5 friction/clutch clearance issue in a 904

You do know there are several different thickness snap rings, right?

I do, but the drum is packed right up to the snap ring groove without the pressure plate going on. It's roughly 3/16" thick. I think it's got to be machined or I need to scrap the 5 clutch/friction setup.

I'm curious to know how others that have made this upgrade have done so. Is it just using the 5 disc direct drum from the 999's? That might require a new pump as well because the drum is different. Thinking out loud..scratching my head..

Thanks all for the help so far!