Not too familiar with bolt grades, but I have a need to replace the blade bolt on my John Deere riding mower. Apparently the tall grass was a little too tall for it, but instead of just stalling the engine the blade bolt sheared. First the gods smiled as I managed to find the washer and blade retainer in the grass, then the gods of broken bolts were favorable as I managed to extract the rest of it from the boss with a bolt-out (first time ever!). I am just in need of a replacement metric bolt, but wondered if I should look for a specific grade.
Bolt grades
- Thread starter Dave Sherman
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Generally.....The bolts only job is to hold the blade to spindle.
Knowing John Deere riders.....It was probably loose from the factory
Was there a grade stamped on the head of the bolt? 8.8, 10.9 etc.
Knowing John Deere riders.....It was probably loose from the factory
Was there a grade stamped on the head of the bolt? 8.8, 10.9 etc.
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You didn't mention the specific mower but on this page they have bolts that are grade 10.9:
https://www.greenpartstore.com/John-Deere-Blade-Bolt--19M7788_p_19287.html
If you can figure out the JD part # you can probably get the genuine bolt for $4 delivered on Amazon or eBay, if not $1-$2 at a local dealer?
https://www.greenpartstore.com/John-Deere-Blade-Bolt--19M7788_p_19287.html
If you can figure out the JD part # you can probably get the genuine bolt for $4 delivered on Amazon or eBay, if not $1-$2 at a local dealer?
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I have found it easiest to go to the John Deere dealer with the deck model number and get replacements. Cost is minimal. I have had to replace them due to rust and rounding off and keep three extras on hand for my mower decks.
Can't tell what grade it was, it just has "JD" and 3 lines stamped on the head. Yes, I could order the genuine bolt from JD online, or the local dealer might even have it in stock, but it also looks like something I could find at Lowe's or HD. Mower is an RX75. Strangely, JD's online parts show it as a 7/16" by 1 3/4", but everything on the mower is metric and it has a 15mm head.
Edit: I see the dealer has it in stock for $1.98. Might as well get the real deal.
Edit: I see the dealer has it in stock for $1.98. Might as well get the real deal.
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Originally Posted by Dave Sherman
Can't tell what grade it was, it just has "JD" and 3 lines stamped on the head. Yes, I could order the genuine bolt from JD online, or the local dealer might even have it in stock, but it also looks like something I could find at Lowe's or HD. Mower is an RX75. Strangely, JD's online parts show it as a 7/16" by 1 3/4", but everything on the mower is metric and it has a 15mm head.
usually 3 lines means grade 5
Can't tell what grade it was, it just has "JD" and 3 lines stamped on the head. Yes, I could order the genuine bolt from JD online, or the local dealer might even have it in stock, but it also looks like something I could find at Lowe's or HD. Mower is an RX75. Strangely, JD's online parts show it as a 7/16" by 1 3/4", but everything on the mower is metric and it has a 15mm head.
usually 3 lines means grade 5
Originally Posted by Dave Sherman
I am just in need of a replacement metric bolt, but wondered if I should look for a specific grade.
Originally Posted by Dave Sherman
Can't tell what grade it was, it just has "JD" and 3 lines stamped on the head.
Are the (3) lines in a shape kinda like this ?
..|
/ .\
If so, that's an SAE (inch) bolt, Grade 5. Honestly, you can buy these at any hardware store. If the JD dealer is convenient, $2 isn't terrible.
Also, you measured 15mm (around 0.59") across the bolt head. A 7/16-14 bolt has a 9/16" (0.56") head.
I am just in need of a replacement metric bolt, but wondered if I should look for a specific grade.
Originally Posted by Dave Sherman
Can't tell what grade it was, it just has "JD" and 3 lines stamped on the head.
Are the (3) lines in a shape kinda like this ?
..|
/ .\
If so, that's an SAE (inch) bolt, Grade 5. Honestly, you can buy these at any hardware store. If the JD dealer is convenient, $2 isn't terrible.
Also, you measured 15mm (around 0.59") across the bolt head. A 7/16-14 bolt has a 9/16" (0.56") head.
Originally Posted by CT8
Is the bolt grade specific to be a shear bolt?
That would be my concern. Slap a grade 8 on there and blow the entire thing to smithereens.
Is the bolt grade specific to be a shear bolt?
That would be my concern. Slap a grade 8 on there and blow the entire thing to smithereens.
I don't think JD would use a shear bolt to hold on a blade spinning at 2500 rpm. From what I've seen blades are held on with a grade 8 or 10.9 which are similar strength.
Originally Posted by Dave Sherman
Not too familiar with bolt grades, but I have a need to replace the blade bolt on my John Deere riding mower. Apparently the tall grass was a little too tall for it, but instead of just stalling the engine the blade bolt sheared. First the gods smiled as I managed to find the washer and blade retainer in the grass, then the gods of broken bolts were favorable as I managed to extract the rest of it from the boss with a bolt-out (first time ever!). I am just in need of a replacement metric bolt, but wondered if I should look for a specific grade.
Take the threaded portion to Lowes where they have a sizer on the wall near the bolts.
Not too familiar with bolt grades, but I have a need to replace the blade bolt on my John Deere riding mower. Apparently the tall grass was a little too tall for it, but instead of just stalling the engine the blade bolt sheared. First the gods smiled as I managed to find the washer and blade retainer in the grass, then the gods of broken bolts were favorable as I managed to extract the rest of it from the boss with a bolt-out (first time ever!). I am just in need of a replacement metric bolt, but wondered if I should look for a specific grade.
Take the threaded portion to Lowes where they have a sizer on the wall near the bolts.
Originally Posted by rubberchicken
https://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx
Thanks for the info. The new bolt and the old have lines more like \ | / along 3 adjacent edges, don't know if that means the same as the 3 arranged radially. Even the parts guy at the dealer was surprised it sheared. i was afraid maybe I had over-tightened it at some point, since I switch between the mulching blade and the high lift blade in spring and fall. This time I used the torque wrench on it, and there is no way I reached the 90 foot pound spec with the wrench I was using; it would have taken considerably more effort. Anyway, it's got a shiny new OEM bolt, there was no damage when the blade let go, and I was able to coax the broken half out of the spindle.
https://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx
Thanks for the info. The new bolt and the old have lines more like \ | / along 3 adjacent edges, don't know if that means the same as the 3 arranged radially. Even the parts guy at the dealer was surprised it sheared. i was afraid maybe I had over-tightened it at some point, since I switch between the mulching blade and the high lift blade in spring and fall. This time I used the torque wrench on it, and there is no way I reached the 90 foot pound spec with the wrench I was using; it would have taken considerably more effort. Anyway, it's got a shiny new OEM bolt, there was no damage when the blade let go, and I was able to coax the broken half out of the spindle.
3 lines on one half as you describe is SAE grade 5.2 or ASTM A325 and is a special material and heat treatment.
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