Loud Chatter From Amplitorc

Caseboy1

Member
I recently made some repairs on our M670
differential and transmission and now have
a loud chatter coming from the amplitorc.
It was not making this noise before I made
the repairs. I replaced all the bearings
in the differential including the axle
bearings. I had everything out of the case
except the pto output shaft. Made sure
everything was set up according to my
service manual with all bearings preloaded
to specs. I also replaced the two bushings
in the reverse idler, because one of them
had walked out of the bore causing it to
jump out of gear when putting a heavy load
on it while in reverse. I noticed that
there was excessive endplay in the
transmission topshaft bearings so I
preloaded them to spec listed in the
manual. Got it all back together and
drove it around to test out all the gears.
Everything sounds good except direct drive
while in 5th gear. It chatters really loud
below 1200rpm. If I speed the engine up
above 1200, the chatter goes away. If I
place the amplitorc in low, the chatter
goes away. Depressing the clutch doesn't
affect it. The chatter is still there
while it is rolling with the clutch
depressed. The amplitorc did not receive
any repairs...everything looked good
there. I never removed the output sun gear
from the rear planetary section, so I
didn't figure I would need to worry about
the alignment of the planetary gear oil
grooves with the center of the sun gear as
it states in the manual. Did I make a
mistake here? Could that be causing the
noise? If so, that doesn't make sense to
me because, if I'm thinking right, the
planet gears are not rotating around the
sun gear while in direct drive. The whole
unit would be rotating. I did put a new
aftermarket clutch disc in. Could the
dampener in this disc be causing the
noise? Any input would be greatly
appreciated. I'm kinda at a loss here and
really hope I don't need to split it
again. Thanks in advance.

Bill
 
The 3 oil lines needing to be lined up is the only way they go together, so if they were not timed correctly it wouldn't have gone together, so no need to worry about that. And yes, the whole planetary rotates in high so they wouldn't be turning anyways when your noise is occuring. If noise is present when clutch is depressed that rules out damper springs on disc in my mind. What oil did you put in it? Straight cut gears chatter. I know mine do. Way worse with thin oil. If you drained out old thick as molasses gear lube and put some nice flowing 80W90 in there now it's not going to quiet things down as well. I think if it was mine I'd run it and see what happens.
 
Thank you for your input Chris. Yes, it
does have a thinner oil in it. I'm running
50wt. I've been running 50wt in the
differential and amplitorc since I
restored it in 2014. I thought the thinner
oil may improve the pto turning when
disengaged and also reduce the warmup time
for the amplitorc. Up until this point,
the 50wt has done fine. The pto clutch and amplitorc discs show very little wear. I
think you're right about the chatter,
though. The thinner oil is probably
contributing to the noise. Along with the
fact that I decreased the ringgear/pinion
backlash from 0.024 to 0.012 and also
removed the endplay from the trans.
topshaft.
I've been wanting to post a picture of it, so here's one of my daughter driving it for the first time. She loved it. I think she's hooked now.
Bill

cvphoto145642.jpg
 

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