O/T Using a Torque Wrench

I need to torque something in in. lbs. and need to use a crows foot on the torque wrench to reach the nut. By installing this crows foot it will extend the torque wrench reach by one inch. How much will this change the torque value? and in what direction. This is on my motorcycle spokes, I would like to have as close as possible. I need 55 in lbs.Thanks Stan

Here is a website with some information.

Rocky in MO
Using a Torque Wrench

Inch pounds with an inch extension measure 1/2 scale reading. Thus your 55/2= 27.5 on the wrench. The wrench is reading pounds of force at 1 inch. Two inches (wrench design plus 1" added, = 2inches. JimN

Motorcycle spokes can usually be tightened by sound. Tap them with the spoke wrench or other metal tool. They should make a sharp ping sound and not a dull sound. You could practice loosening and tightening a spoke to see the difference. A common mistake for some people is to only tighten the spokes that are loose and not make sure the wheel is true. If you have 2 or 3 loose spokes in the same area and just tighten them up, you could pull the wheel out of round. If the spokes are about equally loose all the way around, tighten all the spokes about 1/4 turn. You can start at the valve stem for a good reference. When you do one side, then do the other side. The best way to make sure the wheel stays true is to mount it between 2 centers and have a fixed piece of stiff wire or something similar just missing the side of the wheel by where the tire bead goes. By turning the wheel you'll be able to see the runout side to side and up and down. If it's out a lot, you'll have to loosen some spokes on one side and tighten some on the opposite side to get it aligned. Tightening all the spokes to the same torque is good but won't guarrantee a true wheel. Maybe you can google a motorcycle wheel truer to get an idea? Kind of like using a dial indicator on a lathe but not that critical unless you're going for the land speed record. Hope this helps. Dave

If the crows foot and the torque wrench are at right angles to each other, there is no correction needed.

For the same applied force, the torque with the crows foot will actually be higher. Grab the torque wrench handle where you would normally geip it to apply the force. Measure the distance from the center of the ratched suare drive to the point between your two middle fingers. call this distance A. Then measure the distance from the center of the sq drive to the center of the crowfoot where it grabs the bolt head. Call this distance B.
If the torque spec calls for 100 ft lbs then you will reach that torque when the wrench indicator is at 100 x A/(A+B). So if A = 15 inches and B= 1 inch, 100 x 15/16 = 93.75 ft-lb indicated will be 100 ft-lbs actual.

look here for a calcualator
http://www.norbar.com/Calculators/TorqueWrenchExtensionCalculator/tabid/70/Default.aspx
Ron

Stan, be sure the crows foot is a tight fit on the spoke.Even the spoke wrenches sold with 3 sizes on each end are sloppy.The best spoke wrench is from Buchanons Frame and Wheel shop.[818-280-4003] It is best to just put some tension on the spoke by hand.The torque wrench wont give you any feel to it. If you snap a spoke you will be building a whole new wheel.If the nipple is stainless you must oil first or it will seize.

Test the reality!!!!
Tighten a bolt/nut combo held in a bench vise with some washers stacked between the nut and bolt head. use the torque wrench normally with a standard socket. Mark the nut location with a marker. Put the crows foot/torquwrench on the nut and turn until the mark moves, noting the torque!!!. Reality is a better judge of theory than more theory.
JimN

Hello 37chief,
I know you are not a guest, seen you post before.
Anyhow is is the formula that you need to apply.
It is called pound foot BECAUSE it is based oa the amount of torque applied with a torque wrench that is calibrated to the foot.
1 foot wrench with a 50 pound sack at the other end will exert = 50 footpounds of torque,
Here is the formula:
E= extension lengh
TI= torque indicated
RT= real torque
W = handle to torque axis.
TI= RT x W / W + E.
Here is an example: 12 in wrench WITH A 2.56 in. extension.
w = 12: E = 2.56: RT (TORQUE SPEC) = 125 LB.
TI = 125 x 12 = 1500
12 = 2.56 = 14.56.
1500/ 14.56 = 103. TORQUE APPLIED.
My e-mail is open.
Guido.

Hello 37 chief,
I just need to add some more on my post, to make it a bit clearer. The 125 torque setting on my example will give you 103 ft. Lb. at the fastener, because the lenght of the torque wrench was 2.56 in is longer. In other words it takes only 103 Lb. pressure, with the extension of 2.56 in., to achieve 125 L. Ft. at the fastener.
It also meas that to get 125ft. lb. at the fastener you need to set the torque wrench at 103 Ft Lb. Longer leverage, less effort For a given torque. Also it does not matter if the socket has an extension to the torque wrench.
If the extetion is a crowsfoot, and the head of the torque wrench is perpendicular, not offset to the fatsner, no change in torque applied. If it is offset and makes the lenght of the torque wrench longer, from the sockethead of the torque wrench to the handle, than the formula that i gave you applies.
Also dry threads are not torqued the same as oiled threads. Usually oiled threads are torqued 10 to 20% LESS! Just fallow the manufaturer specifications. You will find that the type of lubricant changes with the manufaturer, form light engine oil to gear oil. All torque specifications Are for clean threads, wet or dry.
Above all, you need to use an accurate torque wrench, steady even pressure while applying torque, and no snappy movements of the arm.
In other words steady pressure,let the torque wrench surprise you when it clicks.
I hope this makes it clearer for you.

Guido.