1 hour ago, Patcon said:

How about leveling with the doors sills, front to back and left to right, then back check with these other areas you picked out

Don't use the seams in doors. Get some small blocks to level off of and use a long straight edge to span across.

I like this idea in principle. 

The assumption that the door sill surfaces are flat, front to rear, is probably a good one, but should maybe be tested with a straightedge, just to be sure.

The assumption that the door sill surfaces were designed to be parallel to the OE front frame rails' top surfaces is probably also a good one, but hard to prove.  You may need to take this as an article of faith.

The straightedge strategy that Patcon is suggesting would require you to get the support points for the two straightedges (one front, one rear) up high enough so that the they will clear the transmission tunnel.  Maybe a pair of 1"-thick rectangular panels (MDF?) cut to 9" x 30" on an accurate panel saw (like the big ones at Home Depot or Lowes), then crossbraced with a few of lengths of 1 x 2 to hold them vertical, parallel and at the right separation distance.  Once set down on the door sills, you'd now have something substantial on which to lay the straightedges.

Question:  How do you now use these door sill straightedges as a datum to see whether the frame rails run parallel to the door sills?  More straightedges?  Laser?  Strings?  Plumb bobs? 

This would suggest the door sills are parallel to the datum line.

When you work on a frame rack. The rack can be assumed to be the datum line. So you measure to the rack. If your concrete floor is very flat you could use that. The floor in my shop is not that flat (>1/16"). Strings might work if they are tight enough not to sag. A nice long metal straight edge might be better. A piece of angle iron or tube stock. I have a laser level but I don't think I would trust it to be accurate enough for this kind of work...

I leveled the car with 6" blocks and a straight edge across the door/rocker sills which are straight. The tops of the rear strut towers aswell as the rear trunk deck are all level aswell at this position so that's positive. Moving forward, the existing frame rail accross to where the old one was is level but things are about 3/16 out of whack at the very front so she's got a bit of a twist to it. I'll have to check the manual later today and see where all the datum measurements line up. I think what I will do is hang a fixture ill make under the car and that will be my zero mark then ill install the frames as needed. I'll also try to figure out a true center line. It has suffered some damage at the front so I'd like to triple check everything. On the datum topic. Where is the "position c" physically on the car, in the picture with measurments. There's multiple holes and such under there haha.

 

Back on topic with the air horns... Ill box those. Im not going to try and tackle the round edges but I will keep the form and dimensions the same

 

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C point

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8 hours ago, Elliott000 said:

Should I attempt to spread this to stock figures while I'm at it?

I have made quick and cheap pushers/pullers with threaded rod an a turn buckle.

7 hours ago, rturbo 930 said:

If I were you, I'd make a wood buck in the shape of the air horn, and then get some sheet metal and start hammering it over. Learn how to shrink and stretch. Could be a fun learning experience.

That's what I would call high level fabrication, would love to do that kind of thing but I would probably stretch the hell out of the thing.

I will try to look tomorrow for "C"

I will try to look tomorrow for "C"

Is it one of the holes on the bttm

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This would suggest the door sills are parallel to the datum line.
When you work on a frame rack. The rack can be assumed to be the datum line. So you measure to the rack. If your concrete floor is very flat you could use that. The floor in my shop is not that flat (>1/16"). Strings might work if they are tight enough not to sag. A nice long metal straight edge might be better. A piece of angle iron or tube stock. I have a laser level but I don't think I would trust it to be accurate enough for this kind of work...

Patcon thanks for all the input. I agree on that drawing showing that the sills can be my level plane. That being said, thier "zero" appears to be the sheet metal floor? That's a tough one because I've replaced the floors therefore it will likely be a couple mm difference than stock. I think with the engine frames I want to be bang on. Just trying to figure out what to call zero then add the measurements to my level plane on top of thier numbers

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Made the new recesses for the cross member. Ill be triple measureung and comparing tomorrow before I center punch any holes. I'll probably cut in the sub frame connectors too and then weld it on the bench. I've got a center line and plumb bobs off the strut towers for reference measurement. BUT i do have a discrepancy of 7mm or about 5/16 of an inch on the dimension between towers. I think tomorrow I will fab a bar and bolt it in there to hold em at the 913mm spec while I build all this

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I've fabricated the driver side rail now and tacked it in place. I'm about 1/16 out of square on the engine bay but I think ill roll with it. Everything seems to line up with my center and outside lines I'm using for reference. I'll fabricate the lower rad support then tackle how I will fix the twist on the upper strut tower pieces of structure. The pass side is pretty straight but the driver side goes low kinda like this guys situation but ot quite as bad and the opposite direction.

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Really need a frame rack to twist it or some good jack stands some "D" rings on the concrete floor and some good chain pullies. With some creativity it can be done without a frame rack, just slower and a little more difficult

That's what i was thinking. I have to either anchor the main body/chassis to the ground or I can fab up and basically anchor it from the ceiling so she can't lift. Then jack the side that's low slow n steady till it recovers in the right spot. Im just worried about creating elsewhere

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