Gearbox play…. How much is too much

[Mustlust]

https://www.aulro.com/mobile-gallery/8890713f5b1341f5b709c4b1d0a34871.jpg
Second gear is probably the most used ‘working’ gear I’m guessing, and probably wears the greatest. Out of all the gears, this one shows evident damage on those little teeth at the front. The outer, larger, teeth seem fine.
Do others think that this gear needs replacing or is it ok for a while longer? I have no history of the gearbox and I have never had it behind a working engine. I’ve just pulled it apart for a look and need to replace a few bearings only at this stage.

[Mustlust]

Or just the telltale sign of an old crash gearbox. This wear is probably linked to that crunch between first and second when you don’t time the shift too well. Fifty or sixty odd years of crunching gears would probably leave its mark somewhere.

[workingonit]

Or just the telltale sign of an old crash gearbox. This wear is probably linked to that crunch between first and second when you don’t time the shift too well. Fifty or sixty odd years of crunching gears would probably leave its mark somewhere.

Hard to tell from the photo, no other angles to judge by, how the components are assembled, I'm guessing you are referring to the male and female splines central to the gear, if in fact they are male and female splines. Bit hard to tell.

Assuming male and female splines central to the gear. In my limited experience (of gears!) some male splines (all?) have machined sloping and tapered leading edges to help with the mating process. Looks to me like these are tapered lead edges in your photo and are just a little worn - although I could be wrong - the dead flat plane before the slope is interesting, but may be just part of the manufacturing process, as they do not look roughed out as you might expect with wear caused by collisions. If male and female splines then best look at the broader area of the spline faces for steps worn into the face, pitting etc. Hope I'm on target with the concerns.

If not actually male and female splines but solid with the main gear, then yep, quite a bit of wear.

If they are engagement dogs then what I have seen elsewhere in gearing has a space machined behind the dog ring (before machining the dogs splines themselves into that ring). The space is where the horizontally running machine tool stops, rather than risk crashing the cutting tip into the side of the gear, and to drop its shavings. Possibly in the day done by an old style shaper machine. Not to say that the cutting tip could not be pushed in on the vertical, aligned with the gear side, with space or no space, and pulled away from the side of the gear. Shaper - Wikipedia (https://en.wikipedia.org/wiki/Shaper)

[5380]

Or just the telltale sign of an old crash gearbox. This wear is probably linked to that crunch between first and second when you don’t time the shift too well. Fifty or sixty odd years of crunching gears would probably leave its mark somewhere.

Phillip,
Is this a pic of the engagement dogs on the 2nd gear mainshaft? Not much "engagement left to "engage" is there? I suppose sooner rather than later the remains of the dogs will shear off and not engage anymore.What model gearbox is it? The layshaft and mainshaft 2nd gears are a matched pair so shouldn't be changed individually. Have you got a spare box to cannabalise? If not give me a call. Oil looks nice and clean!
Cheers, Mike (5380)