hello all, In the process of inspecting a 39 or 40 59ab engine. I pulled a main cap to check the bearing and it looked great so I am putting it back together. Spec is 80-90 ft. lbs On one of the studs 85 lines the safety wire hole up perfectly, on the other stud 85 blocks the hole perfectly. My question is do I add or remove torque to make the hole line up? Thanks for the input. Chappy
if you really want to be fussy you try a different nut, or go tighter until it lines up. generally speaking, never go backwards
Thanks, I was really concerned about going beyond the max torque spec as this is on a main bearing. Below is a picture of what i was dealing with. At 85lbs there was no way I was going to tighten or loosen enough to clear the hole without being way over or way under the spec. I ended up swapping nuts side to side and was able to get the holes to line up enough to get a safety wire installed... However one nut is now at the lower end of the torque range and the other is at the upper end.
Generally speaking anytime a fastener won't line up within the torque range, technically the answer isn't "go ahead - exceed the torque spec." I mean, duh, right? Technically. Try a different nut, a new one. Those look pretty trashed. Or use a peelable shim. This is a fancy name for a thin washer. Magic! I'd wonder what if something hasn't stretched or buggered. They taught us the alternate nut or peelable shim method in aviation school, but I don't recall having to use it very often, and I de-installed and re-installed a shitload of fasteners like that. Is your torque wrench calibrated?
Why not use self locking nuts. Nylocs or Aerotight/Aeroloc if you are concerned about the Nylocs' locking ability failing at temperature -never had that problem yet myself.
I’m with blowby. Fine sandpaper on a flat surface move nut in a figure 8 pattern to thin the nut. It doesn’t take much. You may not get it the first time but will quickly get a feel of what you need. I’ve done it hundreds of times and I learned this from someone in the aircraft field with a licensed airframe mechanic. Sent from my iPhone using H.A.M.B.
The stud itself might have moved a little,,,,a fraction of a turn would do it . Then the nut would not line up when reassembled . I am assuming it lined up correctly when you took it apart ? Tommy