Aftermarket Rear Bumper Attachment?

[BlackWorksInc]

So I was trying to find a couple pictures of CBI and some custom rear bumpers and I noticed that they all seem to just bolt onto the bottom of the frame rails where the tow hitch mounts.

That just seems like a lot of stress on the frame rails, am I missing something here?

 

[zonianbrat]

I'm about to head to bed so I dont have time to look at the pics but from what I am thinking it would depend on mostly the grade of bolts being used to secure the bumper. If they are grade 8 bolts and they are big enough I would think they are pretty tough. I'll look more in depth tomorrow and perhaps I can even send a link to my enginerd buddy at work. He specializes in things like this since we have do lifts up to around 80 tons. I am amazed at what some of the shouldered eyebolts we have will lift.

 

[BlackWorksInc]

I'm not worried about the hardware, they make some seriously tough bolts and nuts. My concern was with flexing the bottom section of the frame rail because that's were it attaches to and no other bracing.

http://www.toyota120.com/forum/showthread.php?t=21193

 

[blk-4runner]

I'm not sure about the older model of the CBI design but the newer model that I have, has a spacer between the bumper and frame from left to right / bottom to back side, given about 1/4" - 1/2" to flex, it seem to hold up fine, considering all the weight that I have on it.

 

[Relentless]

There are 10 bolt locations:
2 on bottom of frame rail on each side (4 total)
4 on the face of the rear cross member where the hitch mounts
2 below the face mounted rear cross member bolts.

With proper bumper design, seems to be plenty stout to me.

 

[darkie3495]

I'm sure someone with the cbi bumper can confirm/deny this but you have 8 bolts secured to the bottom of the frame rails (4 per side), 2 bolts on the bottom of the rear crossmember and 4 bolts on the vertical face of the crossmember right in the center of the bumper.

Most bumper wings directly behind the rear tires have a brace that extends to the outside face of the frame rail that you could potentially weld for added peace of mind.

Edit: relentless beat me to it but the early design of the cbi uses all 8 bolts on the bottom of the frame rails

 

[Dawg4Runner]

I'm sure someone with the cbi bumper can confirm/deny this but you have 8 bolts secured to the bottom of the frame rails (4 per side), 2 bolts on the bottom of the rear crossmember and 4 bolts on the vertical face of the crossmember right in the center of the bumper.

Confirmed!

There are 14 bolts total. 4 on the face of the bumper, 2 on the bottom on either side of the tow hitch, 4 on the bottom of the left frame rail and 4 on the bottom of the right frame rail. Basically the same bolt locations as the OEM weight distribution tow hitch. As Relentless stated, its plenty stout.

 

[BlackWorksInc]

Ah cool, I thought I was missing some other bolt locations. That's good to know! I'll have to start doodling and maybe even do a couple mock-ups on my truck while I scrounge up the money.