[Alpines] Aluminum flywheel question

[Carl Wade]

 From my marine experience, I would recommend installing heli-coils in 
the aluminum flywheel, then you can use the original diameter and thread 
bolt size.  You would then have no corrosion issues if you are using 
steel bolts of whatever the recommended hardness is.  Get a heli-coil 
kit for the original bolt size and thread pitch.  It should include a 
number drill of the correct size for the heli-coil tap supplied in the kit.

In outboard motors, aluminum is used for the cyliinder block and 
detachable heads, also the mid-section and lower unit.  Stainless steel 
bolts are usually used for the fasteners.  Hardened steel bolts were 
used in some brands of outboards in the past, and were quite a chore to 
replace when the service procedure required their removal.  Stainless 
bolts can eventually get badly corroded in place, requiring careful, 
patient drilling to remove, and usually a heli-coil installation is 
necessary due to the aluminum corroding away to powder.

Carl Wade
former owner of Kenyon Marine Repair
Williamson, NY (near Lake Ontario)