It is important to use the correct shear bolt, because if whatever you hit doesn't break the shear bolt, because you replaced it with standard hardware, something else is going to take the brunt of that hit. Many times, it is the gear box, and that damage can cost hundreds of dollars to repair. I just looked up the cost of the shear bolts, and they are $2.85 from Messicks. I usually purchase 10 at a time, and can go through 4 or 5 a snow season. Only once did I break the shear bolt on the fan, and I had to replace both the fan and the shear bolt, along with the drive chain. The snow blower ingested a large rock, which did a lot of damage. That was about 13 or 14 years ago, and it was my first lesson in disassembly of the blower. Since then, I have had it apart for maintenance, and it has been a work horse ever since. I have replaced the bearings a few times, since they are not grease-able, and replacements are inexpensive.