while the clutch is actually slipping between gears and that's when the nub of the input shaft is spinning inside the Pilot bushing. My throwout bearing doesn't seem to be the problem right now, as it doesn't grind while the clutch is down, but while the clutch is SLIPPING. My other TOB that was replaced on march 20 was grinding with the clutch pushed in after 60 miles or so after the initial grinding began. Maybe the one before March 20 was not worn out right away, but because of the Pilot bushing.

 

My friend says "The pilot bearing is designed as a friction or plain bearing to provide a surface for the "nub" to spin inside of. When everything is couple clutch wise, the "nub" is just simply located axially by the pilot bearing and acts as a load bearing surface" So it grinds between gear, while the clutch is slipping, because the pilot bushing is allowing the input shaft to go out of alignment.
Any thoughts from those who know?

 

This is super weird, my car just started doing this recently. Its so annoying and it sounds like I'm grinding gears all the time but I'll just be sitting there with the clutch pushed all the way in. Did you figure anything else out?

 

My conclusion is that the Pilot bearing is what causes the input shaft to go out of alignment, and the input shaft bearing makes the noise. This will be mainly acting up during the clutch being pressed. When the clutch is coupled (unpressed), it holds everything straight after it lines up properly. The damage on my pilot bushing looked negligible but replacing it seems to have fixed it and I've put around 4000 miles on it. The part costed like 1-2 dollars, getting to it was the booger.