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??'s about beefing up frame rails

kewlkatdady

kewlkatdady

NAXJA Forum User
Location
Mansfield TX
I seen people use "C" and "L" shaped steel to beef up the frame rails:
reinforcementpix_L.jpg

reinforcementpix_C.jpg


1. Which is stronger?
2. What material should I purchase?
hot rolled or cold rolled steel?......or does it matter?
 
U is stronger but it depends on what you plan to do in the future. If you're mouting a cage the U might not be necessary as your cage will provide the chassis stiffness while the re-inforcement on the frame rail only provides a nice solid mounting point for various suspension and skid plate items.

I went with the U as I like to keep my mounts and such up high and have welded various things to the inboard side of them.

Hot rolled as that is what typical structural shapes are.
 
Mine is like this with formed 10 guage:

FileHandler.ashx


I don't think one really needs the full 'U'

here is is on the XJ:

FileHandler.ashx
 
I did mine by making a U shape using angle and flat bar. That way I could easily deal with the retarded taper in the uniframe right behind/at the LCA mounts.


To do it again... I don't think I want to. Welding above your head blows.
 
Mine is 3x3 angle. In my opinion the key is tying the front and rear suspension together no matter what type of reinforcment is used. I think having sheet bent to contour the angles is the best way though and then no I dont think you need to do a full U shape. The picture in the post above is one of the best I have seen. Check mine out at.....

http://1997jeepcherokee.blogspot.com

Its the second post down.

Either way you will be happy with the results if you take your time and don't overlook the details.
 
kewlkatdady said:
forgive me for being ignorant, but I don't under stand what you mean.
Click to expand...


You've take a peice of angle like this: L and a peice of flat bar oriented like this: l . If you weld them together like that they'll make a shape like this U (but more square).


I put the angle on the outside of the uniframe rail, and the flat bar on the inside, then welded them together. I cut the pinch welds and a few other things off so it'd all fit nicely. Mostly becuase my uniframe was pretty messed.


It's basically the same thing as if you take a peice of 4x4x.250 HSS (square tube) and cut the top off of it to make a U shaped peice. Other than you can only fit that on the uniframe from just behind the tranny crossmember towards the rear. From there foreward the uniframe rails taper outwards so you can't jsut slip a peice of channel (or whatever) over it, you have to play with the angles a bit. Hence I used angle and flat bar.


I'd get you a pic... But, yeah, I'm lazy. Sorry.
 
ok so use a LI to make a U....

I gotcha...

Is the "I" part of this just for making it easier to weld things on the inner side of the frame rails...or does it also add more supprt?
 
Well, my uniframe was rather messed, I had to massage it back into the correct shape with a sledge...

It'll help if things have gotten bad already, or you want to weld brackets inside. Otherwise don't bother.
 
framestiffeners.jpg


the red lines are pointing the "L" shaped piece...correct

the green line is where the "L" shaped piece and "I" shaped piece are welded together...correct?


I just want tomake sure that I am seeing this correctly.
 
is plating both sides nessacary or can i just use the L shaped part of it how do u mount the cross member that way, bought a new project first thing im doing. i know there is a crack already any advise or anything would be helpfull (newbie)
 
drew91xj said:
is plating both sides nessacary or can i just use the L shaped part of it how do u mount the cross member that way, bought a new project first thing im doing. i know there is a crack already any advise or anything would be helpfull (newbie)
Click to expand...



Read post #9.


In a nutshell, if you want interal brackets or have a heavily damaged uniframe - go both sides. Otherwise, leave it.
 
This may be a stupid question, but has anyone had serious problems not beefing their frame? I really like the flex the unibody has when I'm crawling over rocks, and I do have sliders bolted directly to the underside of my door sills but not to the frame so they may add a bit to the stiffness of the body. I'm running 33" TSL's with about 5" lift and trimming, all else stock for now, soon to have D44 front and 8.8 rear and another 1.5-2" lift. Other than the driver's side door leaking in rain when it's parked a certain way on the street it seems fine. :confused:
 
The flex of the unibody is a misconception...it is actually much stiffer than a standard ladder style frame found on most trucks and many SUV's. The problem with making a stuff structure out of thin materials is that any crack or imperfection turns into a really big stress concentration which creates more cracks...which create more stress concentrations. Once you start getting cracks they spread very quickly.

I wheeled my XJ for 4 years with little problems...then one season I noticed a few cracks...and they spread like crazy. Now I have to re-inforce everything.
 
ok realy dum question after i plate the outside i dont believe the jeep i bought is to bad front half frame somewhere no biggy but do u just drill new holes for mounting the cross memer and skids im sure ur do just want to make sure. sorry for no comen sence jsut want to do it right
drew
 
huh?

drew91xj said:
ok realy dum question after i plate the outside i dont believe the jeep i bought is to bad front half frame somewhere no biggy but do u just drill new holes for mounting the cross memer and skids im sure ur do just want to make sure. sorry for no comen sence jsut want to do it right
drew
Click to expand...
 
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