Definitive list of AHC maintenance items (4 Viewers)
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PabloCruise
SILVER Star
Max 8...
I'm trying to get a recently purchased '06 into AHC spec, and this thread has been fantastic. I'm posting this with the hope that the group can check me/guide me about these readings.
The vehicle's got 146.8k on it now. When I was looking it over at the dealer last month, the AHC reservoir gurgled and drained a bit when raising and lowering the vehicle. The dash AHC "off" indicator flashed one time during that process -- at about the time the gas was bubbling up -- but it hasn't done that since, and the vehicle goes upon and down well. Dealer topped off the AHC fluid, and off I went - to ACC in Atlanta.
The ACC folks said there were no leaks in the AHC system, though the rear shocks were 'wet'. They thought an explanation could be that the rear springs were a little tired and the pressure was high as a result.
I have not flushed or bled the AHC yet, plan to do so this week. I have hooked up TechStream, and it showed a C1762, "Abnormal Oil Pressure for Pump". I cleared that code for now and hope it was related to the trapped air in the system that gurgled out the day I was testing it out, and the flashing "off" indicator light that day.
The vehicle height:
So I have a driver's side lean of 1/8" in the front and 3/8" in the back. The rake is 3/4" on the driver's side, 1" on the passenger side.
I plan to take the pressures after flushing the AHC fluid, but here's where the first three readings were Sunday:
My plan from here:
The first job is to level the front. Looks like I need a full counterclockwise turn of the right torsion bolt, or a full clockwise turn of the left, or a half turn of each.
Then I'll flush the AHC and re-check pressures.
If those pressures hold, my understanding is that I should get both the front pressure (a bit) and rear pressure (a bit more) down a bit. I can do that by:
Front:
My second: Do I need to do anything about the lean in the rear? For example, if I go the spacers-only route, should I use different sizes? If I go the new springs route, will that likely level the rear?
My last, related to the second: What about the rake? Any reason to concern myself with the 0.25" side-to-side difference? (My height sensors currently: FR -0.1, FL -0.3, R -0.3)
Thanks again to all.
The vehicle's got 146.8k on it now. When I was looking it over at the dealer last month, the AHC reservoir gurgled and drained a bit when raising and lowering the vehicle. The dash AHC "off" indicator flashed one time during that process -- at about the time the gas was bubbling up -- but it hasn't done that since, and the vehicle goes upon and down well. Dealer topped off the AHC fluid, and off I went - to ACC in Atlanta.
The ACC folks said there were no leaks in the AHC system, though the rear shocks were 'wet'. They thought an explanation could be that the rear springs were a little tired and the pressure was high as a result.
I have not flushed or bled the AHC yet, plan to do so this week. I have hooked up TechStream, and it showed a C1762, "Abnormal Oil Pressure for Pump". I cleared that code for now and hope it was related to the trapped air in the system that gurgled out the day I was testing it out, and the flashing "off" indicator light that day.
The vehicle height:
Driver | Passenger | |
| Front | 19 1/2 " | 19 5/8 " |
| Rear | 20 1/4 " | 20 5/8 " |
So I have a driver's side lean of 1/8" in the front and 3/8" in the back. The rake is 3/4" on the driver's side, 1" on the passenger side.
I plan to take the pressures after flushing the AHC fluid, but here's where the first three readings were Sunday:
| Reading (MPa) | 1 | 2 | 3 |
| Front pressure | 6.9 | 7.1 | 7.1 |
| Rear pressure | 6.9 | 7.0 | 7.0 |
My plan from here:
The first job is to level the front. Looks like I need a full counterclockwise turn of the right torsion bolt, or a full clockwise turn of the left, or a half turn of each.
Then I'll flush the AHC and re-check pressures.
If those pressures hold, my understanding is that I should get both the front pressure (a bit) and rear pressure (a bit more) down a bit. I can do that by:
Front:
- Cranking both TB bolts 1 clockwise turn for each 0.2 MPa needed. (Looks to be between 1/2 and 1 turn based on current pressures).
- Installing 30mm spacers, to reduce pressure by 0.6 MPa (getting to the 6.4 MPa range).
- Or installing new OEM springs, to get the pressure to the 6.3-6.4 MPa range.
- Some combination: New springs and 10mm spacers, for example, to get into a lower range of the spec.
