Measuring diagonally from left front to right rear, my frame is 3/8" longer than from right front to left rear. How much misalignment is acceptable? The frame rails are equal length, just out of square. I'm building it on my garage floor. My next project will be a frame table.
If you have 3/8" out of square, you have a serious problem. Maximum allowable is 1/16". Usually when you measure a frame (not sure what kind of frame you have) you start from a known hole location on the frame and go X to another know hole lacation. Just measuring from front horn to rear horn will hot give you an accurate measurement. What frame are you working on????????????
3/8's is alot... even 1/8th is kind of pushing it. If you allow it to be off an 1/8th here, 3/8th's there before you know it you're drivivng down the road crooked. Try and eget everything as square as possible. Do it now when the car is apart, don't until it's done and you have to go back and redo everything.
It's not as bad as I thought. With someone helping me hold the tape the difference is 1/8". The frame is 2x3x.120 tubing. Suicide front perch is welded in place. Rear crossmember is just tacked. When I started the frame, I put a centerpunch on the top of both rails at the front crossmember. I've used that as a reference for all measurements. When I measure from that point to the inside of the frame rail at the point where the rear crossmember is attached, there is a difference of 1/8" from one side to the other. The frame seems to be slightly bent outward on the passenger side where I welded in the front Z. The bend barely shows up on my 24" straight edge, but over the length of the rail it makes a difference. Should I bust the tacks on the rear crossmember and try to bend it back in, or is there a better way?
0 to 1/8" is usually the go/no go dimension. You should also stretch a couple of taught strings across it diagonally too to see if it has any twist in it. again, 0 to 1/8" tolerance. The strings should just touch in the middle.
Hey, Are ya dead sure about that 1/8" measurement? Has the frame been welded on the driver's side, as well? Look for what caused the measurement to be off. If the driver's hasn't been welded as much as the shotgun side, will the final welding suck the frame over the 1/8th? You could pull in the rail with a large come-a -long, or a pull ram( A Porta-Power ram that pulls instead of pushes) and a length of 3/8 hardned chain. Cutting the welds loose would be an easy out, but if you have no way to control heat damage from the welding, you'll be back to your original problem once the frame is welded complete. Swankey Devils C.C.
Thanks guys. I've got the frame braced from every angle with 1" tubing while I finish welding. I'll cut the fish plates tomorrow and get them welded on and then try to get back in square.
If you are 3/8 outta square, then you only have to get 3/16ths to be perfect. You can put a comealong in the middle, tie it off to the longest measured side and pull it back. As the rail comes back the other goes forward and all you need is 3/16ths. The term for what you have is Diamond. A very easy fix. Go slowly. When you start pulling it back measure the long side, bring it even then let it off. It may stay or it may go back. If it goes back, pull it a 1/4 inch past, let it off, remeasure. Keep going til it stays. Should take about 30 min. start to finish. Diamond is one of the easiest problems to fix.
The spring pearch center holes front and back should be your constant for measuring from.Start at the front center spring pearch hole and measure out to a known point on both sides to the rear, if it isn't within a 1/16th figure out why.Go to the rear and measure from the center of spring pearch and measuree to a known point on both frame rails forward.If this isn't within a 1/16 figure out why.These two center points eventually triangulated to the kingpin centers and the rear end, and hairpin or radius rod mounting points are what keeps the axels square.The other measurements are important but the spring pearches need to be as dead on as you can get them.
it would be nice if you had a picture here, maybe you can cut 3/16" off the front of one rail and weld it onto the back end of the same rail, good as new.
Also, these guys are assuming the frame is flat. If one corner is raised (or lower) more then the other corners, the cross measurements will also be off. Be sure both front corners are at the same hight and both rear corners are at the same hight. Gene
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