Yes that was a typo. Should be 2.0.4. I will edit my post.
Definitive list of AHC maintenance items (4 Viewers)
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Yes that was a typo. Should be 2.0.4. I will edit my post.
UPDATE After new ahc springs and 30mm spacers
3 lifts
front pressure
7.0 6.6 and 6.5 (respectively)
Rear Pressure
6.7 6.5 and 6.5
Paddo was spot on. You have to use spacers AND new/differnt springs to get to the rear pressure down. Big difference in the ride quality.
One thing I will note is rear pressure readings include my third row seating while the third row was removed for the baseline scores.
Need help with AHC on my 1999 LX; after replacing all 4 globes and shocks plus both rear coils with OEM parts I'm having several problems with the systems operation.
First and most important, when carrying a modest load the system gets stuck in low height mode. I don't believe the weight is the issue as the load is the same camping gear I've been carrying for the past 10 years with no troubles. The system can maintain the normal height until I hit a small bump in the road, then she system bottoms out. Also, it appears to me that it's the rear that is stuck in low and that the font is normal. However, the indicator is showing low. The system can restoe the normal height, but it always requires turn off the car and some times we have to get out of the vehicle to lighten the load. I,m wondering if it's possible to have air in the system that can't be blead out because the bleed valves are located in the middle of the system. I didn't see any reference to priming the shocks in the FSM, but my understanding of the design make me think this could be a possibility. I bleed the system about a week after the repair and found no additional air bubbles in the system. That was about four months ago.
Another issue is the suspension firmness adjustment doesn't make much of a noticeable difference in the ride characteristics as it did before I replaced everything.
Pressures were within specs after the job, but are now high; front 7.3 rear 7.2. Front left TB feels like it's "bottom out" even with a 3' breaker bar. I can see I have plenty of threads left. Front right TB moves much easier. Cross height is good.
First and most important, when carrying a modest load the system gets stuck in low height mode. I don't believe the weight is the issue as the load is the same camping gear I've been carrying for the past 10 years with no troubles. The system can maintain the normal height until I hit a small bump in the road, then she system bottoms out. Also, it appears to me that it's the rear that is stuck in low and that the font is normal. However, the indicator is showing low. The system can restoe the normal height, but it always requires turn off the car and some times we have to get out of the vehicle to lighten the load. I,m wondering if it's possible to have air in the system that can't be blead out because the bleed valves are located in the middle of the system. I didn't see any reference to priming the shocks in the FSM, but my understanding of the design make me think this could be a possibility. I bleed the system about a week after the repair and found no additional air bubbles in the system. That was about four months ago.
Another issue is the suspension firmness adjustment doesn't make much of a noticeable difference in the ride characteristics as it did before I replaced everything.
Pressures were within specs after the job, but are now high; front 7.3 rear 7.2. Front left TB feels like it's "bottom out" even with a 3' breaker bar. I can see I have plenty of threads left. Front right TB moves much easier. Cross height is good.
Good to know. Where did you get the rear oem springs and spacers?
Lexus of Atlanta Ga. I probably could've got them local at the dealership but with two kids under three every trip is an adventure, so I opted to have an online vendor ship to the house.
These are the Lexus part numbers
48231-6A740
SPRING, COIL, RR
48231-6A730
SPRING, COIL, RR
The spacers I got from Sleeoffroad. The price has gone up quite a bit it was almost $80 for both spacers shipped.
These are the Lexus part numbers
48231-6A740
SPRING, COIL, RR
48231-6A730
SPRING, COIL, RR
The spacers I got from Sleeoffroad. The price has gone up quite a bit it was almost $80 for both spacers shipped.
DirtDawg
"It'd be alot cooler if you did"
Posted For Reference:
2-2.5" AHC Lift Using King Coils & Shock Spacers
2-2.5" AHC Lift Using King Coils & Shock Spacers
PabloCruise
SILVER Star
I hope you get an answer to this, it sounds as if something is quite wrong!
