Rods
#151
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Cycling the bolts is only important if you're using the torque method. If you're stretching the bolts then it's still a good idea to cycle them a few times, but this is usually done by the time you've done bearing clearances. Friction is a big factor when torquing a bolt, but not so much when stretching.
Last edited by horsepower1; 12-17-2015 at 10:54 AM.
#152
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Joined: Jul 2004
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From: chicago
Cycling the bolts is only important if you're using the torque method. If you're stretching the bolts then it's still a good idea to cycle them a few tines, but this is usually done by the time you've done bearing clearances. Friction is a big factor when torquing a bolt, but not so much when stretching.
#153
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Not really, but it can hapapen. The most critical relationship between the bolt and the rod is the spot face where the bolt contacts the cap. This is one of the major differences between a "cheap" rod and a good quality rod. If that spot face isn't flat, smooth and perpendicular to the c/l of the bolt then cycling the bolts will make more of a difference as those two surfaces mate. Of course, out of square being the worst condition and this can cause all sorts of problems depending on how bad it is. You can chase your tail all day on a cheap rod trying to get a big end round and true but if the bolt spot faces aren't right, it's a no-win situation. I've re-spot faced plenty of import rods.
#154
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From: taxachusetts
I guess most of the diy guys are just getting lucky because there sure isn't that much talk about tips failures from bolts.hydrolocking and reversion,yes,but cycling rods bolts.no way
And I've seen and done a ton of Builds that don't do that.everything from cheap stockers,eagle's to Oliver and full out drag race aluminum rods(and these guys go to 9600rpm).
The lube on the threads and back side are more critical as well as stretch if that's the process you are going to use.
And I've seen and done a ton of Builds that don't do that.everything from cheap stockers,eagle's to Oliver and full out drag race aluminum rods(and these guys go to 9600rpm).
The lube on the threads and back side are more critical as well as stretch if that's the process you are going to use.
#155
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Cycling the bolts is only important if you're using the torque method. If you're stretching the bolts then it's still a good idea to cycle them a few times, but this is usually done by the time you've done bearing clearances. Friction is a big factor when torquing a bolt, but not so much when stretching.
#156
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From: Traverse City, Michigan
I know I'm being a dick but.....................Just to be a technically correct those fastners you're all talking about are called screws not bolts. A screw goes into a threaded hole in the mating part, a bolt is secured with a nut.
and
I'd still be equally concerned with bad threads in the rod causing a issue vs the screw.
and
I'd still be equally concerned with bad threads in the rod causing a issue vs the screw.
#157
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Joined: Dec 2002
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From: Dallas, TX
I know I'm being a dick but.....................Just to be a technically correct those fastners you're all talking about are called screws not bolts. A screw goes into a threaded hole in the mating part, a bolt is secured with a nut.
and
I'd still be equally concerned with bad threads in the rod causing a issue vs the screw.
and
I'd still be equally concerned with bad threads in the rod causing a issue vs the screw.
#160
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From: chicago
Cycling the bolts is only important if you're using the torque method. If you're stretching the bolts then it's still a good idea to cycle them a few times, but this is usually done by the time you've done bearing clearances. Friction is a big factor when torquing a bolt, but not so much when stretching.
Three basic elements that contribute to the friction factor:
Most importantly - The fastener assembly lubricant
The condition of the receiving threads
The surface finish of the fastener
Because of these variables, a phenomenon known as "preload scatter" or preload error occurs. This is basically the difference between the amount of preload achieved on the first installation of the fastener and the amount of preload achieved on subsequent torque/loosen/re-torque cycles. It's not uncommon to see "preload scatter" in the range of 4,000-8,000 pounds between the first and tenth pull on a new fastener depending on the lubricant used.
The Lubricant is the Key
The main factor in determining friction in a threaded fastener is the lubricant used, and therefore influences the torque required for a particular installation. One of the most overlooked aspects of choosing a fastener assembly lubricant is…the lubricant's ability to "control" the normal function of friction inherent in all high performance engine fasteners. As discussed earlier in this section, friction is at its highest point when a new fastener is first tightened. This "friction" inhibits the fasteners ability to achieve the required preload on the first several cycles. In fact, ARP's in-house Research and Development department has proven that new fasteners using motor oil and other commonly used lubricants such as Moly and EPL typically require 5-7 cycles before final torquing to level out the initial friction and achieve the required preload. Slicker lubricants may reduce the required torque by as much as 20-30% to achieve the desired preload, but compromise in areas of major importance such as preload repeatability, and may yield the fastener prematurely. Typically, the slicker the lubricant, the greater the "preload scatter" or preload error there will be during installation.
http://arp-bolts.com/p/technical.php



