Home
Basic Dirt Bike How-To's - Video
Dirt Bike How-To's - Video
Living The Moto Life - Video
Bike Tests | Shoot-Outs - Video
Forums
What's new
Latest activity
Log-In
Join
What's new
Menu
Log-In
Join
Navigation
Install the app
Install
More options
Close Menu
Forums
Dirt Bike Discussions By Brand
Canadian Daves JustKDX
Torque wrench needed, reasonable suggestions?
Reply to thread
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Message
[QUOTE="Rich Rohrich, post: 1412397, member: 16241"] Actually... ;) [i]( I know mudpack is an engineer, so this is just general info to add to the thread, not directed at him. He has probably forgotten more about the subject than I know)[/i] ... all bolts and studs (regardless of material makeup) are slightly elastic and must be stretched a small amount to develop clamping force. A common engineering rule of thumb is a stretch of .001 inch per inch length of a fastener develops about 30,000 psi clamping force in steel. When you under torque something there isn't any stretch in the fastener and the clamping force will be inadequate. If you over-torque a bolt or stud it can be stretched beyond it's elastic limit and the "springiness" that provides the clamping force will be lost and the part will fail. Measuring the bolt length difference (or stretch) from an unloaded state to a loaded state is the standard way to "torque" connecting rod caps in high performance plain bearing engines Along with the clamping force you apply fasteners constantly stretch and return to their original shape in the course of holding together the parts. A fastener that has gone past it's elastic limit will not be able to function in this stretch -return cycle and will usually fail. There are a limit to the number of stretch return cycles a fastener can handle, but for non-critical bolts with proper torque most of us will never reach the fatigue limit of a good quality bolt. That chinese junk they sell at Home Depot is another matter entirely ;) There are lots of other things involved with this but probably the most important for our purposes is the influence that lubrication on the bolt plays in the final torque reading. Overcoming the fastener friction accounts for a major portion of the torque required to turn a fastener. A dry bolt might obtain the same torque reading as a properly lubed one, but the clamping force applied will be much higher on the lubed bolt because more of the applied torque will be converted into useable clamping force. The OEM's base their torque specs on a torque readings obtained by a low friction lubed connection, so if you plan to use a torque wrench, you need to break out the moly based assembly lube as well. There is an old motorcycle adage that has served me well over the years. [i] Every bolt needs lube or loctite. Nothing goes together dry.[/i] As mudpack pointed out, the root interface for studs or bolts when a steel fastener is threaded into aluminum is also a common point of friction and subsequently becomes a common cause of failure. The fastener can't stretch and apply clamping force if the aluminum threads (the root interface) can't support the load. You need enough contact area between the steel fastener and the aluminum threads to provide the clamping force. Having a good set of metric bottoming taps around to maintain aluminum threads can make all the difference over time. If you measure a few bolts the next time you are working on your bike you'll find the Japanese are very disciplined about following the engineering standard of providing a minimum threaded depth into aluminum of two times the diameter of the bolt. Drop a bolt in a side case hole and measure the distance from the bottom of the bolt head to the case and you'll see what I mean. This is a standard trick to figure out where a bolt goes if you are not sure. Drop it in the hole and if it doesn't stick out 2xdiameter then it's not the right one. To sum it up : - Use clean high quality bolts - Use moly based lube on the bolts - use an accurate torque wrench within it's usable range - DON'T OVER TORQUE [/QUOTE]
Verification
Which ocean is California closest to?
Post reply
Forums
Dirt Bike Discussions By Brand
Canadian Daves JustKDX
Torque wrench needed, reasonable suggestions?
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
Accept
Learn more…
Top
Bottom