Torque to Yield Fasteners
#1
Torque to Yield Fasteners
Hey all, a tech question here. I'm a licensed tech and replacing the clutch on a 2008 Ranger 4x4. After installing the flywheel after machining, I went to install new inverted Torx head torque to yield bolts. While my apprentice was assisting, I followed the fastener specs, performing the first two passes with torque wrenches. Upon the last pass while turning the bolts 90 degrees, my assistant's bar slipped, the flywheel spun, and completely lost track of which were tightened and which were not. I have a truck that needs to be put together, nobody stocks the bolts, and even with an emergency delivery, they're still six hours away. Do any techs out there know what the approximate torque value is after the last 90 degree pass? I don't want to take any chances with a critical fastener and I will suck it up and buy more bolts if I have to, but I'm just curious if anyone has any ideas. Any input is gratefully accepted. Thanks, Ted.
#2
RF Veteran
iTrader: (1)
Pick a bolt and mark it
Set torque wrench to last ft/lb you used
Try tightening, if all have been tighten to that ft/lb then it should "click" or show that.
Increase ft/lb by 10ft/lb
Try it again, if it starts to move then that one hasn't been "90deg-ed"
90deg it
Move to next bolt
As far as the one that has been partially 90deg-ed, once you have a known 90deg-ed bolt you can test it's ft/lb by increasing your wrenches ft/lb until that know bolt moves, 5 more degs won't hurt anything, then back down torque wrench 5ft/lb and check all the bolts with that torque setting.
TTY bolts are tighten this way(degrees) so friction between bolt threads and crank threads(or block or ??) don't come into play like they do when using ft/lb, 90deg is 90deg so there is no exact ft/lb comparison that can be used, you are just best guessing but that will be fine.
ft/lb tighten bolt could be holding pressure of 3,000lb or 6,000lb depending on how clean and matched the threads are, TTY eliminates that large a margin, makes the holding power more uniform.
Set torque wrench to last ft/lb you used
Try tightening, if all have been tighten to that ft/lb then it should "click" or show that.
Increase ft/lb by 10ft/lb
Try it again, if it starts to move then that one hasn't been "90deg-ed"
90deg it
Move to next bolt
As far as the one that has been partially 90deg-ed, once you have a known 90deg-ed bolt you can test it's ft/lb by increasing your wrenches ft/lb until that know bolt moves, 5 more degs won't hurt anything, then back down torque wrench 5ft/lb and check all the bolts with that torque setting.
TTY bolts are tighten this way(degrees) so friction between bolt threads and crank threads(or block or ??) don't come into play like they do when using ft/lb, 90deg is 90deg so there is no exact ft/lb comparison that can be used, you are just best guessing but that will be fine.
ft/lb tighten bolt could be holding pressure of 3,000lb or 6,000lb depending on how clean and matched the threads are, TTY eliminates that large a margin, makes the holding power more uniform.
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