Questions for the ME'S

[jimoshel]

After 30 years of faithful service, winching everything from a 5hp riding lawn mower to a 1923 LaFrance fire engine my winch broke. There are 8 bolts, 4 on each end holding the motor to the gear box. They worked loose and then sheared off. There was nothing locking the bolts, no lock washers or Loctite altho I understand you don't use lock washers on aluminum. I got the broken stubs out on one end but no way in H* could I remove them from the other. I rotated the plate maybe 20 degrees and drilled and tapped 4 new holes, 1/4X20. I have this information someplace but as usual I can't find anything when I want it so taking the easy way and asking on CC.

What should I torque the bolts to in aluminum? What would be the best way to lock them? I prefer not to use LocTite on the threads but will if necessary Would prefer to just use something on the bolt heads, 4 of which will be in the open and 4 which will be inside the gearbox, in oil.

Come on fellas. Help me get another 30 years of service out of this thing. Jim

:hmm:

[HellCreek]

Hi, Jim,

 

With 1/4-20 screws into aluminum, I wouldn't torque much more than 10-12 ft.lbs. As for locking them, if you don't want to use Loc-tite, then you might try "shake proof" washers. I'm sure you know what these are, but in case you don't, they are thin steel washers with locking "teeth" either on the inside diameter or the outside diameter. They will hold without doing as much damage as a spring washer. While I was drilling and tapping, I personally would have gone to 5/16-18 bolts.

 

-Tom

[gl1200aman]

wouldn't the larger 5/16 hole make the walls too thin and allow the walls to crack?

[HellCreek]

wouldn't the larger 5/16 hole make the walls too thin and allow the walls to crack?

 

 

a 5/16" hole is only 1/16" larger in diameter, meaning it is only 1/32" (0.03125") larger in radius, so it would only remove 0.03125" from the walls of the hole. From the pictures, you could easily drill a 3/8" hole without affecting the wall integrity appreciably.

 

-Tom

[sinkrun]

The star washers are a great idea for aluminum I believe they make lock Tite for aluminum also? If you have alot trouble with the threads again I would Heli-Coil them. You can retain the 1/4 size but will have steel inserts in the holes and its MUCH stronger than aluminum that it will be in. The military and aircraft industry them alot and you can do it yourself. Its not cheap though as your buying a tap and drill in the kit.

[HOrnbrod]

Lock wire. http://www.rc51.org/wire1.htm