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Northridge is really great about getting products out fast.
That's good because usually if we make an order today we want it yesterday. :eek:bsessed:
 

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Discussion Starter #22
ImageUploadedByAutoGuide1471146399.748957.jpg

Paint's on!
 

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I find it sad and a bit disheartening that folks simply don't understand the value of a good rocker design versus a poor one and why the difference is so important when protecting the body work if you plan on using the rig in the rocks or actually using them for their intended use. If you are just after some aesthetic mod, disregard the following.


At no point in time should one depend on using the body mounts to trap the lower edge of a rock rail that is intended to be used in the rocks or with any enthusiasm.


Rock rails need to be attached to the body using the same fabrication model that airplanes and similar sheet metal to heavy framing techniques are used. You need lots of small fasteners because the body is thin, only moderately well supported, and you need to keep the spacing small.


Do not skip areas simply because they are difficult to access. Nutserts exist for a reason, use them, use a lot of them.


Larger than 5/16" quality fastener are a waste of time and money and don't allow you to use fewer of them just because they are larger.


Do not use any rail design that causes the torque boxes to be unevenly loaded. The tub is a structural member and it combined with the frame is what provides the overall strength to the rig. You would not arbitrarily go out to your rig, cut off one of the frame side mounts and raise or lower it 1/2", weld it back on and expect good things to happen, why install a rail that does the same thing?


The rear corner of a rock rail is vulnerable to later displacement, don't notch it around the corner. You need the horizontal support to combine the overall strength of the corner and rail to provide the most protection and strength possible.


Corner bent in because rail doesn't go WW to WW.





Not enough fasteners.





Not enough fasteners and no backing plates.





Straight edge showing how far the tub was displaced by the large fastener without a backing plate. The tub and armor need to be unitized with many smaller fasteners like rivets on an airplane skin.





Displacement the other direction when the rig leaned against a rock and there weren't enough fasteners to keep them unitized and no backing plate. The armor wasn't displaced, it just pushed the tub in and then sprung back leaving the wave in the tub.





This is what happens when you push on the lower edge of the corner that is notched around the rock rail.





Now, I already know most all the comments. "mine don't look like that" Good, that means you aren't using it very hard and they are fulfilling your intended use. No harm, no foul.


"That wouldn't have happened with tubes welded on." Yeah well, yes it would have because we see it all the time. This group of pics is just representative of what we see all the time with this method of attachment. In fact, we have never seen a set that didn't have issues but then again, we are in a area where good protection is needed by those that use their rigs. If you fit in that group, you will at some point encounter the same issues.


What we see that isn't shown is the lower edge of the rail gets shoved in toward the frame because it is just sandwiched at 3 locations by the body mounts which lets it lean the vertical face outward at the top and displaces the tub and leaves a big gap to fill with whatever. Once the tub is dimpled around the fasteners, then they are loose and can not be tightened because the metal has been stretched. That allows even more movement and we have seen rails that have almost worn through the metal on the side of the tub due to just vibration going down the highway.


Any rock rail that is intended to be one should be attached with several fasteners to the bottom edge of the torque box to prevent inward displacement.


Also and this is very important if you still plan on using a body mount sandwich style rail, be aware that the foremost body mount is flush to the bottom of the torque box. The second and third ones back from the front are recessed up into the torque box and any trimming of the mounts needs to take that into account so that the same stresses are seen by the torque box after the rail is installed. Don't unevenly load the mounts by trimming the mounts incorrectly.
 

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Great analysis Blaine, I never really understood the structural aspect of the rail until now. My Rokmen sliders have a nice long interior backing plate, now I understand how important that is - I ordered it because it sounded like a good idea at the time :smile2:.

I had to go outside and look at my sliders - everything looks great, straight and normal and I've beat the crap out of them.
 

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Discussion Starter #25
Well that would have been good information to know a week ago. ?

I have been concerned about the aspects you have mentioned, though it seems it's common across nearly all the brands (except ww to ww).
 

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Great stuff, Blaine. You should write a book, but it sounds like you are too busy to get out and have some fun as it is.

