Tominator Posted April 2, 2005 Report Share Posted April 2, 2005 It mercifully dried out enough to till my gardens this week. So I go out to till my first garden, engage the PTO and notice the PTO is spinning, but the tines aren't. After I shut it down, I noticed I sheared the shear bolt on the drive shaft. So I drove back up to where I stored the tiller and lo and behold, I found the broken shear bolt. Now, from what I remember the stampings on the bolt head determine how strong the bolt is. This shear bolt had a 8.8 stamped on it, so I dug around and luckily I found a 8.8 in my old coffee can and slapped it on. Question--Are all 8.8 bolts the same? I PM'd Snapper, (come to find ooot he's a screw guy, not a bolt guy ), but he suggested getting the right shear bolt, which I will once I go back to work, but I was just curious if the bolt I have on there now will work, or do I need the special bolt? Quote Link to comment Share on other sites More sharing options...
Ohiobucks Posted April 2, 2005 Report Share Posted April 2, 2005 Re: Bolt Guys--Gear Heads Too Two words: DUCT TAPE........ Your welcome, glad I could help. Quote Link to comment Share on other sites More sharing options...
tedicast Posted April 2, 2005 Report Share Posted April 2, 2005 Re: Bolt Guys--Gear Heads Too I believe all 8.8 bolts of the same diameter would be the same strength. Not 100% sure, but pretty positive. With the 8.8 marking it is a metric thread bolt, American thread bolts have a different marking on the bolt head to designate their strength grade. Quote Link to comment Share on other sites More sharing options...
OJR Posted April 2, 2005 Report Share Posted April 2, 2005 Re: Bolt Guys--Gear Heads Too Any good hardware store ought to be able to tell you what the strength of the bolt is! I can't remember how they are rated! Quote Link to comment Share on other sites More sharing options...
Shaun_300 Posted April 2, 2005 Report Share Posted April 2, 2005 Re: Bolt Guys--Gear Heads Too 8.8 bolts are metric bolts. they are made from low or medium carbon steel, quenched and tempered. they have a tensile strength of 600 MPa. (mega pascals) they aren't always the same size. you could have the an 8.8 grade bolt and it could come in many sizes. as for your question, the rule of thumb is to use the same grade bolt that came out of it, or stronger. the bigger the number on it, the stronger the tensile strength is. i knew those first semester notes would come in handy someday. i am in the automotive technician student at college, if you were wondering how i knew all this stuff.... Quote Link to comment Share on other sites More sharing options...
tedicast Posted April 2, 2005 Report Share Posted April 2, 2005 Re: Bolt Guys--Gear Heads Too [ QUOTE ] i am pretty sure 8.8's are the same.. Unless they are made out of a diffrent kind of metal. [/ QUOTE ] If thet were made out of a different metal, then the tensile strength would be different, and they wouldn't be marked 8.8. 8.8 isn't a bolt size, it is a strength rating. Quote Link to comment Share on other sites More sharing options...
texastrophies Posted April 2, 2005 Report Share Posted April 2, 2005 Re: Bolt Guys--Gear Heads Too Hey, just put any kind that will fit, for the time being in there, if it is not strong enough, you will find out pretty quick and if that doesn't happen, then you know that it was strong enough. DO NOT TRY TO USE THAT AS AN EXCUSE FOR NOT GETTING YOUR WORK DONE!!!!!!!!!!!!!!! Quote Link to comment Share on other sites More sharing options...
Tominator Posted April 2, 2005 Author Report Share Posted April 2, 2005 Re: Bolt Guys--Gear Heads Too [ QUOTE ] Hey, just put any kind that will fit, for the time being in there, if it is not strong enough, you will find out pretty quick and if that doesn't happen, then you know that it was strong enough. DO NOT TRY TO USE THAT AS AN EXCUSE FOR NOT GETTING YOUR WORK DONE!!!!!!!!!!!!!!! [/ QUOTE ] Trust me, with my mother in law in the house, I'm making up work just to get out of here. Actually, Chuck, as Snapper suggested, and the real concern, is that if the bolt is too strong, the shear effect will be negated and I could do serious damage to the gear box of the tiller. Quote Link to comment Share on other sites More sharing options...
AJ Posted April 3, 2005 Report Share Posted April 3, 2005 Re: Bolt Guys--Gear Heads Too You can see the different SAE grades here, but are not metric. For metric bolts, the 8.8 is the strength grade of the bolt, 8.8 being a high tensile bolt. Bolt grades vary from about 4.6 - ordinary bolts up to about 14.9 - socket head capscrews and the like. The figures work like this - (for say an 8.8 bolt) The first figure (x 100)is the Ultimate Tensile Strength of the material in N/mm^2 i.e. 800N/mm^2 The first figure multiplied by the second figure (and x 100) is the minimum Yield Strength in N/mm^2 i.e. 640N/mm^2 Quote Link to comment Share on other sites More sharing options...
Tominator Posted April 3, 2005 Author Report Share Posted April 3, 2005 Re: Bolt Guys--Gear Heads Too [ QUOTE ] You can see the different SAE grades here, but are not metric. For metric bolts, the 8.8 is the strength grade of the bolt, 8.8 being a high tensile bolt. Bolt grades vary from about 4.6 - ordinary bolts up to about 14.9 - socket head capscrews and the like. The figures work like this - (for say an 8.8 bolt) The first figure (x 100)is the Ultimate Tensile Strength of the material in N/mm^2 i.e. 800N/mm^2 The first figure multiplied by the second figure (and x 100) is the minimum Yield Strength in N/mm^2 i.e. 640N/mm^2 [/ QUOTE ] Ummmmm, Thanks? LMAO Quote Link to comment Share on other sites More sharing options...
konfuzed Posted April 3, 2005 Report Share Posted April 3, 2005 Re: Bolt Guys--Gear Heads Too Dang a subject I actually know something about and I find it too late. Quote Link to comment Share on other sites More sharing options...
Tominator Posted April 3, 2005 Author Report Share Posted April 3, 2005 Re: Bolt Guys--Gear Heads Too [ QUOTE ] Dang a subject I actually know something about and I find it too late. [/ QUOTE ] Never too late bud, tell me what you know. Quote Link to comment Share on other sites More sharing options...
too_pointer Posted April 3, 2005 Report Share Posted April 3, 2005 Re: Bolt Guys--Gear Heads Too Hey, I learned something today LOL. too_pointer Quote Link to comment Share on other sites More sharing options...
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