Thread: cylinder base nuts
02-10-2010, 01:47 PM #1
- Join Date
- Apr 2009
- winston salem, nc
cylinder base nuts
2 of the base nuts are easily accessed with a socket. the other 2 are not. i took mine off with a 14 mm wrench but i also ground down a socket so that it would fit on the nut. the only thing is about the only way to get the ratchet on the socket is to use a wobble bar ( diamond shaped vs square male insert ) and this creates quite an angle. how in the world do you get these nuts torqued correctly. i'm no engineer but it seems like you would need to have the torque wrench close to 90 degrees to the nut you're torquing for the wrench to read right.
newbie question i know.
how do you guys torque yours down.
Last edited by pslt780; 02-12-2010 at 07:24 AM.
02-10-2010, 02:31 PM #2
02-10-2010, 03:15 PM #3
- Join Date
- Apr 2009
- winston salem, nc
ahhhh. didn't know about those. thanks for the info, tony.
getting ready to split the case and send the crank and jugs to sharp's
won't be long we'll be looking at putting er back together.
cant wait to see that pro this summer.
Last edited by pslt780; 02-12-2010 at 06:38 AM.
02-10-2010, 05:11 PM #4
02-10-2010, 05:25 PM #5
Yep as long as it 90deg to the handle. If it is front of the wrench there is a formula to calculate the torque.
One position is to have the adapter center line at right angles to the center line of the torque wrench. In this position, the indicator reading does not have to be calculated and it may be read direct.
The letters in the formula have the following meaning.
A = length of torque wrench
B = length of adapter
C = torque wrench setting
D = desired torque at end of extension
Here is a typical problem:
You have an adapter 42" long and you want to acheive a torque at the nut of 256 lbs.ft.
Your torqye wrench is 18" long.
So, using the above letters:
A = length of torque wrench = 18
B = length of adapter = 42
C = torque wrench setting = ?
D = desired torque at end of extension = 256
So, with your 42" extension on your 18" torque wrench, to acheive 256 lb.ft at the nut you need to set your torque wrench to 76.8 lbs.
02-10-2010, 05:34 PM #6
This explains variences in torque wrench readings. Not sure about a crows foot. But this is informative info to read.
Torque Wrench Accuracy and Moment of Inertia
Torque accuracy achieved during calibration is not what you will get in actual use
Broken cylinder hold-down stud on Continental IO-520 shows evidence of a loose joint: fretting (rubbing) damage, smooth break to stud (1/2 is missing). Loose joint can be caused by improper torque, OR joint loosening, or loss of preload. Smooth break is typical of fatigue failure. Fatigue requires cyclic stress which in turn requires a loose joint. For more information on this subject
Not only does torque accuracy depends on how the operator uses the measurement instrument - the human factor - but it also depends upon how accurately the calibration lab duplicates real world usage. I call the latter reality errors.
Ideally, calibration of any measurement device should try to duplicate actual conditions under which the instrument will be used. There is an implied trust between the calibration agency and the user that the measurements taken during calibration will relate to the results obtained during use. If the measurements a calibration lab obtains do not relate to the results obtained during usage then the calibration lab's measurements have no meaning.
Sources for reality Errors
The reality error occurs when the calibration lab tests the wrench in artificial conditions that do not duplicate real world usage of the wrench. Under carefully controlled conditions a calibration lab can achieve very accurate and repeatable measurements. The error occurs in that these measurements do not duplicate real world conditions. For example, many torque wrench calibration labs use mechanical pullers. These pullers:
- Wrench mounted horizontal
- Apply the force using constant pressure
- Apply for force at a right angle to the handle
- Apply the force at a specific point on the handle
Is this the way you apply pressure to your wrench? Does anyone using a torque wrench apply pressure this way?
I don't think so. Lets take an example of how reality errors adversely affect you, the user.
