Hi everyone new here and looking for sum help i am building a rage buggy style buggy but with zx12r engine .
The rear brake setup is sierra hubs and carriers with custom made uprights but i want to no if they are any lighter disc i can use on sierra hubs as they are very heavy and a bit of over kill as it only was 350kg any help much appreciated

You could use vw/audi rear alloy calipers plus a solid drill and grooved cosworth disc.

The calipers are much lighter than sierra and bolt straight onto the sierra hub.

The only other way is to find a smaller disc and move the calipers in, but dont know if there is any.

i was thinking along the lines of motobike calipers and disc but i will be useing 13inch alloys so cant go to big