I have a 1950 D6 9U #9U6706 that im having a hard time getting the clutch adjusted to get the SNAP on the lever. When i pull back the clutch lever i cant get it to snap so when im driving the dozer i have to hold the clutch lever in place or it will go forward and disengage  the clutch. I have adjusted it according to the book for dry clutches, plus adjusted the rod as well but no luck. Anyone have any ideas?? Thank you in advance.

Maybe just a tinny amount of lubrication on all the pivot points in the linkage. The earlier model D6 (4r,5r) used the same clutch. But no shielding so much more dust, so everyday oil the linkage and once or twice a week wash with gas (yes 40 years ago nobody worried about gas, and was cheap)to get the oil and dust/muck off and start over. Have not had to do that with the 9u's being enclosed. So a easy cheap thing to start with. With the D6 4r it took very little movement of the adjuster to go from to tight, to loose before I was shown to wash the junk off and start over.

I'm not familiar with the design of the D6 clutch, but I have experienced the same thing with the dry clutch on the D8. The solution is usually to lubricate the face and pins of the cams that actually do the SNAP over centre. Oil around the area I've marked with a red dot is usually effective in my experience. 

 

I should have said that my issues weren't due to excessive wear, but because the machines had sat unused outside for lengthy amounts of time. Some lubrication and use rectified the problem for me, without actually making any adjustment.