This is the inside of the M Coupe
differential cover. The main feature here is shown by the red arrow. This is the baffle
that covers up the vent pin-hole and prevents diff fluid from spilling out of the
differential casing during spirited driving. I am not sure yet how well it will work.
But the standard E30 cover did not do a very good job of keeping the fluid contained
during track events so I have little to lose. The baffle is steel and is riveted onto
the cover. I sincerely hope the rivets do not decide to let go some day because that
would in all likelihood spell the end of my ring and pinion.
Someday I would like to remove the baffle and drill and tap the pin hole for a nice
barbed fitting (maybe 3/8" ID) so that I can run a hose to a catch tank.