What is the advantage/disadvantage of using nylon sealing rings on the pump reaction shaft on a 727? I thought maybe it was to reduce friction but I wouldn't think they would last as long.

They are supposed to seal better at high clutch apply pressures. As far as I am concerned, the jury is still out on this. I just use the metal ones. They have always worked good for me. Just try to keep your input shaft endplay on the tight side so it wont knife-edge the sealing rings for the front drum

Thats what I am going to do. Ready to assemble and try it out. Thanks for the input.

I like that nylon idea ....especially on an alum drum. It would tend not to eat into the drum as badly ...I would think.

WHO has these ?

Pat Blais has these available. Here is the link
Gerry

They are Teflon not Nylon and they tend to eat a drum worst than metal.The reason being is the metal rings tend to spin with the drum,the Teflon tend to stand still while the drum spins on them.
Also any small amounts of metal will in-bed in them.
That being said the Teflon do work well at sealing and will last a long time.It is really more of just what a builder likes better or what the suppliers include in there kits.

Actually chrome or Teflon are probably the best choices when it comes to high pressure. Metal rings are supposed to spin with the drum. With high pressure, this side loads the ring in its groove, and wears the rins and sometimes the grooves.
The majority of OE now use Teflon or Vespal (hard plastic). Very few rings are metal anymore.
Pat