hi have a 1976 d100 with 3speed trans.started having probs shifting gears so adjusted clutch and prob solved. Have had to do this more than once and clutch sometimes makes a ?roaring? kind of sound when pushing it to the floor? Am running out of threads on my adjusting rod?!?

 

Worn clutch and throw out bearing.

 

I believe you have over adjusted your clutch and the throw out bearing is spinning. Meaning it has to much pressure on it even when you are off the clutch. The roaring is from you over centering the pressure plate when you bottom the clutch. meaning the fingers on the pressure plate are going past the point they should and are rubbing on the fly wheel bolts.