constant thruth bearing rattle

[slim91]

hi all i have recently put and m52 in the e30 with a 318is gear box with lightweight m20 flywheel and new sach clutch im using a 325i release bearing first one bought from euros and lasted about a week bought one from bmw at the price of 70 quid and the f***er rattled from the second i started it am i using the wrong trush bearing?

[ross_jsy]

Sure it is the release bearing and not a rattly Getrag? A lightened flywheel will magnify this problem

[jmc330i]

Does the noise disappear when you depress the clutch pedal? It may not be the release bearing, but the lay shaft bearings in the gearbox.

The E30 325i bearing should work, although as I've found does result in a high biting point.

[slim91]

The gearbox is mint it's only had this problem since I bolted the m52 in and yes when I press the clutch the noise goes away. That's the other thing I don't have a high bite point it's quite low cheers

[ross_jsy]

How do you know it's mint? Have you rebuilt it? If not, then it's a 20+ year old gearbox. Getrag's tend to rattle.

Just for your information, I have 2 Getrag boxes (both "sport" boxes) and both their layshafts rattle and both stop rattling when you depress the clutch. One is so bad I thought it was the bottom end going before I pushed in the clutch, the other is ok but every now and then has a rattle

[maxfield]

My dad had a brand new gearbox on his M3 from BMW, the lay shaft rattled on that.

Very very common.

[HairyScreech]

The lay shaft rattle problem was/is common enough that they took to putting orings in the transmission to help dampen the oscillations in the layshaft.

Even brand new boxes were doing it so I have been told.