Posthole Digger County Line shear bolts

[nap61]

Last year I bought a County Line (TSC). I just got around to using it this weekend. A neighbor had his mailbox pole demolished by vandals (another thread)and asked to use it. I said OK but only if I go with it. We had to put it together (a little) and found that they had given me the wrong bolts and no shear bolts. The manual said to use 5/16 grade 5 shear bolts. I tried that size and found that the bolt was a little small for the hole. It was 3/8 which fit easily and had no "play". I was afraid that the 5/16 would cause the hole to elongate (become oval) under torque. I used a 3/8 grade 2 bolt and all went well but it was only one hole. Do you think the manual had a misprint or should I have used a 5/16 grade 5? I have several holes to drill and want to use the correct shear bolt.

Norm

 

[mogwai]

You will do no harm by using grade 2 instead of grade 5. If you find that you are shearing them too often, you might consider going back to grade 5, but I might just stay with grade 2.

As for size, sounds like 3/8 fits best. I'd keep using them

 

[nap61]

Mogwai,
Thanks for the reply.

Norm

 

[KennK]

Just for further understanding ... Is a Grade 2 bolt "softer" (more likely to shear) than a Grade 5 bolt?

Thanks!

 

[MESSMAKER]

yes
I always use grade 2

 

[gwdixon]

Have to agree with the above responders. Grade 2 bolts are cheap and good insurance. A 5/16" Grade 2 would pretty much guarantee that the bolt would go before the implement vitals. (I'm assuming you are using a PHD since it was not mentioned but it sounds like the job is one for it.)

Odd about the size. I don't have specific data but 3/8" Grade 2 may have a similar shear threshold as 5/16" Grade 5. Use it with caution.

At any rate, using 3/8" Grade 5 would likely void any warranty. If you really want to use 3/8" be sure it is Grade 2

 

[tower59]

Sorry for resurrecting an older thread, but it's very similar to my situation. Recently bought a post hole digger from Tractor Supply, and after lubing it and getting it mounted on the 55HP tractor, I triumphantly made one test hole. And snapped my shear bolt! I have about 75 holes to dig for a fence in our soil which is dirt and clay (no rocks), and don't want to break a shear bolt for each hole I drill. First question: the 5/16th in shear bolt is indeed a little loose, so I'm interested in trying the larger 3/8" size. Has anyone else done this with success? How often should one actually break a shear bolt in non-rocky soil? Any tips to avoid breaking them and to avoid getting the auger stuck in the dirt? Finally, where can you buy these things? I just bought the last package of shear bolts at Tractor Supply, and I want to be digging holes this weekend! Thanks for your help!!!

 

[George2615]

Sorry for resurrecting an older thread, but it's very similar to my situation. Recently bought a post hole digger from Tractor Supply, and after lubing it and getting it mounted on the 55HP tractor, I triumphantly made one test hole. And snapped my shear bolt! I have about 75 holes to dig for a fence in our soil which is dirt and clay (no rocks), and don't want to break a shear bolt for each hole I drill. First question: the 5/16th in shear bolt is indeed a little loose, so I'm interested in trying the larger 3/8" size. Has anyone else done this with success? How often should one actually break a shear bolt in non-rocky soil? Any tips to avoid breaking them and to avoid getting the auger stuck in the dirt? Finally, where can you buy these things? I just bought the last package of shear bolts at Tractor Supply, and I want to be digging holes this weekend! Thanks for your help!!!

The shear bolt should be the size of the hole. If it's smaller it will not last long. A shear bolt smaller than the hole will chuck back and forth in the loose hole. If a 3/8" shear bolt will fit that's what should be there.
Running the digger slow and easy works well. Too fast and it only takes a second to shear a bolt. I believe they should be grade 2 (mine are). Any grade 2 bolt of proper diameter will work. I buy mine either at TSC or a local fastener (nut and bolt) store.
If you get the auger stuck you'll need a big pipe wrench with a pipe slid over the handle to unscrew it from the ground.

 

[SPYDERLK]

Sorry for resurrecting an older thread, but it's very similar to my situation. Recently bought a post hole digger from Tractor Supply, and after lubing it and getting it mounted on the 55HP tractor, I triumphantly made one test hole. And snapped my shear bolt! I have about 75 holes to dig for a fence in our soil which is dirt and clay (no rocks), and don't want to break a shear bolt for each hole I drill. First question: the 5/16th in shear bolt is indeed a little loose, so I'm interested in trying the larger 3/8" size. Has anyone else done this with success? How often should one actually break a shear bolt in non-rocky soil? Any tips to avoid breaking them and to avoid getting the auger stuck in the dirt? Finally, where can you buy these things? I just bought the last package of shear bolts at Tractor Supply, and I want to be digging holes this weekend! Thanks for your help!!!

As for the beginning of the thread -- Total BS.

Get a standard 5/16 grade 5 long enuf so the unthreaded shank goes all the way thru both the shear points. They are available at TSC. No more nuisance but still will shear if you snag a rock or root.

 

[PoorPlowboy]

Shear bolts are supposed to fit snug in the hole. If its wobbly, it will meet an early demise every time.