Using a name brand 3/8" torque wrench we will apply pressure to the wrench handle just as you might in normal usage:
Wrench is set to 800 inch poundsWrench set to 1000 inch pounds
Wrench pulled horizontal: 800
Wrench pulled vertically: 790
Wrench pulled horizontal with a slight inward twist: 810
Wrench pulled vertically with a slight outward twist: 796
Test results: Wrench pulled using full hand: 1020
Wrench pulled with force applied at specific spot on handle: 1000
Using the first example, in normal usage you should expect to see this wrench to click anywhere from 790 to 810 inch pounds. A calibration lab using a mechanical puller would only detect one reading - probably the 800 reading. What is the correct result? They are all correct in that the wrench gave the same results under the same conditions. However, when the lab reports that this wrench, when set to 800 inch pounds, will snap at 800 inch pounds, they are not correct. This wrench, under normal expected usage conditions, will snap anywhere from 790 to 810 inch pounds. In this case the calibration lab introduced the "reality error".
Lets now say that the calibration lab advertises that their equipment can calibrate with an "accuracy" of 1/2 of 1% Should we be impressed? This means that we can be very confident that the 800 number that the calibration lab reported is indeed 800. This is nice.
But when you use the wrench you may use the wrench horizontally, vertically; you may apply the force fast or slow; or have a slight inward or outward pull. Your and will also not apply the force at the same spot that the calibration lab did. We know how "accurate" the lab's equipment is; We don't know how "accurate" the wrench is! Isn't that what we want to know?
If I had a wrench that always snapped at 800 inch pounds regardless of how the wrench was oriented, how the force was applied, and how I applied the force, wouldn't that wrench be more accurate than the wrench used in the above example. A calibration lab using a mechanical puller would report both wrenches as being the same when obviously they are not - at least not in the real world!
Using a mechanical puller is not the only source for reality errors. How many of you take a torque wrench out of the box where it has been stored and take some "warm-up" snaps. Often, the first snap of a wrench that has been in storage is not accurate.
The reality error gives the user a false sense of accuracy - not only in the calibration lab's accuracy, but also in the accuracy that you will achieve when you use the torque wrench. Engineers who specify torque values need to allow for unavoidable errors when applying a torque.
Snap style torque wrenches exhibit a variance in torque due to:
- Not applying the torque at a 90 degree angle. Worn wrenches exhibit greater error of this type.
- Applying the force to the wrench quickly or very slowly.
- Applying the force on the wrench at different spots on the wrench.
- Applying the force for the first time after the wrench has been in storage
- Moment of Inertia
A rotating body has the same tendency to maintain its state of rotational motion that a body moving in a straight line has to maintain its linear motion. The moment of inertia is a measure of a body's resistance to changes in rotation rate, analogous to mass as the measure of resistance to changes in transitional motion. Specifically, torque T and angular acceleration (designated by the Greek lower-case letter alpha) are related through the moment of inertia I by the equation T = I(alpha) , just as force f and acceleration a are related through the mass m by the equation f = ma.
The moment of inertia depends not only on the mass of the body, but also on the distribution of mass relative to the axis. This distribution accounts for the fact that objects of various shapes with the same masses and diameters (such as sphere, solid cylinder, hollow cylinder, or wheel and axle) will not take the same time to roll down an inclined plane. Objects whose mass is concentrated near the axis have the smallest moment of inertia and thus, reach the bottom of the plane sooner than the others.
If you apply the torque to your wrench quickly the mass of the wrench resists acceleration because of its moment of inertia. This resistance to turning reduces the turning force on the fastener. You apply 40 ft-lbs of force and the wrench snaps at 40 ft-lbs but 5 lbs is used up in overcoming the wrench's moment of inertia and never gets to the fastener. There is probably a better (more accurate) explanation of how the Moment of Inertia can introduce inaccuracies to our torque values -- if you have one please contribute to our understanding.
