Over/under clutch question.

bison

Well-known Member
I am in the process of rebuilding an over and under. Upon dismantling I found that 3 of the 6 friction discs of the direct clutch had lost all of the teeth, the forth one had 90% of the teeth gone but # 5 and 6 discs where still perfect. The 4 bad ones had cut grooves in the splines of the shaft where they ride but the 2 good ones had made hardly a mark. The friction facing on all of the discs are still good and no visible wear on the separator plates either.
I wonder what caused this uneven wear.

The 3 speed never gave me any grief in the 35 years I've owned the tractor and it was never taken apart and was performing good, the reason I took it apart was because I am rebuilding the whole tractor front to back
 
Nope, it did not answer my question by a long shot.
I want to know why 4 of the discs wore the teeth off but not the facing.
The last 2 discs took all the torque since the other 4 were gone but hardly show any wear.
The rest of the O/U is in excellent shape including the overdrive clutch and the sprag clutch.
 
(reply to post at 18:53:52 02/18/19)

You wore the teeth off the disc
Just think how many times they have done the pulling
If you didn’t find teeth chunks you just wore them out
 
I had that on the three speed I just rebuilt in my 4-150. I asked
the mechanics at Maibach about it. The grooving in the shaft
is common, but it has the effect of turning the shaft splines
into a file so to speak. Every time the clutch pack engages
and releases the plates pop in and out of the groves which
causes accelerated wear on the clutch plate teeth and in
extreme cases wear the teeth completely off. As the teeth get
wore the slack it creates in the tooth engaugement make the
plates hammer when engaged which cuts the groove in the
shaft even deeper and it?s a snowball effect from there. Plus it
will cause uneven wear on the clutch lining because the plates
can hang up momentarily in the groves when releases and
slip against the pressure plates. Long stories short if your
shaft is grooved to bad, consider replacing it.
 
(quoted from post at 13:23:59 02/19/19) I had that on the three speed I just rebuilt in my 4-150. I asked
the mechanics at Maibach about it. The grooving in the shaft
is common, but it has the effect of turning the shaft splines
into a file so to speak. Every time the clutch pack engages
and releases the plates pop in and out of the groves which
causes accelerated wear on the clutch plate teeth and in
extreme cases wear the teeth completely off. As the teeth get
wore the slack it creates in the tooth engaugement make the
plates hammer when engaged which cuts the groove in the
shaft even deeper and it?s a snowball effect from there. Plus it
will cause uneven wear on the clutch lining because the plates
can hang up momentarily in the groves when releases and
slip against the pressure plates. Long stories short if your
shaft is grooved to bad, consider replacing it.


This makes sense.
thanks.
 
Here I my guess as to why the 2 are still good. When the clutch pack releases the 2 on the solid end don't move much to release but each one
out the thicker the clutch pack is the farther it has to move to get the needed space between the discs and plates so as they rub the
splines moving between engaged and disengaged it wears the teeth off. Just my thoughts
 

Total piston movement is only 1/16th of a inch between full release and full pressure.
Hardly any room for an delayed reaction if you ask me.
 

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