Definitive list of AHC maintenance items (6 Viewers)

[codertimt]

I'm going to jump in here as another data point since I too have installed 80 springs. I don't have answers, but the numbers you are getting in TS are definitely odd and not what I experienced at all. I don't have exact numbers, but when I tested after spring install and after rear hitch/bumper skin removal, I was getting readings in the high 3s. After 4x4 labs bumper install the reading crept into the low 4s. After a bit of sensor lift(not much since I was actually a little low in the rear to begin) I settled on a rear pressure of near 5. Set the front to the low pressure side of normal also and overall I think it rides pretty decent now. Nearing 200K miles on original globes so probably not perfect, but as good as it did before I started adding weight. Comfort mode can be a bit "floaty" depending on speed. Sport mode tightens things up to bordering on harsh. I usually stay in the middle two settings, again depending on speed and road quality.

However, ignoring the techstream numbers, your experience of harsh ride(if that's what bouncy means to you) without enough extra weight is spot on to what I would expect. I only took one drive without weight on mine and it was pretty harsh. Friend put non AHC 100 springs on his and it was too much to deal with even after sensor lift.

So, again, don't have an answer to why you're seeing the numbers your seeing, but can offer encouragement that the 80 springs can work in the correct scenario. I will get some current numbers from mine soon and report back to the thread also for comparison...

 

[ihadmail]

@PADDO I believe your comment about how the front and rear solenoids open simultaneously on the first lift attempt explains my inaccurately in spec rear pressure. Tech stream is reporting the last pressure at the pump outlet when the valve was opened. Both valves open and see the 6.4, and my rear instantly jumps to the correct height. The front barely moves so instead of doing a front/rear dance to balance the height only my front solenoid opens again. The rear valve never opens again so techstream reports the value it saw when both valves were open.

 

[PADDO]

Yes, I believe that explains why you were seeing 6.4MPa but it was behaving like an over sprung 3.4MPa. The last step of the raise cycle is the front coming up, after the rear has settled to N. You can actually observe the pressure reading sequence by watching the fields SLFL (solenoid Front Leveling) and SLRL (..Rear Leveling) as their status changes from Off-On-Off and the respective front and rear pressure fields populate.

 

[DirtDawg]

Can you tell me more about the King AHC coils?

They are a aussie company I believe. They sell two types of coils for our AHC system that is meant to increase the load capacity while still maintaining the stock coil characteristics. Heres the medium load ones: ktrs79- Coil spring King Springs (Coil spring King Springs) - - Toyota Landcruiser (series 100) UZJ100 4.7i V8 petrol IFS 1998->2007

 

[PabloCruise]

Thanks man! No need for spacers with these?

Have you received yours yet? I am curious what you think, and how the purchase went. 2 month lead time?

 

[DirtDawg]

I haven't ordered them yet, but am going to do some research in this next week and I'll post my findings on here. Maybe I can get on some Aussie boards or something to see how everyone is using them.

 

[ihadmail]

I took some time after work this morning to do some more experimenting with the 80 series rear springs. I fabbed up a new sensor bracket for the rear per the sensor lift thread. The placement of my sensor is now above the rear upper control arm, as low as possible without spacing the bracket out. As I was installing the sensor it began to rain, so I took it for a test drive with some extreme stink bug going on.

The results were its still really stiff but is no longer bouncy and is going to be manageable until I get the rear bumper to add some more weight. Measurements were 23.25" rear fender to center of hub and still 20.5" front fender to center of hub. I will adjust the heim joints in the front when it's not raining outside.

It no longer jumps in the rear when going from L to N. The rear pressure reading on techstream still boggles me. It initially reads low, 4.5. Then as the truck begins cycling front/rear it goes to 5.6 and stays there when the rear feels like it's done moving. The front continues cycling and then the rear reads 6.8 again.

Here is a screenshot after going from L to N on very close to level gas pump area of local gas station:

 

[Ramathorn15]

I just pulled the trigger on some ebay King KTRS-79's. I figure I will give them a shot and if they aren't enough to get me in spec, I will sell them and go to 80 coils.

I'm going to be sure to do before and after pressures and will update with ride quality.

 

[codertimt]

...

It no longer jumps in the rear when going from L to N. The rear pressure reading on techstream still boggles me. It initially reads low, 4.5. Then as the truck begins cycling front/rear it goes to 5.6 and stays there when the rear feels like it's done moving. The front continues cycling and then the rear reads 6.8 again.
...

Agreed that's still weird reading on the rear...you do have it way up there though compared to the front so maybe that has something to do with it. I finally got mine connected up again and have actual numbers to share.

