Here is my design work on my Rock Rails.

I got a set of incomplete rails from someone on the Colrado XJ list, for cheap. That is good because after looking at several different designs and thinking about the mounts myself I have completey redesigned them.

The first thing I though of changing was the mount. Commercial mounts use angle iron to attach to the Cherokee's ¨Frame¨¸ the ones I bought just had flat mounts.

Here is a picture of the rails I got for a case of beer. If I had not wanted them to stick out further from the car¸ I would have bolted them on and forgot about it.
Then I felt that I wanted the rails to stick out farther from the body¸ to try to protect the door panel some as well. While working out this problem¸ I decided that instead of just putting longer mount arms on the rail I had which would leave a gap between the rail and the body of the car¸ I wanted to go with some 1 1/2 by 3¸ or 2 by 4 box so there would not be a gap. This meant the bars I bought were now just some 1 1/2 inch square tube I could cut up to make my new rails.

I then worked on the design I wanted. I have a drawing of them but it is a large page. I can´t seem to get it to be smaller than a letter size piece of paper and still have it legible, so you can visit it here if you like. If you want to print these drawings for yourself¸ after you hit the print button on your browser¸ select properties when the print page comes up¸ the select ¨Landscape¨ for the orentation and the drawing will print on one piece of letter size paper.

While thinking about this design¸ I thought that the piece of angle iron that I had running from one frame support to the other was too long. Even with 1¨ angle with a 1/4¨ wall, my weight would be able to bend a piece supprted 46¨ apart. If this piece is supposed to transfer the load from the rock rail to the frame (right at the body pinch seam) then it needed more streagth or more support. So I am now working on a design with three supports per side instead of two. The other thing about this design is the piece(s) of angle I am using to pinch the body seam to the rock rails. I deciede to use four seperate pieces for the purpose because there are some bulges in the body seam. That picture is a little lower on the page. If I had only used a one piece pinch¸ then it would really only touch the body seam in three places instead of all along the leangth of the seam. At least with the four pieces¸ it will touch for most of the length of the seam.

Here is the drawing with the three supports. The only change is the addition is a third mount to the frame in the middle of the rail. I think this will help transfer the load from the piece of box to the frame of the truck much better. I might be a little overkill¸ but all in all the whole thing is overkill. It is made from much heavier material than other rails I have seen.

Here are the rails along with the steel I bought to make them into the one´s I designed.
My first step was to cut a notch into the pinch seam for the support arms. I wanted the arms and the angle that was to go along the pinch seam to be right on the body. I figured that way any load would go straight to the body of the car.
I have read of people having trouble with their rails denting their body¸ it seems that when they hit a rock the rails deflected into the rocker panel and dented them. I figure if the rails can´t move before they contact the body, there is no room for flex and the load is transferred directly to the body (along the pinch seam) and to the ¨Frame¨.
After I cut the notches¸ I held the pinch seam Angle Iron up so I could mark it to cut the notches out of it also. You can also see how I bolted the 3½¨ angle up to the frame in preperation for tacking everything together.
After I marked the angle¸ I drilled the holes for my pinch bolts. The I put them back on the car and drilled the pinch seam.
I meant to take pictures when the rails were held in place on the car ready to be tack welded¸ I forgot. Here they are all tacked together and ready for welding.
I painted them before I bolted them up. I only painted the parts you can see. I sprayed the under the car parts with rubberized undercoating. It is cheaper than paint and easier to apply.
I used 12 pinch bolts per side. The rails warped a little bit when they were welded. I had to tighten up the pinch seam bolts first to pull the frame mounts up against the frame. Then I put the self tapping bolts in.
Here is another look at how I bolted the rails up to the pinch seam. You can also see here that the angle iron on the frame side is in several pieces to go around the bulges in the pinch seam.
After the rails were in place I masked off the painted part so I coulsd spray the unseen part with the rubberized undercoating.
Here is a picture of the underside after I sprayed the undercoating on them. I hope this will also help keep the bolts from loosening.

The Money part. I bought the original rails for a case of beer¸ $22.00. I went to Colorado metal to buy the parts I needed¸ including some metal cutting blades that I put on my radial arm saw to make the cuts I needed at home. I spent $57.00.
But them I figured out that I bought the wrong angle iron for my mounts to the frame. When I measured for them I measured 3 ½¨ from the body pan to the bottom of the frame rail. With this measurment¸ 3 ½¨ angle would be ¼¨ too short¸ or I would need to cut 4¨ angle ¼¨ to get them to fit. So I bought the 4¨ Angle. This was fine till I got them home and held them up to the frame. Sinch the Cherokee is a unibody car¸ I neglected to take into account the radius in the body from the frame rail to the body pan. That meant I would have to cut ½¨ off of each piece of 4¨ angle. It also means that 3½¨ angle would be just right. Instead of cutting the angle I had¸ I went back and bought some 3½¨ angle to make my mounts. So I need to add $10.00 for this mistake to the cost of my rails (hey I spent it¸ it counts).
I bought the self tapping bolts at an auto parts store. They are from the ¨Help¨ section. They are sold as oversize transmission pan drain bolts. If anyone knows of a better source let me know, I also here that ¨Thread rolling¨ type of bolts are better to put through the unibody. Anyway they cost me $20.00 for the 24 self tappers and the temporary screws I used to hold the mounts up while everything was tack welded together.
The welding cost me a case of beer (it is amazing the barter value of beer!) so that was $22.00.
I sprayed them with three coats of paint¸ that cost me $10.00. The undercoating I had¸ but that would have been $3.00.
Total cost has been $144.00. Much less that any I have seen for sale¸ and I am very happy with how stout they are.

E-Mail me. 4X4 Home