My second: Do I need to do anything about the lean in the rear? For example, if I go the spacers-only route, should I use different sizes? If I go the new springs route, will that likely level the rear?
My last, related to the second: What about the rake? Any reason to concern myself with the 0.25" side-to-side difference? (My height sensors currently: FR -0.1, FL -0.3, R -0.3)
Thanks again to all.
uHu
Bridgeburner
Get new springs for the rear. No point in trying to rejuvenate an old sagging horse with a spacer. Get the brown one, 48231-6A780, 500 mm.
The lean is adjusted only at the front. Adjust the left a bit up, and recheck front and rear on a (different) level floor. If the front leans one way and the rear the other, you have a twisted body. That said, the 100 is heavier on the left/drivers side than on the right (most cruisers are). Some cruisers have a higher coil spring on the left than on the right for that reason, but with the adjustable torsion springs it's OK to adjust only up front.
Bleed the fluid, and when all the specs are OK, check the graduation count for accumulator health.
The lean is adjusted only at the front. Adjust the left a bit up, and recheck front and rear on a (different) level floor. If the front leans one way and the rear the other, you have a twisted body. That said, the 100 is heavier on the left/drivers side than on the right (most cruisers are). Some cruisers have a higher coil spring on the left than on the right for that reason, but with the adjustable torsion springs it's OK to adjust only up front.
Bleed the fluid, and when all the specs are OK, check the graduation count for accumulator health.
Flushed the AHC fluid, stuff was pretty clear through the tube with the exception of some small black colloidal stuff in the height accumulator.
Cranked the torsion bolt, got the front end level. Back is still 3/8 high on the passenger side.
Really bad result on the graduations test just now. 6, maybe 7, was 9 or 10 last month when I bought it. Ride is soft if anything - not rough at all and seems to go through the corners well.
No error code (had reset a “abnormal oil pressure for pump” AHC code last week), but struggling to get Techstream to stay connected on my underpowered laptop when trying to retrieve the data, so don’t know the pressures yet.
Giving up for the day, try again tomorrow. Thought the gurgling in the reservoir that I saw on test day was air trapped in the system but now wondering if it was a little higher in nitrogen content.
Cranked the torsion bolt, got the front end level. Back is still 3/8 high on the passenger side.
Really bad result on the graduations test just now. 6, maybe 7, was 9 or 10 last month when I bought it. Ride is soft if anything - not rough at all and seems to go through the corners well.
No error code (had reset a “abnormal oil pressure for pump” AHC code last week), but struggling to get Techstream to stay connected on my underpowered laptop when trying to retrieve the data, so don’t know the pressures yet.
Giving up for the day, try again tomorrow. Thought the gurgling in the reservoir that I saw on test day was air trapped in the system but now wondering if it was a little higher in nitrogen content.
I'm returning my VCI cable, try my luck with a new one. I've got an underpowered laptop (2GB memory), but it worked once and reasonably well, now the software just thrashes away and the indicator light stays red.
In the meantime:
@uHu and @PADDO have referred to this with regard to the graduations test.
After twisting the torsion bolts, my heights are within an 1/8" on the front and close on the rear (a 3/8" rear tilt toward the driver side in the rear).
If my pressures are close (when I read the pressures before the AHC change, it appeared that new rear springs and a few twists of the torsion bolt would bring me in spec), is a failure of the graduation test *guaranteed* to be failed globes?
Would the 16-step test be more definitive? I think I'm going to replace all four if even only one of them is bad, but would like to be reasonably sure that that's the issue before dropping these $$$. [Add: Trying to beat the government's proposed 25% tariff on these items - could happen as early as May.]
Springs are a given.
In the meantime:
@uHu and @PADDO have referred to this with regard to the graduations test.
After twisting the torsion bolts, my heights are within an 1/8" on the front and close on the rear (a 3/8" rear tilt toward the driver side in the rear).
If my pressures are close (when I read the pressures before the AHC change, it appeared that new rear springs and a few twists of the torsion bolt would bring me in spec), is a failure of the graduation test *guaranteed* to be failed globes?
Would the 16-step test be more definitive? I think I'm going to replace all four if even only one of them is bad, but would like to be reasonably sure that that's the issue before dropping these $$$. [Add: Trying to beat the government's proposed 25% tariff on these items - could happen as early as May.]
Springs are a given.
