two very good points. 3/16" and the frame brackets. i would use 1/2" grade 9 corrosive resistant mil-spec bolts to bolt it to the frame. 3 horizontal and 1 vertical.

 

What do you mean about the bolts? How can I have a vertical one? I'm planning to bolt it to the frame in the OEM location, similar to the OEM mounting style (2 bolts on each, top and bottom of bracket open). I will look for fancy bolts, but I did calculate with my statics & strength of materials professor that 3/8" grade-8 bolts should easily handle the shear.

 

D1 off road bumpers typically mount with 3 vertical bolts. D2 off road bumpers typically mount with 2 veritcal and 1 horizontal due to the differences in the frame structure. The D2 has angular supports that the D1 doesnt have limiting access to where the 3rd vertical bolts lies on a d1.

a 1/2" bolt is snug in the stock holes in the frame. may need a little nudge from a dead blow to get them in. i rather have snug bolts then loose bolts. that's why i said 1/2".

 

The reason I'm confused is the stock bumper mounts with only 2 bolts per side, and they are both horizontal. I was planning to mount right to the end of the frame rails just like OEM. It's a D1. Where do I mount 3 vertical bolts?

 

Does anyone know where I can get anti-theft bolt covers for the winch? I saw them in an off-road customization book once, they are made of copper I think. It's basically a small cylinder the bolt head goes through, then you pound a metal cap onto it. The only way to remove it is drill out the center. I've been trying to find them online and at hardware stores but no one knows what I'm talking about.

 

you should really take a look at how an ARB or similar bumper fits on the frame. they dont just site on ends like a stock bumper they go all the way back to the crossmember.

 

I see what you mean, I'll change in my next update of the design.

 

I got a bit behind on this project, but I do have some updates.

I found out the first assignment for the class is building a toolbox, then I get to build all the other stuff I want. Decided to modify the design of the toolbox so it will fit behind the back seat of my Rover. Tool box uses nearly a full sheet of 16-gauge steel and weighs about 70 pounds.

Sorry for the camera phone pics, I guess you can't see how good (or bad) my welds are.













I'm almost done with the toolbox, I just need to add barrel hinges and weatherstripping. Also need to decide how I'm going to mount it in place. Went ahead and ordered a full 4x8 sheet of 3/16" steel so with any luck I can start on the bumper Friday.

 

Also have made some minor changes to my bumper design to comply with state law. There is no safety inspection, but I talked to my insurance agent and if I want to be covered properly in the event of screwing over someone's car with my bumper I had better be in compliance.

Technically he said "if they let you register it that way, you're insured" but I see potential liability in being on the wrong side of the law on this one. He also may not have realized they let people register all kinds of vehicles without even looking at them...

But here's the statute: Statutes

If I'm reading that correctly, and my GVRW is around 4501 and 7500 pounds, I'm allowed 27" of daylight under my front bumper and 29" under the rear. So I'll weld some small skirts to the edges that should not interfere with approach angle in any significant way. I hope I don't end up moving to a state with stricter lift laws or I may be faced with some tough decisions...



Also, I'll extend the mounting flanges so I can strengthen the frame a bit and offer adequate clamping force.

 

now you're talking with that second pic! that little metal thing your insurance wants you to put on is useless. i wouldnt even bother. but then again im ruthless. i just re-read my earlier post. i must have been drunk. every time i said vertical i meant horizontal and every time i said horizontal i meant vertical. haha....