C-clip from Roczen's shock exits the chat...

GH28
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4/23/2024 11:02am

The swingarm will stop against the lower part of the main frame pinching the chain slider if the shaft were to separate from the body.  Most likely the spring would still be contained.

The violent bounce near the end is the lack of rebound damping.  No fluid = no damping.  That's also why I think the reservoir failed, instead of the main body.  It took a bunch of those large displacements for the rebound control to disappear entirely.  There must have been some fluid behind the piston for the first couple of whoops.  If the main body broke, that little bit of rebound damping force would be gone that instant.

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Monkeys6.7
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4/23/2024 3:35pm Edited Date/Time 4/23/2024 3:38pm

 


I’d like to give my Synopsis, for anyone who cares… 

my guess is that the bottom land of the shock reservoir where the circlip is retained is only about 1/8” thick or so failed and blew out. When it did that the clip, bladder cap and bladder itself got wedged between the shock and the exhaust. All while spewing shock oil over the exhaust obviously. During the pounding from the whoops the clip was able to wiggle out of there and go flying. As you can see on the RM250 shock I have in front of me, the bladder with no pressure in it is huge, think how big it would be with 150 plus psi of nitrogen in it.. if the bladder would even stay on the cap, I’ve never tried pressurizing a bladder with it outside of the shock body lol. and also you can see the main body circlip that holds the seal head, usually has a end gap smaller than the shock shaft diameter and would be difficult to just fall right off of there being there’s a cap holding it in and the spring would most likely trap it as well. Either way very unfortunate for Kenny and as he was absolutely flying. 

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GH28
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4/23/2024 3:48pm

The bladder will only grow to the size allowable by the incompressible fluid on the other side of it, and any air that may still remain in the fluid. 

This is where there's opportunity for a lot of variability depending on who's installing it and how they're establishing the bladder volume (fill to a few psi before closing system, don't fill at all, fill to a lot more than a few psi, etc).  That volume can be all over the place and you'd think would be more controlled.

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Monkeys6.7
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4/23/2024 5:40pm
GH28 wrote:
The bladder will only grow to the size allowable by the incompressible fluid on the other side of it, and any air that may still remain...

The bladder will only grow to the size allowable by the incompressible fluid on the other side of it, and any air that may still remain in the fluid. 

This is where there's opportunity for a lot of variability depending on who's installing it and how they're establishing the bladder volume (fill to a few psi before closing system, don't fill at all, fill to a lot more than a few psi, etc).  That volume can be all over the place and you'd think would be more controlled.

Yes very true. I was only referencing the size of the bladder as I think it may of contributed in holding the cap and snap ring against the exhaust after the initial failure when Kenny landed from the triple before the whoops. A shock breaking its casting is very rare but as we saw with Shane’s failure, anything can happen. And I’m sure there’s thousands of pounds of force exerted on that snap ring during a gnarly bottom out like that. But at the end of the day without seeing photos of the shock… who the hell knows what happened lol.

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The Shop

4/23/2024 6:30pm Edited Date/Time 4/23/2024 8:41pm
Monkeys6.7 wrote:
  I’d like to give my Synopsis, for anyone who cares…  my guess is that the bottom land of the shock reservoir where the circlip is...

 


I’d like to give my Synopsis, for anyone who cares… 

my guess is that the bottom land of the shock reservoir where the circlip is retained is only about 1/8” thick or so failed and blew out. When it did that the clip, bladder cap and bladder itself got wedged between the shock and the exhaust. All while spewing shock oil over the exhaust obviously. During the pounding from the whoops the clip was able to wiggle out of there and go flying. As you can see on the RM250 shock I have in front of me, the bladder with no pressure in it is huge, think how big it would be with 150 plus psi of nitrogen in it.. if the bladder would even stay on the cap, I’ve never tried pressurizing a bladder with it outside of the shock body lol. and also you can see the main body circlip that holds the seal head, usually has a end gap smaller than the shock shaft diameter and would be difficult to just fall right off of there being there’s a cap holding it in and the spring would most likely trap it as well. Either way very unfortunate for Kenny and as he was absolutely flying. 

If you put the bladder on the bladder cap, and try to inflate the bladder, it won't take much pressure to blow the bladder off the bladder cap.