We really appreciate the knowledge you share.
 

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Well that would have been good information to know a week ago. ?

I have been concerned about the aspects you have mentioned, though it seems it's common across nearly all the brands (except ww to ww).
I have posted the design criteria for good rails that are intended to be used many times over the years. In fact, it was the posting about it and the subsequent ******** by many saying theirs held up just fine and they were "hardcore" users that was the impetus for me to design the ones I did for Savvy.


Then it gets worse because now I'm accused of brand bashing even though you can go back and dig up multi page threads about the design parameters and concepts from long before I ever met Gerald.


At that time, I didn't even know that particular version used the body mounts. I saw a set of rails when someone visited and when they stepped on the tube to get out, the whole rail flexed and rotated pulling away from the body which caused me to examine the mounting method more intently because I thought the owner had installed them incorrectly. He hadn't.


What you have isn't common and is unique to that logo as far as I've seen. That little tail on the full corners that notches around the end of the rail is especially vulnerable and we see them bent inwards frequently and the damage to the tub that results.


You can improve them by adding some nutserts and getting some fasteners up into the torque box after you lay out the height you need to cut the body mounts down very accurately. You will know you have it correct when you view the lower half of the OEM body mount and they all look like they have the same amount of squish going on.


When you trim the mounts, don't forget to account for some squish. To get an idea, measure the height of the front pair to get an idea of how much preload is on them before and after you remove the bolts.
 

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Great stuff, Blaine. You should write a book, but it sounds like you are too busy to get out and have some fun as it is.

We really appreciate the knowledge you share.
We'll get out more when Kat gets better. Helping folks solve problems provides a level of enjoyment that can be considered fun. Not as much fun as driving the trails, but it will do until we can do something different.
 

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Great analysis Blaine, I never really understood the structural aspect of the rail until now. My Rokmen sliders have a nice long interior backing plate, now I understand how important that is - I ordered it because it sounded like a good idea at the time :smile2:.

I had to go outside and look at my sliders - everything looks great, straight and normal and I've beat the crap out of them.
It is like most things John, the clues about the strength of things are already present in the tub, you just have to listen to the story they want to tell. Anyone who has ever removed a set of factory flares that was damaged by a tree or a rock has seen the outward dimples of the holes and nutserts that are under the flares and used to attach them to the body. The metric machine screws with the large washers are 5mm. That is a tiny fastener and yet it has the strength to dimple the body outward when the flare is subjected to high loads.


If a 5mm fastener can distort the sheet metal, then the only reason to use larger ones is purely packaging. Reality is we could use 1/4" and they would be overkill. (Currie used 1/4" with no issues before they quit making rails) The only reason I use the larger 5/16" fasteners is I know that customers like to tighten the crap out of stuff and why someone twisted off half of their fasteners trying to install a set of rails is not a continual conversation I wanted to have.


Another thing I will never understand is the use of Allen drive fasteners. Jeep owners by and large despise Torx drive and it is easily twice as good as the Allen drive stuff. The driver size is simply too small for the shank diameter and Torx improves on that by a fair bit. If you look at a normal bolt (hex head cap screw) the driver size is many times the diameter of the shank in surface area. A typical 1/4-20 bolt (HHCS) has a 7/16" hex drive and there are many times that isn't large enough to easily break free a contentious connection. This isn't some great revelation, anyone who has worked on a vehicle has seen it so at what point does it make sense to use fasteners that have drivers that are smaller than the shank diameter other than looks?


I use a lot of Phillips drive for flat heads. A 5/16" flat head cap screw uses a #4 Phillips driver. If you use that with a good small impact and quality bits, it will twist off the fastener before the head strips out. That never happens with Allen drive, the head strips out first.
 

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Discussion Starter #30
This is certainly not a one-man job. I've bitten off more than I can chew.

ImageUploadedByAutoGuide1473037977.650519.jpg
 

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Discussion Starter #31
I recruited some help. They are on.

ImageUploadedByAutoGuide1473055739.576497.jpg

I'll have a review up soon. There are some things that I'm not pleased about, but I'll survive.
 
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