Bulldog Main Bolts/Nuts Torque....
02-23-2006, 09:50 PM
#11
Registered
Re: Bulldog Main Bolts/Nuts Torque....
Rob,
I dont think you can really compare them that way. The bolt is usually coarse thread and the stud fine thread. That makes a difference in the amount of torque required to achieve the same amount of stretch. Also, the lubricant used makes a big difference. There are also differences in materials that come into play. A mild steel bolt or stud will stretch a lot more than a high strength one at the same torque reading.
Steve, I am not trying to be "smart". I have been building engines for over 30 years and the one thing I have learned is to listen to manufacturers. That rule has served me well as I have had very few failures of any type. Technology is changing so fast that it is difficult for anyone to keep up with it. I will not guess on anything. If I dont know the answer, I will call someone and find out.
As far as tightening studs ... try this test... put a stud in a block and tighten it up good. Put a good machinists square up against it and I will bet you that it will not be pefectly perpendicular to the block surface. If you were to torque it in that position, you will be bending the stud ever so slightly. If you leave it slightly loose, it can "float" as you tighten the nut, this will pull the stud straight up and not bend it.
I dont think you can really compare them that way. The bolt is usually coarse thread and the stud fine thread. That makes a difference in the amount of torque required to achieve the same amount of stretch. Also, the lubricant used makes a big difference. There are also differences in materials that come into play. A mild steel bolt or stud will stretch a lot more than a high strength one at the same torque reading.
Steve, I am not trying to be "smart". I have been building engines for over 30 years and the one thing I have learned is to listen to manufacturers. That rule has served me well as I have had very few failures of any type. Technology is changing so fast that it is difficult for anyone to keep up with it. I will not guess on anything. If I dont know the answer, I will call someone and find out.
As far as tightening studs ... try this test... put a stud in a block and tighten it up good. Put a good machinists square up against it and I will bet you that it will not be pefectly perpendicular to the block surface. If you were to torque it in that position, you will be bending the stud ever so slightly. If you leave it slightly loose, it can "float" as you tighten the nut, this will pull the stud straight up and not bend it.
02-23-2006, 10:42 PM
#12
VIP Member
Re: Bulldog Main Bolts/Nuts Torque....
I never thought about the stud bending over like you said if you put it in over hand tight.
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02-24-2006, 07:24 AM
#13
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Re: Bulldog Main Bolts/Nuts Torque....
axial deformation ( stretch) is defined by the formula PL/AE where P is the axial load, L is the length, A is the cross sectional area, and E is the modulous of elasticity for the material. so it is clear that length is a factor in determining how much force is required for a given stretch. the manufacturer will determine thru what ever means how much clamp load they want and, as such how much pre load they want as defined by how much they stretch the bolt .... the load is achieved thru the unit loading on the threads... which is a whole other set of calculations... which is why the thread lube is so important because the frictional aspect of the tightening procedure is very significant if you are TORQUING bolts... as opposed to actually measuring the stretch. when they give you a torque number they are saying " put THIS radial load into these threads at this frictional level and THAT will translate into THIS axial load that will then RESULT in this stretch... and everything will be fine" once you deviate from what they tell you in any way you introduce a variable that makes their torque number ' wrong" . wrong enough to hurt you ? maybe.. maybe not.... no way to know.
as for loose studs... no way on the planet am i pulling up a stud that is loose in the anchoring threads ...i.e zero preload.
that would be transfering the loads to the slope of the thread as opposed to the root which emprical testing proves reduces t the load carrying capacity by as much as 50 %.... won't happen on my watch.
not saying clamp vice grips on them and reef on them until they sieze but a little oil or loctite and a small double digit torque number is sufficient to preload the stud and allow proper load transfer. thats what THEIR engineers told me which confirmed everything i already knew... we had this conversation when carrillo sent me connecting rods for a 500 hp motor w/ 5/16 rod bolts and my hands sweat so bad when i looked at them that i just couldn't BELIEVE they would work... i conferred w/ the engineers and they showed me the numbers and .. of course.. they were correct... and none of those bolts ever broke or came loose.
as for the studs being straight.... that depends on what you mean by straight... i would suggest that if your hole is tapped crooked enough to worry about this or that the stud is that badly made then one or the other or both need to be corrected... and that allowing the stud to " self center/align" on the edge of one side of the threads and bury itself in the root of the other side is not a trade off i would make at all. i suspect we are talking about "angels dancing on the head of a pin" in a zillion motors, the only times i had problems with studs being straight where when guys had tried to drill and tap blocks for helicoils or bigger studs or something and screwed them up. the factory stuff has always been satisfactory with a zero failure rate in my experience.
as for loose studs... no way on the planet am i pulling up a stud that is loose in the anchoring threads ...i.e zero preload.
that would be transfering the loads to the slope of the thread as opposed to the root which emprical testing proves reduces t the load carrying capacity by as much as 50 %.... won't happen on my watch.
not saying clamp vice grips on them and reef on them until they sieze but a little oil or loctite and a small double digit torque number is sufficient to preload the stud and allow proper load transfer. thats what THEIR engineers told me which confirmed everything i already knew... we had this conversation when carrillo sent me connecting rods for a 500 hp motor w/ 5/16 rod bolts and my hands sweat so bad when i looked at them that i just couldn't BELIEVE they would work... i conferred w/ the engineers and they showed me the numbers and .. of course.. they were correct... and none of those bolts ever broke or came loose.
as for the studs being straight.... that depends on what you mean by straight... i would suggest that if your hole is tapped crooked enough to worry about this or that the stud is that badly made then one or the other or both need to be corrected... and that allowing the stud to " self center/align" on the edge of one side of the threads and bury itself in the root of the other side is not a trade off i would make at all. i suspect we are talking about "angels dancing on the head of a pin" in a zillion motors, the only times i had problems with studs being straight where when guys had tried to drill and tap blocks for helicoils or bigger studs or something and screwed them up. the factory stuff has always been satisfactory with a zero failure rate in my experience.
02-25-2006, 12:04 AM
#14
Re: Bulldog Main Bolts/Nuts Torque....
Ok steve you showing out . making my head hurt 
Rob
Rob
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The Only Time You Have To Much Ammo Is When Your Swimming Or On Fire.
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The Only Time You Have To Much Ammo Is When Your Swimming Or On Fire.
