TOTM: Unibody Improvements

[SirFuego]

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]

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]

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]

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]

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]

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.

[CrawlerReady]

^ That's exactly how I feel about them....I curse every time I use one, but I'm so glad they exist.

[Jeep Whore]

Alright great thanks,

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

[chadjans]

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]

Yeah I actually generally have the dewalt ones and really like them!

[IndyZJ]

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]

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]

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?

[squashman702]

*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]

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]

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/sho...+brake+cleaner

[Jeeptech01]

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]

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]

What's that supposed to do, prevent rust?

Make them float.

[chadjans]

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/sho...+brake+cleaner

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

[Jeeptech01]

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]

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]

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]

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?..

[cowboy63b]

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?..

wow, sounds like a solid idea.