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rstrucks
02-01-2011, 07:18 PM
Frames, we don't need no stinking frames! Well, they'd be nice to have but we don't need them.

Bracing, plating, reinforcing, cage tie ins, etc..... What helps your unibody live a longer life? Let's hold off on the full on "tubed out" tech as we will cover that topic before too long.

JohnBoulderCO
02-01-2011, 07:51 PM
WJ's are stiffer to start off with then a ZJ. :flipoff2:

Adding Clayton's long arm kit gives you a "sub-frame" which helps a bit.

OverkillZJ
02-01-2011, 08:26 PM
Claytons subframe helps, so do bumpers and sliders - but my belief is that unless you build some kind of structural cage to keep it square, eventually it will turn into a tin can. The only reason I buggied my first ZJ, is it was driving crooked, the doors were inches from lining up, and there was just no way to repair the damage. Cutting it up, we found cracks in almost every structural "corner" of the unibody.

moparrr07
02-01-2011, 08:32 PM
the wj unibody was designed and then further redesigned by porsche who said when they were done with it, it was equal to a full frame strength,

theres always room for improvment, unibody or full frame

slim616
02-01-2011, 09:28 PM
The only way I've found out to improve it, is to start with something with a frame:smt023

But to be honest between the cage which was tied into a sleeved rail ive had no issues with the unibody other then typical b.s. of having to use/tie into it. Prior to that my unibody used to flex so much that non of my doors worked.

chadjans
02-01-2011, 11:59 PM
and then further redesigned by porsche
who said when they were done with it, it was equal to a full frame strength,



What are your sources for this info?

moparrr07
02-02-2011, 12:02 AM
What are your sources for this info?


i saw it on wikipeida and i didnt believe it, so i searched, i found it stated on a couple sites but this one seems to have the most info....

cool reading

http://findarticles.com/p/articles/mi_m3012/is_n6_v178/ai_20846019/pg_2/

moparrr07
02-02-2011, 12:05 AM
i mean just because something has a "full frame" doesnt mean its all that great, ever flex out an late 80s ranger? full frame and i can guarantee it twist way more than a stock zj

like i said there is alway room for improvment

blackbeer
02-02-2011, 06:00 AM
Seems like as good a place as any to bring up the TNT frame sleeves vs claytons sub frame...
Off the bat claytons go under the uni and are thicker material where as TNT sleeve the outer side and bottom but are thinner.
I've heard support for both in my opinion I like the TNT design for welding sliders/boatsides or cage tie in going all the way up the uni is nice. I don't think claytons can be much stronger? Thoughts? Corrections or comments. I've seen some amazing home mad jobs done but none that make extra sets.. Takers?

Steel City ZJ
02-02-2011, 10:03 AM
Seems like as good a place as any to bring up the TNT frame sleeves vs claytons sub frame...
Off the bat claytons go under the uni and are thicker material where as TNT sleeve the outer side and bottom but are thinner.
I've heard support for both in my opinion I like the TNT design for welding sliders/boatsides or cage tie in going all the way up the uni is nice. I don't think claytons can be much stronger? Thoughts? Corrections or comments. I've seen some amazing home mad jobs done but none that make extra sets.. Takers?

I posed this question not to long ago to some friends and it was never really answered. I just ordered the Clayton rear LA upgrade which comes with the stiffeners so I'm interested to see if I notice a change

AgitatedPancake
02-02-2011, 10:11 AM
I really like the TnT stiffeners. They offer extra clearance under the frame rails where claytons sticks down, and go further front to back to offer protection. I plasma'd out some evenly spaced holes in Andy's TnT stiffeners so I could weld it to the unibody with some nice even weld spacing, it should have a hard time removing itself haha!

