AHC pressures in High Setting? Using Techstream (1 Viewer)

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Joined
Sep 27, 2018
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5
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Location
Bend, Oregon
Website
www.couleecreative.com
Howdy. I have 2002 LX470 that I drive in the "High" AHC setting as I have oversized tires and want the "free" lift. I'll be adding front diff drop soon to reduce wear on CV.

I recently got Techstream working and noticed my pressures were way high for the front, 10.9 in the High setting, I don't recall the Neutral setting. I cranked my torsion bars clockwise six full rotations and brought the pressure down to 8.8 in High setting. I checked the pressure at "Neutral" and it's reading 6.5. As I understand it from a post I previously read, the AHC control is balanced when the torsion bars take around 60% of the spring load, which is supposedly 6.7-6.9 reading in Neutral from the front.

My question is, should I be "balancing" this system to have the correct pressure for "Neutral" if I'm running it in "High" mode? ...or would I want to shoot for those numbers of 6.7-6.9 in High mode? ...or maybe 8.8 in High Mode is actually fine since the numbers in Neutral are close to what is recommended?

Neutral Height - AHC numbers
IMG_6530.JPG



High Height - AHC numbers
IMG_6531.JPG
 
The system was never meant to "run" in high mode. High is just for crawling off-road and poser pics. Long term use at those pressures will likely shorten the life span of the actuators significantly.
 
Thanks for the input. I have it locked in H, it drives fine in N too however the wheel alignment was recently done in H. I probably only drive 3-5k a year, the wife's Subaru is the main errand vehicle and MPG champion so I'm just wanting to make this vehicle fun and capable without throwing down a few grand to delete the AHC. I just hope to get some input from someone that's perhaps gone down a similar path of what's worked well for them, other than keeping the AHC in the N or neutral position.
 
Doing a sensor lift is also "free" and will allow the suspension to work as designed (as long as you aren't lifted too much). That would be my recommendation.
 
Doing a sensor lift is also "free" and will allow the suspension to work as designed (as long as you aren't lifted too much). That would be my recommendation.
Sensor lift with corresponding adjustments to the torsion bars (tighten up) and rear springs (spacer?)
 
Sensor lift with corresponding adjustments to the torsion bars (tighten up) and rear springs (spacer?)

this is the way - I am up 1-1.5 inches with sensor lift and adjusted TB - had to re-index driver side, rear spacers and am completely within stock pressure specs.

I am actually still considering AHC delete though since all the bushings must be worn to death and I have replaced every other suspension bushing which made great improvements. I feel the labor of replacing all AHC shock bushings and potential for sensor, wiring etc issues aren't worth keeping the system.
 
Thanks again for the input. I'm wondering, what is the difference in the wear to the AHC system in having the ride height set to High with no sensor lift vs doing a sensor lift and setting the height to Neutral? Is there inherently higher AHC pressures with the High setting or is just the fact that the ride height is a bit higher or something else?
 
As long as the “shocks” are not over extended and the alignment and pressures are correct I wouldn’t think there would be any difference in wear. A sensor lift allows you to keep all of the benefits of AHC and still be able to raise it further (or lower it) as needed, so why wouldn’t you?
 
Thanks again for the input. I'm wondering, what is the difference in the wear to the AHC system in having the ride height set to High with no sensor lift vs doing a sensor lift and setting the height to Neutral? Is there inherently higher AHC pressures with the High setting or is just the fact that the ride height is a bit higher or something else?
This is actually a good question. I still think you're going about this all wrong (no offense), but clarifying the difference between locking it in high and doing a similar sensor lift is a good point.

I believe the damping and active height adjusting is altered and handling is affected since that mode was only intended for slow speeds. If I'm bored with some couch time tonight I'll see if I can grab the manual and see what it says. I thought there were a few differences.


More importantly though, is this a task worth doing? :) Nobody cares how much ground clearance you have on the highway or the parking lot.

Keep it low and raise it up when you get to the trail head.

What's the harm in doing a sensor lift? That keeps the AHC system as a whole more in tune with it's design and tuning and yields the same effect for you PLUS AN ADDITIONAL LIFT FOR TRAILS. :)

Locking it in high at standard heights is more work and you lose a pretty big benefit you could have by just doing the sensor lift.
 
The differences are the pressures you have in the AHC system. A sensor lift while adjusting torsion bars and adding spacers keeps the pressures in proper range.

Running in high all the time stresses the membrane in the actuators beyond their intended parameters. More heat and momentary pressure when running at highway speeds.
 

Correct but personally I wouldn’t bother with anything less than 30mm. Old springs and lifting both ask more from the hydraulic system. If you’re adding weight to the rear axle as well skip straight ahead to Kings AHC springs.
 

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