01 LX
Dissent Front Bumper with Engo 12K winch(synthetic)
OPOR Sliders
4x4Labs Rear Bumper
40L Fridge mostly empty
Half drawer with a few tools
Sub and enclosure that weigh about 100lbs.
80 Series rear springs(used)
Stock AHC Torsion bars
Rear measures out at ~21.5"
Front measures out at ~20"

Rear Pressure 5.3-5.4
Front Pressure 6.2

 

[ihadmail]

I did more tinkering with the height sensors. I lifted the front to match the rear. Front height ended up 22.75" and rear was 23.5"

The rear pressure stayed at 6.8 and the front settled out at 6.6. The ride was still very harsh.

Yesterday I installed my new oem AHC springs with the 30mm spacers. I also installed my Japan 4x4 shock spacers and SPC upper control arms.

The rear pressure went up to 8.8 and the front stayed at 6.6. Even with the higher pressure it rides much better on the proper springs. I'm finished messing with it until I get my rear bumper and get it installed. I will try the 80 series springs again then and report back. If they still don't work out with the extra weight I will spend the coin on the King springs and play with my lift height and the amount of spring spacer to get my pressures lower while maintaining a good ride.

 

[PabloCruise]

I did more tinkering with the height sensors. I lifted the front to match the rear. Front height ended up 22.75" and rear was 23.5"

The rear pressure stayed at 6.8 and the front settled out at 6.6. The ride was still very harsh.

Yesterday I installed my new oem AHC springs with the 30mm spacers. I also installed my Japan 4x4 shock spacers and SPC upper control arms.

The rear pressure went up to 8.8 and the front stayed at 6.6. Even with the higher pressure it rides much better on the proper springs. I'm finished messing with it until I get my rear bumper and get it installed. I will try the 80 series springs again then and report back. If they still don't work out with the extra weight I will spend the coin on the King springs and play with my lift height and the amount of spring spacer to get my pressures lower while maintaining a good ride.

Isn't a rear pressure of 8.8 out of spec (high)?

 

[ihadmail]

Isn't a rear pressure of 8.8 out of spec (high)?

It is. But, it is much more comfortable at the 8.8 on new stock springs with spacers than it was at the same ride height with a lower pressure on 80 series springs.

I honestly believe I have either binding in my rear shocks or a pressure sensor that has drifted in its calibration giving me falsely high readings.

It's comfortable enough to drive now, especially for 3" of lift. I have no issues cycling through L, N or H. I have lost my motivation to keep messing with it at this point.

 

[planomateo]

Great thread, I just acquired a 2004 LX470 yesterday.

My settings at normal below. I'm going to be replacing the AHC fluid in the next week, too much other stuff going on today/tomorrow to get it done this weekend.

I'll check this again after fluid exchange and then see what kinda wrenching I need to do to get the front up and rear down.

 

[ihadmail]

I would start with measuring bottom of fender to center of hub. It should be 19.75" front and 20.5" rear with the same measurement on both sides.

If your measuring low that would make the front pressure low. Solution would be to raise the sensors approximately 1/4-3/8" in their mount per inch of lift needed.

If you're measuring correct then the solution would be to loosen the adjusting bolt on the torsion bars. I would start with 1-2 full turns per side and determine how much that's affecting pressure.

If you're uneven left/right then you would loosen the high side torsion bar. I like to do this in 1/4 to 1/2 turn increments.

For the rear, if you're sitting high simply lowering the sensor in its bracket will lower pressure some.

If you're sitting correct in the rear the only solution is new springs and/or 30mm rear spring spacers.

 

[planomateo]

I would start with measuring bottom of fender to center of hub. It should be 19.75" front and 20.5" rear with the same measurement on both sides.

If your measuring low that would make the front pressure low. Solution would be to raise the sensors approximately 1/4-3/8" in their mount per inch of lift needed.

If you're measuring correct then the solution would be to loosen the adjusting bolt on the torsion bars. I would start with 1-2 full turns per side and determine how much that's affecting pressure.

If you're uneven left/right then you would loosen the high side torsion bar. I like to do this in 1/4 to 1/2 turn increments.

For the rear, if you're sitting high simply lowering the sensor in its bracket will lower pressure some.

If you're sitting correct in the rear the only solution is new springs and/or 30mm rear spring spacers.

Current measurements:
Driver Front: ~19.75"
Passenger Front: ~20.25"
Driver Rear: ~20.5"
Passenger Rear: ~20.5"

 

[nnnnnate]

So back in October I added a 25mm spacers to the rear springs and got the following pressures via TechStream:
Front: 7.6
Rear: 6.9

I knew I needed to crank the TBs to drop the front but for some reason thought that would require an alignment and just never got around to it. Well, I'm headed out of town Saturday and am borrowing a trailer so I thought I'd finally crank them after learning I was mistaken on the alignment aspect.