http://agitatedpancake.com/random/jeep/5.9andy/DSCN4040.jpg

In this one you can see out of the entire TnT suspension, pretty much none of it rests directly below the frame rails like Claytons, where he has LCA mounts underneath the frame rail. This design saves you a few inches of clearance where it's important. On my WJ I've hammered the ever living piss out of all my LCA mounts and the Claytons subframe connectors
http://agitatedpancake.com/random/jeep/5.9andy/IMG_0937.jpg

SirFuego
02-02-2011, 10:17 AM
This is a relevant post Maxx made about Elliott's thread mentioning an FEA that Kraqa did regarding frame stiffeners.

found it on elliott's build over on nc4x4

All ZJ's/XJ's/WJ's/KJ's are unibody, meaning the frame and body are in itself one piece. It is a cheaper way of mass producing vehicles which is all Daimler Chrysler cares about. Trying to design suspension around this can be very tricky but thanks the the popularity of the 4x4 sport almost every approach has been conceived and executed. Manipulating the unibody is inevitable when building one of the afformentioned rigs into a capable crawler. For all information on welding related to the unibody, please take a moment to read the Unibody Welding Bible (http://www.mallcrawlin.com/forum/showthread.php?t=5878). Thanks to a good friend of mine Kris Fraser for the comprehensive research on unibody strengths and how to modify them.


Option A: Sleeve the frame rail with chopped 4x4 3/16". Plug weld throughout. This is pretty easy to do with the correct tools. This is pictured below. Graphically shown: Green area being the ZJ frame and the orange part being new sleeve.
http://fototime.com/2BF7446DC15EB1A/standard.jpg
http://i14.photobucket.com/albums/a349/Puma297/longarms/sleeve1.jpg

Option B: Weld a smaller size SUBFRAME onto bottom of existing unibody. This is what the Clayton kit uses. Links are not as easily mountable to this type of setup and you lose approx 1" of clearance at the frame. Also a pic is shown below.

http://www.mallcrawlin.com/productreviews/claytonlongarms/claytonla029.jpg
http://i14.photobucket.com/albums/a349/Puma297/longarms/sleeve2.jpg

The plate on the ends are used for the analasys. The force to the frame rail is applied to the 2" portion sticking off the right side. The frame rail is anchored and the opposing end from where the force is applied. The force is 1000LB. This is the deformed DIY Sleeve (option 1).
http://i14.photobucket.com/albums/a349/Puma297/longarms/sleeve3.jpg

And here is the subframe (option 2).
http://i14.photobucket.com/albums/a349/Puma297/longarms/sleeve4.jpg

If you look at the numbers to the right of the framerails you can see that the subframe actually moves less. This was surprising to me. These aren't exactly the same forces applied while wheeling but it gives you an idea of its strength. Tests on torsional rigidity would need to be run to get a more comprehensive analysis of its true strength. (Thanks to Kris for crunching the numbers on software I can't afford. )

I know this is probably boring for 99% of the readers on here but this kind of stuff really fascinates me and I'm sure someone will have a good appreciation for it. I will update this thread tomorrow as more work is getting done.

SirFuego
02-02-2011, 10:54 AM
I know that bumpers were a previous TOTM, but I'm posting it here, because I seriously think that if done properly, a bumper could also help to strengthen the unibody.

When you are working with the bumpers, you are able to sleeve inside of the frame. I think this is important because it makes the bumper mount much stronger and also less prone to getting stress cracks in the unibody. My primary motivation for thinking that this really helps is that despite the abuse my ZJ has been subjected to, the unibody around the bumpers hasn't cracked yet despite this internal sleeving being the only real reinforcement that has been done to the front and rear of my rig (in reference to the pre-roll cage stage of my rig -- my rear "bumper" is now just a piece of 2x4 welded to the rear unibody channels due to the dovetail/bob and the cage obviously strengthens everything, but I won't get into that since that's not the focus), but the bumper I posted here is living on in O'Tools new 5.9 ZJ.

Of course this method of internal sleeving is really only possible for the bumpers, so this isn't going to replace any of the other plating/subframe ideas already mentioned.

