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Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

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post #1 of (permalink) Old 12-07-2002, 07:06 AM Thread Starter
 
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opinions please, Frame design

Ok, i not an engineer so i am wondering if there will be any structural strenght differences between these two designs.

And where the steel will be box tubing should i prep the joints at all before welding. the tube is rolled on the edges so i was gonna just stick weld them with 7018 3/32 rod and run 3 passes.

What do ya think. Should get good penetration with the 3/32 rod.

Opinions?
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post #2 of (permalink) Old 12-07-2002, 08:05 AM
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Re: opinions please, Frame design

Why not just cut a "V" into the tube, bend it to the angle, weld and plank the sides over the joint? I did that when I built my frame out of 2x4 .125 tube.
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post #3 of (permalink) Old 12-07-2002, 08:06 AM
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Re: opinions please, Frame design

1. Disclaimer: I'm an engineer, just not a Mechanical one. So what I say ain't worth squat.
2. I'd favor the 45* angle cut.
3. The 3/32 rod should work fine.
4. I would add to the joint plating:
a. Top and bottom of the joint.
b. Both sides of the joint.
5. Yes, prep the joint... nice shiney, bright metal!
6. What dimenson material are you using for the frame?
7. When finished will you have the frame chemical stripped and dipped?
8. Please, take pictures of the build and share them!
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post #4 of (permalink) Old 12-07-2002, 08:18 AM
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Re: opinions please, Frame design

I'm not an engineer,but in my opinion(approx.$.02)they would be the same depending on how much you overlapped them. Draw a vertical line through them and measure the distance,it should be at least the same thickness as the tubbing you are useing or this will be the weakest point.
The only differance I see is the 45deg. wouldn't have to overlap as much to have the same strenth.
Rember this info is approx.$.02 please send remittance to..... [img]images/graemlins/shocked.gif[/img]
post #5 of (permalink) Old 12-07-2002, 08:48 AM Thread Starter
 
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Re: opinions please, Frame design

Ok the idea of the vertical line is good. I favor the look of the larger angle design and i think i can' make them equally as strong with this method.

LEVE: I am just going to POR15 the frame and paint it not chemically strip it or anything. I can weld and a good weld is strong than the metal it joints so is plating really necessary. I would rather not plate it. I have seen similar designs without plating and it is a cleaner look. The material is 2x4x3/16. I will clean the metal but by prep i meant should i grind the tub and make better joints to weld or will the space between the roll of the tube be sufficient.

Jim
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post #6 of (permalink) Old 12-07-2002, 09:08 AM
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Re: opinions please, Frame design

1. Lots of good questions!
2. Is plating necessary?

IMHO it is necessary, because I haven't gained enough confidence in my own weldeding skills.

The downside is that this would stiffen this area.

3. Where the pieces mate, are you going to open up the mating pieces so that there is no flat to flat area? This would open up the full length of the frame. IF the material will be mated flat to flat then I'd encourage you to drill two holes through the mating pieces and insert a bolt an threaded reciever plate. It will accomplish few things: a) Keep the pieces in place as you weld the seams, b) give a good ground for the welding, and c) keep the pieces together if and when one of the welded seams breaks. A floppin' frame ain't fun.

4. The roll space will be sufficent, but I'd still girnd/sand it to nice bright metal.

5. IMHO... stay away from POR-15, it's not worth the power to blow it to heck. I've used it with very, very disapointing results. IMHO... use some good ol' tractor frame paint or Hammerite. I'm a big fan of coating the inside of the frame, if you can, or galvinization.

6. As most Jeep frames rot from the inside out, install a couple of hose bibs where you can hook up a garden hose and flush the inside of the frame of all the muck and yuck. It'll add years to the lfe.
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post #7 of (permalink) Old 12-07-2002, 09:42 AM Thread Starter
 
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Re: opinions please, Frame design

This will be an entirely custom frame with a tube frame rear section. The design i have proposed will be for the middle (under door area) and front of the jeep. All of the tubing will be capped off so no dirt will be getting inside.

Where the peices overlap there will be flat to flat area. The bolt idea is great. This way the frame will still be connected hopefully if i find out i really should have plated it.

I por15'ed my old jeep frame and then did several coats of hamerite over it. Only used that frame for 1 yr though so i dont know how well it would hold up over time. Maybe i will just save the money and Spray my hamerite on it.

Thanks for all the input

Jim
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post #8 of (permalink) Old 12-07-2002, 10:47 AM
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Re: opinions please, Frame design

Any input from the mechanical engineers? I am not positive, but depending on the different loading that the frame will undergo at that joint, I am pretty sure the angle effects the different stress/strains and deflections of the steel. Without knowing the loading I don't have enough experience to generalize what design would have the best results.
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post #9 of (permalink) Old 12-07-2002, 08:56 PM
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Re: opinions please, Frame design

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post #10 of (permalink) Old 12-08-2002, 07:29 AM
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Re: opinions please, Frame design

Three suggestions:

Galvanizing is really great. After doing the necessary repairs, I took my frame, skidplate and several other pieces to a shop in St. Louis and had it all hot-dip galvanized for $250.00.

In doing the repairs I developed what I think is a pretty good scheme for bolting things to the frame. Look through my old posts for one titled 'frame repair tips' or something like that. Probably in about August.

Third, I don't know if it's realistic to attempt to get the whole frame sealed. EVERYTHING bolted to it will have to use 'through-tubes.' If you try and fail "You'll be in a heap o' trouble, boy." If you get stuck in a creek and some water sneaks in somewhere, you'll never know it, and it will stay forever. If I were doing it, I'd make sure it was completely open and flushable.
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