I am trying to establish what I "think" is the centerline of the factory straight axle. I have two frames, a '55 that is original and has the factory running gear in it, and a '56 that is a bare frame, without any original brackets removed. Both of them have the 1/2" pilot hole located on the top of each frame rail in the engine compartment area, real close to the factory front brake line connectors coming out the side of both frame rails. I hooked a tape measure on the front end of the frame (not bumper brackets) and pulled it back towards the rear of the truck. I get 29-1/2" to the center of the holes on both frames. I have looked in my factory assembly manual, and in Section 2, Sheet #24, it shows the "Centerline of Front Wheels", but doesn't reference them directly from the front of the frame end. It does show a "Front of Dash" reference line from the front of the frame, and that dimension of 43.240" inches, minus 15.750" shown from the "Front of Dash" reference line back to the "Centerline of front wheels". This give me an axle center line of 27.49". Both of my frames have these holes located at 29-1/2" . Let me know if I am on the right track or 2" way off! Thanks for your help
Not sure if this will help or not Oleblue55 , but heres a few pics. I,d say Your on the right track it appears to Me right at 28" . Hope it helps some. Bob
Bob, Thanks for the pictures. My 56 frame doesn't have the original front axle and springs on it, they were already removed. My '55 does have all of the original front suspension on it, and I measured it just like you did, and sighted down at the front axle and actually used a square to establish where my axle is, and it does coincide with the 29-1/2" of my pilot hole. Your pilot hole is located to the front side of where your axle actually is. I am wondering if after all the years of use, that the original springs relax and move the original axle mounting centerline? In my factory manual, it does reference the pilot hole as the centerline of the axle, yet it looks like yours is more like 27-1/8", where mine is located at 29-1/2". Interesting! Thanks again. Ed
Should be 27 1/2 on 55-57 chassis 58 and 59 are 2 inches longer, makes it 29 1/2....... I moved mine forward to 25 to center the wheel in the fender, on a 56.
Hey, The centline for a short bed is 113 inches wheel to wheel .You can use a plumb bob to find them as well. Cliff
Hey guys, I finally figured out what I have going on! I have two "55" frames that are 180-3/4" long overall, making them obviously 58-59 frames. I guess that is why my assembled '55 doesn't have a front bumper on it, and the guy who sold me the "56" frame was wrong. It is my fault, I took a tape to verify it was the same length of my "original" 55 frame, of which it was! Digging into my factory assembly manual, I found that the 3100 frame for the 55-57 should be 178.05" to be exact. I have roughly 2-3/4" in length difference which I am assuming is in the very front of the frame? I am guessing the 58-59 frames which I now know I have,had the extra material added in front? I am also assuming that the front and rear spring locations and everything in between including the cab mounts are all the same in the 55-59 frames? Of course you know what happens when you assume! Can anyone verify that for me. I couldn't find the 58-59 frame drawing in my 55-59 truck assembly manual unless I am missing something. Thanks.
Hey, The 58 and 59 frames are almost 2to3" longer then the 55,56,57 frames. The hood hinge holes on the cabs are farther apart on the 58,59 cabs then the 55,56,57 cabs. Cliff
Thanks for the reply. Is the additional frame length added to the very front, in front of the front spring frame mount? I don't have a frame drawing to the 58-59 frame, and it is not located in the 55-59 Assembly Manual that I have. If I cut off the additional material on the very front of the frame rails, I can re-drill the front bumper mounting holes in the same location, just further back? I just want to make sure that the cab mounts and suspension locations are the same, which I am almost certain they must be.
