BMW E36 Tranny Rattle

With most any lightened flywheel, everyone sees the benefits immediately due to the reduction of the rotation weight.  However, if there is a downside (besides the price), it's the increase rattle that comes from idle/low rpms.  Because of the weight removed, a common side effect is an annoying rattle that comes from the tranny.

Not satisfied with this outcome, Alan Taur started experimenting with different weight transmission lubricants.  He even went as far as visiting the Red Line Synthetic Oil factory in Benecia, CA and spoke with the technical people there for recommendations.  What seemed to work best to eliminate most all of the rattle happened to be their 71W140NS Gear Oil.  The "NS" oils have no friction modifiers, thus does not increase shifting effort.  From the Redline information about the gear oil:

"a GL-5 which does not contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin."

Raising the idle speed by 100rpm with a Jim C chip also helped.

Contributed by Alan Taur.