1960 Dexta 4th & 6th intermittant "raking gears

When in 4th or 6th I get an intermittent "raking gears" sound while traveling down the road. I can't feel it through the shifter, the balls & detents that hold the shift sliders in place appear to be doing their job, and the sound will quit if I throttle down a bit or shift to 5th. Transmission & rear end fluids are full. Hydraulics work fine. Any ideas on how I can solve this? Thanks.
Marlin
 
That does not sound good, I had a similar noise in my Dexta gearbox a couple of
years ago and it was a small needle roller bearing in the front of the gearbox that
had failed. The gearbox had to be totally stripped down to get to it which meant
splitting the gearbox into three pieces.

Some bearings are no longer available, I had to spend many hours before I could
locate the one that failed.

The Dexta gearbox is semi-pressure lubricated with holes drilled in gears to push
oil through to some bearings, also there are timing marks on the gear couplings that
have to be lined up on re-assembly.


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Are there more than one of the needle bearings in the Dexta transmission? I replaced one when I had the tractor apart 2 years ago. It was described as "spigot roller bearing" in the diagram that I have and is located in the rear of the main drive shaft.
 
That is the only one in the gearbox and, according to the workshop manual, should be
replaced every time you have the gearbox apart.

When mine failed, the noises came in every gear under load except third and sixth and
was caused by the large gear rubbing on the lug holding the reverse idler shaft.

Did you use a full roller replacement or a roller bearing in a cage?
 
I'm not sure I know the difference between the two. As I recall, the individual roller bearings were laying flat in a round collar that I pressed into the shaft.
 
A full roller bearing is one where the rollers all touch each other rather than have
individual rollers separated by either a metal or plastic cage.

The bearing should not be a press fit onto the shaft as the shaft is the bearing
surface it runs on. It should be a gentle push fit into the gear.

Problem with these gearboxes is that you cannot see anything until you get it stripped
out. I did not find my faulty bearing until I took the last shaft out of the box. There
were no rollers or metal bits in the oil either when I drained it.
 

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