For many of the things I am doing or about to do having the frame level would be a good and useful thing to know. However, getting reliable knowledge about it appears to be quite a challenge. So how do you know if and when a dent side truck frame is level?

Of course there are levels and inclinometers both digital and analog but where do you place them? It's a wavy navy down there under the bed and body of our trucks. Then there is the fact that our old springs may no longer be equal to one another if they ever were. How do we eliminate the springs as a confounding variable and still have enough room to safely get underneath and do some actual work?

Looking forward to the insights that are both penetrating and common here.

 

I use a building level on a tripod and my wife with a retired piece of tape measure zipped tied to a straight 8' 1" x 2" board plumbed off the points you know that are meant to be level with each other, level accordingly.

 

I think there are level to flat plate measurements points. Should be in shop manual or body builders guide. Info probably here under search area. There are points in every shop manual from Ford for every vehicle year. Hard to follow but there.

 

To eliminate all variables in checking a frame for damage,being level,ride height etc.;you need to only measure the frame less suspension.
The vehicle needs to be on a level.flat floor.Jacking the truck up until rear wheels are off the ground.
The frame now needs to be supported on each side rail, in roughly the same spot. Why not a flat ,exact place on side to side ? Because you are measuring from the floor up to an EXACT,CORRESPONDING spot on each side of the frame. (you don't care if the frame is supported here on one side and a different place on the other side as long as the MEASUREMENT FROM THE FLOOR TO THE FRAME IS THE SAME).
Jack it,shim it. whatever it takes to get the exact measurement L.side compared to R.side, frame to floor.
The place to measure could be a corresponding rivet,hole,bolt.... whatever is the same on each side of the frame.
Now, do the same procedure on the front of the truck. The objective is to eliminate the front suspension by raising the front wheels off the floor.
Where to support, r. or l. frame rail? You don't care . Support,jack,shim again to get each side (we are only up front now) the same measurement from the floor to each frame bottom (or maybe a factory hole in each side frame) in the SAME spot per side.
Go back to the rear,remeasure,readjust a bit if neeeded.Recheck front ,adjust if needed.
The frame ,itself ,can now be checked at different spots for straightness, damage etc, Very ends of the frame are a good place to check for a problem.

A major reason for going through this process is of course an accident but very common to STARE at the front or back of your truck and think" Boy, that looks lower on that side. Have I got a bad rear spring?. Is that weak coil spring on that side?. "
You have eliminated the frame ,if all measures properly, and now tracking down suspension parts that control ride height.

 

I am working on eliminating the suspension as a potentially confounding variable and will report back on that. Here is the relevant illustration of the Body Builder Handbook for my 133" WB '76 F-150. As you can see, it doesn't have much in the way of vertical measurements. It does not identify flat reference points that I can see with the bed off the frame.
There are some further mysteries though that these diagrams do make visible. One is the difference between the CL of the frame and the CL of the engine. According to this handbook the CL of the engine is 1.5" to the passenger side than the CL of the frame. However, I measure a 3" difference so I need to check to see where my error is. The drive shaft, pinion etc are definitely closer to the passenger side of the frame.
Finally, there are four tapered pins on the bottom of the frame (two in front and two in back) that look like they may have been used to locate the frame rails on a factory jig while the crossmembers were being attached. Perhaps they can tell us something interesting.

 

If you look at the frame (side view) you see what they are representing as the top of the frame. That line where it travels from the back of the frame up to the cab has a flat area pick two points on each frame rail in that area and level it like four legs on a table . Once you have that level with ends frame supported but not yet checked for level. Now looking at the Body builder handbook drawing it gives you measurements that tell you how far above the table you have established you need to be to match that flat line established by the table points you created. I hope that helps. If you need further clarification just let me know. I've never used anything but a building level to accomplish this because I Found it to be the easiest when working by yourself. You' will need someone to hold the measuring stick (storey pole).
Notice at the front of the frame it tells you the frame in the front at the bumper horns it is 1.24" above the "top of frame" height and in the back it tells us the frame at from a point behind the rear axle is 2.53 in. above the "Top of frame line".

