Hello all,
I am just working on a acouple of Alpino 500 engines for a friend. The crankshaft thread on the alternator side is left hand, M12 x 1.25 mm, genuine (picture one). This is intact in one of the two engines, which by the way has no balance shaft and I'm in the process of cleaning and dismantling for inspection.
In the other engine these threads have been stripped by some previous owner, then repaired by cutting and welding a length of right hand, M12x1.75 studding (picture two). This engine has come already dismantled, has balance shaft and blasted cases, cylinders and head. Other than the repaired threaded tip and worn camshaft lobes it seems to be in pretty good nick, hence the owner has preference in putting this one back to life first. My concern comes from the crankshaf threads and this is where I seek for some advice from you.
First, is welding this kind of crankshaft an option at all? Or should I expect the welding to fail in service?
Second, provided that a fine weld is acceptable, should I expect the non standard right hand nut to work loose in service? The alternator rotor leaves very little room for using any kind of lock tab washer, so I?m thinking of cutting the threaded tip away and re-welding a left hand, fine thread piece resembling more like the original arrangement.
Other options might be drilling and left hand tapping the hole to use a bolt rather than a nut for pressing the rotor in place, or replacing the relevant cranckshaft wheel/end, but I see them as anything but a very last resort. Any comments and suggestions will be much appreciated.
I am just working on a acouple of Alpino 500 engines for a friend. The crankshaft thread on the alternator side is left hand, M12 x 1.25 mm, genuine (picture one). This is intact in one of the two engines, which by the way has no balance shaft and I'm in the process of cleaning and dismantling for inspection.
In the other engine these threads have been stripped by some previous owner, then repaired by cutting and welding a length of right hand, M12x1.75 studding (picture two). This engine has come already dismantled, has balance shaft and blasted cases, cylinders and head. Other than the repaired threaded tip and worn camshaft lobes it seems to be in pretty good nick, hence the owner has preference in putting this one back to life first. My concern comes from the crankshaf threads and this is where I seek for some advice from you.
First, is welding this kind of crankshaft an option at all? Or should I expect the welding to fail in service?
Second, provided that a fine weld is acceptable, should I expect the non standard right hand nut to work loose in service? The alternator rotor leaves very little room for using any kind of lock tab washer, so I?m thinking of cutting the threaded tip away and re-welding a left hand, fine thread piece resembling more like the original arrangement.
Other options might be drilling and left hand tapping the hole to use a bolt rather than a nut for pressing the rotor in place, or replacing the relevant cranckshaft wheel/end, but I see them as anything but a very last resort. Any comments and suggestions will be much appreciated.
