Shear bolt

[ianamke]

This probably has an obvious answer but I don't want to risk a major gearbox repair. I either lost or sheared off the shear bolt on the PTO driveline of my Betsco flail mower. The PTO driveline is FHM Agri-Machinery. I need to know what hardness of bolt to use for replacement. The manual is no help. From what I can learn a standard driveline takes a #5 bolt, but some say #2 and others #8. Thanks for the help.

 

[North Idaho Wolfman]

#2 will give you more protection as it will shear easier.
#5 will hold up to more abuse, but also allow the fail to take more of it too.
Never a #8, that's not a good shear bolt for really any small equipment.

 

[ianamke]

#2 will give you more protection as it will shear easier.
#5 will hold up to more abuse, but also allow the fail to take more of it too.
Never a #8, that's not a good shear bolt for really any small equipment.

Thank you. I'll go with #5,

 

[D2Cat]

I'd go with #2 and see how they last. Only when that is not long enough use before failure would I go to #5, but it's your hardware!!

 

[Sammy3700]

As always go with wolf man

 

[bbxlr8]

I'm with Wolfman: I have developed an intense interest in this over the years with the 60"mmm on my older tractor. Since moving to PA and the inherent ability of my property to continually "grow" rocks, I have not only sheared the bolt, but also the gear in the driveline for the mid-pto on my 1210 (read as very expensive rare part & splitting the tractor). In its defense, it is shocking the amount of abuse it can tolerate...

Factory New Holland shear bolt is number 5 but after my ordeal and several unfortunate unforeseen attempts at repeating said driveline shock, I have gone to hardware store #2, and then even now put a strategic cut in those.

You want that to be the weak point - full stop!

 

[Magicman]

Use a Grade 8 only if the PTO shaft has a (slip) clutch.

 

[Flintknapper]

#2 will give you more protection as it will shear easier.
#5 will hold up to more abuse, but also allow the fail to take more of it too.
Never a #8, that's not a good shear bolt for really any small equipment.

Agreed.

#2 grade will actually shear.
#5 will shear but tend to bend/tear sometimes making it difficult to drift out of its hole.
#8 is NOT for shear bolt applications.

 

[GrizBota]

A few Grade 2 bolts are probably less expensive than the next weak link in the system.

 

[SDT]

I'd go with #2 and see how they last. Only when that is not long enough use before failure would I go to #5, but it's your hardware!!

Agreed.

Grade 2 unless it shears routinely, then grade 5.

Never grade 8.

 

[BonnySlope]

Grade 5 x 2.5 is the standard shear bolt, at least for the FH-EFGC, just like you had assumed.
You can buy one at a time or in groups, some with relief groves to insure clean shear, some without (hardware store) at a very reasonable price (cheap). Put a manufactures name on packaging and the price goes up. I would think one is all you need in your tractor tool at a time.