No answers yet. I bled the system again and found no air bubbles. I replaced the front left t-bar adjuster bolt and can now make adjustments freely. This allowed me to get the front pressure to spec, but I can't get the rear pressure to come down much. It's still high at 6.9 I would think with new rear OEM coils the rear pressure wouldn't be an issue. I may have to add spacers. I think I'll confirm the overall frame height this weekend and check the pressures again. I'm amazed by how much the pressure readings can vary. I may try to put a heavy load in to see if I can determine what's causing the height to sag under load. The height has collapsed on all 3 road trips since I overhauled the system. Unfortunately, when you have the family packed up and headed out on a road trip, you don't have time to troubleshoot. What's frustrating is that the overall ride quality is worse now than before I replaced "everything". Could have save $6K and the headache.
Agent, have you reset the AHC computer? Are all the fuses good? Are the height sensors reading correctly in tech stream? This sounds more electronic than hydraulic now. Although, it's going to be stiff if you're riding in low mode and bouncing off the bump stops...
Regarding your AVS there are a several tests you can do to establish if the damper assemblies are working: 16 step check; signal input check; damper assembly motor resistance check and you can lock the system in the softest setting and drive it. Still too rough in the softest setting? Then you've likely established it a hydraulic/mechanical problem. Much better? Then you've established the AVS control system maybe playing up when you're in motion. I also have the guts of a damper assembly that I connect to each damper harness to observe the step motor responses while doing the 16 step test, I'll send it to you if you need it. You can also hook up Techstream and monitor the system paying attention to the front and rear damper steps, SLFL (front leveling) and SLRL (rear leveling) and actual height sensor feedback whilst in motion. If the front height is creeping up while driving then this means your pressures are raising to the detriment of your damping.
Regarding your rear height dropping to low whilst lightly loaded and in motion - working on the assumption you're not overloaded then we'd have to consider the likelihood your AHC is inadvertently commanding the drop. Possible worn rear height sensor that is experiencing intermittent problems when moved through its range, exaggerated by being loaded and at speed. I'd check its harness, clean connectors, check its linkages and stick a $55 Dorman aftermarket sensor in.
With your front and rear neutral pressures they need to be read in context of your actual vehicle height. Your rear, at 6.9, is high and closer to 6.0 is far more preferable but if your 6.9 is at a rear height of 21.5 or 22 in (axle center to fender bottom) then you'll get it down nicely if you get the rear height closer to 20.5 which is near stock. How many graduations are you seeing in your L to H test and at what neutral pressure?
How do you bleed your system? Are you dropping it to the bump stops (from L) by sequentially opening all 5 bleeders for approximately 1 L of fluid/gas?
Finally got around to adjusting my front suspension. Since my last post I have noticed that the front was becoming increasingly harsh. After getting the Cruiser up on a lift it became apparent that the front shocks were weeping/leaking to a certain extent as well.
The last Techstream test I ran before the adjustment I saw Front Pressure at 8.3 and rear at 7.3 at the shop were I was having some other work done. 5 turns on the TBs and now I'm looking at the below results. These were taken at two different locations with me in the car, a full tank of gas, 3rd row installed, and 3 child seats
I can definitely tell the front is more compliant now and it feels like the rear is still harsh.
I'm planning to address the rear with either new springs or spacers. Then take a look at the whole system again and tweek as needed.
Thanks again @PADDO
The last Techstream test I ran before the adjustment I saw Front Pressure at 8.3 and rear at 7.3 at the shop were I was having some other work done. 5 turns on the TBs and now I'm looking at the below results. These were taken at two different locations with me in the car, a full tank of gas, 3rd row installed, and 3 child seats
I can definitely tell the front is more compliant now and it feels like the rear is still harsh.
I'm planning to address the rear with either new springs or spacers. Then take a look at the whole system again and tweek as needed.
Thanks again @PADDO
I finally ordered techstream and finally got it installed/working after much frustration. If anyone in Atlanta wants to use it or help installing it, PM me.
While I was waiting for my techstream and rear springs, I figured I would crank each torsion bar one full turn clockwise.
Is this possible, front pressure=2.9? Did I go way too far? This is with the truck running, N to L to N - reading.
Is my steering angle (18) affecting the reading?
I got the rear springs today, should I just go ahead and replace them and get a few turns on each torsion bar counter clockwise to increase front pressure?
While I was waiting for my techstream and rear springs, I figured I would crank each torsion bar one full turn clockwise.
