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s40 major failure, balancer hitting case, cause? (Read 613 times)
Ruttly
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Re: s40 major failure, balancer hitting case, caus
Reply #60 - 06/29/20 at 22:29:58
 
You cannot use a impact to install that nut , ok to take it off , thats a hand tighten then torque it nut. Or your gonna have a problem. Guess I was lucky when I heard it break ( cam chain drive gear/sprocket ) . So thatís how I know. And everyone who has used a impact gun on it had better go back in and check it. Iíll have that cover off soon to change the clutch pushrod to the proper length and i will recheck it. Thatís the last thing I need to happen while breaking the ton mark !!!
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BlakeEM
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Re: s40 major failure, balancer hitting case, caus
Reply #61 - 06/30/20 at 02:31:10
 
I think it's more likely he used an impact wrench to remove it not realizing it's reverse thread at first since it was his first time working on this specific engine (he usually works on high performance track bikes). He's a master mechanic so I assume he torqued it properly when it was installed however the damage would have already been done. It's hard to prove anything and I don't know what I'd expect the shop to do about it. It's a very crappy situation and the shop is extremely unlikely to admit the mistake however the shop owner is asking the tech about it.

I don't see any other way to make sense of it, those marks and the scrapes behind the drive gear seem like the smoking gun.
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justin_o_guy2
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Re: s40 major failure, balancer hitting case, caus
Reply #62 - 06/30/20 at 08:23:20
 
I think its obvious enuff.. That nut Says
Impact, CCW..
Which results in Overtorque,,and damage done..
Once he realized the mistake, flipped the switch, CW impact, took it apart..

Too late,, damage done..
Thats the only thing that adds up in my mind
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BlakeEM
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Re: s40 major failure, balancer hitting case, caus
Reply #63 - 07/01/20 at 11:09:32
 
I'm riding over to talk with the tech today. Wanted to get some pictures to prove that the crankshaft was out of alignment as well as a picture of the hole for the main drive pin on the crankshaft.

The hole for the pin in the crankshaft

https://imgur.com/8EzRg9g

I noticed the main bearing wasn't fully seated, you can see the gap.

https://imgur.com/f0wmwca

https://imgur.com/DBp00WV

On the other side it looks like the crankshaft was scraping the case. Notice the white part.

https://imgur.com/npU7tD9

I don't have a flywheel puller. Is there an easy way to get off the flywheel so I can get a better look or do I need a puller?

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BlakeEM
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Re: s40 major failure, balancer hitting case, caus
Reply #64 - 07/01/20 at 12:39:19
 
From what I've read I need a puller, so I probably won't be getting it off anytime soon. I wanted to have a look at those bearings.
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Dave
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Re: s40 major failure, balancer hitting case, caus
Reply #65 - 07/01/20 at 12:54:45
 
You don't need a puller for the flywheel - you need the puller for the magnetic rotor.

You do need a big deep socket to get the flywheel nut off though - and if you don't have an impact you will need a holder for the flywheel to keep it from turning while you loosen the nut.

The rotor is on a tapered shaft, and there is no way to get it off without a puller. †Take it to the shop with you and maybe they will pull it.
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justin_o_guy2
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Re: s40 major failure, balancer hitting case, caus
Reply #66 - 07/01/20 at 13:04:59
 
You mite wanna do your arguing with the mechanic before ya go deeper,,
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Re: s40 major failure, balancer hitting case, caus
Reply #67 - 07/01/20 at 16:18:24
 
I believe I know what happened after talking with their tech.

This could not have happened from over torquing the main drive nut. The marks on the nut were from his impact on the low setting (45 ft-lbs) and he torqued it by hand. Over torquing this bolt would put pressure on the bearing and it's not possible for it to move the crankshaft since it pinches the side of the case.

What we think happened was that the key in the balancer sheered off over time. This bike saw a LOT of freeway. At high speed the balancer was making contact with the crankshaft. The crankshaft has a small amount of play side to side from the factory, this is that gap we see in the bearing seat. The crank likely saw a lot of vibrations and this caused the main drive pin to come loose causing the balancer to spin freely and leave the engine.

So I think the weakness is that balancer key, this can cause your balancer to loose timing and hit the crankshaft. Over time this can cause the crank to shift side to side and the main drive pin to come loose.

It blew when coming off the freeway. Before that it made a sound similar to a misfire or exhaust leak, this was likely the balancer hitting the crankshaft.

See the failing balancer key here.

https://i.imgur.com/VEBUgRo.jpg
https://i.imgur.com/F7ldFCB.jpg

If you use this bike for a lot of freeway riding this could be a major failure point to watch out for. The balancer has springs to dampen the rotational force so although it has a 1/2 inch gap when not moving when running at a high speed this gap will shrink and if the pin starts sheering off it gets even smaller and it can hit the crankshaft.

