4-speed rebuilt - "click" while in 4th

[dbdevkc]

I'm bench testing a fresh 4-speed rebuild. Brand new Andrews mainshaft, final drive gear, and shifter clutches. All bushing clearances checked, all end plays set and checked. Sounds perfectly fine in 1st, 2nd, and 3rd. In 4th there is a noticeable "click" sound every rotation (at exactly the same spot in the rotation). It is not noticable when turning by hand, but when I put a drill on it to spin it faster... that is when I get the click and it doesn't sound good. If when turning it by hand I pay very close attention I think I feel/hear ...something... but it is so minor I can't see anything that might be causing the issue.

I have removed the ratchet top, and removed the shifter forks. I move the shifter doga/clutches by hand and still get the same thing in 4th gear only. I can't figure out why it would only be in 4th that i get the noise. 1st, 2nd, 3rd even spinning it fast with the drill - completely fine.

Any ideas?

[JW113]

I don't know if this is any help, and probably obvious, but the difference between 4th gear vs. the other gears is there is no load on the counter gear. It is free wheeling. Is there any unusual "click" when you spin it in neutral?

-JW

[dbdevkc]

I'll check again, but pretty sure neutral had no click. Nice and smooth just like 1-3. Yeah I was thinking about how while in 4th, the countershaft gear is just along for the ride, so to speak. 

Just wondering without looking at it at the moment, I wonder if the shifter dog is tapping something in the case when it is over in the 4th gear position. Shouldn't be anything there though. 

[dbdevkc]

N and 1-3 I can hear a noise IF i rotate the transmission by turning the sprocket. So it seems to be generated when the final drive gear is the driving force. It is barely noticeable when turning slowly, and gets more noticeable when turning faster. When turning with the drill it is a click that sounds 'not good'.

I marked the sprocket so I can confirm it always happens at exactly same spot in the rotation of the final drive gear. It is not clear or obvious to me if is something with the final drive gear itself, or something about the countershaft.

I may opt to remove the countershaft again and then try spinning it with just the mainshaft.

[fbn ent]

Just wondering for my info only....Do you have oil in it for this test?

[dbdevkc]

Lubriplate No. 105 Motor Assembly grease. No oil/fluid yet.

[JSD]

Try with oil