Gen2 Live Valve Full Stiffness Cause?

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TravisHTX

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i guess the complete assembly could/can be called a solonoid..

the coil is a magnet, and the part that screws into the shock is a needle valve, that yes controls the flow of oil into the shock reservoir internal piston area..

but basically, its a needle valve array for controlling oil flow, outside of the piston/shim stack mounted to the main shock shaft..

all its really doing is turning the manual knob that is on the older shocks, until you talk about gen3 that is adjusting the knobs constantly..


maybe something in the live valve is failing and making them full stiff after time... thatd be pretty lame.

if the needle isnt pulled back, they are full stiff..

so id bet its possible that the needle is getting stuck in its seat and the magnet cant pull it back...

I understand your point. And yes, that has been one of my questions, how likely is it that the valve just gets jammed in the closed position. Maybe that possibility is so slim it’s not worth considering.

The “emulsification” of the oil does certainly makes a lot of sense.

I am thinking of getting a new set of shocks so I have limited down time.

I have no problem cracking one of the old ones open, I just don’t know how helpful it would be since I have no experience doing that before. We need a pro to give us a demo of what one of these look like old vs new!
 

downforce137

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you can see here theres some springs and ports and oil flow control to act as a secondary adjustment..

idk if this is gen2 or gen3 stuff but something is stuck closed in there, id bet..Screenshot 2024-04-05 210041.png
 
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TravisHTX

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you can see here theres some springs and ports and oil flow control to act as a secondary adjustment..

idk if this is gen2 or gen3 stuff but something is stuck closed in there, id bet..View attachment 450293

I like that graphic. It is no surprise that it takes a lot of engineering for a simple low power “solenoid” to be able to control forces of a system that has incredible amounts of pressure being applied to it.

Guys here on this forum have been saying for a long time that there is a lot more for there to go wrong on these live valve shocks. For good reason.
 

letsgetthisdone

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i guess the complete assembly could/can be called a solonoid..

the coil is a magnet, and the part that screws into the shock is a needle valve, that yes controls the flow of oil into the shock reservoir internal piston area..

but basically, its a needle valve array for controlling oil flow, outside of the piston/shim stack mounted to the main shock shaft..

all its really doing is turning the manual knob that is on the older shocks, until you talk about gen3 that is adjusting the knobs constantly..


maybe something in the live valve is failing and making them full stiff after time... thatd be pretty lame.

if the needle isnt pulled back, they are full stiff..

so id bet its possible that the needle is getting stuck in its seat and the magnet cant pull it back...

The needle doesn't directly control oil flow from the body to the reservoir. It controls hydraulic pressure on the actual valve that controls flow. If you'd had one of the apart you'd know what I'm talking about-
In the non-livevalve gen2 shocks, the reservoir orifice (on the compression side) is controlled with a shim stack, just like there is a shim stack on the main piston. The live valve shocks replace that shim stack with a solid piston/valve assembly, the opening and closing of which is controlled by the livevalve solenoid/needle metering flow/pressure to the back side of the piston. This design allows the shock to be controlled by PWM, otherwise you would only get soft/firm out of the live valve, which would be dumb.

On rebound, both shocks just have a pop-off valve to allow max flow back into the shock body from the reservoir as the shock extends.

And the Livevalve electronics are constantly changing damping with gforce and ride height inputs. It is not in 1 position per drive mode, and its not just soft/stiff.


Oh you found a picture, good. I wish it showed how the oil actually flows through the assembly. The orange needle (the live valve solenoid) controls the orange piston via differential pressure. Which in turn controls how much flow there is.
 
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downforce137

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The needle doesn't directly control oil flow from the body to the reservoir. It controls hydraulic pressure on the actual valve that controls flow. If you'd had one of the apart you'd know what I'm talking about-
In the non-livevalve gen2 shocks, the reservoir orifice (on the compression side) is controlled with a shim stack, just like there is a shim stack on the main piston. The live valve shocks replace that shim stack with a solid piston/valve assembly, the opening and closing of which is controlled by the livevalve solenoid/needle metering flow/pressure to the back side of the piston. This design allows the shock to be controlled by PWM, otherwise you would only get soft/firm out of the live valve, which would be dumb.