Is this possible, front pressure=2.9? Did I go way too far? This is with the truck running, N to L to N - reading.
I got the rear springs today, should I just go ahead and replace them and get a few turns on each torsion bar counter clockwise to increase front pressure?
I would guess either not flat ground or someone previously blindly cranked the T-bars
2.9?? Spurious reading I reckon. Do a few more checks - L to N and wait 30 seconds till the height accumulator finishes charging and see what the consensus is. I've seen similar ridiculous readings before that come good after one or two more L to N cycles. A legit reading of 2.9 would equate to about 20 turns if you started at 7.0MPa, you'd have all spring and no damping.
As long as you're on flat ground and the front wheels are pointing roughly straight and you aren't loaded up then that's good enough. Don't be too concerned about the steering angle that Techstream is reporting.
As long as you're on flat ground and the front wheels are pointing roughly straight and you aren't loaded up then that's good enough. Don't be too concerned about the steering angle that Techstream is reporting.
Thanks guys! One full counter clockwise turn on both torsion bars, new rear springs (no spacers) and a couple of up and down cycles.
Now 6.8 and 7.4.
What are the goals 6.9 +/- 0.5 for the front and 5.6-6.7 in the rear?
How do you find flat ground?
How concerned about -.6 and +.5 front height sensors?
Now 6.8 and 7.4.
What are the goals 6.9 +/- 0.5 for the front and 5.6-6.7 in the rear?
How do you find flat ground?
How concerned about -.6 and +.5 front height sensors?
Found a flatter piece of driveway, using a 3' level...
Not sure a couple torsion bar tweaks made a difference.
Is this as good as it's going to get for the rear without spacers? (these are new springs) 7 and 7?
Not sure a couple torsion bar tweaks made a difference.
Is this as good as it's going to get for the rear without spacers? (these are new springs) 7 and 7?
Much better. If you're interested you might try experimenting with the front pressures, maybe try a little lower and see how that responds. It's all about finding the best combination of mechanical springs (torsion bar) and gas springs (remaining charges in your damper accumulators). Your rear pressure isn't going to lower unless you jettison weight or drop the vehicles height. Adding 30mm spacers while you've got the springs out will normally give you another 0.6MPa pressure reduction. I haven't encountered anyone yet who has had to deal with too low rear pressures by adding spacers on new AHC coils.
Regarding the factory pressure tolerance and range. The front's design pressure is 6.9 MPa and the design engineers concluded that the acceptable deviation from their design pressure is +\- 0.5. There is a marked difference between new globes and 6.9MPa and how it performs at the outer limits of the tolerance. For the rear we obviously don't have 30mm bolts to dial in/out tension so the designers gave us a range of 5.6-6-7MPa but the best I've heard off is for new coils to get the rear's pressure down around 6.3 or 6.4MPa. It doesn't take much weight (about 210lbs for +1MPa over the axle) to creep up into the high pressure/poor damping and drop to L when loaded up zone.
Regarding the factory pressure tolerance and range. The front's design pressure is 6.9 MPa and the design engineers concluded that the acceptable deviation from their design pressure is +\- 0.5. There is a marked difference between new globes and 6.9MPa and how it performs at the outer limits of the tolerance. For the rear we obviously don't have 30mm bolts to dial in/out tension so the designers gave us a range of 5.6-6-7MPa but the best I've heard off is for new coils to get the rear's pressure down around 6.3 or 6.4MPa. It doesn't take much weight (about 210lbs for +1MPa over the axle) to creep up into the high pressure/poor damping and drop to L when loaded up zone.
Thank you for the insane amount of information here. I have ordered a version of techstream and am putting together the list now for an AHC refresh. My plan as of now is to see if I can get it working flawlessly versus switching it out totally for an oem kit.
PabloCruise
SILVER Star
Where did you order your techstream?
@PADDO, How critical is is to accomplish the "0.00" reading for the height sensors? Also, I'm ok with the rear pressure reading here correct? This is with half a tank of fuel, and no rear seats. I've just replaced my OEM coils with new, 30mm Slee spacers and installed Air Lift 1000 bags in the rear. I adjusted the TB's a bit as the new rear setup had my front pressures at 5.9 upon first check with TS.
