Sooo.. I now have a loadcell brake. A brake pedal that no longer translates motion into a signal, but pressure. How did I do that? Did I pull out the 100€ needed for a plug&play kit? Following the theme of this thread, of course I did not.
Instead I googled around a little, and came across this forum thread made by user RacingMat
https://www.xsimulator.net/com ... ke-pedal-short-tuto.6042/
Second page of it makes mention of the Nintendo Wii Balance Board as a good source for load cells (four of them, all in Wheatstone layout)
So I went on ebay, found a board like that for 7€. The three listed electronic components were another ~13€.
The Balance Board without its bottom cover. Really sturdy build, all metall. Sticker says 150kg max... I believe it can take double. Safety factor ftw
Each corner has a Wheatstone bridge with two nice mounting plates. Internet says each of these is rated for 75kg max
Each metal-metal bolt has loctite applied - Nintendo does not mess around
Cue a few hours of tinkering, taking measurements on the G25 pedal, scavenging through my scrap metal bin. This is the bottom part, as you can see it uses the Nintendo mounting plates, as those probably guarantee the best pressure actuation of the load cell itself. The square alu tube acts as the guide for the spring (heaviest spring I had left from my earlier endeavours).
Installed. Needed a few attacks with the Dremel to make it all fit in the original rail.
Upper part installed. I was lucky to have a piece of stainless tube laying around that fits neatly,but not too tightly into the spring. This is somewhat essential to guide the whole contraption and stop it from folding up- or downwards. Tho with the original pedal layout the motion of the cylinder is almost linear. Upper mount, lower mount and centre of the loadcell are all on one axis.
The stainless tube is ~25mm shorter than the spring, meaning I still have some motion in the pedal before the tube touches a layer of vinyl inside the alu square. This took some tries, initially it was too long.
Now onto wiring:
The thread linked above has it in detail, which parts you need to amplify the loadcell signal into something that is readable like a poti. I needed some brain acrobatics to translate it for the "Nintendo bridge".
Important: If you want to wire it like I did, DON'T choose wiring loom this thick. This was an old PSU loom, many nice colours to keep it tidy, but after soldering the whole thing was so stiff that I almost bend the pins off the chip.
Last line reads:
E+ E- A- A+
Blue Green White Red (colours of the wires already on the load cell)
This is how it all splices into the G25 brake pedal wiring. I did it like this just in case it wouldn't work, to easily be revertible.
With some electric tape applied. I've since secured everything with some hot glue in an old tupperware box, with a small hole for the gain resistor to peak through, which you need to for fine tuning.
And it works fine ingame, no additional controllers needed, its the normal Driving Force GT brake pedal.
Now I only need to finetune myself for the new hardware