Ah, I thought I’d already commented on this. Yes the interfaces (the triangular bits which bolt to the hub and hold the springs) must be different for each hub because the flanges are different on each hub they use (both different diameter and different offsets from the centre line).
I have to admit I’d not considered the idea of a custom interface. My plan was to get some flanges made which bolted to a uni hub and provided holes in the same place as one of the hubs they use, so that you could just bolt the supplied interfaces on - something similar to what is described in this post: Aaaagh - broken flange on my Schlumpf - #14 by nickjb
I’m sure it wouldn’t be too hard to get something like that made - whilst a custom interface would be a better solution, it would involve a lot more complex machining. The remaining issue though is that the interfaces will be under preload when fitted to the hubs - I suspect they attach the springs last and have some mechanism to preload them when they fit them. It’s not going to be straightforward to do without that.
Very interesting to hear that they will fit different weight springs though - that certainly solves one issue, as it’s a lot simpler to make something to front hub dimensions. I wonder if I supplied them with a hub with identical flange dimensions to that whether they’d build one up for me? Looking forwards to your feedback.