AHC front shock absorber (1 Viewer)

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Good day cruiser heads, I've noticed that my 100's front left shock absorber is leaking oil through the shafting, i dont want to f¥ck up the AHC system, its working great, just want to replace the leaky one, can i just remove it and install the new one? Or is there any step by step procedure to do it the right way?

20181112_133656.jpg
 

Ramathorn15

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The AHC shocks typically leak due to pressures being too high. I would first check your pressures using techstream, then adjust the torsion bars to lower the pressure into the acceptable range 6.9mPa +/- 5mPa if I remember correctly for the front. That should stop the leak.

If you're not familiar with techstream, do a search. Lots of threads on where to buy the cable and CD and how to set it up.
 
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Ive noticed that the torsion bars L&R does not have the same number of threads left, the passenger side TB is almost at full while the DS is only half but when i measure the wheel well clearance it is at level w/ each other. Does this affect the pressure reading?
 
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I recently had to replace the same shock due to the seal breaking and loosing fluid. If you need to replace yours I recommend Lagrange Toyota in Lagrange, GA depending on where you are at. I got a good price online and Tim in parts there got it to me in two days for like $10 priority mail.
 

Ramathorn15

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Ive noticed that the torsion bars L&R does not have the same number of threads left, the passenger side TB is almost at full while the DS is only half but when i measure the wheel well clearance it is at level w/ each other. Does this affect the pressure reading?

Sounds like someone messed with the torsion bats without knowing how the system works.

Adjusting the bars on an AHC equipped vehicle doesn't change the ride height. It only changes the ratio of weight the hydraulic shocks vs. the bars hold. If one torsion bar is very loose, then the shock is holding more weight than it should and will leak.

Only way to tell for sure is to get techstream and take a reading. Otherwise you're just playing a guessing game.

Assuming the bars are indexed equally, you could try evening them up, but again, you won't know where to go with them without techstream.
 
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Adjusting the bars on an AHC equipped vehicle doesn't change the ride height. It only changes the ratio of weight the hydraulic shocks vs. the bars hold. If one torsion bar is very loose, then the shock is holding more weight than it should and will leak.

Only way to tell for sure is to get techstream and take a reading. Otherwise you're just playing a guessing game.
The front shock actuators are connected in parallel so they have the same pressures and therefore provide the same lifting/lowering forces. This lifting/lowering force is superimposed over the net lifting torque of the torsion bars. If you’ve got one slack bar not doing it’s balanced share you’ll get a net higher hydraulic pressure because the hydraulics do more work for the system to maintain and stay at N height and you get a lean on the slack side; however the two shock actuators will always have equal pressures as long as the gate valve is open. When a shock actuator starts to leak due to too high neutral pressures then that’s just the weaker sealed shock or the first to fail of the two. Correct pressures and fluid that’s not old and degraded usually fix a weeping shock actuator.
 
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We have no techstrem software here at toyota philippines, does this mean that the shocks on D/S TB which is less torqued than the other carries more pressure than the T/B that is almost on its max torque? can i just re index the TB to be equal w/ each other?
 
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@PADDO Can i replace the leaky shock absorber w/o hooking the system up on the computer?
Yes. But you must set the front neutral pressure correctly for the damping system to work as designed regardless. If you don’t have Techstream or won’t get Techstream then do you have access to a LSPV gauge set? If so then it’s perfect for setting pressure by temporarily fitting it to a front damper and adjusting the torsion bars to read ~5.6MPa/825psi on the gauge.
If you’re hellbent on changing the weeping shock actuator then ensure you safely support the vehicle before relieving pressure from the front circuit. Connect some clear plastic tube up to the replacement shock and draw in fluid like a big syringe and expel that out to flush the actuator of any manufacturing debris (don’t assume its perfectly clean) and fully precharge the actuator before installing with a new top O ring. You always precharge with fluid because the best way to get air out of a system is to minimize it from entering in the first place. You’ll need to do a post install bleed of the front circuit.
 
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We have no techstrem software here at toyota philippines, does this mean that the shocks on D/S TB which is less torqued than the other carries more pressure than the T/B that is almost on its max torque? can i just re index the TB to be equal w/ each other?
Don’t get hung up on what the TB adjuster bolts look like because you’re dealing with a system that uses height sensor feedback, mechanical springs (TBs in this case) and hydropneumatics to determine vehicle ride height with self leveling and adaptive variable damping. If you just adjust or reindex a TB to what “looks good” then something else will be out like your front end side to side level and neutral pressure and your damping will really suffer. Have a look at the FSM for adjusting AHC system height and pressure.
 

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This is what my TB adjuster bolts look like.
1st pic is the passenger's side, 2nd is driver's side
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Bump. As I've been going through the maintenance records of our new-to-us 2006 LX 470 with 204k, the AHC systems the only regularly serviced system (per the owner's manual) that has no specific mention of being serviced. The only record I see is at 180k they replaced the UCA, inner and outer CV axle boots, replaced both front absorbers shock/strut and bled the hydraulic system, and performed an alignment. The fluid looks clean in the reservoir (I have not checked reservoir levels at H and L yet). I assume the shocks and hydraulic system is the AHC and the fluid is good to go. Am I making a correct assumption?
 
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Bump. As I've been going through the maintenance records of our new-to-us 2006 LX 470 with 204k, the AHC systems the only regularly serviced system (per the owner's manual) that has no specific mention of being serviced. The only record I see is at 180k they replaced the UCA, inner and outer CV axle boots, replaced both front absorbers shock/strut and bled the hydraulic system, and performed an alignment. The fluid looks clean in the reservoir (I have not checked reservoir levels at H and L yet). I assume the shocks and hydraulic system is the AHC and the fluid is good to go. Am I making a correct assumption?
Yes, the shocks and hydraulic fluid is the AHC but the fluid doesn't circulate so clean fluid in the reservoir doesn't mean clean fluid in the system.
 
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Yes, the shocks and hydraulic fluid is the AHC but the fluid doesn't circulate so clean fluid in the reservoir doesn't mean clean fluid in the system.
True. However, if the fluid was replaced 24k ago and the recommended service interval is 60k, can I then assume I don't need to replace the fluid now? And if someone else paid for the AHC to be replaced I'm feeling even better about buying this 100! I was not having any issues with AHC, I was just looking at what needed to be done and AHC was my only question mark. Looks like it is not a question mark any longer.
 
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True. However, if the fluid was replaced 24k ago and the recommended service interval is 60k, can I then assume I don't need to replace the fluid now? And if someone else paid for the AHC to be replaced I'm feeling even better about buying this 100! I was not having any issues with AHC, I was just looking at what needed to be done and AHC was my only question mark. Looks like it is not a question mark any longer.
You are correct about the fluild. The shocks rarely ever need to be replaced, since they are just hydraulic rams, I wonder if they meant they replaced the globes. There's a definitive AHC maintenance thread here on mud if you want to learn more about AHC. You can learn how to make sure your ride height/AHC pressures are in range, which will make the AHC last a long time.
 

ramangain

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Careful, that could be Canadian dollars. Call them to ensure it is US dollar pricing?
 

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