KanakaRick
Silver Member
I have a woodmaxx 84" snowblower that keeps popping it's 5/16" grade 5 shear pins. Would I be asking for trouble if I moved up to a grade 8?
Got blasted in the Sierra with lots of snow....
- Thread starter KanakaRick
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ning
Elite Member
Grade 8: why not just weld it together? Just kidding. Still, not a good idea.
Are you sure those are grade 5 and not 2?
My auger eats shear bolts (grade 2, pretty sure) like they're candy but there's usually a good reason and I'm glad it's breaking a 50 cent bolt instead of my pto...
Can you afford to push it a bit slower?
msb1766
Platinum Member
Check the chain tension/tensioner to see if it set correctly.
oosik
Epic Contributor
Go to grade 8 bolts - yes, you would be looking right in the face of trouble. When stresses get too great the shear bolt is designed to break - not something else. And likely - something else that's a whole lot more expensive.
ning has a good thought. Be absolutely certain that what you have there is GRADE 5 and that they are actually shear bolts. Go slower - it won't cause the auger to choke and the pin to shear.
ning has a good thought. Be absolutely certain that what you have there is GRADE 5 and that they are actually shear bolts. Go slower - it won't cause the auger to choke and the pin to shear.
KWentling
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If they are Woodmax shear bolts they are grade 2 according to the manual. I also have an 84" and have never sheared one but it hasn't seen much use. It's been extremely dry here.
A grade 2 bolt will have no markings on the head other that possibly a manufacture's mark.
A grade 2 bolt will have no markings on the head other that possibly a manufacture's mark.
OP
KanakaRick
Silver Member
I was only going .0148mph
OP
KanakaRick
Silver Member
I didn't use actual shear bolts, but the bolts with the 3 marks on the cap in the grade 5 bin. Do I need to use an actual SHEAR bolt?
leonz
Super Member
Sierra Cement, Cascade Concrete, Bismark Boulders, Yup, you need to use the shear bolts as they
are specifically designed to break from shearing stress as standard bolts will only break if they are
pulled apart UNLESS they are rotating at a high speed and encounter an object that is going to hit
the nut or bolt etc.
The top flight of the roller chain should be tight and the lower flight should be a little loose UNLESS there
is an idler sprocket on a rubber tortion arm.
are specifically designed to break from shearing stress as standard bolts will only break if they are
pulled apart UNLESS they are rotating at a high speed and encounter an object that is going to hit
the nut or bolt etc.
The top flight of the roller chain should be tight and the lower flight should be a little loose UNLESS there
is an idler sprocket on a rubber tortion arm.
ericm979
Super Member
if the bolts you are using are fully threaded or there's sideways force on threads (because the shank is too short), it will break with less force than the correct shank length shear bolt that's only threaded where the nut goes.
oldnslo
Super Member
With the shear pin removed do the feed augers turn freely?
Does your PTO start and stop abruptly? If yes this can also fatigue sheer pins.
Does your PTO start and stop abruptly? If yes this can also fatigue sheer pins.
OP
KanakaRick
Silver Member
Good information to know, thanks everyone for a lesson on shear bolts.
KWentling
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This has got me thinking. I made mounts and a front PTO for my Kubota M7060. I sized all the drive components for the 64 PTO HP of the 7060. That called for size 6 drivelines.
I believe the WoodMax driveline is a size 4 rated at about 40 HP. 84 inches of blower may be too much for that driveline. This is the second season I've had the blower and the first it was used on the rear. Due to severe drive line angles I only used the Woodmax drive line once and then mounted the blower with a quick hitch which required a longer drive line which was a size 6 that is now incorporated in the drive line to the front. If I have shear bolt problems I'll probably try drilling it out to 3/8" and start with grade 2 bolts. I realize I may find the weakest link in the snow blower and I'm OK with that. What's anybody's thoughts on using a slip clutch on a blower? You would have to be sure it's not rusted stuck before each season.
I believe the WoodMax driveline is a size 4 rated at about 40 HP. 84 inches of blower may be too much for that driveline. This is the second season I've had the blower and the first it was used on the rear. Due to severe drive line angles I only used the Woodmax drive line once and then mounted the blower with a quick hitch which required a longer drive line which was a size 6 that is now incorporated in the drive line to the front. If I have shear bolt problems I'll probably try drilling it out to 3/8" and start with grade 2 bolts. I realize I may find the weakest link in the snow blower and I'm OK with that. What's anybody's thoughts on using a slip clutch on a blower? You would have to be sure it's not rusted stuck before each season.
WranglerX
Super Member
Please enlighten me, thought "shear bolts" were a FUNCTION and not a bolt type, bolt types are far as I know (common) are grade 2 (no head markings) grade 5 (three bars) and grade 8 (6 bars)... Metrics have numerical markings pretty much equivalent to SAE grading...
And soon as your snow blower eats a hidden rock or tree branch I belt you will be glad you did not go up in size because the blower did not eat some very expensive replacement parts that are only available this summer because of back order from people breaking them from using to large "shear bolt"....
Dale
And soon as your snow blower eats a hidden rock or tree branch I belt you will be glad you did not go up in size because the blower did not eat some very expensive replacement parts that are only available this summer because of back order from people breaking them from using to large "shear bolt"....
Dale
Peter 315
Super Member
Some are not just a regular bolts.....Shear Bolt Kit - 3 Pack - Ariens
ruffdog
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You really don't want the threaded portion of the bolt in the shaft or shear area. The threaded portion will shear way sooner and will wear threads into the holes.
oosik
Epic Contributor
I don't understand the point you are trying to make DL Meisen. My snow blower and now my Wallenstein chipper both used grade 5 bolts at the shear point. The blower used 5/16" and the chipper uses 3/8". The Op manual for my chipper says - use either factory made shear bolts or buy Grade 5 x 3/8" bolts.
I agree, going up to grade 8 is not a good idea. Something other than the grade 8 bolt will - shear, break or grenade.
I agree, going up to grade 8 is not a good idea. Something other than the grade 8 bolt will - shear, break or grenade.
bigtiller
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Maybe try an 8 millimeter bolt. It is a hair larger than a 5/16.
KWentling
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8mm is only .00246" bigger that 5/16" Never notice any difference. The Woodmax parts sheet does show the shear bolt as an 8mm.
KWentling
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By the way, Woodmax rates the 84" for 25-65 HP. Their driveline is likely only 42 HP if it is a size 4. A size 6 is rated at 69 HP and uses a 10mm shear bolt.
