Grease the threaded portion of your pullers!

[Guest Hal Davis (MODEL A HAL)]

As you may know from my other thread, I was having a problem pulling the rear hubs on the A. I was about convinced that I needed finer threads on my puller until I "crunched some numbers" and found that all I really needed to do was lube the bolt in the center of my puller. My puller used a 3/4-10 bolt. Dry, I calculated that at the 300 ft-lbs or so that I was able to apply by standing on the breaker bar, I was pulling with a force of around 11,000 lbs. If I changed to a fine thread bolt (3/4-16), the force would only increase to 14,000 lbs. If I greased the coarse thread bolt, the pulling force increased to 47,000 lbs! I had never dreamed that so much of the applied torque was being used up by friction, but it was. I came home, put a good coat of grease on the bolt, and voila, she popped off.<P>Moral? Grease the threaded portion of your pullers. You may be able to do away with that cheater bar.

[ply33]

Very interesting. If possible, I'd like to see the calculations. Could you scan them and either email or post them? Thanks, Tod.

[impala]

Great advice Hal. As a Millwright I appreciate the effects of lubricant on torque. Even from one type of lubricant to the next it greatly effects the amount of torque on a bolt. For instance if you're torquing head bolts using a dry torque spec. and you oil the threads you could be over torquing by as much as 50%. I do have more accurate info. at work if anybody needs it.<BR>impala