Rear Bumper Design Feedback

Looks great overall. The receiver does not seem to stick out enough to put a pin through it though. Wish I had the skills to do something like this.

Looks like good start.

a few comments: 1/4" is way heavier than needed. 3/16" is plenty, 1/8" is ok depending on what you want to do with it. You need to review how long to make it: if you do rock crawling, you will want to expose the entire tire to the rock, ie about 45" long. If you do heavy brush like I do, the bumper should come to about the center of the tire so that brush does not get hung up between the tire and the frame, about 57" long. If it is mostly show and city traffic, any length is fine but longer is better to protect your ride from the other guys.

You are showing clamping the mounts between the sides of the frame rails. This does not work on a YJ because the shackle mount is welded into the frame itself. IIRC, the CJ hangs the shackle mount below the frame, your drawing may work. Better check carefully that there is no interferance at full cmpression.

I didn't see any provisi> First off, I want to thank Roy and Jeff for sending me some pics of

Nice.

I would recommend crush sleeves in the back frame between the angle irons. These are easy to make. You drill the 3/8" hole in one side for the bolt to run through and on the other side you drill a hole to fit a

3/8" ID piece of pipe the width of the frame minus one layer of frame. The pipe then slides and butt to the 3/8" hole on the other side to cross the frame and fits flush on the larger hole side. Your bolt will then not crush the frame.

It is amazing the stress that can happen in an extraction. I bent my Warn HS9000i's mounting plate the first time I used it. I am glad the frame had crush sleeves that came with the kit....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: N> First off, I want to thank Roy and Jeff for sending me some pics of

Bumpers are designed to absorb impact. That is why many of them are far lighter than you would at first expect to see. A bumper that heavy is going to seriously tweak your frame if it is ever used for its intended purpose. The other guy is going to feel it too, heh.

Earle

Looks good, and looks like solid feedback so far.

Just one thought: you might want to look into extending the shackle mounts through the bumper, perhaps to use as the inner mounting plate? I'm only mentioning this as others have pointed out the relative weight and high thickness of the tubing you proposed @ 1/4"

-- if you do indeed go thinner, and if I'm correct in seeing the shackle mounts as stubs that weld to the surface, you're looking at a slightly more complicated weld (very thick metal welded to relatively thin tubing - tubing heats much quicker), combined with the potential for deformation on a flat surface -- perhaps only on rather oblique pulls.

Conversely you could just extend them through both faces for strength and keep the channel/angle iron setup for mounting, but I'd skip the bolting of the angles to the channel -- since nothing is ever drilled perfect and something might be a tiny bit tweaked, I'd put together the frame mounting system, position the bumper (complete with channel affixed), and tack it all in place. Unbolt the assembly, and then weld up the channel/angle junction good and solid.

Just some ideas - - Jon

First of all, I want to thank everyone for their design feedback. I'm starting to move forward with a slight re-design based on the inputs. I plan on taking some measurments sunday to get things a little more accurate, plus to give me a better idea of what's feasable and what is not. Here are the plans so far though.

1) Receiver Hitch Pin. I was planning on having the hitch pin placement on the rear of the bumper. That is, if there is enough clearance there. I'll figure that detail out once I get some measurements. For now, the receiver hitch is more or less a placeholder. 2) Safety chain hookups. Good catch by everyone, I'll be sure and add these. 3) I'm going to change my design to use 3/16" thick steel instead of 1/4". I figure more give is a good thing, plus it's an overall weight savings. 4) Shackle mounts I will plan on having go through the bumper and attach to both the front and the back walls. Extra durability is a plus, and also, good point about the welding and deformation. Hopefully this will help out. 5) The crush sleeves are a good idea, I'll be sure and incorporate that. 6) As for the frame connection/mounting. I'll have a better idea of that after this weekend and taking some measurements. 7) Tow hooks, I'm not sure these are really necessary with the shackles, seems like overkill to have both. Maybe I'm missing something, let me know if I am. 8) Rear lights are a good idea. As for the best place to put them, I'm not sure. Any suggestions are welcome.

---------- Tim J Chassis - 1984 CJ7 Engine - SBC 305

Looks almost like the one I am designing for my 2000 TJ. All I like is the Mounting brackets myself. Here is a link to what I have done.

As for the front bumper this is what I did for it. Tom