Tracer 9 GT Transmission failure - Yamaha refusing coverage under warranty

[Manxkiwi]

Aren't all the gears in constant mesh? If you smashed through the gears, you would damage the dogs, not the teeth. Am I right in my understanding of bike gearboxes? It's certainly a huge failure whatever the reason/cause.

[theog]

3 hours ago, Manxkiwi said:

Aren't all the gears in constant mesh? If you smashed through the gears, you would damage the dogs, not the teeth. Am I right in my understanding of bike gearboxes? It's certainly a huge failure whatever the reason/cause.

Your understanding is correct.  I suppose it’s possible that smashing a dog could possibly transmit a load spike into a specific tooth, but that sounds like a stretch for me. Constant mesh gear trains are specifically used to REDUCE the wear due to gear change loading. 
 

This is not the first time a new motorcycle of any variety had this issue and it’s most commonly the result of design and/or manufacturing defects. But Yamaha, specifically, has had the issue in recent history:  https://www.motorcyclistonline.com/recall-news-yamaha-recalls-r1-and-r1m-sportbikes-for-defective-transmissions/#:~:text=Faulty transmission gears could lock up on 2%2C921 Yamaha superbikes.&text=THE RECALL%3A Yamaha Motor Corporation,transmission gears that may fail.

 

But in fairness to Yamaha, none of us know the full story and we can only hope that both the dealer and Yamaha conducted themselves professionally and honestly in this failure. I feel for the owner as this is a very expensive job. 

[duckie]

Thing about using the QS is……you gotta also shift quickly……quicker than when the clutch is used.

The shift has to be quick and full movement of the shifter.

[duckie]

Yamaha also had issues with FJR trannys. 
So, Yamaha will take care of tranny issues when there is enough evidence to prove there is a true issue. 

[Lone Wolf]

2 hours ago, theog said:

...I suppose it’s possible that smashing a dog could possibly transmit a load spike into a specific tooth, but that sounds like a stretch for me.

This particular damage appears like a chunk of metal landed between gears, then grenaded the tooth.

The video posted earlier on this thread shows a chunk of metal broken out of a shift drum, and he shows a chunk of metal that was floating around in the transmission (that could land between gears).

He also notes that the bearings were full of metal fragments. He comments that the shift drum failed due to improper shifting, which the customer (for that video) openly admitted that he was jamming gears and abusing it.

Edited August 24, 2023 by Lone Wolf

[Ride365]

Hopefully QS being done correctly both up/down? 

[theog]

2 hours ago, Lone Wolf said:

This particular damage appears like a chunk of metal landed between gears, then grenaded the tooth.

The video posted earlier on this thread shows a chunk of metal broken out of a shift drum, and he shows a chunk of metal that was floating around in the transmission (that could land between gears).

He also notes that the bearings were full of metal fragments. He comments that the shift drum failed due to improper shifting, which the customer (for that video) openly admitted that he was jamming gears and abusing it.

I must have missed the video, thanks for the info. I was about to type into my response that it looked like something got jammed between the teeth. Didn’t know about the failed shift drum, so this is starting to make sense. 
 

Not all quickshifters are created equally…depending on the tuning, they can be very harsh on the drivetrain. 

[Lone Wolf]

3 hours ago, theog said:

I must have missed the video, thanks for the info ...Didn’t know about the failed shift drum, so this is starting to make sense. 

Just to be clear, I was commenting on the video Heli ATP linked to on the previous page that was not this same "broken tooth" transmission - but was an excellent example.  That video is by Motorcycle MD, who has a day job working as a professional Honda mechanic in the north east, does side repairs and has a good YouTube channel.

In that example video he explains how that shift drum broke out a chunk of metal. We don't "know" if that happened on the Yamaha transmission mentioned by the OP. But it certainly has the appearance of a stray chunk of metal landing between the teeth. Ouch. I will paste that video here: