By Eric B
While doing my 2H diesel swap, I had to remove the timing gear cover and that involved removing the crankshaft pulley. Removing the nut was easy with an air impact gun. Once time to install the nut, I checked the torque required, 325 ft lb, and realized I didn’t have a torque wrench that size. I didn’t want to pay the costly amount for one that size and attempts to borrow or rent one failed. After a few days of thinking about what to do, I realized I can use my 150 ft lb wrench and multiply the torque using an extension.
The extension I am referring to is not a socket extension which extends perpendicular to the wrench, but an extension to the output end extending horizontally that effectively changes the length of the wrench itself. Lets say the torque wrench was 1 foot long, so you are applying 100 pounds of force for a 100 ft lb reading on the wrench. Now add a 2 foot extension, now that 100 pounds is actually 3 feet from the bolt. Now the bolt sees 300 ft lb of torque.
To find out the length of extension needed, you will have to use some math.
torque wrench setting = desired torque + wrench length / (wrench length + extension length)
To find the length of your torque wrench you measure from center of the socket head to the center of the handle. My 150 ft lb wrench measured 18 inches long. To obtain the 325 ft lb needed, I needed a 21 inch long extension.
I picked up a piece of steel flat bar that was 1.5 inches wide and 1/4 inch thick, and a 5 inch long 1/2 inch drive impact socket extension to use for the ends of the extension.
I drilled two 5/8 inch holes 21 inches apart. I then cut the socket extension in half and placed them opposite each other in the holes I just drilled.
Now weld them in place. Once welded, cut off the excess and admire the $20 spent for a larger torque wrench.
Remember to make sure that the torque wrench is positioned straight in line with the extension to achieve the desired torque for the extension just made. Any angle other than that will change the overall length, effectively changing the torque value put on the bolt.