Hopefully this makes sense and provides some closure.
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justin_o_guy2
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Re: s40 major failure, balancer hitting case, caus
Reply #68 - 07/01/20 at 16:21:11
 
He didnt do That with an impact,,
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justin_o_guy2
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Re: s40 major failure, balancer hitting case, caus
Reply #69 - 07/01/20 at 21:00:53
 
Now do you want to sell the forks?
Mine broke when a woman turned left across me..
I could use the tank, too.
Mine got bent,,
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justin_o_guy2
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Re: s40 major failure, balancer hitting case, caus
Reply #70 - 07/01/20 at 21:02:16
 
Need some other stuff, but need to look again,, left peg is off, but don't remember exactly what got smashed.
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Dave
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Re: s40 major failure, balancer hitting case, caus
Reply #71 - 07/02/20 at 04:37:18
 
BlakeEM:

The bike is not damaged by freeway riding......we have lots of riders who do that every day. Our member Oldfeller was the king of high rpm riding, MMRanch has been to Texas and back to Tennessee several times, and I believe Batman is a daily highway rider.†Your bike is the only one on this forum that has ever done this. †The only known issue with extended freeway riding at high rpm is the oil consumption increases, and you need to check the oil level regularly as it will drop faster than normal.

The "TECH" caused this damage with the impact wrench when he was taking the bike apart......not when he was putting it back together. †He mistakenly tried to remove the "left hand thread" nut by running it counterclockwise in the right hand thread direction - that is when the damage was done. †The over-tightening while trying to loosen the nut in the wrong direction resulted in the camshaft drive sprocket flange being fractured........and no matter how careful the tech was when he reinstalled it - the stress cracks were formed and over time the sprocket flange broke off and allowed the clamping tension to be released. †Once the clamping tension was released everything on the right side of the crankshaft was no longer properly attached and things began to move around in a destructive way. †The damage to the key and pin and ultimate engine destruction were all caused by the parts no longer being clamped together and the resulting "hard impact" when the crankshaft hit the balancer shaft.

The Suzuki Savage is fully capable of freeway riding when properly assembled - the "tech" at the shop is at fault for this engine failure.
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Re: s40 major failure, balancer hitting case, caus
Reply #72 - 07/02/20 at 07:32:15
 
@Dave

Could you explain how the release of clamping force would cause the balancer to hit the crankshaft? Because this was happening a while BEFORE the pin came out of the main drive gear. The crankshaft is free floating side to side so the loss of clamping force would not have caused that to happen nor would it have caused it to jump teeth on the gear since it's made to move side to side (there is no evidence of it jumping teeth). The only cause that makes sense is that balancer key failing first, especially based on how it failed. We thought the sound was an intermittent misfire or exhaust leak but it was only on the freeway at full throttle. I tried resealing the exhaust a couple times and she was complaining about issues at high speed for a while as well, I just couldn't pin point it. It may have been hitting it for a while. Most of my test rides were around town however it was only noticable at full throttle on the freeway.

Just because it hasn't been mentioned on the forum doesn't mean it can't happen. Others have mentioned that key being a weak point.
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Re: s40 major failure, balancer hitting case, caus
Reply #73 - 07/02/20 at 07:41:59
 
I shouldn't have said clamping force before since it doesn't actually clamp that side of the crankcase, it clamps between the nut and the crankshaft which freely floats in the bearings.

The guy is a master mechanic and I'm just a hobbyist. He drew it up on paper to explain it to me and it made sense what he was saying.
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Re: s40 major failure, balancer hitting case, caus
Reply #74 - 07/02/20 at 07:45:16
 
When the clamping force was lost, the crankshaft was no longer prevented from moving within the right crank bearing.......this right bearing is a ball bearing and is what keeps the crankshaft centered (the right bearing is a roller bearing and accounts for the different expansion rates as the engine warms/cools.

When the flange on the sprocket broke the crankshaft moved left (as evidenced by the gear cutting into the right case half). †When the clamping force was lost as the crankshaft moved left, the gear on the crankshaft that drives the counterbalancer was no longer contained and it was able to start rocking forward/back as the power and compression pulses occurred - and over time the pin was distorted and came loose toward the inside of the crankshaft (you showed a photo of that pin extended to the inside of the crankshaft). †Once that pin was no longer keeping the counterbalance shaft in time with the crankshaft.....the timing between the two was lost and the destruction began. †The pin does the locating and provides some of the strength needed to keep the gear in time with the shaft - but the clamping force also prevents movement.

The gear on the counterbalancer shaft is dampened with springs to help smooth out the rotation at varying frequencies and reduce the load on the key that was damaged - I suspect the damage to the key actually occurred when the collision between the crank and counterbalancer occurred.

I have been on this forum for more than 8 years, and I have seen a lot of stuff........this is the first time anyone has had this type of failure.  You and your riding style did not break the engine.......your mechanical "tech" did.
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