Now this is accurate, it would be really helpful. now i only need to find someone with a big cutting-plotter to cut me a paper template like the ones in your pictures 🙂
I think with alle the information i have now i should be able to get it right now. Thanks all for your contributions. Awesome!

Today i installed my footrest. It took me a while to figure out the position of the footrest and holes.
It seems the holes measured by @HS30-H above are for the footrests version with two
inward facing L-shaped "Feet" of the footrest. I have the two leftward facing Feet, which i think was introduced a bit later, for whatever reason.
My idea is that because of the missing reinforcement of the floorpans in later versions, they decided to have the holes more towards the transmission tunnel where it would
be a bit more stable and less "rattly" compared to two attachment points in the middle of the floorpan without any adaditional reinforcement. But that's just pure guessing.
At the end, i think i figoured out the position with the Drawings and pictures and measurements and the insulation mat drawings done previously by others (See above).
So thanks all for your input:

Please ignore the uncleaned welds, i will complete that task soon. here you see the holes from the underside...

 

I first thought one of my "feet" was bent by accident or so. But after talking to @RIP260Z, who told me that he had see those bent ones before, and after realizing that the material
is way too thick to just bend it in a such nice way by accident (without cracking the paint in the bending area), i started to mock it all up and then realized that the shape must be like this from factory to follow
the shape of the floor pan in the transmission tunnel area. I'm not sure if this is specially for LHD cars or if it also would fit the same on the other side in RHD cars (where the bent area would
face towards the door and should follow the shape of the floorpans towards the inner rocker panel).
Again, please ignore the welds that need to be cleaned... and note that i left some mm space where the insulation mats and floormats will go later...

 

At the end i had it all installed and with a nice fit, if you ask me, and it looks and feels just right to me.
It looks very "unaligned" in this picture, but first the footrest has a bit of a weird shape from factory, and second it's because of the camera angle...

1 hour ago, JDMjunkies.ch said:

My idea is that because of the missing reinforcement of the floorpans in later versions, they decided to have the holes more towards the transmission tunnel where it would be a bit more stable and less "rattly" compared to two attachment points in the middle of the floorpan without any adaditional reinforcement. But that's just pure guessing.

But are you going to add some factory-style doublers to the underside of the mounting holes? It seems like a no-brainer to me. The footrest - in use - exerts quite a lot of leverage force on the floorpan. The factory doublers - with their turned-up edges - beef up the mounting points considerably. I think they are worth the effort of replication.

 

13 minutes ago, HS30-H said:

But are you going to add some factory-style doublers to the underside of the mounting holes? It seems like a no-brainer to me. The footrest - in use - exerts quite a lot of leverage force on the floorpan. The factory doublers - with their turned-up edges - beef up the mounting points considerably. I think they are worth the effort of replication.

Alan, thanks for the detail-photo. I thought it was more of a "Positionining ring" rather than actually beeing a real reinforcement of the floorpans. But with the picture now it looks different.
Now i have to rethink the whole plan. My initial idea was to just use big washers as "reinforcement" to spread the force of the bolt over a bigger area.
On one hand the later cars didn't have these "doublers" from factory, so i guess the idea was to have the footrests installed without those in cars built after 1971 or cars where the footrest was bought later as an option...
On the other hand i can see how this would improve the stability of the floorpans in a nice and factory-looking way.

Just thinking out loud here...

You could, perhaps, approximate the shape of the lipped doubler plates by finding an appropriately-sized metal bottle and sawing off the bottom (leaving a lip).  The only donor item made from steel that I can think of would be a small propane bottle -- empty, of course!  Not sure about the metal gauge used for these pressurized bottles.  Too thick?  The usual metal drinking bottles (as used by joggers, cyclists, etc) would perhaps be closer to the correct thickness but I think they're made from aluminum, so not easy to weld to the floor pan.

You might be able to make your own by hammer-forming 0.7mm sheet steel over a piece of shaped and contoured hardwood.  The lip could be finished to a uniform height afterwards with a grinder.

On 11/22/2020 at 3:38 PM, Namerow said:

Just thinking out loud here...

You could, perhaps, approximate the shape of the lipped doubler plates by finding an appropriately-sized metal bottle and sawing off the bottom (leaving a lip).  The only donor item made from steel that I can think of would be a small propane bottle -- empty, of course!  Not sure about the metal gauge used for these pressurized bottles.  Too thick?  The usual metal drinking bottles (as used by joggers, cyclists, etc) would perhaps be closer to the correct thickness but I think they're made from aluminum, so not easy to weld to the floor pan.

You might be able to make your own by hammer-forming 0.7mm sheet steel over a piece of shaped and contoured hardwood.  The lip could be finished to a uniform height afterwards with a grinder.

to be honest i think just hand-making something is probably the easiest way - it's not a really complicated part. if you have a workshop hydraulic press it's even easier i think. I meen even the original item in Alan's picture look really "handmade"

This might help. From my 1972 JDM Fairlady Z L.

Floors were stripped back and rust patched. Excuse the thin layers of seam sealer. This has since been covered with underbody paint. 

 

 

thanks a lot for the detailed picture this hels a lot again. I can see now that the inner side not has a completely circular shape. perfect 🙂

The Bolts that hold the footrest to the floorpans have custom specs, that do not fit into any DIN / EN / ISO norm, so it's not possible to purchase them at any standard hardware supplier.
There are similar ones, but most of them have a too large head, that needs cutting to fit with the L-shaped "Feet" of the footrest).
So i had a local milling shop (specialized in oldtimer-parts) make the bolts for the footrest according to the drawing i made (see below) in stainless steel, since the original ones where bent, and pretty worn.

Original ones:

New ones:

Perfect tight fitment, as the factory ones.
What might be interesting is that the bolts where added to the "feet" before painting the whole thing as one unit, from the factory.
You can clearly see (not in these pictures), that there is rust and no paint on the area below the original boltheads.

Here's the drawing if anyone ever needs to make those. I have a set leftover, since i ordered two. If anyone is interested, let me know.
(since the "f" value is covered by my logo - it's also 4mm)

Nice. When the "foot" faces in, as with the M8 coach bolts I got from a hardware store ( where d1 was 20mm) meant the "hoop and rivet") made getting the bolt into the square hole impossible. Machining 1mm means a fit.

Carrying on with the making parts for the footrest, and relevent, I needed to make some rivets for my SR/SP replica footrest, you see in the first post. I am using a S30 footrest as the donor here. The original rivets (either type) can't be removed without destroying them, (see ealier post). I wanted them to look original as much as I can....

With the original set up, the rivet holds position on the hoop, and the pivot point is on the foot. I decided to use a M8 coach bolt with a square shoulder, just like JDMjunkies above is using and turn it down. The hole size on the hoop is 6mm, so I  drilled and tapped to take the M8 thread. The flat side of the rivet I have done is the correct size, whilst the "star shape" end is cut with a hacksaw. I also put a centre hole in (not what the original had) but the plan is use a centre punch to splay the "star shape" out from the centre. It looks a bit like the original, which I think was a press fit, as these type of rivets are found elsewhere on the CSP311 (seats).

Plan is to thread the rivet on, can use the hacksaw blade cuts to tighten with a screwdriver until the required tension, then splay the rivet. It seems to work on some trial threaded bar. I think I need to trim the star part back a bit, it sticks out a little too much, but it is the prototype...

 

Very clever!