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Box vs. Angle

I

Incredible Hulk

NAXJA Forum User
Location
Burnsville, Minnesota
I am going to be sleeving my frame rails in some way shape or form. I was curious if there were more strength benefits with box, or if you would be gaining the same thing by just doing angle? Both would add structural rigidity, the question is if doing a full box or C channel would be drastically stronger? Curious to hear opinions on this....
I have searched but have not found an adequate answer to this yet.
josh
 
Exactly how do you plan on sleeving the frame with full box tubing? The only way I can think of would be to cut the frame off of the unibody, sleeve it with the box tube and then weld it back to the body. I’m sure it could be done, but man would that be painful. You would be a lot better off just welding c channel over the frame. Crawl underneath and take a look at your frame. It won’t take you long to figure out what size and how much c channel you need.
 
Wiley Coyote said:
Exactly how do you plan on sleeving the frame with full box tubing? The only way I can think of would be to cut the frame off of the unibody, sleeve it with the box tube and then weld it back to the body. I’m sure it could be done, but man would that be painful. You would be a lot better off just welding c channel over the frame. Crawl underneath and take a look at your frame. It won’t take you long to figure out what size and how much c channel you need.
Click to expand...


I believe he is saying to cut the box tubing in half and use it like C Channel.
 
In my opinion they are are both just as good. They don't give as much extra frame strength like people seem to think, but it's still good.

The only reason I did full c channel was because I wanted the inside and outside of the frame rail nice and smooth as to attach crossmembers/brackets to easily. _nicko_
 
gearwhine said:
In my opinion they are are both just as good. They don't give as much extra frame strength like people seem to think, but it's still good.

The only reason I did full c channel was because I wanted the inside and outside of the frame rail nice and smooth as to attach crossmembers/brackets to easily. _nicko_
Click to expand...

I did mine forfrom angle iron, but my reasoning behind it was that it will not be as much of a frame stiffener as a skid for the frame rails.
 
Incredible Hulk said:
Right, I mean using box tube, and then cutting it in half to make C channel. That, or angle iron- which one?
j
Click to expand...
Sorry I misunderstood what you were trying to do. If that’s the case, I think that C channel and box tube with the top cut off would be the same strength wise. C channel is cheaper and would be easier to work with. Angle iron (I’m assuming 2 pieces per rail) would be weaker, but you could compensate by using slightly thicker material. Just be careful you don’t add an extra couple of hundred pounds to the vehicle. If you are sleeving from just behind the lower control arm mount to in front of the leaf spring mount I bet you could do it with two 4 ½’ pieces of c channel. What thickness were you looking at and any idea how much weight it would add? Slightly off topic, but when I installed my transfer case skid plate (14” wide, frame rail to frame rail) it stiffened things up quite a bit. If you are going to sleeve your frame rails it would be worth your time to build a transfer case skid that will tie them together. Mine is made out of 1/8” plate and seems to be holding up well, but 3/16” wouldn’t hurt my feelings either. Good luck and take some pictures when you get it done.
 
I suppose you could use full box section if you cut out the bottom of the existing frame first and inserted it up inside and plug welded sides and stitch welded the bottom. Not much of an advange though as you lose the original bottom section and replace it with the bottom of the box but gain another at the top!
Always wondered if fitting extra cross braces would be of more benefit to torsional stiffness than plating just the frame rails which would really only give more stiffness in a vertical plane. I think most of the damage in cracking comes from those that run big tyres in rock where they are doing a lot of twisting to the frame which is different to say a JeepSpeed one which would have it more in the vertical only. Your HD front and rear bumpers are effectively cross members but you need it in the centre of the body as well so the stress is not concentrated there. Those that run long arms would have substantial centre cross member and those with large tired in skids like mentioned above would also have this. Some of your old chassis's used to run one in an X shape which would be very effective in creating torsional stiffness. I wonder how you would go fitting them to run across ways from the front of the leaf spring mount to the back of the LCA mount on the opposite side? Clearance around the driveshaft and exhuast and others things make it maybe impossible though and you have the problem also of the mounts being at different heights also. Might be a good opportunity to lower the the leaf spring mounts so you can run a flatter spring which will give greater comfort and travel than those in a stiff arch. The rear mounts would have to be dropped also as many have done by welding plate over the top of the existing mount and fitting a new one under it.

Food for thought ;) Fire away with any comments.
 
I do alot of metal fabrication and c-channel is stronger. It would increase your structural integrity far more than angle iron.
Welding to pieces of angle iron together to create a channel would cost more and take more time. You would have to rely on your welds to be a strong point, when comparing to c-channel they would definately be a weak point.
 
gearwhine said:
In my opinion they are are both just as good. They don't give as much extra frame strength like people seem to think, but it's still good.

The only reason I did full c channel was because I wanted the inside and outside of the frame rail nice and smooth as to attach crossmembers/brackets to easily. _nicko_
Click to expand...
i think this statement needs some backup. how much do people think it helps, and what evidence do you have that they are wrong?
 
I wasnt sayint htat I wanted to make C channel out of two pieces of angle iron. I was saying I would ONLY put angle on teh outside of the rail and leave the inside edge as is- OR put on a C channel to box in the whole thing. The reson I am asking is basically spurred by the TNT customs pieces they make. I am curious which would be stronger. Eventually I will be mounting a cage to it as well....
josh
 
I was thinking of using angle iron that has holes allready drilled into it every inch or so, I know i've seen it before but I dont remember where or when.
It would eliminate the need to drill holes for plug welds.

I think it was 2x2x1/8 I dont know if it was for a specific application or what but it would make things easier, especially for those that dont have a drill press.
 
BrettM said:
i think this statement needs some backup. how much do people think it helps, and what evidence do you have that they are wrong?
Click to expand...

Just read posts, which I know you do. I've read a few where people think it's just as stiff as having a full cage thinking their body will survive with 60's and 38's.

Then also think about it. You're not going to stop much twist unless you attach both frame rails together solidly through crossmembers also, no matter how much material you add. That's one reason frame attachments on a cage are vital. It acts just like many crossmembers. _nicko_
 
On that TNT stiffener, it looks like formed metal in the shape of an L. That is different than Angle Iron. Also, a piece of box tubing cut in half lengthwise is not the same as C-channel. It works quite well for fitting around the frame rails though. Jeff
 
Jeff 98XJ WI said:
On that TNT stiffener, it looks like formed metal in the shape of an L. That is different than Angle Iron. Also, a piece of box tubing cut in half lengthwise is not the same as C-channel. It works quite well for fitting around the frame rails though. Jeff
Click to expand...

Guys, the stiffeners are broke to contour to your unibody shape but they are basically a complicated "L" like angle iron.

Check out the instructions for more pictures...this may give you a better ideahttp://www.tntcustoms.com/Products/XJ Parts/HD StiffnerZ/TNTStiffnerZInstall.pdf
 
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