I mix and match different clutches with clutch bells and flywheels all the time. BUT, I never mix and match the Losi 8 clutch with anything else. The Losi 8 parts go with Losi 8 parts and nothing else.

I have a few issues with different things on my cars but clutches is never one of them.

I picked up a supply every possible kind of shims, spacers, and washers I could find including 3mm X 4.9mm X.1 that use to make up that difference. And that's even with the Losi end washer for the screw that holds it on.

Duratrax makes those little end washers too that seat part way into the bearing but it's still important to keep a mm of slop there. I have that set and 1 is a little too short and the other is a little too long. Comes with 3 different lengths of that little shank to go inside the bearing.

Last night, I used one of those washers and 3 of those 3mm X 4.9mm X .1 shims to get that 1mm play for the bearings on an OFNA clutch/flywheel on my Beat 5.

I think sometimes there might be a little bit of difference form one engine to another on the length of shaft sticking for the clutch. Variations in tolerances or something. So the idea of filing down the collet comes in. That's probably the best idea if there's enough space between the flywheel and crankcase but I'm too lazy to file anything if I can at all help it.