Front
In the front, if you want a very tight fit of the internal sleeve, you will need to cut out the front crossmember. An air chisel is your friend to get remove the stock nut serts.
http://i131.photobucket.com/albums/p302/SirFuego/Jeep%20Stuff/030808_17101.jpg

With a little grinding an notching of the steel tube, you can get a 5x2 to fit snugly.
http://i131.photobucket.com/albums/p302/SirFuego/Jeep%20Stuff/pic041308_1.jpg

http://i131.photobucket.com/albums/p302/SirFuego/Jeep%20Stuff/pic041308_2.jpg

Once you get the bumper designed the way you want it (my front bumper is intentionally very simple-looking, but there is no reason you can't just use the same concepts for a more aesthetic bumper), you can drill some holes and weld in some nuts in the internal sleeve. The way my buddy designed the bumper, the entire thing is actually one single piece -- including the internal sleeves. It's such a tight fit that he needed a sledgehammer to get it in. He joked that it's in there so tight that I could probably winch without bolting it in -- and to get it off, I'd probably need to remove the bolts, hook the bumper to a tree and floor it in reverse a few times to get it out. And of course he went overkill with grade 8 bolts:
http://i131.photobucket.com/albums/p302/SirFuego/Jeep%20Stuff/DSC00251.jpg

Rear
A similar idea for the rear was developed that was actually a hybrid of the way ZJ and XJ rear mounts. A 2x4 was sleeved and notched (around the gas filler tube) into the rear frame rail and mounted using the "ZJ" style mounts that the trailer hitch uses. He then welded some angle iron at the end of the sleeve, drilled some holes, and made some nut plates to mount it "XJ style:
http://i131.photobucket.com/albums/p302/SirFuego/Jeep%20Stuff/DSC00257.jpg

rstrucks
02-02-2011, 10:54 AM
I'll try to post some pics later of the small amount of unibody plating/bracing that I have done. For now I will say that I have not had the issues many others seem to have. I have never not had a door shut or line up and the body of my ZJ does not feel tired or worn out or make too many noises when wheeling. Granted, I don't wheel mine as much or as hard as others but I do wheel it. Adding the cage last year and tying everything together has helped keep the unibody feeling solid.

For the most part I think the biggest advantage to having a true frame is having a strong and convenient place to add mounts and brackets. Just because you have a frame doesn't mean that you don't have to worry about stress cracks and fatigue either.

downtowncb
02-02-2011, 12:28 PM
Hell on a ZJ even the tow hitch is structurally integral. I was rearended in the Polar Bear about a month ago, I took off the tow hitch and gas tank skid to get the damaged bumper out and start designing a steel bumper. In the mean time I'm driving around without a rear bumper or tow hitch and if I park on the SLIGHTEST of hills the tailgate won't close properly. I'm suprised how bad it actually is, it's pretty pathetic.

For the sake of sharing my frame plating again. I plated from the cab forward on the outside and from the cab to the motor mounts on the inside in .125" plate.

http://i34.photobucket.com/albums/d133/dtcb70/Motor%20Swap/IMG_6022.jpg

http://i34.photobucket.com/albums/d133/dtcb70/Motor%20Swap/IMG_0385.jpg

http://i34.photobucket.com/albums/d133/dtcb70/Motor%20Swap/IMG_6039.jpg

Kauzi Zj
02-02-2011, 12:42 PM
So, Im not looking for facts and technical data, but how many of you think this is a necessity for a DD/Expedition Trail/part time Crawler, thats only going to be mildly modified(compared to some of you on here)?

OverkillZJ
02-02-2011, 12:53 PM
My ZJ on 6" lift, long arms, rocker protection, stiff bumpers, etc - was essentially wheeled like an expedition rig. And eventually I had to cut it up because it was so tweaked it was no longer square. Given that as with 3-5 years of wheeling on it, but it's not like I was always crawling rock gardens or jumping the rig. The unibody just gave up the fight. I intend to brace the hell out of the 5.9 to prevent that from happening, it still has doors that line up!