With 4 clockwise turns I got the following:
Front: 6.4
Rear: 7.0

Since I know the sweet spot is 6.9 +/- 0.5 for the front and 5.6-6.7 in the rear I decided to spin it back one turn, these are the results:
Front: 6.7
Rear: 7.0

I was thinking that as the front went down it would also help the rear pressures but I'm not seeing that. Right now I'm running stock + 33s and sliders. I'll be getting a rack and an RTT (RTT only mounted for trips) soon and wondered how the numbers looked. The rear is off but still pretty close to in spec. Down the road I think I'll end up with King springs if the rest of the system continues to behave but feel like for my current needs those springs would be way over kill. I DD this rig.

 

[ihadmail]

Your pressures look way better than mine in the rear.

What's your rear fender to hub center measurement? By lowering the rear you will lower the rear pressure. Stock should be 20.5"

 

[nnnnnate]

I measured this morning actually and the rears are both 20.5". The fronts were off side to side though. DF was 19 and PF was 19.75. I think this means that I need to adjust the height sensors but will have to search here to see what they look like and figure out how to do that. I feel like a fool because when I went looking for the TBs I was thinking they went left to right right up along the front axle which is not the case. I obviously don't have any experience with torsion bars but did eventually find them and the adjusting bolt more than half way back by the rear tire.

Edit: To level my front side to side I need to adjust the actual AHC height sensors right? Lots of conflicting info in old threads on this and I just want to make sure I get it right.

 

[PADDO]

To level the front side to side you do not touch the height sensors, you add turns to the low side torsion bar bolt and subtract turns from the high side. One turn will lower/raise its respective side about 1/8 inch. Get it to within 1/4 in difference. It's an iterative process but easily achievable. Do it via one or two turn steps, remeasuring and bouncing the front between steps. Only after you've got the front level then you set your heights by adjusting the links in their sliders and the last thing you do is set the front neutral pressure by applying equal turns to both torsion bar bolts so as to not undo your cross level you just set.
Everything you need to know about setting cross level, setting heights and setting front/rear pressures is in this thread. There is lots of good, old, info posted by knowledgable people in some of the older threads but be cautious as there is lots of speculative rubbish that has no AHC technical basis what so ever too and that will lead you down the wrong path.

 

[99RichieLx470]

Pretty standard approach to dialing this in, and yes your F and R pressures are a bit high.
First, on flat ground check and adjust front cross level, you should be able to easily get in within 1/4". One turn on one torsion bar bolt will lift/lower that corner approximately 1/8". Engine doesn't need to be on for cross level check/adjustment. Wheels on the ground, if the TB bolts are really tight you can raise to H to take some preload off. Use penetrating oil liberally if they haven't been adjusted in a while. Breaker bar doesn't hurt either.
Second, measure all four corner heights at N with engine running and AHC settled. If you have 19.75F and 20.5R hub center to fender bottom you are very close to stock spec height. Adjust height sensors if necessary, engine off, to avoid potential injury.
Lastly, hook up techstream and check pressures, same number of CW turns on both TB bolts to lower pressure, one turn (on both bolts) will lower pressure about 0.2MPa (CCW to raise pressures). Target front pressure is 6.8 - 6.9MPa. All you can do for the rear pressure is to ensure you aren't physically too high and then you may need to add 30mm spacers to get the pressure down a reasonable amount or ideally, new AHC coils AND spacers to get the pressure down to the lower end of its design range of 5.6 - 6.7 MPa. Expect a small variance in the front height sensor height values, if they fall within say 0.3" from 0 there isn't any need to tweak them. Best just to see how it all plays out. Additionally, lowering the front pressures also has a positive effect on the rear, and vice versa.
I know the FSM says to adjust pressures with full tank of gas etc etc well lately I've been adjusting pressures with the vehicle set up how I normally drive it and that's with 2nd and 3rd row seats out, 1/2 tank gas and my tool box, myself in the drivers seat. I just think it makes better sense that way. If I'm loading up for a trip I readjust TBs as necessary, it only takes a minute.
HTH

Im in a similar situation. My rig is a 99 LX470 with 160k. I understand everything you have stated except "adjust front cross level".
Im hoping its something simple that I'm over thinking. My heights are good at all 4 corners within 1/8 inch with regards to oems specs.
my fluid was changed at 135k. My pressures kinda suck 7.1 front and 7.8 rear respectively, (funny i thought the truck rode fine.)
I also have the third row removed but i do have a reese frame trailer hitch installed.

I know what to do based on your response to others, crank the t-bars a bit and order new oem factory lx AHC springs with 30mm Slee spacers. Just want to make sure I'm no missing anything prolific with checking the vehicle for front cross level. i know you explained it above but maybe someone can do a video quick for some reason I'm getting a popsicle headache.

also you really need to take 5 or so readings and take the average score. I tested in 5 locations all supposedly with a level grade, ( one a tennis court )and I got a high of 8.0 front and a low of 6.9. For the rears 7.8 was my highest and 6.9 was my lowest. Never were the font and rear in spec together at any point.

thanks!