Where you apply the force to the torque wrench makes a difference in how much torque is applied at a give setting. For example, today, just for fun, I was calibrating a Snap-On click style wrench and thought I'd record some readings for you. With the wrench set to 100 in-lbs, I applied the force on the wrench handle at the very end of the knurled portion of the handle. The wrench clicked at 106 in-lbs., six percent high! Next, I applied the force at the inside portion of the knurled knob. The wrench clicked at 98 in-lbs. six percent high or 2 percent low! Download our Torque Wrench Extension Calculator from The Mechanic's Toolbox
02-10-2010, 05:35 PM #7
Heres another to read as the snows flies!
Keeping It All Together Torque Wrenches- How Good Are They?
By Joseph C. Dille
Part 3 of 3
It is important to have a reliable, accurate torque wrench to properly tighten fasteners to specification. A torque wrench is probably be one of the most expensive hand tools in your collection. In this, the final installment, I explain the differences between the two common types of torque wrenches and explain how to use them. I also share data I obtained by testing a bunch of wrenches.
There are two common types of torque wrenches for home shop use; the "beam" type and the "clicker" type. The beam type torque wrench is shown in Figure 1c and is the least expensive torque wrench. The beam wrench works by the beam bending in response to the torque applied as shown in Figure 2c. This type is very simple, reliable, and accurate, and there is little that can go wrong with it when used properly. When tightening a bolt, make sure to only apply force in the center of the handle. This allows the beam to bend in the manner it was designed to indicate the correct torque. Do not over torque the wrench or the beam may bend permanently. Do not drop the wrench because rough handling can bend the pointer arm or pointer. If the pointer is bent, it can be bent back to the center without affecting accuracy. If the beam is bent it cannot be bent back.
Figure 1c, Parts of A Beam Torque Wrench
Figure 2c, Beam Torque Wrench Operation
Figure 3c shows the clicker torque wrench, which is sometimes called a digital wrench. A clicker torque wrench works by preloading a "snap" mechanism with a spring to release at a specified torque. When the mechanism releases the ratchet head it makes a "click" noise as shown in Figure 4c. The torque is set by rotating the handle until the desired torque is shown in the window. Older clicker wrenches have a micrometer style scale along the handle instead of a window. The clicker wrench is much easier to use because it is easy to set the desired torque and just pull until you feel the click. The ratchet head also makes it easy to use in confined spaces. It is good practice to set a clicker wrench to its lowest setting before putting it away to prevent the spring from taking a set. Avoid rough handling and dropping because it can damage the mechanism. Do not use the torque wrench to loosen tight fasteners since this may damage the calibration.
Figure 3c, Parts of A Clicker Torque Wrench
Figure 4c, Clicker Torque Wrench Operation
I always wondered about the accuracy of torque wrenches, so I made my own torque wrench tester. The tester consisted of a lever arm that lifted a series of weights off the floor. The torque tester is shown in operation in Figure 5c. By changing the position of the weights on the lever arm and changing the weights, I could obtain torques from 3 to 105 ft-lb. The weights were barbell weights that I determined the exact weight using a digital shipping scale. I then calibrated the lever arm by using a precision electronic torque wrench and then back calculated the lengths using my known weights. A known torque exists when the arm is horizontal and the weights jar lifted off the floor. I made a table of lever arm lengths and weight combinations so I could determine the applied torque in any situation. I estimate the accuracy of my home-built instrument to be +/-3% of the calculated torque.
Joey Dille Demonstrating the Torque Tester
Using the torque tester is straight forward. The pivot tube is placed in a vise and the desired weight is placed on the holder. The lifting chain/cable is then adjusted so the lever arm is parallel to the floor and located at the desired length per the torque table. The torque wrench is then inserted into the tester so it is approximately even with the lever arm. For beam wrenches, the wrench is rotated until the weights come off the floor and the indicated torque and applied torque are recorded. For clicker wrenches, the procedure is a little different. The wrench is set for torque slightly below the calculated applied torque. The wrench is then inserted in the tester and rotated slowly until it clicks. The wrench is set for the next higher torque increment and tried again. Successively higher torque settings are tried until the weights can be lifted from the floor without the wrench clicking. The highest setting where the wrench still clicked was recorded along with the applied torque. I learned that it was important to rotate the wrench slowly to avoid premature clicking caused by the inertia of the weights.