Kauzi Zj
02-02-2011, 01:36 PM
Well, I won a set from Moonworks, so once I get them, I will get them installed. I just wasnt sure ho "needed" they are.

SB406
02-02-2011, 06:08 PM
I think the key is to add strength BEFORE it gets all screwed up. If you wait until it's rotted out or smashed, you are doing a repair, not adding strength. Remeber, shapes add strength, but smashed is not a shape.

We had to add a lot of metal to Jared's ZJ in order to fix the weakened floor structure, and add additional strength for repeat abuse (cage).
Remember, cars like ZJ's were designed with the intention to take 1 really good hit, and fold up. As long as the occupants walked away, it was a success. In the wheeling world, we expect our vehicles to take multiple really good hits, drive out of it, and run the obstacle again.

Jeeptech01
02-02-2011, 11:37 PM
Subscribing for when I have a spare min or two.

chadjans
02-03-2011, 01:07 AM
So, Im not looking for facts and technical data, but how many of you think this is a necessity for a DD/Expedition Trail/part time Crawler, thats only going to be mildly modified(compared to some of you on here)?

This made me laugh.

Doesn't the already been posted "facts and techincal data" show that frame rail plating is a "necessity?":smt039

FearTheDentist
02-03-2011, 02:53 PM
Doesn't the already been posted "facts and techincal data" show that frame rail plating is a "necessity?":smt039

I don't have anything like the technical\fabricating background to have an "informed opinion" on this, but I do have an observation. From what I've seen the majority of unibody rigs wheeled in the manner Kauzi is describing have no unibody plating with the posible exception of the frame rail stiffener in a Clayton's kit. I haven't seen many such rigs develop issues resulting from over-stressing the unibody- this seems to be reserved primarily for boneheads like myself who beat the snot out of their rigs. Matt's experience above may suggest otherwise, but I suspect his rig saw a lot more use than is typical, and I doubt he took the bypasses very often. SO- maybe from a "purist" point of view plating is necessary for all unibody rigs in this application, by my practical experiece says that it's hardly neccesary for the average Joe.

On a seperate note- A concern I've always had with unibody plating is that by plating in one area, aren't we creating a stress concentrator in another? It seems like you would be focusing the stresses on smaller sections of the unibody, and thus could actually increase the chance of a failure. I think my reasoning is flawed, as this obviously isn't a problem in the real world, but I'm curious what your thoughts on this are.

chadjans
02-03-2011, 03:16 PM
Plating is moving around the weak points. With that being said, plating ZJ is a necessity. The control arm mounts tear off, the rear near the gas tank cracks, the areas around the motor mounts cracks and the steering box area tears around the bolt holes. The areas around the middle are the strongest because of the structure around it. The areas at the peripheries are the weakest and MUST be addressed.

I have seen all these issues first hand either with some on my rig or Kevin’s and others. I have yet to see any issues with a WJ, I guess because Porsche has touched the engineering. Although I do know HalfDoc’s and Justin’s doors are starting to change characteristics in opening and closing.

A systems approach is the best way to address the issues. Which is why I beleive the Clayton's kit has been successful. But a cage with tie ins and some sort of frame rail stiffener and plating at the ends will tighten up the characteristics of the rig substantially.

AgitatedPancake
02-03-2011, 03:54 PM
My WJ has held up pretty damn well with Claytons. I've had to rebend the top of my doors a couple of times to make them follow the body lines again, but never had issues opening or closing them. I also have the forward most part of both frame rails plated on the inside, supporting the power steering box and other main structures.

