Multi-Disk Clutch

I was thinking in this thing from some time now.

The automatic transmission have multi-disk wet clutches inside of the transmission, those clutches last years and years. Otherwise the dry clutch from the manual transmissions don't last that time.

Why the clutch from the manual transmission don't evolved to the wet multi-disk clutch type?

And there are another type of clutch, the magnetoc clutch that have a magnetc powder inside of it between two moving parts that couple when the electric current is applyed to it.

The manual transmission would benefit from these 2 concepts of clutches.  
Don't mess with my chevy metro!

automatic trans wet clutches really do not slip very much when they are used...

dry clutches are much cheeper than the wet clutches... cost per unit...  time hundreds of thousands.. or millions...

take a look at the porsche dual disc clutch...  they have 2 input shafts... one inside the other... one clutch graps for gears 1, 3,and 5... the other for 2,4 and 6..   so the shift can be done faster...you don't have to wait for the blocker rings to move.. the blocker rings move before the other clutch disc is released...  instant shifts... and they are computer controlled..

i wonder how much slippage the magnetic power clutch will allow... that would take a lot of electronics to vary the current to the magnet to get a slow engagement.  or to hold your car on a hill at a stop sign..

i also know people who go through clutches every 25,000 miles.. and others who get 150,000 miles on one...

it all depends on how one drives...  the gear ratio,    how heavy the car is...   how many fat friends you haul around... and if you stop and start a lot on hills...