More recently I have encountered a number of newer Masport mowers with 4 blade disks that have shattered from some sort of stress fracture in the centre of the disk and completely fallen off the crankshaft obviously while the motor is running however I cant be 100% sure because this is how I find them at the recycle yards. I am curious if I have just been unlucky as I have found 3 or 4 over the last month. This problem only appears to occur with the four blade disks and not the 2 blade disks.
Up until this point I have replaced the damaged disks with the 2 blade set up and haven�t had any problems. The cranks and bosses don�t have any notable damage with the exception of a couple of snapped crank shafts which I will mention later.
I am trying to understand why this is becoming a common occurrence (if others think so) as this disk seem to shatter and break off as wide as the washer used underneath the bolt that secures the blade disk to the crank shaft.
Thoughts so far.
- Blade disks not being torqued correctly to the crankshaft
- Blade plate is too heavy.
- Blade disks hitting a hard object i.e street gutters/ rocls. I would think this would be more common with bar blades and not disks.
- I thought the cranks might have been bent however with a replacement boss and plate I can confirm the cranks were not bent. (My good spares are running low)
I have found reference to a Masport blade plate stiffener. Is this the key to ensuring reliability and ongoing safety?
On a more extreme note I have found 2 relatively new masport mowers (2-3 years old) with Briggs Engines where the crank shafts have snapped off completely. These are great parts mowers but that�s about it.
Any thoughts or experiences would be appreciated.
Thank you
Jaffa