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Mit12
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4/23/2024 10:01pm

ML,

Do you know if Ken runs real light rebound Damping? Maybe the shock internals acted like a slide hammer thus blowing the cap off? Might be time for limit strap to keep the shock from topping out? 

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soggy
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4/24/2024 7:58am
Camp332 wrote:
Put my sleuth hat on. I'm going with the actual shock body had a failure because the reservoir looks in tact in this zoom in. Also...

Put my sleuth hat on. I'm going with the actual shock body had a failure because the reservoir looks in tact in this zoom in. Also look at where that smoke is still coming from lower below the number plate.

MxAddic wrote:

You don't need to be a sleuth. KRoc said the end of the shock body was gone. Not sure why this is so hard.

So you believe Ken here but don’t believe Yamaha when they say a valve cover had a leak. How do you compartmentalize it all. 

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MxAddic
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4/24/2024 8:08am
soggy wrote:

So you believe Ken here but don’t believe Yamaha when they say a valve cover had a leak. How do you compartmentalize it all. 

I have my reasons. Not sure why is a big deal to you other than another putdown..

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fourfourone
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4/24/2024 11:16am
soggy wrote:

So you believe Ken here but don’t believe Yamaha when they say a valve cover had a leak. How do you compartmentalize it all. 

MxAddic wrote:

I have my reasons. Not sure why is a big deal to you other than another putdown..

What are the reasons? 

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MxAddic
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4/24/2024 1:38pm

What are the reasons? 

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ML512
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Fantasy
4/25/2024 7:27am
Monkeys6.7 wrote:
  I’d like to give my Synopsis, for anyone who cares…  my guess is that the bottom land of the shock reservoir where the circlip is...

 


I’d like to give my Synopsis, for anyone who cares… 

my guess is that the bottom land of the shock reservoir where the circlip is retained is only about 1/8” thick or so failed and blew out. When it did that the clip, bladder cap and bladder itself got wedged between the shock and the exhaust. All while spewing shock oil over the exhaust obviously. During the pounding from the whoops the clip was able to wiggle out of there and go flying. As you can see on the RM250 shock I have in front of me, the bladder with no pressure in it is huge, think how big it would be with 150 plus psi of nitrogen in it.. if the bladder would even stay on the cap, I’ve never tried pressurizing a bladder with it outside of the shock body lol. and also you can see the main body circlip that holds the seal head, usually has a end gap smaller than the shock shaft diameter and would be difficult to just fall right off of there being there’s a cap holding it in and the spring would most likely trap it as well. Either way very unfortunate for Kenny and as he was absolutely flying. 

Body failed, not the clip.

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Monkeys6.7
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4/25/2024 7:57am
Monkeys6.7 wrote:
  I’d like to give my Synopsis, for anyone who cares…  my guess is that the bottom land of the shock reservoir where the circlip is...

 


I’d like to give my Synopsis, for anyone who cares… 

my guess is that the bottom land of the shock reservoir where the circlip is retained is only about 1/8” thick or so failed and blew out. When it did that the clip, bladder cap and bladder itself got wedged between the shock and the exhaust. All while spewing shock oil over the exhaust obviously. During the pounding from the whoops the clip was able to wiggle out of there and go flying. As you can see on the RM250 shock I have in front of me, the bladder with no pressure in it is huge, think how big it would be with 150 plus psi of nitrogen in it.. if the bladder would even stay on the cap, I’ve never tried pressurizing a bladder with it outside of the shock body lol. and also you can see the main body circlip that holds the seal head, usually has a end gap smaller than the shock shaft diameter and would be difficult to just fall right off of there being there’s a cap holding it in and the spring would most likely trap it as well. Either way very unfortunate for Kenny and as he was absolutely flying. 

ML512 wrote:

Body failed, not the clip.

That’s what I was attempting to say, the land where the clip resides in the reservoir probably broke off. Rare but I’m sure there’s tons of force exerted on that spot from a hard landing like Ken was doing from that triple before the whoops. 

Steve125
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4/25/2024 10:43am

This thread delivers more than the Zapruter film.

Good stuff. Bad situation. get well K-Roc.

 

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