Gear Box Screws are Backing Out

[cprice12]

So the mounting hex screws for my gear box keep backing out on my Bush Hog ZT25 zero turn.
I've used lock washers (which is factory) and applied loctite. And after an hour and a half of mowing, they backed out again.

You guys have any tips, tricks or ideas on how to keep those damn things from backing out?

Thanks, as always.

 

[reynoldston]

What Loctite are you using? Are you torqueing the bolts to the proper lbs. If this is all good there has to be a problem with the threads or bolts. Maybe try some lock nuts?

 

[cprice12]

What Loctite are you using? Are you torqueing the bolts to the proper lbs. If this is all good there has to be a problem with the threads or bolts. Maybe try some lock nuts?

The Loctite is in a stick form, like a glue stick...it's blue. I don't have it in front of me if you are looking for more info.

The screws go into the gear box. They don't stick out the other side, so I can't use lock nuts.

I have no idea what the proper torque would be. I tightened them until they were snug. I have a torque wrench, but not sure what to set it to.

 

[motoman]

On the head of the cap screw is tensile strength mark (should be , don't use low unmarked commercial grade). Identify the cap screw thread diameter and go on line or in this forum to find the torque range. Use a thread chaser rather than a tap , if possible, if cleaning out the threads. Locktite usually wants "primed" threads before applying. Check the bottle. Dirty threads will not lock with threadlock. In a pinch I have used brake cleaner. If the threaded holes enter the gearbox sump and you do not want spray cleaner entering try using a clean cloth saturated with brake cleaner or alcohol and work each hole 'TIL THE CLOTH IS CLEAN." Clean male and female threads. Hope this helps.

 

[reynoldston]

They also make a stronger Loctite. Its red in color. If used proper the problem is that you need heat to remove the bolts.

 

[exotion]

They also make a stronger Loctite. Its red in color. If used proper the problem is that you need heat to remove the bolts.

rigid impact cordless gun works good to.

 

[reynoldston]

rigid impact cordless gun works good to.

I looked that impact up on line. Sure looks like a nice outfit that puts out 300 ft. lbs. Got me thinking it would make for a nice addition to my shop. Now back to the post. Over tight is just as bad as under tight. It all depends on the bolt size, type, and then use a hand torque wrench. You just can't get a good torque value with a impact wrench. Not saying a impact doesn't have its place, because I use them all the time.

 

[exotion]

I looked that impact up on line. Sure looks like a nice outfit that puts out 300 ft. lbs. Got me thinking it would make for a nice addition to my shop. Now back to the post. Over tight is just as bad as under tight. It all depends on the bolt size, type, and then use a hand torque wrench. You just can't get a good torque value with a impact wrench. Not saying a impact doesn't have its place, because I use them all the time.

I've never used an impact to put screws and bolts in, just out.

Generally I like to tighten them hand tight then 1/4 turn more

 

[reynoldston]

I've never used an impact to put screws and bolts in, just out.

Generally I like to tighten them hand tight then 1/4 turn more

Yes with some of the newer style gaskets that is the proper way to tighten. I do use the impact to install some bolts but then tighten by hand with a toque wrench. Just a faster way.