Definitive list of AHC maintenance items (4 Viewers)

[ChuckB]

Hi!

I have recently imported my 287k miles lx470 from the states and spent some time on these forums trying to catch up. My ride seems “ok”, but when I do tech stream and the reservoir check they seem to be worn. The right shock and fluid was changed by a Toyota dealer in June 19 before it was put for sale.

I would appreciate if anyone could comment whether my readings calls for a replacement.
View attachment 2313015

Also your pressures F/R are a bit high. Once you know your graduations, I would start with the front and crank those torsion bars 4-5 times making sure to do all the appropriate measurements. You may need to replace your rear springs as well, but I would focus on the front first.

 

[sigjar]

What do you mean by "worn"? How many graduations do you get when doing that test?

From what I gather, it’s 3-4, but a bit hard to read.

 

[ramangain]

From what I gather, it’s 3-4, but a bit hard to read.

FWIW, I find that shining a flashlight in the side of the resevoir from the engine block side and looking in to see where the light is half diluted by the fluid is an easy way to get an accurate measurement in old, dirty reservoirs. Head mounted lights work best, held by hand.

 

[LndXrsr]

Alright, I just read through all 39 pages of this thread while in the process of doing an initial eval and adjustment of my AHC to OEM spec. This thread should be considered a right of passage for anyone with AHC. I will say that thanks to the help here, my assessment and adjustment went flawlessly. I have a 2000 LX with 189k miles; somehow my heights were all within 1/4", my pressures required 4 TB turns each for the front, and my rear is in spec despite definitely being the original springs (rear seats are removed, admittedly). AHC flush procedure went smoothly also. That had never been done either. Thanks to everyone who's contributed, collated, and provided patient feedback to so many on here!

Planning to post a Cliffnotes, highly condensed version, of my start-to-finish AHC re-spec process: measuring, flushing, leveling, pressures.

 

[gamecock2009]

Alright, I just read through all 39 pages of this thread while in the process of doing an initial eval and adjustment of my AHC to OEM spec. This thread should be considered a right of passage for anyone with AHC. I will say that thanks to the help here, my assessment and adjustment went flawlessly. I have a 2000 LX with 189k miles; somehow my heights were all within 1/4", my pressures required 4 TB turns each for the front, and my rear is in spec despite definitely being the original springs (rear seats are removed, admittedly). AHC flush procedure went smoothly also. That had never been done either. Thanks to everyone who's contributed, collated, and provided patient feedback to so many on here!

Planning to post a Cliffnotes, highly condensed version, of my start-to-finish AHC re-spec process: measuring, flushing, leveling, pressures.

That’s awesome! I just got my mini obd cable so hopefully can get my LX to talk to techstream tonight. I definitely will need some TB turns

 

[ls6]

Planning to post a Cliffnotes, highly condensed version, of my start-to-finish AHC re-spec process: measuring, flushing, leveling, pressures.

sub'd for the cliff notes

 

[LndXrsr]

Okay, here’s an attempt at a succinct, start-to-finish, “Cliffnotes,” version of my AHC assessment and re-spec for anyone who is attempting to measure, bleed, and adjust for the first time. It is entirely a collation of information found in this thread. Thank you to all who shared this with myself and everyone on here. It seems daunting, but it’s really just a highly mechanical thing that needs to be approached one step at a time, in the right order.

I’m calling it “The ABCs of AHC.”

A - Assess: Figure out where you’re starting from

1. Wheels on level ground, no ramps, jacks, or stands needed for parts A, B, or C. DO NOT PUT YOURSELF PHYSICALLY UNDER THE VEHICLE FOR ANY OF THIS.
2. Get your rig loaded/unloaded to what is “typical” for your use.
   • FSM calls for no passengers, full tank of fuel.
3. Measure ride height at all 4 corners from center of wheel cap vertically to fender lip on a level surface
   • Front OEM: 19.75” (50.2cm)
   • Rear OEM: 20.5” (52.1cm)
   • Drive a bit, then park in the same level place. Take 3-5 measurements and get a mean or median.
4. Measure difference in AHC tank level between H and L suspension heights
   • >7 graduations acceptable, 14 graduations new from factory
   • Need to replace globes/spheres if <7 after parts A, B, and C are complete.
   • Backlight AHC fluid tank with a light to help see fluid level
   • Again, 3-5 measurements and take a mean or median value
5. Measure your front/rear pressures and sensor heights using Techstreamand a Mini-VCI cable
   • Front spec: 6.9MPa +/- 0.5
   • Rear spec: 5.6-6.7MPa
   • Start car, connect Techstream, make sure you choose your exact model, not the default Land Cruiser with no AHC installed
   • Open AHC channel and select "data list" to monitor values
   • Cycle from N to L to N again. Take a screenshot of your values. There are Front R and Front L height sensors but only one rear sensor for pressure and height. May need to disconnect the AHC temp sensor to get accurate rear readings per FSM.
   • Again, 3-5 measurements and take a mean or median value for each data point.

