Grinding sound when disengaged clutch while moving

[axtray]

Hi all,

I"m new to the forum but definitely not new to Pelican Parts. The site had helped me numerous times in trouble shooting the issue with my bimmer.

However, for this 1 issue I'm having, I've tried to search all over the internet (here included) but somehow unable to find an answer since i was not sure whether the scenarios are all similar to mine or not.

2 weeks ago, my GM 4 speed autobox (driving a 1996 328i sedan) decided to bite the bullet. So instead of sending it to the specialist to overhaul it, i decided to convert it to manual instead. Got quite a reasonable offer for the whole complete package which includes new oil, clutch kit, master and slave clutch pump. The gearbox is Getrag 220 which comes from 325.

I've been testing the car after I got it back for a few days already. One thing that I' notice is that, each time when i press the clutch when the car is traveling/moving, there will be a grinding sound.

How the sound comes to, 1st gear, accelerate to about 3-4k rpm, press (or disengaged) the clutch, you will hear some sort of grinding sound (more of like a wheel with a bad bearing spinning). The sound is gone as soon as the clutch is engaged (release pedal) and you continue to accelerate. So far, i've tested 1st, 2nd, 3rd, and 4th. All these gears have these symptoms. Though the speed where the sound will appear are different (so easier said, each gear to rev until at least 3.5k rpm and disengaged/press the clutch) Didn't manage to try 5th year since have not gone that fast to try and press the clutch. But since majority of the gears are having the same problem, 5th should be the same as well i guess.

I've been reading all over the internet, and most of them are saying it is not synchro problem since if it is, it will be hard to get shift into gear (no issues with gear shifts).

Culprit could be from one of below,

-Pilot bearing
-Throwout bearing (I don't think it is because this bearing was provided along with the new clutch kit
- Input shaft bearing

I''ll be extremely grateful if any of the gurus here could provide an advice on this. The car is a joy to drive now as a manual. but this little problem is driving me nuts each time I have to downshift or doing some sprint (since it requires to shift at high rpm which when the rpm is high, pressing clutch = the sound will be there though only for a second since will immediately shift to another gear).

[Manolito]

You have identified the two most logical suspects, the pilot and the throwout bearing. Do you happen to recall the brand names of the parts in your clutch kit?