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.

 

[sdef]

In my limited experience, shear bolts are an iffy piece depending upon ones conditions. The grade 1 or so in the flair mower worked just fine as it was just twirling away spinning grass cutting blades that never impacted anything substantial. However, My Fred Cain subsoiler's shear bolt snapped every time it dove into my very rocky soil; I could not get any work accomplished and it was frustrating. I went to grade 5 bolts and all is well with no shear bolt breakage and no damage to the equipment.

If I had an auger's gear box to content with in my soil, I would use a slip clutch, which I have in storage waiting for my auger selection.