Shackle Mount: Drill & Tap or Thru Bolt?

[R.E.M.]

I recently bolted up my winch mount to my FJ60 that I got made that wraps around the outside of the frame rails. To attach recovery points to this I want to bolt 1"x3" flat bar to the INSIDE of the frame rails, basically sandwiching the frame between the winch plate and the 1x3. The 1x3 will stick out far enough to allow a standard 3/4" shackle to hang on the front.

Right now, I'm leaning toward drilling and tapping 4 1/2"-20 holes in each mount that matches the hole pattern in the frame and the plate. This would be cleaner looking than having nuts and washers, take up less space and lower hardware cost. Downside would be buying the tap and tapping 1" steel. Any reason why I should use a through hole with nuts and washers?

Welding is not an option because I'm trying to avoid welding to the frame for this bumper project.

 

[GLTHFJ60]

My SROR bumper has holes drilled through with nuts welded to the inside of the mounting bracket. You get the same effect as tapping, but it's much easier to tack weld a nut to that bracket than to tap 1" steel imo.

 

[Fast Eddy]

If you've got a good way to tap 8 1" holes, I see no reason for nuts. Use lock washers on the bolts.

 

[rusty_tlc]

Tapping that many holes by hand would be a chore. I'd take that job to a machine shop that has the correct equipment.

If you go with welding captive nuts on remember to run a bolt through the nut before you weld or the threads will be distorted.

Through bolting would probably be my last choice.

 

[R.E.M.]

Didn't consider a weld nut on the inside. That would be easier than tapping my hand. I'll have to see what kind of help I can get from the guys in the machine shop here at work.

I'll probably use loctite instead of any lock washers.

 

[rusty_tlc]

....
I'll probably use loctite instead of any lock washers.

I'm a belt and suspenders guy I'd use both.

 

[Mace]

I tapped both ends of my 60's Bumpers. Not a big deal. And very strong. Welded nuts would be just as effective tho.

 

[camcruiser13]

good tip on putting the bolts in as you weld. not easy to bolt something down when the nuts are full of splatter

 

[rusty_tlc]

good tip on putting the bolts in as you weld. not easy to bolt something down when the nuts are full of splatter

It's more to keep them from warping than keeping splatter out. Because the heat isn't applied uniformly the nut will expand faster in one direction than the others, it never comes back into shape unless there is a bolt to hold the shape of the threads as it cools off.

 

[Dynosoar]

I usually grease the bolt up too before welding the nut.

Dyno