Pri case fill amt difference.

[hogpipes1]

I been filling my 85 FXRT  pri  oil to bottom of clutch diaphragm  with  no issues .Big book says fill to top of clutch  cover opening bike upright.  1990 & up fill to bottom of dia. or 2 3/4 " from center adj screw to bottom . bike upright.  Any major reason for the extra oil in  the 85  vs. 90 up ?  something different about the plates.?
  hard shifting, clutch drag etc . has  always been  mentioned with too much oil in pri.  Thanks .

[dr evo1]

I add 1 quart when I change oil in my 85 ands it't at bottom of spring never have had a problem. I use atf in mine.

[Dan89flstc]

In my opinion you are filling it to the correct level, I think the factory service manuals for those early (85-89) diaphragm clutches were calling out the wrong level.

[hogpipes1]

Fill to the top of cover oil sales are up.