Broken zero turn mower front wheel caster bolt...use better bolt grade?

[rbstern]

Have a circa-2015 Ariens Zoom zero turn. Been a good machine for us.

Today, the wife was out mowing when the right front caster fork separated from the frame. Scared her a bit, but no harm to her or the machine, other than the cause: The 1/2" grade 5 caster swivel bolt sheered off about an inch below the head. We don't treat the equipment harshly (no running into walls or posts), but our lawn and surrounding areas are somewhat bumpy, and I suspect this was caused by an accumulation of impacts over time. A little bit weird, because the bolt is fully supported by bushings in the assembly, although it's two short bushings rather than one continuous, and I am dewelling on whether or not the break was where the two bushings meet in the assembly.

Figured I would replace the bolts on both front casters, in case it is a wear and tear issue.

Any reason why I can't or shouldn't use grade 8 bolts, for upgraded durability?

 

[Tinhack]

Is there a way to grease the bushings? If not, that could lead to heat when mowing a bumpy lawn. Hot/cold cycles are hard on metal. I'd go with grade 8 bolts and maybe add some grease fittings.

 

[rbstern]

The bushing were indeed dry, and I am at fault for not addressing that as part of routine maintenance. I've added it to the annual list. Gave them and the replacement bolts (grade 5 again, local TS was out of grade 8 in that size) a heavy coat. Thanks for the suggestion.

Back up and running.

 

[bearthebruce]

May I suggest that you order a pair of grade 8 bolts from McMaster?

McMaster-Carr

Replace the grade 5 bolts on your next service.