interesting.....frame stiffeners

[dunl]

http://calgary.kijiji.ca/c-cars-vehicle ... Z176433063

 

I've never seen anyone sell anything like this before.

[freakjeep93]

looks like theyd be pretty easy i wouldnt pay 150 for them.'

interestin thought though

[89eliminator]

i've seen them before. a couple of companies make them for the XJ.

[dunl]

Anyone ever use them? Not that I'd pay $150 for them either....but isn't the idea of having a unibody the same as the older willys jeeps....it's meant to be flexible?

[freakjeep93]

but if you use them on the front you suspension mounting poins would be stronger .

i think on the xjs there really made to keep them from bending frames

[Wildman]

Yea, that is interesting............

 

But........I can buy a whole lot of steel for the price there asking for just 2 "frame stiffeners" and also make it fit where it has to go.

 

Just another item on the market for the 'unknowing buyer' :shake:

[freakjeep93]

oh yea :agree:

[dunl]

I can't really see where angle instead of tubing is going to resist bending anymore than the current frame rails. Unless I am missing something here?

[Eagle]

Questions:

 

1. I wonder if they have multiple models, to account for the two different mounting locations for the cross member.

 

2. They have two cuts running almost the entire height of the vertical leg. Those cuts become hinges. It makes me wonder what they think the vertical leg is going to go, if they make it into a hinge.

 

3. Does anyone know how it attaches? When I saw the first two photos I thought, "Wow! That's a lot of plug welds." Then I saw the third photo and it leaves me wondering if the screws are just to hold it in place until all the rosettes get welded, or if the screws are all they intend for mounting them.

 

Interesting concept. Need more data.

[Eagle]

I can't really see where angle instead of tubing is going to resist bending anymore than the current frame rails. Unless I am missing something here?

Tubing is nothing more than four angles with the legs solidly connected. Any 'L' or 'U' or tube shaped steel section has resistance to both bending and twisting -- it's just a matter of how much.

 

As my structures prof used to say (in a heavy Scottish burr that would have put Sean Connery to shame), "Strrrrrress goes where therrrrrrre's mateeeeerial ta rrrresist it." In simplistic terms, if some is good, more is better.

[Wildman]

Angle or any shape with a 90* bend is much stronger in 2 directions than round, or tubing is.

 

So, any angle shape would support, or hold up to bending and flexing, where a round shape, would be easy to bend, or even "collapse" with-in it's self.

 

(I see Mr. Eagle beat me to the punch ;) )

[dunl]

3. Does anyone know how it attaches? When I saw the first two photos I thought, "Wow! That's a lot of plug welds." Then I saw the third photo and it leaves me wondering if the screws are just to hold it in place until all the rosettes get welded, or if the screws are all they intend for mounting them.

 

Same thing I thought....helluva a lot of BIG plug welds.

[Wildman]

Assuming the "big holes" are for plug welds.........What you do if you have a "weak" spot (aka......frame rot) right at one or two of the plug welds :hmm:

 

Like I said, that's a lot of sticks of steel to make my own "stiffeners" :brows:

[dunl]

Yup.

 

I still don't quite understand how angle steel will resist bending or twisting more than tube. :dunce:

[pingpong]

Yup.

 

I still don't quite understand how angle steel will resist bending or twisting more than tube. :dunce:

 

 

 

I suggest you get some 1/8 in wall tubing and bend it by hand. Then get a piece of 1/8 angle iron and try bending it. See which one is easier.

[freakjeep93]

i don't tink you could bend either one there pretty tough. but angle would be stronger.

[dunl]

i don't tink you could bend either one there pretty tough. but angle would be stronger.

 

Sure. Tell me why.

[freakjeep93]

i don't know why but ive done what wildman has done and pipe bends easier . just trust us on this it does :brows:

[Wildman]

Yup.

 

I still don't quite understand how angle steel will resist bending or twisting more than tube. :dunce:

 

 

 

I suggest you get some 1/8 in wall tubing and bend it by hand. Then get a piece of 1/8 angle iron and try bending it. See which one is easier.

