STUCK IN TOP HIGH BOX AND WHEELS LOCKED UP

[mauchie]

HI wondered if any one could help or has come across the same problem 1951 major
driving along the road in top gear suddenly wheels locked up an is stuck in top gear really tight to move put it in and out of high and low and seemed to free off and get home wondered if anyone has ideas what it could be before having to do a major strip of gearbox

[AdrianNPMajor]

A sudden event suggests that a component has failed. My guess is that a gearbox bearing is busted. If so, it's likely to be the rearmost bearing on the main upper shaft. This shaft carries the high/low ratio gears. The bearing in question gets starved of oil if the seals between gearbox and rear transmission fail. That leads to a couple of questions. Have you had problems with maintaining the correct oil levels in the gearbox and rear transmission (one being too low, the other too high)? And did you hear excessive transmission whine when traveling in top gear prior to the failure?
If the bearing in question has broken up, one or more of the rollers could have lodged between the meshing gears, causing the sudden event that you experienced. By moving the primary gear lever between high and low, if this theory is correct, you would have dislodged the roller, and the shaft would then be free to rotate again, with the rear end of the shaft being supported by the meshing gears below.
Best to remove the inspection plate on the clutch side of the gearbox, the plate that carries the oil filler cap. With this plate off you'll be able to look up at the bearing in question. The photo below shows the broken bearing from a different angle.
I may be wrong with the above theory, but it's probably not a bad place to start looking for the problem.
Good luck.
Best, Adrian.

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[Brian]

Another area to check is the transmission hand brake, even if you were running with the brake on a couple of notches you could have overheated the brake plates.

If you take the gear selector plate off on the clutch pedal side you will be able to see across the box and also be able to get a lever in to check the bearings.

You will need to drain some oil out to do this so see what you have in the drain plug, that can also give clues..