Ford 8N Transmission

HMMMMM... a 9N has only THREE forward speeds.

Of course, there were several auxiliary trannies that could be added to made an 8N 8 or 12 speed, and a 9N 6 or 9 speed.

First off, is the PTO shut off... the PTO drives the hydraulic pump, which is a piston pump, and they are known to knock when worn a bit, even with lots of service life left.

Check for any loose wheel bolts... wouldn't be the first tranny knock that turned out to be a loose wheel bolts.

If not any of that, it's likely a bad bearing in the tranny or rear axle, or a gear with a chipped or broken tooth in the tranny or final drive... the frequency of the knock will give a clue as to where the problem may be... gears and bearings near the engine obviously turn faster than the final drive or axle gears and bearings.

The tranny is "constant-mesh" and the two gears at the front are the common factor in all speeds.

(Thank's to JMOR for correcting me by email on the last line of the post!)
 
(quoted from post at 17:08:02 06/10/14) HMMMMM... a 9N has only THREE forward speeds.

Of course, there were several auxiliary trannies that could be added to made an 8N 8 or 12 speed, and a 9N 6 or 9 speed.

First off, is the PTO shut off... the PTO drives the hydraulic pump, which is a piston pump, and they are known to knock when worn a bit, even with lots of service life left.

Check for any loose wheel bolts... wouldn't be the first tranny knock that turned out to be a loose wheel bolts.

If not any of that, it's likely a bad bearing in the tranny or rear axle, or a gear with a chipped or broken tooth in the tranny or final drive... the frequency of the knock will give a clue as to where the problem may be... gears and bearings near the engine obviously turn faster than the final drive or axle gears and bearings.

The tranny is "constant-mesh" and the two gears at the front are the common factor in speeds one through 3, but just idle in fourth, unless driving the PTO.
I just checked it with the PTO engaged and it still has the noise. Sounds like hitting a solid piece of metal with a hammer. The faster it runs, the faster the noise. It is a good tractor, so I would like to fix it. The hydraulics stay up longer than any I have seen. The brakes work. Starts fast, but some issue with the choke. Has to be on to stay running until it warms up. Smokes a little.
 
That would seem to rule out most of the transmission, except for the upper rear bearing, and point to the ring and pinion or differential area, IMHO.

Might want to pull the rear drainplug and see what kind of pieces fall out, followed by removing the lift cover.

Anyone else got some better suggestions?
 
It is coming from the lower part of the transmission. I pulled it with my truck and you could hear it. As soon as it gets, cooler I am going to take it apart and I will let you know.
 

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