Ritothebull
Gold Member
- Joined
- May 5, 2018
- Messages
- 348
- Location
- Brooksville, Florida
- Tractor
- Massey 461 Massey 165 . KTM SDGT
A grade 5 bolt from China is probably equal to a grade 2 USA made bolt if you're lucky. :laughing:
Constantly breaking shear bolts on my cutter....help?
- Thread starter Trophyduck
- Start date
- Views: 71275
darmstrong2319
Gold Member
I have been using grade 5 for years and it always seems to shear when it should. I could not get anything done with grade 2, every time i hit a small clump of grass it would shear so I finally changed it to grade 5 and if I hit something it breaks like it should.
sweettractors
Advertiser
Make sure the blades are sharp to reduce stress on the driveline. Try increasing mowing rpm and slowing ground speed. Ken Sweet
Coyote machine
Super Member
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- May 4, 2009
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- 7,641
- Location
- Southern VT
- Tractor
- 22 SANY SY 50U, '10 Kioti DK 40se/hst KL-401 FEL, loaded tires, KB-2485 bhoe, Tuffline TB160 BB, Woods QA forks, MIE Hydraulic bhoe thumb & ripper tooth, Igland 4001 winch, & GR-20 Log Grapple. Woods BBX72" Brush Mower. Diamondplate aluminum canopy
To the OP, What's the answer to something bent or bound up under the deck surface? If you have a problem and don't solve it, even by going to a stronger grade bolt, eventually you'll break your PTO stub/gears in the rear end- then you'll wish you'd found out what the actual problem is/was.:confused3:
Fallon
Super Member
Believe it or not, they are pretty accurate. Home Depot Bolt vs. USA Made | Offshore Suprise! - YouTube
Personally I always read the manual & follow what it specifies. There are a number of combinations that will work. But unless you read the manual you wont know what the engineers specified for that particular implementation. Just because grade 5 are specified commonly doesnt mean the engineer that designed your machine didnt specify ungraded or grade 8 for some reason.
DK35vince
Super Member
I had the same problem breaking shear bolts on startup with my 6' brush cutter. Solved it with a slip clutch on the brush mower.
The problem was not the mower. The problem was the harsh startup with the electric/hydraulic PTO (even at idle).
OP
Trophyduck
Member
Everything seem to be fine. I can rotate by hand, blades are free. Once it's mowing I'm fine......usually. I got to thinking, I hit a clump of dirt one time and it broke the bolt too. I didn't think that was right since it's supposed to handle a 2" sapling...
Also when running, it's smooth, no vibration or anything like that. I would think if something was bent, it would always shake
DMW
Platinum Member
What is the size of the shear bolt? Have all the bolts that have been shearing from the same batch? Some chinese 3/8" Gr2 bolts can be sheared with hand tools quite easily, they are not all equal. I scrapped a lot of bolts because of this problem.
compact
Silver Member
It may be normal for your setup, I would use the recvomended bolt.
My RC2072 with slip clutch calls for a grade 8 bolt which regularly shears after about 20 hours use. I engage at 600 rpm etc. But the abrupt electric PTO clutch and rocks seem to batter it enough to fail. The clutch is set loose and even then... I think its the free play in the coupler that gives things a running start before the bolt binds up abruptly.
My RC2072 with slip clutch calls for a grade 8 bolt which regularly shears after about 20 hours use. I engage at 600 rpm etc. But the abrupt electric PTO clutch and rocks seem to batter it enough to fail. The clutch is set loose and even then... I think its the free play in the coupler that gives things a running start before the bolt binds up abruptly.
OP
Trophyduck
Member
I got the first batch at TSC....My Father-in-law picked some up at another Hardware store...Those do seem to last longer but probably my imagination.