On rebound, both shocks just have a pop-off valve to allow max flow back into the shock body from the reservoir as the shock extends.

And the Livevalve electronics are constantly changing damping with gforce and ride height inputs. It is not in 1 position per drive mode, and its not just soft/stiff.


Oh you found a picture, good. I wish it showed how the oil actually flows through the assembly. The orange needle (the live valve solenoid) controls the orange piston via differential pressure. Which in turn controls how much flow there is.

on the gen2 there is one shock mode per drive mode.. with bottom out protection probably built in, but they are not constantly adjusting like the gen3 does...

i understand how they work but youre right, i have not had them apart..

but looking at the picture, the orange needle valve is what moves and the magnet pulls it back against a spring (that would close it with no input from the VDM)to open the needle for softer damping, more oil flowing into the reservoir as the shaft is pushed or pulled into the shock.. stiffer live valve leaves more up to the shaft piston mounted valving and opening it up allows easer oil flow past the livevalve..

in the above picture the needle is fully open, allowing full oil flow..

its been show in shock dyno chart that livevalve affects both compression and rebound.


Screenshot 2024-04-06 180732.png
 

letsgetthisdone

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Again, the needle is not the main control for oil flow. It is a small bleed port. When it is shut, the main flow control piston is hydraulically locked in place, and can’t move. When open, it relieves this pressure and allows the piston to open and allow oil to flow through.

The pressure comes from the center off all the components having a passage (red line) which allows oil into the the internal chamber of the flow control piston (green circle) this chamber is exposed to the pressure created by the main piston in the shock, and the shock shaft displacement. The same pressure being exerted in the piston through the shut reservoir orifice.

The needle controls a small <1/8” bleed port, when it opens, the differential pressure drops and the piston opens, allowing flow.

And the factory VDM does constantly adjust damping, per Fox. That being said, the DSC unit does a much better job. I have it in my truck and spent a lot of time tuning it to get it to ride how I want with the Eibach springs and Deaver +3HD, along with having made some small changes in the shocks. Which that took some experimenting because these shocks don’t have a typical high flow main piston, so there aren’t a lot of shims in them to begin with.

IMG_1324.jpeg
 

letsgetthisdone

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Regardless, in theory I guess that internal valve stuff could sludge up over time. But there’s so much pressure moving that stuff around I don’t see it getting stuck.
 
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TravisHTX

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Regardless, in theory I guess that internal valve stuff could sludge up over time. But there’s so much pressure moving that stuff around I don’t see it getting stuck.

Stupid question. What would you all say the odds are of some sort of grit (like particles from the worn seals), that may cause the needle valve to get sticky?

That may explain some reported cases where some hard use may dislodge that debris and the system behaves better for a bit. Or variations in perceived harshness.

I could swear that just today while driving on the road, while still harsh, the ride seemed a tiny bit better today without changing a thing.

With how much this needle valve moves, I would find it unlikely for any scoring in the piston to be unlikely, but I very well could be wrong.
 
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TravisHTX

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That sort of thing is an issue with some of these Gucci AR15s, where the bolt assembly is machined for such a tight fit, any grit of what so ever causes jamming. The most reliable ARs, actually have a bolt assembly that are not as tightly machined.
 

smurfslayer

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That sort of thing is an issue with some of these Gucci AR15s, where the bolt assembly is machined for such a tight fit, any grit of what so ever causes jamming. The most reliable ARs, actually have a bolt assembly that are not as tightly machined.
I don’t think the Ar15 analogy works. Although very efficient in its application, it’s an open and overtly dirty operating system, where the shock is a closed system.

Also, props to you for humor for mentioning AR15 and reliable in the same sentence

A definite LOL.
 
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