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How do you measure the frame to see if it is square


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My truck is up on blocks and I want to take measurements to see if the frame is square before I start the body work.  What points do you use to start?  What techniques do you use to do the job?  This is a 1/2 ton Dodge RC Humpback Panel Truck.  Thanks

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The simplest way would be to take a measurement from the front left farthest point to the right rear farthest point and repeat from front right to left rear and compare the measurements.  Maybe some one has the crash repair book with other points of measure. 

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Basically measuring diagonals.  It's going to be pretty hard to get accurate measurements with everything still in and ,on the frame. My suggestion would be  using a plumbbob and marking identical drop points on the shop floor, moving the truck and measuring those marked spots.  I'd suggest using the ends of the frame, a point where the front of the rear springs are hung and a point where the rea of the front springs are hung.  Measuring between sections will help you locate where the frame is bent if your overall diagonals don't match. Using a chalk line from drop point to drop point may also help you visualize it.  If diagonals don't match, find a square section, probably the one the rear suspension is in, try to establish a center line front to rear in that section and then extend that line the entire length of the frame.  That will show you how much the frame has to move to get it square.

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I assume there are.  The main thing is to measure from it's corresponding hole, point, bracket, crossmember, whatever on the opposite frame member.

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9 hours ago, pflaming said:

Aren't there mfg gig hold  holes that can be used as well? Seems those holes are shown on the frame schematic. 

 

These schematics are definitely in the car books, and while I don't have any books for the pickups, I would assume that they would be included there as well.  The advantage of using those is that you would have the correct measurements, and you could much more quickly identify where the issue is.

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  • 5 months later...

Get the frame level all the way around. If Its not able to get to level, It might be "twisted".

This may indicated stress cracks etc in the frame itself.

Frames from this era were designed to flex to handle road conditions (what we call rural roads now) but panel trucks may have faired better.

Having owned many frames and built up a good number of them for friends and customers.....the cracks are hard to see.

Front mounting points for the rear leaf springs are one area, the other being the rear cab mounting area.

Once you decide your frame is straight, or curved, the next thing to decide is if you can live with its potential.

My feeling is, in an original usage plan, the fix is small. Matching springs, good tires and boxing the weak areas if there are some, you're good to go.

If you're racing your neighbor down the street at the local track, it will most definitely take more work. 

 

48D    

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