I will tell you where I have some flexing that has become a pretty serious issue. The rear frame rails, at the frame side sway bar brackets. Back when I had a 4" lift I had an upgraded swaybar, well over time the frame rails cracked at the mounts for the sway bar brackets. I removed the sway bar and didn't really worry about it, until this last year. I took a couple massive hits on my rear bumper in which the frame rails flexed up to the point where it slightly bent the floor, and the top of my bumper hit my hatch and actually cracked a tail light. It sprung back to the normal position, but to do that damage the bumper had to move 2"+ vertically up into the hatch, and it's definately not the bumper itself doing the moving, the frame rails are hinging at the cracked point. I hope to have them plated before KOH

squashman702
02-03-2011, 04:10 PM
And of course he went overkill with grade 8 bolts:
http://i131.photobucket.com/albums/p302/SirFuego/Jeep%20Stuff/DSC00251.jpg




Not to nitpick, but the rearmost bolt won't do much . . . supposed to be 3*(bolt's diameter) worth of material between the hole for it and the edge according to what I've read. Highly unlikely that the bumper would go anywhere with the other bolts holding it in, however.

What did you do to strengthen the steering box portion of the unibody? Did you tie it into the bumper at all? We just build a bumper for my buddy's XJ, and plated the outer unibody rail and tied it all in with the steering box bolts, which is why I ask.

SirFuego
02-03-2011, 04:34 PM
IIRC, there was already a hole in the unibody there. I'll be damned if that bumper's coming off, though. If it comes off, I have bigger things to worry about...

All I did for the steering box was run a steering box brace. Once I installed that, I had zero issues with the bolts loosening up or braking. Although I admittedly wasn't running it very long. I'm not saying that one shouldn't beef up that area -- by all means do. But that area hasn't cracked on me.

SB406
02-03-2011, 05:43 PM
Not to nitpick, but the rearmost bolt won't do much . . . supposed to be 3*(bolt's diameter) worth of material between the hole for it and the edge according to what I've read. Highly unlikely that the bumper would go anywhere with the other bolts holding it in, however.


*Disclaimer- I didn't build that bumper, but I personally know the guy who did, and watched the progress of it being built.

Go back and look at the pics again. There is a piece of Box tubing INSIDE the frame rail, with a nut welded inside. Those bolts go through an outter plate, threading into the above mentioned box tubing (using existing factory holes where possible). This sandwiches the unibody "framerail" wall. IMO, you will not rip that bolt out of the plate, but YES it is serving a purpose. It may not be providing a ton of shear strength, but it is providing a clamping force between the outter plate, unibody, and inner box tubing.

Jeep Whore
02-03-2011, 11:43 PM
So any recommendations for plating the unibody? like how to get the stuff off the unibody, what to use to get the steel cut to, welder settings?

I'll be adding some sliders soon, and since I have to weld them on I'd like to plate the unibody first.

AgitatedPancake
02-03-2011, 11:52 PM
Twisted wire wheels on the angle grinder are pretty good, or the surface prep pads . They work pretty fast but I don't think those last very long stripping underbody coating and sealant stuff. Fine grit flap disc would work well too but ya gotta make sure you don't start taking some actual material off

Jeep Whore
02-04-2011, 12:05 AM
Alright, should I scrape as much off as i can by hand? so I don't gum up the flap wheel or the wire wheel?

AgitatedPancake
02-04-2011, 12:09 AM
You wont gum up the wire wheel, it's a BEAST on an angle grinder. Just be careful not to wear baggy clothes you can catch the wheel on, and a full face mask! It can eject peices of wire that'll stick in you, but it takes everything down to bare metal without taking any base material away.

I have a love hate relationship with wire wheels on angle grinders. They kinda suck to use, but damn they get the job done.

http://ecx.images-amazon.com/images/I/51RU9I8R9OL._SL500_AA280_.jpg

CrawlerReady
02-04-2011, 12:29 AM
^ That's exactly how I feel about them....I curse every time I use one, but I'm so glad they exist.