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The damper accumulators naturally degrade over time via gas permeation and this is evidenced by the diminishing L to H graduations check. What you’re reading when you count the graduations is the combined volume displacement of the four shock actuators stroking (which will be a constant for the same L to H travel) and the fluid expelled from the four damper accumulators as the preload (neutral) pressure goes from a lower value (in L) to a higher value (in H). The variable is the gas charge in the accumulators and it is a generalized indicator: it can’t single out a better globe from a lesser globe. When you do the 16 step test that “should” identify a particular corner that feels different, ie harder, to the others. But it’s a bit subjective too. You should do both tests on the understanding that overall globe/damping performance and degradation is roughly linear until, or if, it ruptures.
Thanks for everyone's help. I am making progress, maybe by accident:
Something weird happened yesterday. I drove 15 or so miles to a Rent a Center (to see if a better laptop was the solution to my Techstream problems - and it was). Still bouncing all the way there.
On the way home, the ride seemed a ton better.
Ride seemed good today on the drive to the garage where I can level the vehicle out.
Dialed torsion bolts in to get to 6.8 MPa front, which resulted in the rear hitting 6.8 MPa as well. I left it there.
Did the 16-step test. Very cool, went from bouncy (especially in the back) to almost too firm to push down. Techstream reported the 16 steps.
I thought in the lower steps that the passenger front was a little stiffer than the driver front, but it was a close call. The front sides were always stiffer than the back until the very high steps, when the difference was negligible. But basically everyone was comparable, and everyone stepped up nicely.
I then did the graduations test and got to 11. (Vehicle has 147,000 miles.) This was quite an improvement, but earlier problems could have been measurement error. I had a more powerful flashlight on the reservoir (which is discolored, and the new AHC fluid is more translucent) and after my flush I had a little more than max level at neutral, which in low resulted in the fluid level rising above the graduation ticks - to the top of the joint/seam in the reservoir. Eleven seems right-ish for a 13-year-old, 147,000 mile vehicle that was reasonably well cared for and not off-roaded.
Ride felt good on the way home.
Something changed yesterday. Don't know what. But I'm holding off on globes for a while.
Something weird happened yesterday. I drove 15 or so miles to a Rent a Center (to see if a better laptop was the solution to my Techstream problems - and it was). Still bouncing all the way there.
On the way home, the ride seemed a ton better.
Ride seemed good today on the drive to the garage where I can level the vehicle out.
Dialed torsion bolts in to get to 6.8 MPa front, which resulted in the rear hitting 6.8 MPa as well. I left it there.
Did the 16-step test. Very cool, went from bouncy (especially in the back) to almost too firm to push down. Techstream reported the 16 steps.
I thought in the lower steps that the passenger front was a little stiffer than the driver front, but it was a close call. The front sides were always stiffer than the back until the very high steps, when the difference was negligible. But basically everyone was comparable, and everyone stepped up nicely.
I then did the graduations test and got to 11. (Vehicle has 147,000 miles.) This was quite an improvement, but earlier problems could have been measurement error. I had a more powerful flashlight on the reservoir (which is discolored, and the new AHC fluid is more translucent) and after my flush I had a little more than max level at neutral, which in low resulted in the fluid level rising above the graduation ticks - to the top of the joint/seam in the reservoir. Eleven seems right-ish for a 13-year-old, 147,000 mile vehicle that was reasonably well cared for and not off-roaded.
Ride felt good on the way home.
Something changed yesterday. Don't know what. But I'm holding off on globes for a while.
I posted this in a separate thread that’s not getting a lot of traction so I’m trying here. 2001 LX470 170k miles.
Suspension feels loose after stopping. It rocks back and forth with oscillation movement till it holds still.
Here is a video shot from outside the car. Notice the oscillation after every stop. This was during step test at step 16 so the vibration was very obvious from outside. At step 1 it’s still there but could only be felt inside the car.
Ahc was flushed. Graduation test returns 11-12 marks. New rear king springs brought pressure within specs.
What do you think this might be?
Suspension feels loose after stopping. It rocks back and forth with oscillation movement till it holds still.
Here is a video shot from outside the car. Notice the oscillation after every stop. This was during step test at step 16 so the vibration was very obvious from outside. At step 1 it’s still there but could only be felt inside the car.
Ahc was flushed. Graduation test returns 11-12 marks. New rear king springs brought pressure within specs.