B - Bleed: Flush out the old AHC fluid

1. Procure three 1L bottles of OEM AHC fluid (08886-81221)
2. Put AHC in Low, turn engine off
3. Suck all old fluid out of AHC tank (~1L if level was between Max/Min at N height)
4. Pour in new fluid to top of tank (~2.5L)
5. Bleed accumulator until fluid stops (long cylinder on left side frame rail) (~300mL, 10mm wrench)
   • Bleeder torque spec: 62 in-lbf (5.5 ft-lbf, 7.5 N-m)
6. Bleed one front and one rear damper (globe unit) until both front and rear are on the bump stops and fluid stops flowing (~300-400mL each)
   • Bleeder torque spec: 73 in-lbf (6.0 ft-lbf, 8.1 N-m)
   • Careful, as the car will lower significantly during this process. Don't put yourself under the vehicle!
7. Start car, put AHC in Neutral
8. Bleed the remaining front and rear dampers on the other side of the car for just a second until fresh fluid and no air comes out (~50mL each)
9. Start car, cycle to AHC to L then back to N
10. Top off AHC fluid in the reservoir. Should be between Max/Min at N height.
11. Recheck graduations in the tank as described in step A2. May see some improvement, may not.

C – Crank/Check: Adjust the side-to-side height and neutral pressures front/rear

1. Remeasure your ride heights as in Step A1. Measure twice, cut once.
2. Fix any left-to-right ride height imbalance, i.e. lean. This is commonly called “cross-leveling” throughout this thread. This is done entirely by adjusting the front torsion bars (TBs), not height sensors.
   • Tighten (CW) a TB nut to raise a low side, loosen (CCW) to lower a high side. 30mm wrench/socket
   • Mark your TB nuts (permanent or paint marker) so that you don’t lose track of where a full turn is
   • Place AHC in H to lessen pressure on TBs and make turning easier. Put back to N for measurements.
   • ~1/8” correction in left-to-right height imbalance per full turn of a TB nut
   • Best to turn TBs equal amounts in opposite directions until level
   • Drive a bit, repeat, measure until satisfied with left and right ride heights being equal
3. Adjust the three ride height sensors as needed to achieve as close to 0mm on all values at N in Techstream.
   • Engine off, ignition on. Monitor changes in real time on Techstream.
   • Raise: Shorten heim joint (the adjustable threaded rod) or move the top of the joint up in its slider
   • Lower: Lengthen heim joint or move the top of the joint down in its slider
   • Rear sensor only has a slider
   • <10mm (0.3-0.4in) between the two most discrepant sensors is acceptable
   • Recheck ride height as in step A2. If all sensors at/near 0mm, ride height should be very close to OEM spec, otherwise sensor(s) may be malfunctioning.
4. Adjust front N height pressures by cranking the TBs
   • Place AHC in H to lessen pressure on TBs and make turning easier
   • Lower pressures: tighten (CW) both TBs the same amount
   • Raise pressures: loosen (CCW) both TBs the same amount
   • ~0.2MPa change in pressure per full turn of a TB nut
   • Cycle H to L to N. Recheck pressures as in step A5.
5. Check rear N height pressure
   • OEM specs in step A5
   • May need to disconnect the AHC temp sensor to get accurate rear readings per FSM.
   • Rear pressures can be changed with new springs (OEM or King), spacers, airbags, or rear sensor height adjustments (but this last one also change the height of your rear and the car’s rake front to back).
6. Check graduations in the tank as described in step A2. Again, may see some improvement, may not.

Good luck! Hope this helps summarize it all into a (relatively) short document that can be used for easy reference. Feedback encouraged. I’m sure at least one thing in here is incorrect. Long live AHC!

 

[riffman12]

That’s awesome! I just got my mini obd cable so hopefully can get my LX to talk to techstream tonight. I definitely will need some TB turns

Should be no issues with it talking to TechStream as long as you follow the TechStream in 5 minutes thread and download the virtual machine software. Also make sure you set the vehicle to LX470 and not Land Cruiser once it connects.

