Shot one shows the rear Z being laid out. One very important step in the alignment is to insure that the upper flat portion of the Z (the piece that will be over the rear axle housing) is exactly parallel with the main (lower) frame rail. I used a rather crude method involving two carpenter squares. You will probably be able to figure out a better method - but make certain that his angle is right. If it's not you are bound to end of with a twist in your final product.
The second shot shows all the welds on the Z completed and ground down. I like to keep the welds ground at each step of the way rather than putting it off until the end. It's not a job I enjoy so it's better to spread it out over time. It's too daunting a task if you wait until then end and have to look at doing an entire frame at one sitting. Also, as I noted above, it does assist you in determining if you are getting good penetration on your welds. And finally, it just makes me feel better about the project...if I get up the next morning and my first look at the frame has all nice clean welds. Just puts me in a better state of mind.
The final shot shows the completed welds with temporary primer applied to the ground areas. This is just a rattle can job so I'm not sure it really does much good in terms of preventing rust. But again, I just like the look of a nice, fairly clean frame as I move through each step of the construction. It's probably more of an esthetic's things than a required step because I'll just knock the primer off later when I sand and smooth out the grinder scratches and put on a coat of por or epoxy primer with my gun.
Shots one and two show the second frame rail being laid up. It is critical here that the second rail match up perfectly with the first rail that has already been completed - in terms of total length as well as each individual section of the rail. I do this by first doing a quick and dirty layout of all the pieces to insure they are "close" to right. I then take it all apart and weld ALL the "Tab A" ends of the gussets into place and drill all the weld holes where they will be required for the B side of the tabs.
All the pieces are then friction fit together, often with the aid of a good size hammer, and clamped to the finished rail. (Note: try to clamp together with the manufacture's welded seams on the outside. These welded seams do cause a slight distortion on one side of the frame rail resulting in a little hump. So it's best if you can clamp flat side to flat side.) Then comes the long and arduous task of measuring and adjusting, measuring and adjusting, measuring and adjusting until you get all the pieces (and the total length) in precise alignment. A bit of a warning here. This took me one entire day of futzing around to get things where I wanted them - so it's no quick task. Just believe me on this...it takes a LOT of plinking here and plinking there to get it on the money.
Also note in the pics that the frame is not clamped directly to the table but is held a uniform distance from the table by extra pieces of the 2x3 tubing. This is necessary in order to get clamps in as many places as possible. I've seen some guys who actually drill holes through their tables in order to mount all the clamps. That may be a better solution than mine, but it sure messes up a nice flat table.
The last shot shows the second frame rail clamped tight to the first and ready to be welded. Again I go through a series of tack or "spot" welds at different points on the rail to try to minimize heat build up and warpage.
Once the side rails are complete we move on to the cross members. At this juncture I will install three primary cross members all made with 2x3 tubing. The rear member, the front member (used for mounting the front I-Beam), and a second "front" member, approximately 9" to the rear of the first front member and used to mount the other I-Beam. All the cross members were cut to a 28" length.
The first and second shots show the cross members being laid out on the floor. I tried the layout on both the floor and on my "flat table" and had better results with the squareness and alignment doing it on the floor. I'm not sure why that was - but I just went with the flow. You will note in the pictures a series of wooden 2x4s inserted at various points along frame. These are simply to keep the frame from bowing in or out along the long run of the bottom rails.
The third shot shows the frame, with the cross members welded in place, back up on the "flat table" being checked once again for alignment and "twist". If you can "rock" the frame by pressing on any one corner and lifting the opposite corner at the other end of the frame, you have a twist. I ended up with about a 1/16 - 1/8" twist in mine (in other words when I press down on the front left corner of the frame the rear right corner rises up 1/16' - 1/8"). I think this is within a reasonable tolerance but if it causes problems later on I will take it into a local shop and have it straightened on their machine.
This shot shows the end caps welded in place to close up the tubing. The welds have been ground and primered. One little trick I used here was to cut and grind the caps to just slide inside the tube ends. I held them for test fitting and for the final weld by tearing off about a 3" length of duct tape, pressing about 1/2 inch of the right end of tape to the right side of the cap and pressing about 1/2 inch of the left end of the tape to the left side of the cap and then pressing together what was left in the middle of the tape. This gave me a nice "handle" to hang onto while I fiddled to get the cap exactly into the right position. I then just held it while I tacked the edges in a couple of spots. The duct tape held surprisingly well.
Next comes what may turn out to be the trickiest part of the chassis construction. Installing the Independent Front Suspension (Twin I-Beams) from the F-150. I have a little help by studying how Charlie's Rod Shop did my 32 pickup (see pages 1-4 of this journal to see that build). However, my pickup took the suspension out of a 78 F-150 and my "Rat on a Shoestring" is using the front end out of an 81. And they are quite a bit different - most importantly one is a front steer and one is a rear steer. As a result I have to rely primarily on all the measurements and pictures I took while I was stripping down the donor vehicle.
As these three pictures show, I started by cutting and installing the bracket for the front I-Beam. This is the beam for the driver's side wheel. Each I-Beam basically rotates on a bolt through the "eye" end of the axle (the end opposite the wheel). I had referenced the position of the center of this eye in relation to a number of other points on the donor vehicle. Using these reference points I was able to locate the center of the eye along the front cross member the correct distance from the center of the frame. The height off the ground of the center of the eye was set to match the height as it was in the donor vehicle. I was then able to determine the distance from the center of the eye to the bottom of the cross member and thus, the height of the bracket I needed to attach the "eye" to the cross member.
The bracket itself if a piece of 2x4 1/8" wall rectangular tubing with a portion of one side cut off at an angle so that the I-Beam has adequate travel. Fortunately, the eye of the axle and its rubber bushing are exactly 1 3/4" wide and fit nice and snuggly into the 2x$ tubing. I then centered and drilled the hole for the eye bolt (I am using the stock bolts for the time being). I then attached the I-beam (with the wheel and tire still on it) to the bracket and then clamped the bracket in position on the cross member, rechecking all my measurements once again. I installed the bracket exactly parallel with and perpendicular to the cross member. With a feeling of "I can't go back from here", I welded that puppy in place.
Is this the correct way to do this? Well no one knows for sure since there isn't a whole lot of literature on how to graft an I-beam suspension into another vehicle. We'll just have to wait to see if I've made some sort of huge error here. But comparing it to my '32 pickup, it looks pretty well on target. And that's the fun of doing things The Old Way - you get to be surprised at every turn of the corner. Some of the surprises are good. Some not so good. Keeps you on your toes. But with the first I-Beam bracket in place, I now had a "core" to build around.