What do you think this might be?
uHu
Bridgeburner
I think you are chasing windmills. That looks like normal movement in the tires and other rubber components. Change to all steel tires/wheels and exchange all rubber bushings with ball bearings, and you'll get rid of it..
@Castamile have you checked your front hub Barings? possibly need to be tightened
May be the video is not expressing the issue fully but you can certainly feel the vibration / oscillation inside the truck. It rocks back and forth for 4-5 times till it holds still.
The reason I don’t think it’s normal because I had the opportunity to compare with another lx same year same miles ( even same color
)and the ride was so much different. I suspected the globes, when I swapped them to confirm there was no difference in either trucks. I will try replacing front control arm bushings and ball joints and see if that makes a difference.
Yes I did and tightened them. No effect.
I had Slee put an old man emu 2 1/2 inch lift on my 100 series LX along with sliders on my 100 series LX 470 the AHC suspension system is not as robust as a 200 seriesMay be the video is not expressing the issue fully but you can certainly feel the vibration / oscillation inside the truck. It rocks back and forth for 4-5 times till it holds still.
The reason I don’t think it’s normal because I had the opportunity to compare with another lx same year same miles ( even same color
I will try replacing front control arm bushings and ball joints and see if that makes a difference.
Yes I did and tightened them. No effect.
I need the help of the masters.
My height values are (hub center to fender):
Front Left: 18.5 inches
Front Right: 19 inches
Front left height sensor: 12.2
Front right height sensor: -10.6
Front pressure: 7.2 (was 8.5, but turned CW TB adjusters, 5 on the left and 3 on the right)
Rear height: 1.4
Rear pressure: 8.1
This is with both front sensors adjusted to the lowest possible setting on the UCA's (if I adjust them heigher the rear is sitting lower than the front, however the rear adjuster is already maxed out at the topmost setting)
Let's not talk about the rear, as that's totaly screwed right now, would like to fix the front first.
So my question is: How do I get the front end level? My guess is turn the left TB adjuster a couple more turns CW?
And after the tape measures both fronts equal I then adjust the sensors to display 0 on both sides?
My height values are (hub center to fender):
Front Left: 18.5 inches
Front Right: 19 inches
Front left height sensor: 12.2
Front right height sensor: -10.6
Front pressure: 7.2 (was 8.5, but turned CW TB adjusters, 5 on the left and 3 on the right)
Rear height: 1.4
Rear pressure: 8.1
This is with both front sensors adjusted to the lowest possible setting on the UCA's (if I adjust them heigher the rear is sitting lower than the front, however the rear adjuster is already maxed out at the topmost setting)
Let's not talk about the rear, as that's totaly screwed right now, would like to fix the front first.
So my question is: How do I get the front end level? My guess is turn the left TB adjuster a couple more turns CW?
And after the tape measures both fronts equal I then adjust the sensors to display 0 on both sides?
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Haha, I'm pulling my hair.. I must be the only one ever with this problem, but No matter how much I (dis)crank the TB's, they don't change the height (and right-left lean) at all.. Altough I'm doing it on the ground as I don't have a lift - could that be a problem?
uHu
Bridgeburner
You have some reading to do. Start at the beginning. It's just too much to write in one single post, and since all you need is covered here already...
PabloCruise
SILVER Star
I did go through roughly earlier and didn’t seem to find out why my ahc is behaving as it is - unlike others, but I’ll go through the thread again
I collected my favorite pearls of wisdom here:
Definitive list of AHC maintenance items
So I am happy that my heights are adjusted, and pressures are now w/in spec for F & R, but still want to know about adjusting the height sensors. For the rear, it looks like only one adjustment at the slider. For the front, it looks there are 3 different opportunities to adjust - the big slider...
forum.ih8mud.com
Hopefully that can help you!
I collected my favorite pearls of wisdom here:
Definitive list of AHC maintenance items
So I am happy that my heights are adjusted, and pressures are now w/in spec for F & R, but still want to know about adjusting the height sensors. For the rear, it looks like only one adjustment at the slider. For the front, it looks there are 3 different opportunities to adjust - the big slider...
Hopefully that can help you!
Thank you! My problem so far is that I've turned the left TB 9 turns, and the hub to fender lip distance didn't change a bit - which IMO is beyond science and everything in this thread
