Frame Horn (bumper mount) Mod

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....back in the saddle again....
Sep 29, 2004
Truckee, CA
Looks like I'll need to swap the frame horns (bumper mounts) from my '84 fj60 to my '88 hj60 in order to use my ARB bullbar.

First: I'm seriously questioning the bullbar. But I think it'll maybe be worth it.

Here is the plan: remove bumpers (mostly done) from each vehicle.

Grind off rivets.

remove horns
don't forget which is which.

swap horns using best-quality bolts I can find to secure horns- 4 bolts per side

Here's the rub: Those rivet holes aren't very big. Should I also get them welded on? Would it make that much of a difference in strength? I'm thinking just run a bead along the back of the horn where it touches the frame rail.

I'm so frustrated.... this bumper swap was *supposed* to take a few hours and now here I am looking at killing a second weekend to complete it. :eek:
Grade 8 bolts should be pretty secure, but we're also talking a lot of bolts - frame to horns and horns to bumper. Are you winching or just want protection? Will it affect a shackle reversal should you decide later to have one? Just questions I'd as myself.

Class 3 receiver hitches are designed for 5k lbs gross pulling weight and a 500 lbs tongue weight with bolts alone.

Other than the lack of maintenance, I also don't see rivets as inherently stronger than grade 8 fasteners.

You could also drill out the holes to accept bigger bolts.

Personally, I'd probably do both drill out and weld, especially if I winch.

If I ever get the winch working... I'll be winching ;p

Since I can get someone to run a quick bead for two or three dollars, I think I'll do that to backup the bolts.

One of the big problems we have here is vibration-- lots of dirt roads and low quality "paved" roads. So the thing that gets my attention about nuts/bolts would be working themselves loose. I'll use some locktite and locking washers. But once the bullbar is on, it'll be pretty tough to get in there with a wrench to tighten the bolts should that become necessary, so the welds will give me some extra security/strength. Regardless.... this job is turning out (in typical cruiser fashion) to be a lot more work than I thought it would be.
Rather than welding the actual bullbar to the frame, why not spot-weld each bolt/nut to prevent the vibration from loosening them? This used to be very common in Venezuela, but for another reason (to prevent accessories from "walking away"). If you ever need to take the bumper off, easier to grind off some spotwelds.
good idea.
The bullbar, I'm not so worried about. The darn thing has what, 5 bolts per side with big 'ol bolts (19mm heads). And getting them off "quickly".... not easy to do.
I may tack one down as a safety measure, but beyond that, those torque down pretty well and aren't impossible to access for tightening.

What I'm more worried about is the bolts I'll be putting in to the frame horns/rails to put them back together. I don't think that there is any way in heck that I can get at those bolts one the bullbar is back on and I don't want them jiggling loose.

Maybe the best option is to tack weld a nut to the horn, then simply bolt through the frame to said nut... easier to install, easier to tighten, less vibration problems. But I may as well also weld horn to frame for extra strength.
I used grade 8 bolts/nuts w heavy washers & red Loctite. Don't think they'll ever come off accidentally (including theft unless they carry a big breaker bar/compressor & have a lot of time).

Be careful to never weld across a frame rail - weakens it almost like a perforation.
didn't realize the weld would weaken it- glad someone said something.
I'll go the grade 8 route and maybe a tack or two, but that's it.
Grade 8 bolts washers and a lock-washer should do it. I wouldn't worry about them vibrating loose. I don't see it happening if you tighten them down good. Make sure your lock-washer is good quality and once you tighten down, don't back off of it.
I never used to worry about vibration....
but around here, we use more loctite than we do wd40. Seems like just about everything is loose whenever you go to pull it. Unnerving, to say the least. I recently watched a mechanic pull the bolts out of a steering box- by hand- on an fj40. Still had to hit the box with a hammer to get it off- it was rusted pretty well- but... the bolt thing was a wakeup call

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