Jeep Whore
02-04-2011, 12:33 AM
Alright great thanks,

I just need to get the sliders and some steel now.

chadjans
02-04-2011, 01:00 AM
http://ecx.images-amazon.com/images/I/51RU9I8R9OL._SL500_AA280_.jpg

The GOOD ones last a long time and do not eject nearly as many pieces as the Harbor Freight ones. My favorite ones are the Hilti ones. Hard to find but I had a group of three of them that lasted for six years and used quite often. I can't get a Harbor Freight one to last a month with the same use.

AgitatedPancake
02-04-2011, 01:02 AM
Yeah I actually generally have the dewalt ones and really like them!

IndyZJ
02-04-2011, 02:21 AM
Yeah I actually generally have the dewalt ones and really like them!

The Dewalt ones are MUCH better than the pieces of shit from Harbor Freight. I haven't noticed wires being ejected from the Dewalts, but shit goes EVERYWHERE.

Plating heavily stressed areas (suspension, steering, bumpers, and drivetrain mounting areas) and tying them together with a well-designed cage is IMO the best way to make a unibody survive. Disperse loads over as much of the structure as possible. Even if you plate the rails front to back, you don't have much additional bracing against the torsional loads that eventually tear sheetmetal and break spotwelds.

SB406
02-04-2011, 09:47 AM
So any recommendations for plating the unibody? like how to get the stuff off the unibody, what to use to get the steel cut to, welder settings?

I'll be adding some sliders soon, and since I have to weld them on I'd like to plate the unibody first.

Make cardboard templates to get the sizes & shapes. Make sure the wled area is CLEAN. Welder settings depend on the thickness of your plating.

Jeeptech01
02-04-2011, 10:48 AM
Warm the undercoat with oxy acetelyne just enough for it to get really black. Then it will literally fall off with a scraper. Get residual off with brakleen or laquer thinner. I used that process for my XJ and it was painless. Im plated front to rear.

I had some questions about plating my unit body further for all you smart types.

My main rails are plated with an L shape stiffener (hd offroad) and my front and rear plates are flat on a vertical plane along the outer side of the rail. I would like to plate the inner of the front like Downtown did but my uca's wont clear it. So I was considering plating the bottom side of the front rails and tieing it into the existing plate so I have an L shaped plate along the front from the lca all the way to the bumper. For the rear Id like to plate the other vertical plane and the bottom so I have an LI shaped deal from leaf hanger to hanger.

So heres my question (finally) will this plating help or will I just be adding weight for no reason since there is either 2 (front) or 1 (rear) plane that remains un bolstered. Will I be transferring all the stress to the unplated plane and the factory spot welds for those areas?

http://i420.photobucket.com/albums/pp286/jeeptech01/01%20XJ%20Traitor/100_7166.jpg

http://i420.photobucket.com/albums/pp286/jeeptech01/01%20XJ%20Traitor/100_7164.jpg

squashman702
02-04-2011, 11:24 AM
*Disclaimer- I didn't build that bumper, but I personally know the guy who did, and watched the progress of it being built.

Go back and look at the pics again. There is a piece of Box tubing INSIDE the frame rail, with a nut welded inside. Those bolts go through an outter plate, threading into the above mentioned box tubing (using existing factory holes where possible). This sandwiches the unibody "framerail" wall. IMO, you will not rip that bolt out of the plate, but YES it is serving a purpose. It may not be providing a ton of shear strength, but it is providing a clamping force between the outter plate, unibody, and inner box tubing.

I fully understand that there is a slim-to-none chance of it shearing/tearing out of the bumper mount. I didn't realize it was reusing a factory hole, which makes a lot more sense.

Back on topic, I bought T&T stiffeners, but haven't mounted them yet. Has anyone found issues/easy improvements that can be made to these?

SB406
02-04-2011, 02:44 PM
Has anybody on here ever gone through and fully welded all of the seams on their rig? I know some rally/ ricers do this to stiffen up the car. After all, the entire body is held together with spot welds.