 

[gamecock2009]

Finally got my techstream running and front pressures were 8.4 (sheesh) and rear was 7.7. Going to have to do some cranking on the front and im planning on removing the third row anyways and seeing what the rear is like.

 

[LndXrsr]

Like I said above, feedback appreciated (edits, additions, ways to make it shorter if possible). I've already added a couple things to add detail or clarity. Once we’ve tweaked it as a group, I might copy over to its own thread as well for easy reference instead of getting buried here in what will ultimately be an 800+ post thread in the near future.

I’ll reserve this post for a potential summary of AHC mods (springs, airbags, spacers, sensor lift, OEM vs aftermarket globes) as well.

 

[ouzo12]

Recently installed new globes and needed some guidance on dialing in my pressures.

Pressures are around 6.2 on the front but I am afraid to back out the torsion bars now because the height is dropping to 19.25 at the drivers front. The Passenger front looks to be close to spec.

Do I continue to adjust the torsion bars and focus on the pressures and then adjust height via the sensor? If so, do you accomplish this via adjusting the entire link (step 5 in manual) and then try to fine tune the height differences between both sides?

If anyone is a pro at this in the Charlotte area, your social distanced help will be rewarded with booze of your choice : )

 

[LndXrsr]

Left-to-right height differences (especially up front) should be corrected with the torsion bars, by cranking them in opposite directions. See #767 for a general overview and pictures/extra details are throughout this thread.

After you've leveled the front, then check your height sensors to make sure they are close to in agreement with each other. It's weird, but height sensors don't really adjust side-to-side height in AHC. What are your height sensor readings currently? If close to 0mm despite the car not being level side-to-side, I especially wouldn't mess with them, though I don't think you will have to anyway after using the TB method to start.

Once that's done, you can correct your pressures by cranking the TBs in the same direction tighter or looser as dictated by your pressure readings.

 

[Zer0zg]

The car adds pressure until the average of the front height sensors meets the desired value. You're pretty close to the low end of the spec, which is good. I'd get the car level by backing out the passenger side and see where you land on pressure once that's done. Back off both from there to get to spec.

 

[skipdup]

How does one "disconnect the AHC temp sensor"? Sorry, I bet it's in here somewhere, but I can't find...

I did and AHC flush, new rear springs, and adjusted the front torsions yesterday. Checked pressures again today (as sanity check). Apparently, I'm not sane. Front changed from 6.9 to 7.6 overnight. Rears stayed at 6.9, (so springs made no change) which was surprising...

 

[ouzo12]

How does one "disconnect the AHC temp sensor"? Sorry, I bet it's in here somewhere, but I can't find...

I did and AHC flush, new rear springs, and adjusted the front torsions yesterday. Checked pressures again today (as sanity check). Apparently, I'm not sane. Front changed from 6.9 to 7.6 overnight. Rears stayed at 6.9, (so springs made no change) which was surprising...

Walk away, take a deep breath and look again. Don't let it get to you like it does to me!

Did you notice and seat of the pants difference with the new rear springs?

 

[skipdup]

It seemed like a definite improvement. Maybe??? Not sure if it was confirmation bias or not.

 

[LndXrsr]

How does one "disconnect the AHC temp sensor"? Sorry, I bet it's in here somewhere, but I can't find...

I did and AHC flush, new rear springs, and adjusted the front torsions yesterday. Checked pressures again today (as sanity check). Apparently, I'm not sane. Front changed from 6.9 to 7.6 overnight. Rears stayed at 6.9, (so springs made no change) which was surprising...

4th pic in this post:

The ABCs of AHC - How to Measure, Flush, and Adjust all in one place

I initially put this in the Definitive list of AHC maintenance items thread, but at almost 800 posts long and growing, it's going to get buried and the thread itself is very unwieldy. In an attempt to make as focused a summary as possible, I present "The ABCs of AHC." It's intended as a...

forum.ih8mud.com

 

[skipdup]

Thank you!

 

[skipdup]

Is it normal to get a zero reading for the Accumulator Pressure Sensor while the Temp Sensor is unplugged? I've consistently gotten ~10, until I disconnect the rear sensor.

Thanks!!

 

[skipdup]

OK. I think I got it. Front at 6.8. Rear at 6.8. Accum Presssz came back after plugging back in - 10.1.

Thanks all...