 

 

 

The point is........you can bend round tubing by hand, take a piece of brake line, and bend it by hand..........but. angle with the 90* "fold", it will not bend as easy, or as tight of a bend, at least with out heat.

[Eagle]

Yup.

 

I still don't quite understand how angle steel will resist bending or twisting more than tube. :dunce:

I didn't say it will resist either bending or twisting more than tube (at least, square or rectangular tube). But an angle shape also is far from zero resistance to bending and twisting.

 

But ... those two slots they cut in the vertical leg really REALLY bother me from a structural perspective. They weaken the angles considerably against both bending and twisting.

[LEAD_NOT_FOLLOW]

They are cut to reflect the angle of the frame rails. From a manufacturing standpoint it's easier to make a relief cut and have the customer simply "push" them up to fit the proper angle.

 

[FXWorks]

I have the TNT version of these on my XJ. I will be doing same on my MJ.

 

These make a huge difference in the stiffness of the uni-body. You can feel it right away as soon as you are done welding them on just by opening and slamming one of the doors on the truck. Completely different sound.

 

These are stitch welded on. The idea for the holes is to rosette weld them. For the stiffeners shown in the advert I'd be inclined to stitch weld them on opposite diameters at the 45 degree angle. Those holes are big enough to want a stitch weld if I am visualizing what they are showing correctly.

 

The vertical cuts also get stitch welded. There is no "hinge" remaining after everything is welded. IIRC there are three vertical cuts in the TNT version.

 

As for strength, these really help in a bunch of ways. First, the angle shape adds material at the bottom of the frame. This increases the area moment of inertia and hence the resistance to beaming.

 

The vertical part adds material for the same forces in the transverse plane if you follow.

 

If you think of the uni-rails as a monocoque adding the material both planes stiffens the box which in turn stiffens the entire structure.

 

On top of all this you now have more material to weld and/or drill and tap for mounting sliders. If done right you can incorporate this in such a way that you have another semi-monocoque structure outboard of the uni-rails. Who says unibodies suck? :)

 

Regarding the price, these are not just some angle iron cut to shape. There is a double bend at the corner that conforms tightly to the factory uni-rail. At least the TNT version is this way.

 

There are at least two other versions of these stiffeners out there as well.

 

For the price of these it is good value unless you have access to a press that can bend multiple bends in tight proximity along the entire length in 3/8" steel. Right, didn't think so. ;) You can do the same with a plain 'ol piece of angle iron but it isn't as elegant. I'll pay the what, $40-60 difference in the price of steel for angle versus a manufactured part if it looks better and reduces the amount of work I have to do.

[dunl]

Thanks for the explanation for those of us who haven't used or fabbed them. :cheers:

 

You can feel it right away as soon as you are done welding them on just by opening and slamming one of the doors on the truck. Completely different sound.

 

I can understand that totally. I used to have an 80 Mercedes 300SD turbodiesel sedan. The sound of the heavy, well-made German door closing on it compared to a car of today was....well.....almost erotic. There's something to be said for solid construction.

 

However, back to my original question...isn't the idea of the unibody so that it can flex?

[DirtyComanche]

They are cut to reflect the angle of the frame rails. From a manufacturing standpoint it's easier to make a relief cut and have the customer simply "push" them up to fit the proper angle.

 

 

Regardless, it isn't right.

 

In fact, very little about them is 'right'. Granted, I didn't bother to read any of this thread other than your post, but these products break about half of the basic rules of frame modification/repair.

 

And regardless of everything else, they offer minimal advantage on the MJ uniframe. It is much more rigid to begin with. The main issue is that you can crush it easily if you slam it on rocks. I'd rather see somebody build a cage over plating the shizz out of everything in sight.

[CWLONGSHOT]

Looks to me like it would add more "balast" or armour plating than stiff-in-ers.... :D

 

I have seen stiffners that attcah to the front control arm mounting brackets, weld up along the "frame rail" and terminate at the rear spring hanger, again welding in place....

 

can't seem to find a link to them... I remember reading about the and seeing install in a issue of either JP or 4WD offroad rag...

 

CW