this one is a mine field - nissin calipers appear on genuine ScootRS and Spaq - its all about the hub/backplate.
ScootRS do a kit which they say is specifically for their disc hub (wider plastic ring and metal worm) - this is probably the one but I would ring Andy and ask
I have had no success with the ScootRS one - only success has been with the MB all metal ring and worm until I changed the back plate to fit an anti dive - all worked well on the stand but as soon as I rode it - the worm chewed
think the biggest problem is the amount of different hubs and back plate - indian, Italian, Spanish, pattern (ScootRS etc)
Just fitted a new all metal one and spend ages setting it up on the stand - used grinding paste to bed it - as advised - ended up with having to put a spacer between the backplate and the speedo bush to get everything to mesh correctly - it was working perfect and smooth when I left it - ran out time and haven't been out on road yet.
was looking on Scooter Restorations site today and they have a worm specifically for a disc brake - I didn't know there was a difference between drum and disk but on the picture the top part of the worn after the cog part looks thicker than the drum type.(if that makes sense)
http://www.scooterrestorations.com/lamb ... ion-nylon/
http://www.scooterrestorations.com/lamb ... ion-nylon/
My ScootRS one has been a pain in my backside since day 1 with regard to the speedo
I have a Spanish hub/backplate and it has a £4.00 cheepo plastic set and it has never skipped a beat since it was built about 10 yrs ago