I have a 1990 2+2 300zx 5 Speed that has a grinding noise coming from either the clutch or flywheel. Not very loud when cold but noise increases when the car is warmed up. It makes the sound in all gears including idle. It goes away when I disengage the clutch (pedal down, TOB engage). Also it drops about 200 rpm or so when I engage the clutch (pedal up). The car drive fine and shifts into all gears with no clutch slips. I've taken the transsmission off three time already switching off parts that i've thought was the problem. Things i've replaced (Clutch, TOB, Pilot Bushing, Rebuilt Transmission "thought it might be the input shaft bearing", Flywheel, Pressure plate). All that and still and can't find the problem, need HELP!!!

 

Did you check out the bearings on the counter shaft in the trans?

 

yeah, the transmission shop replaced all the bearings.

 

And you are sure they actually replaced all of the bearings and did the rebuild correctly? Also did you change the fluid after breaking in the new trans?

Having the RPM drop like that and having a noise would lead me to believe that someone either didn't assemble the trans correctly, or didn't actually replace everything they should have during the rebuild..

 

I'm pretty sure, I did pay for a $600 bearing kit that included all the bearings and synchros so there should be no reason for them not the change them out. Before the rebuilt it did the same thing too except i had some play in the input shaft. How long does it the tranny to break in? I just got it 2 days ago and only driven it onces for like 5 miles. If for some reason they didn't assembly it correctly it does have a 1 year parts and labor warranty. I do most of the work on my Z myself so I took only the transmission to them for the rebuilt. I put Vavoline High Performance 80w-90w in the tranny.