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Hello there, I'm new here and I wanted to ask you what kid of bolts I should use in order to fit 2 discs on a grimeca rim. Now I have one on, and it uses hex socket screws, whose heads fit into the hole at the side opposite to the one of the disc, being the hole as large as the head (hope you can understand my explanation!).
Was just wondering if I can use regular bolts, going from one disc to the other thru the rim, or if these would tend to be too loose in the hole. Maybe I should find them threaded only at the end?
Thanks for the tips, and soon again on a Morini!

You should use a shanked bolt, that is with threads only over part of the length. For preference I'd use cap head (hex socket) bolts. I'd also use nyloc nuts, making sure that 2 to 3 threads are fully through the nylon insert.

The wire wheel disc hubs use two sets of bolts threaded into the alloy casting, so the strength of the bolt is in no way critical. I'd still use a high tensile bolt '8.8' or '12.2' as an indicator of basic quality.

Do you have the speedo drive for twin discs? If not you can modify the single disc drive.

What are the "wire wheel disc hubs"?
If by speedo drive you mean that "cap" on the side of the wheel which you put the speedo wire in, I have it for twin discs.
Thanks for your help!

Alright you mean the hubs that keep the discs onto the wire wheel? I.e. the alloy is threaded in the wire wheel, so that each side uses bolts which are screwed directly into the alloy?
Thanks again anyway, I'll go search for long shanked bolts tomorrow, hope I'll be able to find the right length!
Will post pictures of my new Morini Valentini, finally found one year after my stolen seconda serie

Alright, the two discs are up, now I have an issue on the fitting of the right caliper: is this one supposed to be different from the left caliper, as the right disc is more distant from the damper than the left one? I would need a few washers (or a small piece of pipe) in order to set it at the right distance for the disc to go into the crack.
Thanks a lot for your kind help!

There is not a lot of clearance in the gap in the Grimeca calipers is there ?

First time I took the front forks apart on my twin disc 500, one of the calipers needed a few very thin washers between the fork and caliper to make it fit.

Well, actually this one would need around a half inch of thickening to be at the right distance. I'll post pics later, maybe I got something which has been mounted incorrectly...