Gearbox pitting advice

[Doubleyoupee]

Hi all,

My XT600 project has been sitting for a year now because I can't decide (well also because I don't have time).

Basically I have ordered a new 5th input gear because it looks like this:
https://www.dropbox.com/s/o6gowyc09o...5.24.jpg?raw=1

However, I'm now doubting whether I should also do 4th gear:


These 2 are the only tooth of all 22 that have pitting. The rest are fine.

All the other gears, including those on the output shaft are fine.

The problem is that 4th gear is another €95.

Any thoughts? Thanks

[turboguzzi]

known issue on our beloved 600s.
Some 600 gearboxes seem to live fine forever, but relative to other bikes ive worked on, 5th and 4th tend to fail more often. problem is well documented in this and other xt forums.

hurts, but I would change also 4th, of course you should do both pinions as a pair, not just the one where you can see the damage.
check also your oil pump as the steel debris might have passed through it



try not to lug the engine after you put it back together and add a magnetic sump plug for safety....

[Tomkat]

Pitting doesn't get better, it gets worse, then it takes the mating gear with it, then the hardened metal particles take other things with them. Change it, a couple of gears is cheaper than a new motor or wasted trip.

[Doubleyoupee]

Originally Posted by Tomkat

Pitting doesn't get better, it gets worse, then it takes the mating gear with it, then the hardened metal particles take other things with them. Change it, a couple of gears is cheaper than a new motor or wasted trip.

Is it really that bad? I've seen pictures that are 100x worse, and they are only opened up because of some noise, not because the engine blew.

Originally Posted by turboguzzi

known issue on our beloved 600s.
Some 600 gearboxes seem to live fine forever, but relative to other bikes ive worked on, 5th and 4th tend to fail more often. problem is well documented in this and other xt forums.

hurts, but I would change also 4th, of course you should do both pinions as a pair, not just the one where you can see the damage.
check also your oil pump as the steel debris might have passed through it



try not to lug the engine after you put it back together and add a magnetic sump plug for safety....

The gears on the output side are 100% fine, like new.
I know it's better to change all of them, but I'm not spending €360 on some gears.... I'm not doubting about 4th gear for no reason.

[turboguzzi]

the problem is longer term, those steel shavings dont dissapear, they are floating in the oil and can destroy oil pump and cam bearings.


noise is just the first sign things are going bad, a later engine blow is going to cost quite a bit more that 360



once the hardened surface is gone, there's soft steel underneath, that's why it's a downhill path from there.


if you do a couple K km x year, maybe acceptable, if you intend to take the bike to long adv touring, then deffo fix it properly

[Jens Eskildsen]

I'd atleast replace the pitted gears.
Thats a lot of piece of mind for 95 bucks.

[*Touring Ted*]

That pitting is not too bad. I've seen a lot worse go on for a long time.

However, if it were my bike, I'd change it. I would also very carefully inspect or change the gear that meshes with your damaged gear.

If that is the only pitting anywhere in the box, it could be a casting fault or maybe your gears were meshed in that specific place where the box has jammed etc. It's very hard to speculate.

Doesn't David Lambeth sell an alternative harder replacement 5th gear for these ??



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[turboguzzi]

Ted, gears are never cast, usually they are machined from forgings or cold rolled stock and then tooth shape is broached before surface hardening .
you can of course continue using it in this condition "a long time", but that pitting will be a constant source for fine steel dust in the oil. run it like that and eventually it will damage metal on metal sliding areas like the oil pump and cam journal.
360€ for gears is going to look cheap compared to a oil pump, head, cam and what else when the shit hits the fan. Agree it's hard to say if it'll happen in 2K or 20K km.

[*Touring Ted*]

Originally Posted by turboguzzi

Ted, gears are never cast, usually they are machined from forgings or cold rolled stock and then tooth shape is broached before surface hardening .
you can of course continue using it in this condition "a long time", but that pitting will be a constant source for fine steel dust in the oil. run it like that and eventually it will damage metal on metal sliding areas like the oil pump and cam journal.
360€ for gears is going to look cheap compared to a oil pump, head, cam and what else when the shit hits the fan. Agree it's hard to say if it'll happen in 2K or 20K km.

You can still find cast gears in modern machines. Cheap stuff.

However, yes I agree that these won't be cast.

That was more me just posting quickly without thinking rather than suggesting the XT has cast gears.



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