Stellite welding 2nd gear fix

[Twintorsk]

Anyone on here have any experience doing this?
Since i am a proficient licensed welder and i happen to have some stellite lying around and an xs1100 with a 2nd gear that slips under full throttle(which would mean its only slightly worn) and clunky shifting (bent selector fork)
I am thinking it would work to dress up the cogs with a thin 1/10 mm bead of stellite at the end of the cog, so backcutting would remove nothing of the base material. Of course welded as cold as possible to not remove any hardening, stellite is sufficiently hard w/o temper.
Also do the shift forks from xs750s fit since i have a bunch extra from my xs900 build?
Now i think i will not try backcutting myself, there are guys doing that in town i think, a simple welder cant get the cogs to match perfectly i think..

[TopCatGr58]

Hey there,

Don't know about anybody having tried using Stellite?, we have a few certified welders on our site so they would be more capable of chiming in with their opinions or experience.

However, once the dogs get rounded off they have already gotten worn into or past the hardening layer, so not sure if you're really preserving anything. And as you said, trying to use the lowest temp for performing the welding, but you're still talking about several thousands of degrees to attain a proper weld and not just a glue/tack, so the temper might still be affected anyways.

The dremmel fix isn't rocket science, the underlying dog metal will be a little softer than the hardened surface, but this actually allow for less than micron precise grinding/alignment, the dogs/slots will bash together and eventually wear into each other to even out the contact surfaces to have even pressure on them at the same time. The more important feature is the undercutting angle which helps to PULL the gears together under stress/load vs. the square cut which lead to the rounding and eventually spreading apart under load.

Finally a review of the Yamaha Fiche reveals that the part numbers for the shift forks are DIFFERENT, 2H7 prefix vs. the 1J7, so they are NOT the same part/shape/design/size and won't work.

T.C.

[Twintorsk]

Ah, of course nitride/surface hardening will have worn off.. actually the heat affected zone can be kept extremely small with a careful hand, but then it seems better to add stellite across the dogs and slots, to get some uniform hardness.. may have to read this paper first, seems right on the money.
https://www.google.se/url?sa=t&sourc...zyQCr-nkCyledQ
Pre and postheating.. This could be fun!

[jetmechmarty]

I don't know what Stellite is, so I'm going to have to look into this. Please explain the process.

Do you know what alloy the gears are made of? Do you normalize after welding/grinding? What about case hardening?

[Twintorsk]

Stellite is cobolt based filler material for welding, can be used on all carbon steels, and especially developed for wear surfaces in gearboxes, metal on metal contact and such.
I will TIG weld it, and it sounds like no hardening or tempering will be necessary other than normalizing the haz steel structure post weld.

[jetmechmarty]

no hardening or tempering will be necessary other than normalizing the haz steel structure post weld.

So, you simply normalize the gears that you welded? "haz steel structure" has me unsure about what you're saying.

Hopefully, I will remember this next week, so I can research it.

[Twintorsk]

Heat Affected Zone, the steel grains can become austenitic or martensitic depending on cooling rate post-weld.
Here's a general wiki: https://en.m.wikipedia.org/wiki/Martensite
This is as much as i understand about it anyway, given my educational level 😂

[motoman]

Heat Affected Zone, the steel grains can become austenitic or martensitic depending on cooling rate post-weld.
Here's a general wiki: https://en.m.wikipedia.org/wiki/Martensite
This is as much as i understand about it anyway, given my educational level 😂

Laying ANY type of weld bead on top of any type of carbon density steel would NOT be my choice. What little dove-tail type grinding is necessary in this type of application is so minor, even a tiny weld bead would definitely create more work, and likely not produce anywhere close to the result of of just dove-tail grinding of the 'dogs' and slots. JMO from a cerified welder/fabricator of some 30yrs.........of course, now retired for some 10yrs..

[ViperRon]

There are actually 2 things with metal that give them wear capability and when combining metals especially a harder metal to a possibly softer or flexible I one is the bonding and will it stand up to the vibration harmonics and not crack or splinter off. I know when you have a rub wear surface this works very well but way in the past had some experience with high speed gears that were treated and rebuilt with a harder metal coating. It worked great for a while and then broke loose and damaged other gears in the box. Current metal and bonding physics I can not speak for, but in the past it was a failing process.

[trbig]

... and an xs1100 with a 2nd gear that slips under full throttle(which would mean its only slightly worn) and clunky shifting (bent selector fork)

Before going into all that, could you please explain? SLIPPING isn't a 2nd gear problem and clunky shifting on these is the norm.

[Twintorsk]

Before going into all that, could you please explain? SLIPPING isn't a 2nd gear problem and clunky shifting on these is the norm.

Well its not the kind of quiet clutch slip i mean. I can feel the dogs disengage and bang together again with a hard jerk when i open it up wide. It only happens in high rpm, full throttle as yet, so i dont think damage is too great.
And i wont be welding on these unless there is not enough base material, but i am confident stellite and tempering Will work even in this application. Just have to find something cheap but equally powerful with a bad box to try it on first.. 😁

[jetmechmarty]

I teach at a tech school. We teach welding. I asked one the the instructors about stellite welding the dogs and slots. The short answer is the whole thing has to be annealed before you weld it. Then, it must be case hardened after the job is done.

[Twintorsk]

Well all here loves the long answer 😁 but im pretty sure neither annealing or the tiny welds would remove the case hardening on the gears. And wont stellite become way way too brittle from case hardening?
I'm really not that well read on metallurgy (welder, not engineer) but i know i can keep the gears below or at annealing temp when welding the dogs.
But since i expect wear to be very slight i think in this case undercutting is the way to go.
Would just love to know the correct process if it becomes necessary one day. Knowledge is power!

[jetmechmarty]

I was told that the weld won't work well unless you anneal first. Then, case harden after working.

[Bonz]

Which brings us full circle, why not do the regular second gear fix?