Torquing Large Fasteners

This is a question that comes up pretty regularly so I thought it would be wise to address it on this page. The question is how to torque large nuts such as the rear axle nut or the flywheel gland nut without having a torque wrench. Accurate torque is important for these nuts, and luckily there is a way to do it without a torque wrench.

First, you need the proper tools. The rear axle nut for the air-cooled cars is 36mm, and for the Buses/vans it is 46mm. The flywheel nut is also 36mm on Type 1 engines. So, the proper tool here is a 6-point 36mm and/or 46mm socket, ideally welded to a 6-foot long piece of cheater pipe (basically a thick, heavy pipe to give the leverage necessary for the task). Bob Hoover has a 6-foot long pipe with a 36mm socket welded to one end and a 46mm socket welded to the other end.

The proper use of the tool can be found through some very simple math. First you need the torque specification for the particular nut. Check your Bentley manual. Let's say for the sake of example that the torque spec for the rear axle nut is 300 foot-pounds. And let's say for the sake of example that you weigh 150 pounds. Well, you simply divide the 300 foot-pounds by the 150 pounds, and that gives you 2 feet. The two feet is the distance from the center of the nut that you will apply force. So go out two feet on your cheater pipe. Make a mark at the 2-foot point and put one hand on either side, right up to the mark. Then push down and keep pushing steadily until your feet clear the floor. Don't jump up and down on it or anything like that. That will give you the proper torque. Then you have to make sure that the hole for the cotter pin is aligned so go tighter if you have to, not looser, whichever is closer, to get the holes lined up and there you are.

Now that you know the mathematical relationship, you can simply substitute the real numbers into the equation for the example numbers above.