Question for 4x4 Labs rear bumper owners

[Surfdc]

My rear bumper will arrive soon and I’m removing old bumper in preparation and forgot that years ago I removed the captive frame nuts to double-bolt my recovery points.

Can I still mount new bumper? Can I reach in? Accessible holes to reuse my nuts? Through- bolt?
Thank in advance!

 

[Rusty Marlin]

You could reach in there and tack the nuts in place.
Obviously pull the closest one out first to give access to the back one, then put the close one back in and tack it.

It would probably take longer to get the welder out than complete the job.
Other than that, I can offer no other assistance as I haven't got a 4x4 labs bumper....yet.

 

[MUDZLLA]

Double Bolting is a thing? From a tensile strength standpoint if the length of thread engagement by a nut is equal to the bolt diameter that is as strong a connection as you can achieve. From a shear strength perspective two nuts do not improve anything. Maybe from a locknut perspective?

 

[Rusty Marlin]

Double Bolting is a thing? From a tensile strength standpoint if the length of thread engagement by a nut is equal to the bolt diameter that is as strong a connection as you can achieve. From a shear strength perspective two nuts do not improve anything. Maybe from a locknut perspective?

I just assumed they were used as check nuts; and that he must have damaged his OEM welded nuts, that's a good question. @Surfdc, why did you pull the welded frame nuts?

 

[JohnVee]

My captive nut on one side broke free while removing the old bumper years ago when I installed the 4X4L bumper. Pretty sure I just had someone tack it back in place. I've used the bumper for many recoveries over the years without issue.

I don't there's anything you can do beside that because I don't think there's any kind of access once you slip the bumper on.

 

[Surfdc]

I just assumed they were used as check nuts; and that he must have damaged his OEM welded nuts, that's a good question. @Surfdc, why did you pull the welded frame nuts?

The off road shop that installed them recommended double 8.8 or higher nut if through-bolting and sleeves were not reachable. They believed the frame was not strong enough to withstand a recovery that yanked on a single point if not through-bolted and sleeved.
They did my front points this way.

 

[MUDZLLA]

The off road shop that installed them recommended double 8.8 or higher nut if through-bolting and sleeves were not reachable. They believed the frame was not strong enough to withstand a recovery that yanked on a single point if not through-bolted and sleeved.
They did my front points this way. View attachment 3647749View attachment 3647751

If I'm not mistaken the original bolts are larger diameter, fine thread and grade 10.9. The other thing is that those bent metal "recovery points" you indicate are actually shipping tie-down points - though almost everyone uses them for recovery at some point. Actual recovery hooks are heavy forged metal and often bolted to the bottom of the frame with a winch plate. If you do pull on those tie-down points hard enough to snap the original bolts there probably is a good chance you would bend the frame if it's not reinforced.

 

[CJK]

My rear bumper will arrive soon and I’m removing old bumper in preparation and forgot that years ago I removed the captive frame nuts to double-bolt my recovery points.

Can I still mount new bumper? Can I reach in? Accessible holes to reuse my nuts? Through- bolt?

I just checked mine right now (built and installed at 4x4Labs)
There's no access once the bumper is on so you'll need to weld those nuts on ahead of time

 

[Surfdc]

Thank you all

 

[Surfdc]

If I'm not mistaken the original bolts are larger diameter, fine thread and grade 10.9. The other thing is that those bent metal "recovery points" you indicate are actually shipping tie-down points - though almost everyone uses them for recovery at some point. Actual recovery hooks are heavy forged metal and often bolted to the bottom of the frame with a winch plate. If you do pull on those tie-down points hard enough to snap the original bolts there probably is a good chance you would bend the frame if it's not reinforced.

I did not know that about the strength of the original capture nuts.

Yes I ditched the tie down points for 1/2 in bent plate for points you see in the pics.

 

[Marvelicious]

The off road shop that installed them recommended double 8.8 or higher nut if through-bolting and sleeves were not reachable. They believed the frame was not strong enough to withstand a recovery that yanked on a single point if not through-bolted and sleeved.
They did my front points this way.

Their solution on the front should provide some extra strength, but I don't know about their double nut theory... or rather I do know, and it's B.S.

I could see installing a reinforcement plate (say, a piece of 1/4" plate that's sort of like an elongated washer including both bolts) but that second nut isn't going to make any difference to the frame. That makes about as much sense as a seatbelt on a motorcycle: it's doing nothing to address the problem.

I do appreciate that they anti-seized them thoroughly though.

 

[CharlieS]

Take those double nutted bolts off, mig weld a couple of nuts to the inside of the frame rail to make them into captive nuts, move on.

 

[alia176]

Instead of welding those zinc nuts to the frame, might I suggest you find square weldable nuts? See if you can find the same diam/thread pitch as the OEM ones!! Afterwards, I'd spray paint them to slow down corrosion. It goes w/o saying, wire brush the hell out of the weld zone!

 

[Marvelicious]

Instead of welding those zinc nuts to the frame, might I suggest you find square weldable nuts? See if you can find the same diam/thread pitch as the OEM ones!! Afterwards, I'd spray paint them to slow down corrosion. It goes w/o saying, wire brush the hell out of the weld zone!

Zinc comes right off with a little overnight bath in a mild acid. Household vinegar works.

 

[Surfdc]

thank you guys. Looks like my next task is sourcing weldable nuts!

 

[alia176]

thank you guys. Looks like my next task is sourcing weldable nuts!

My local Ace and True Value carry square nuts, not sure if they deal with metric though.

 

[Surfdc]

Oops. I cut one side angle too steep. Any ideas?

 

[mudgudgeon]

Another option instead of welding in nuts could be a bit of steel flat bar. Drilled and tapped with two holes in one bit of bar.
A bit of 1½x⅜ or ½ bar might work

 

[Surfdc]

That’s a good idea because it would not have to be welded. The rectangle shape would span the with of the inner frame to hold it while torquing down. Or weld a nut to same bar?

 

[mudgudgeon]

That’s a good idea because it would not have to be welded. The rectangle shape would span the with of the inner frame to hold it while torquing down. Or weld a nut to same bar?

If the bar is long enough to pick up two bolts, it cannot spin in the frame.
Just need to be thick enough to get sufficient thread engagement. Minimum would be ⅜. ½ would be better.
A little JB Weld, or Sikaflex to glue it in place ahead of time would help with alignment. Not adding any strength, just to make install easier.

Same can be done for a single bolt, again the bar just needs to be longer than the width of the space inside frame, and it can't spin