Once complete, I decided to use my new toy to check a bunch of torque wrenches to see how good they really were. I asked my friends in the Mac-Pac* to bring their torque wrenches to one of our wrench sessions at Bruceís garage. I was able to test a total of 13 wrenches, 3 beam, and 10 clickers. The results of my testing is shown in Table 1c and Figures 6c and 7c. I found the clickers to be much more repeatable than I expected. The beam type and clickers were both fairly accurate and linear over their range. The bottom line is torque wrenches, even inexpensive ones, were quite good.
Owner Size Type Range
ft-lb Maximum Error Average Error ft-lb % ft-lb % Joe 3/8 Clicker 5-75 -7.3 -12.3% -5.0 -11.0% Joe 3/8 Beam 2-50 1.3 0.3% 0.6 0.2% Roger 3/8 Clicker 2-21 -1.6 -13.9% -0.8 -8.6% Bruce 3/8 Clicker 2-21 1.0 5.3%0.8 1.7% Mike D. 3/8 Clicker 10-80 1.2 0.6% 0.2 0.1% Wayne 3/8 Clicker 10-75 -2.8 -6.8% -1.6 -4.0% Joe (new) 1/2 Clicker 10-150 -4.3 -4.7% -1.7 -2.4% Joe (old) 1/2 Clicker 10-150 4.7 -10.7% 0.2 -0.6% John 1/2 Clicker 10-150 -3.3 20.0% -1.0 1.1% Mike D. 1/2 Beam 5-150 7.8 28.1% 4.9 12.7% Ron 1/2 Beam 5-150 -4.3 -6.8% -2.5 -4.3% Bruce 1/2 Clicker 25-250 -1.8 -3.4% -0.8 -1.3% Mike B. 1/2Clicker 10-150 2.73.9%1.22.0%
If you wonder about the accuracy of your wrenches, you can get them calibrated by a Snap-On tool dealer or a local metrology lab. Griotís Garage can also calibrate torque wrenches on a mail order basis for $25 plus shipping.
Torque Wrenches and Accessories
From time to time people have asked me if it is OK to use an extension with a torque wrench. The answer is yes. Using an extension or reducer with a torque wrench does not affect the accuracy. Others have asked if it is OK to use a universal joint with a torque wrench. The answer is NO. Universal joints change the torque as the drive angle increases. I checked this out with my torque tester. The results are shown in Figure 8c. Donít use universal joints with torque wrenches.
Torque extensions are sometimes required to tighten fasteners in locations where the torque wrench will not fit such as the drive shaft flange on older airheads. Figure 9c shows the extension I made for this purpose. To work correctly, one must understand how the position of the extension affects the torque as shown in Figure 10c. There is a formula for relating actual bolt torque to the wrench torque based on the length of the wrench and extension and the angle between the two. It is best to keep the two at right angles so the torque will be the same.
Figure 9c, Home-Made Torque Wrench Extension
Figure 10c, Proper use of Torque Wrench with Extension
02-10-2010, 05:45 PM #8
- Join Date
- Oct 2006
- Cleveland OH
Instead of a wobble shaft, I use a universal. Works just fine with Snap On sockets. (best sockets in the biz IMO)
Not sure about the exact torque reading though....
02-10-2010, 06:05 PM #9
I have some snap-on tool sockets that are thin wall type. maybe that would work for those tight places! sometimes just that little bit of clearence is enugh.
02-11-2010, 10:24 AM #10
Cylinder base nut tool
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