This is another example of where the internet is at its best and at its worst. Tom has obviously spent a good amount of time putting this info together and sharing it. For that he deserves credit. On the other hand this is not 1998. The site needs to be tweeked to provide better organization and a clear purpose. High marks for effort, mediorcre marks for execution.
One big criticism. Tom states,
I HAVE FOUND THE BAR STYLE TORQUE WRENCH TO BE MORE THAN ADEQUATE WHEN TIGHTENING THE FASTENERS AND IT COST A LOT LESS THAN THE ADJUSTABLE STYLE WRENCH.I have to disagree with this. A bar type torque wrench is about as truthful as a 5 year old trying to explain cookie breath before dinner. A click style torque wrench
is pretty cheap when you watch for a sale and is dead on for getting head, case, and transmission bolts exactly even.
I disagree with your opinion on torque wrenches. The beam type is bone simple and does not lose accuracy with age or use. Cheap old technology.
ReplyDeleteA quote from Wikepedia:
Click type torque wrenches are precise when properly calibrated—however the more complex mechanism can result in loss of calibration sooner than the beam type, where there is little to malfunction. Beam type torque wrenches are impossible to use in situations where the scale cannot be directly read—and these situations are common in automotive applications. The scale on a beam type wrench is prone to parallax error, as a result of the large distance between indicator arm and scale (on some older designs). There is also the issue of increased user error with the beam type—the torque has to be read at every use and the operator must use caution to apply loads only at the floating handle's pivot point. However, for inherent accuracy, the beam (P.A. Sturtevant / Chrysler Engineering) type wins hands-down[citation needed]: As long as the pointer is free to move, and rests at zero (or is bent to achieve this), 100% accuracy is inherent -- no matter how shoddy, rusty, dinged, etc., the tool may appear. Dual-beam or "flat" beam versions reduce the tendency for the pointer to rub, as do low-friction pointers.
For the click type, when not in use, the force acting on the spring should be removed by setting the scale to 20% of full scale in order to maintain the spring's strength. Never set a micrometer style torque wrench to zero as the internal mechanism requires a small amount of tension in order to prevent tool failure due to unwarranted tip block rotation. If a micrometer tool has been stored with the setting above 20% the tool should be set to 50% of full scale and exercised at least 5 times before being used. In the case of the beam type, there is no strain on the component that provides the reference force except when it is in use, therefore, accuracy is inherent
Here is my thinking. Beam types, as is cited, require precise user interaction. My experience is that this is rarely possible. Parallax error is the most common problem and there are others.
ReplyDeleteA click type torque wrench takes that human element out of the equation. Torquing the sprocket nut is fine for a beam type but torquing head nuts or case bolts is not. The critical element is that ALL the head nuts be torqued to EXACTLY the SAME value. If it is +/- 5% that is OK so long as they are ALL torqued to the same error. Same with the case bolts clamping the crankshaft and transmission shafts.
Most click type wrenches have the added advantage of "releasing" for about 5 degrees when the target value is reached. This is further insurance that all the bolts are torqued symmetrically.
I do agree that they must be reset to a minimal value after use and re-calibrated periodically.