Catastrophic 2nd gear failure!

[Ranger_xs1100]

As pictured, the 2nd gear in my newly aquired 79 SF is missing a few teeth!

Background: The previous owner said the gears had been replaced in the past and all was working well. He also stated that this event occurred on a brief short ride after an oil change. The gears will not shift at all now, the transmission is completely locked up.

One mistake that I made was not pulling the oil pan down before turning the engine upside down to inspect the gears. So now I am concerned that there may be bits of teeth that dropped down throughout the engine. However that is a possibly anyhow since the gear was spinning high revolutions and likely throwing off bits of steel as the gear was being destroyed. You can see 2 of the teeth laying on top of the gummed up oil pump screen. Some of the teeth are sticking inside of the gummy jello sludge in the bottom of the oil pan. The sludge itself, along with some teeth and metal filings actually stuck to the bottom of the oil pan even though the engine was turned upside down to remove it.





After the breakdown, the bike sat outside for a couple of winters under a tarp with the right side engine cover and clutch assembly removed. So possibly some water got into it. Would that explain the gel consistency in the bottom of the oil pan?

Before I tear into this thing any further, what should I look for that may have caused this failure in the first place?

And if there are metal filings and teeth throughout the rest of the engine, Which I can’t really prove or disprove, I may be looking at future engine/transmission problems…So should I just forget about attempting any repairs on this thing? (I have another whole engine that I could just swap and be done with it!)


Thanks in advance for your thoughts and opinions.

[skids]

Ha! I would swap out the engine/transmission if you are sure the donor parts are good. Then, you can operate on the mess while it is in the open if you have the desire.

[Ranger_xs1100]

Ha! I would swap out the engine/transmission if you are sure the donor parts are good. Then, you can operate on the mess while it is in the open if you have the desire.

Thanks Skids,
I should have mentioned that I have the engine out and it is now in the open,
On the work bench and flipped upside down, So it's now or never to try and salvage this engine/transmission.

[skids]

Thanks Skids,
I should have mentioned that I have the engine out and it is now in the open,
On the work bench and flipped upside down, So it's now or never to try and salvage this engine/transmission.

I am not a transmission expert, but I would think there is something else wrong to cause the gear to be crewed-up like that. I would be inclined to swap out the transmission at least, and use the engine with the better compression...

[skids]

I wonder if the middle or final drive locked-up?

[Ranger_xs1100]

I wonder if the middle or final drive locked-up?

I wondered the same thing so I removed the 4 bolts under the rubber boot and was able to turn the rear wheel freely, then I pulled out the middle drive and was able to turn it by hand with no problem. I thought the engine must have been locked up until I removed the clutch assembly and then I could turn the engine over. I agree with you Skids, there must have been something else going on to cause such a major gear failure, but I sure don't know what that could be.

[DiverRay]

I have two engines that lost teeth on the main shaft. One I KNOW was ridden VERY HARD by the P.O., and the second is still in the bike I got from him.
I've also had my '79 lock up on me at about 85mph passing on a two lane road. I've yet to take it apart, but I think it may be the same thing, although that engine has about 125K on it.

[rangerguy302]

Any idea what caused it other than abuse? Not sure I have the skill to stay upright if a tranny locks up going interstate speed. In Mt it's 80....

[DiverRay]

Yours is on the lay shaft, not the main. I don't know what would cause that except maybe a bad gear. I could also be that something else broke, and the bits caused the damage to the gears. Andreas should have some spare parts in good condition, so I'd send him a PM first.

[Ranger_xs1100]

Due to the stress that the jammed gears were placing onto the end bearings, I had to break the end bearing cover to remove the bearing and gears,. After I got the gears out, I found that 1st gear also has broken teeth and the teeth are ground off of the 2nd pinion gear which is on the main shaft.



AND what is really interesting is 5th gear dogs! Did that happen during the failure and as a result of the failure, or maybe that was the cause of the failure?





I'm wondering if all of those broken teeth and metal filings have been scattered throughout the engine somewhere? And also wondering how to find and remove them all? I keep imagining that after all of the time and expense to replace the complete transmission, (which Andreas does have btw), the first engine startup could be catastrophic. Do you think that is a legitimate possibility and concern?

Thanks,

[JeffH]

Have you closely inspected the oil filter?

Just curious if you cut the pleats what you might find. That might be the tell.
You did say the PO said this happened after an oil change but I'd be curious about what may or may not be trapped in the oil filter pleats.

I'd be inclined to fix the tranny but that might be conditional depending on what the PO has told you about the bikes history. I wonder how many miles the PO rode the bike after the transmission had been replaced. Or maybe it is one of those PO of PO of PO deals.

Jeff

[DiverRay]

I would plan on a tear down and rebuild. I would NOT try and replace the transmission and then run it! What got into the main and rod bearings? What does the cam chain and gears look like? Just too many questions with possible BAD answers. a few very small missed bits of hardened steel will kill the engine very quickly. That is why my '78 engine is in bits and needing to go back together.

[Tenorman]

Ouch!

Hey Ranger,

I live in Butler, PA and I think I may have the old gears from my rebuild...they are yours, but you'll need to come and get them...I hope I didn't trash them...I'll check over the weekend...

Let me know @ jimschaffner@zoominternet.net if you are interested...

Plus, this is on ebay now:

https://www.ebay.com/itm/80-81-YAMAH...9ajvmM&vxp=mtr

I bought a complete used set of gears and only used one or two...

Tenorman

[Ranger_xs1100]

JeffH, I took a close look at the oil filter this afternoon and saw nothing unusual, in fact the pleats and residual oil look very clean, as you would expect to see after a recent oil change.

DiverRay, I have been thinking the same thing. I have done a couple of the 2nd gear fixes in the past, but never a complete total teardown and rebuild, which I’m sure is beyond my capacity and willingness. Thanks for your expert feedback, it definitely helps with the decisions that I have to make about this project.

Tenorman, thank you for the kind offer, an email has been sent.

[kboehringer]

Kick that motor to the curb.... buy a donor motor.

I would plan on a tear down and rebuild. I would NOT try and replace the transmission and then run it! What got into the main and rod bearings? What does the cam chain and gears look like? Just too many questions with possible BAD answers. a few very small missed bits of hardened steel will kill the engine very quickly. That is why my '78 engine is in bits and needing to go back together.

What he said!!!

Personally, I'd buy an entire donor bike & motor.

I have two spare XS11 motors in my garage. Both came from failed "Boober" attempts and I didn't pay more than $100 for either bike.

There has got to be a couple cheap bikes in your area you can grab a motor from?

In my opinion, that motor is going to be too costly to repair properly.