FearTheDentist
02-04-2011, 03:43 PM
Get residual off with brakleen...

VERY bad, potentially fatal idea. Brake cleaner seems fairly mild compared to many solvents so you'd think it "safer", eh? FYI, courtesy of Chad (no original info from me, I'm just re-posting):

http://www.mallcrawlin.com/forum/showthread.php?t=20130&highlight=welding+brake+cleaner

Jeeptech01
02-04-2011, 06:13 PM
Yes I have read that several times. The brakleen we have here at the shop is basically alcohol. But yes if you use brakleen do be sure to make sure all the remnants are gone before welding.

Also anyone tried using that spray foam inside the unit body rails? Apparently that is what the drifting guys do.

downtowncb
02-04-2011, 07:24 PM
Also anyone tried using that spray foam inside the unit body rails? Apparently that is what the drifting guys do.

What's that supposed to do, prevent rust?

chadjans
02-04-2011, 08:10 PM
What's that supposed to do, prevent rust?

Make them float.

chadjans
02-04-2011, 08:11 PM
VERY bad, potentially fatal idea. Brake cleaner seems fairly mild compared to many solvents so you'd think it "safer", eh? FYI, courtesy of Chad (no original info from me, I'm just re-posting):

http://www.mallcrawlin.com/forum/showthread.php?t=20130&highlight=welding+brake+cleaner


The non-chloronated stuff doesn't make mustard gas like the chloronated stuff does.

Jeeptech01
02-05-2011, 12:17 PM
LOL it is supposed to add stiffness. I suppose the rails would be less flex prone if the area inside was filled with something. Why wouldnt it work?

Also could someone plz answer my question from a few posts back?? I think I have posted it several times on the board but never gotten an answer to it. Id really like to know.

AgitatedPancake
02-05-2011, 01:11 PM
I think plating the bottom of the front section of the frame rails would be pretty beneficial. It would help protect the chassis incase you ever have an impact that trys to bend the front frame rails side to side.

Walking around a jeep junkyard with a lot of wrecked WJ's I got to really look at how the structure was designed, WJ frame rails are designed with a consistent fold point right at the motor mounts. Almost every one I saw with a front impact was folded at this point, and I'm not sure just outside plating would protect a whole lot against it

hvac man
02-05-2011, 04:37 PM
Hey guys, first post here but I might as well add my 2 cents. In the last year I have bought a ZJ that had been previously modified and wheeled. This ZJ was built (in his shop Stage West 4X4) by myself and the previous owner. The thing I have noticed about the ZJ is even with moderate wheeling the control arm brackets had begun to crack in places. I attribute frame "twist" or "flex" to the fact that most problems occur when the suspension binds. During suspension bind the added stress causes the frame to twist to compensate for the lack of suspension movement. This is why most people we hear about with this problem usually have short arms stock or after market or are lacking limit straps and bump stops. Imagine if you had an unlimited amount suspension movement...basically the frame would stay straight/square while the suspension did all the flexing. Soooo, the problem I see is that we are always trying to get more flex out of our rigs without spending more money for it ;) even in the case of long arms there is still a point where suspension bind can still occur. In conclusion I think that if you are working on a budget, frame stiffeners should be employed from the get go. But, keep in mind that most "out of the box" long arm lifts will need modification to work with frame plating. I am currently building a semi-custom long arm upgrade around my TnT frame stiffeners. This is just my opinion and also some fuel for the fire.

Jeeptech01
02-05-2011, 10:26 PM
I think plating the bottom of the front section of the frame rails would be pretty beneficial. It would help protect the chassis incase you ever have an impact that trys to bend the front frame rails side to side.

Walking around a jeep junkyard with a lot of wrecked WJ's I got to really look at how the structure was designed, WJ frame rails are designed with a consistent fold point right at the motor mounts. Almost every one I saw with a front impact was folded at this point, and I'm not sure just outside plating would protect a whole lot against it

Yea I remember you saying that in your build and it is what got me thinking actually. I was thinking for the rear and the mid sections where I would basically have the LI config of plating that I may just holesaw through from one side to the other and weld in a section of dom everey foot or so. That way both vertical planes are joined together by something other than just the weak ass floorboard. Meh?..:smt105

cowboy63b
02-06-2011, 12:20 PM
Yea I remember you saying that in your build and it is what got me thinking actually. I was thinking for the rear and the mid sections where I would basically have the LI config of plating that I may just holesaw through from one side to the other and weld in a section of dom everey foot or so. That way both vertical planes are joined together by something other than just the weak ass floorboard. Meh?..:smt105


wow, sounds like a solid idea.

rstrucks
02-08-2011, 11:07 AM
Here are some pics of my unibody plating and cage tie ins. THe cage is welded to plates at the roof as well. So far I am really happy with how solid it feels. Time (and use) will tell if it holds up in the long run. I think it will.

http://i358.photobucket.com/albums/oo22/ryanshand/ZJ%20build%20pics/IMG_2482.jpg

http://i358.photobucket.com/albums/oo22/ryanshand/ZJ%20build%20pics/IMG_2395.jpg

Rockers are tied into the unibody rails. Here is the start of the plating. The 1/8th inch plating is on the outside of the rail and the bottom before and after the suspension mounts.

http://i358.photobucket.com/albums/oo22/ryanshand/ZJ%20build%20pics/IMG_2429.jpg

I reinforced the front crossmember as well.

http://i358.photobucket.com/albums/oo22/ryanshand/ZJ%20build%20pics/IMG_1791.jpg

I plated the area where the steering box bolts on along with installing a box brace. There is also a track bar bracket brace that runs under the engine and attaches to the passenger side frame rail. I thought I had more pics of the plated rails.....

geeteesjeep
02-08-2011, 11:30 AM
What if you use option B and weld a subframe inside the jeep overtop the frame rails? Would this be just as strong?

This is a relevant post Maxx made about Elliott's thread mentioning an FEA that Kraqa did regarding frame stiffeners.

jpeterson
02-20-2011, 11:32 PM
I can add a little tech to this TOTM.

Let me say first this is not a DD; it is a street legal trailer queen.

First to strengthen the unibody a full cage was installed. It started life as an essentially off-road kit that has been modified. I was not really impressed with their kit; it did not fit together well. (It still needs more triangulation, itís on the things to do list.)

http://i55.tinypic.com/1zqpqqa.jpg

The cage is tied into the frame at all the pillars. The floor is sandwiched between two plates at all pillars, with bolts that are welded to the nuts. I welded some tubing to the plates in order to connect the cage to the unibody as well as the outer lip/rock sliders.

http://i55.tinypic.com/qx8dpz.jpg
http://i54.tinypic.com/2q0v8jr.jpg

In the rear I made sure when the pillar hit the floor it would be centered on the unibody. This made it possible to weld two pieces of angle iron on each side of the unibody frame. This is welded to plating on each side of the rear unibody.

http://i52.tinypic.com/2yuage8.jpg

Like I said above there rear of the unibody was plated on each side for strength.

http://i55.tinypic.com/242e4xs.jpg
http://i56.tinypic.com/f2my68.jpg

In the front the whole unibody was plated on the outside.

http://i54.tinypic.com/240yyx3.jpg
http://i52.tinypic.com/2j330xc.jpg

There is also a Clayton Off-road unibody sub frame welded along the unibody, it is also welded to all the link brackets. The sub frame is also welded to the opposite side via a cross member.

http://i52.tinypic.com/28i1coz.jpg

In the future I plan to add more triangulation to the cage, as well as weld bars back from the shock hoops under the hood through the firewall to the A pillar of the cage. Even more will be done if we get into Top Truck this year.

Thanks hope this helps people out.