 

 

As Redroad stated there are a couple of level spots towards the rear of the cab area. On a frame bench with a vehicle to be repaired,"pulled", or checked; that is called the "house" by some frame guys.As in my setup reply , a person needs to establish a level starting point. Whether the center area which is desirable, or along other portions of a frame; you are only getting an accurate starting pointing to start measuring. Whether on an actual frame machine, table or flat floor makes no difference. If a frame is suspected of problems then the Frame Dimension Charts come into play. (Those Dimension Books were Very expensive over the years to purchase but I truly needed them to repair and check frames!) The pegs ARE for factory jigs; most frame type vehicles have them.Great measuring points !.Again... corresponding factory holes,bolts,tops,bottom of frame are the places to measure and analyze. I noticed this in your last post ," As you can see, it doesn't have much in the way of vertical measurements".If I am interpreting correctly, I will say this; you do not NEED vertical dimensions from a chart.They would be strictly arbitrary.That is why they are not there. You set up your frame 1 foot off a flat surface or 3 feet of a flat surface.Then YOU establish the actual vertical measurements from the table,bench or floor to the corresponding spots side to side. Majority of chart dimensions are horizontal.

 

You measured right.

Put 3 black dots in a line on paper, 2" apart. Now move the center dot to the right 1/2" by just using a different color pen. You only moved it 1/2", but you now have a full inch difference it measuring left or right.

When the engine center was moved by Ford that 1-1/2" to the passenger side, they removed 1-1/2" of space from engine center to the passenger frame rail, but they added 1-1/2" to the driver side distance.
As a Trooper, I inspected a few garage floors as part of my inspection station approvals ... and finding inch or two waves was not uncommon in a floor being presented for an inspection lane. An easy way I tested a floor for being "all in one plane" was by opening my kit and pulling out three blocks cut from the same 2x4. I put one at each end of a submitted "inspection bay", then pulled a string really tight as someone stood on it on the end blocks, then I took the third block and checked along the now straight tight string, I've seen floors that were said to be in the same plane suddenly look like ocean waves before putting that third block down near that string.

Inspection bays needed to be "in the same plane" end to end ... if a headlight aimer was to be accurate.

 

If you are measuring from frame to floor you need to make sure the floor is level first.
A 1/4" to 1/8" dip in the floor will throw you off. Dont forget left to right and front to back level.
You need to make sure your supports (jack stands?) are level to the tops as this will level the floor before placing the frame on them.
They say floor tiles under the stands can level them.
Dave ----

 

I used these two old timey screw jacks in concert with a modern hydraulic jack to adjust each frame rail independently. This worked pretty well but it is hard to imagine how the old timers used these without a hydraulic assist.


The area between these two strips of tape is the only significant stretch of flat frame rail that I could find. Once this area was level I looked for other level spots but found nothing of any size. Not even the carb was level as I expected it to be. Although the distance between frame and floor is arbitrary the fact that both sides measured the same was a source of some satisfaction. This flat spot is definitely a good point of reference.

As for the amount of room available on the passenger side of the drive shaft, thanks for the confirmation that this is, in fact, 3" less than on the driver side. Of course this has important implications for exhaust system planning which is my current task. However, it also might matter to those folks considering an engine swap in conjunction with an IFS (i.e. Crown Vic) where they no longer have to make way for a steering box. They might want to center the engine in the frame. Fabricating different engine and transmission mounts wouldn't be a big deal but what about the offset of the rear axle? Might this complicate setting a proper pinion angle?

 

It may not be that easy to just move the motor / trans over look at the hump down the center and foot wells.
I bet you will find them off set as well.
Dave ----

edit not the hump, I was thinking car but the transmission area might be off set also.

 

Plus the angle of the cooling fan in relation to the motor and rad support. It's a jungle in there. Lol

 

Besides gaining steering box and column room, etc, I think Ford took into account

• the position of the pinion gear in relation to the rear axle center
• room for an inside the frame mounted gas tank
• the need for more driver room gained by moving the engine that 1-1/2" to the right (moved the TC stick and floor shift if present)
• and not least of all, the very real need for a evenly balanced weight distribution from side to side for times when Bubba climbs in alone to go check cows on the back 40. Seeing as the engine and transmission likely weigh more than Bubba, that 1.5" shift represents a sizeable weight shift that offsets Bubba, and a good reason for Bubbe to pull Bertha up close away from the passenger door so she doesn't upset the delicate balance should she decide to ride along.. Hence the bench seat.
• they obviously used the battery as a "fine tuning" tool in getting the balance just right.