AHC Paranoia?

[TeCKis300]

Do I have any paranoia after doing some research? No. If it was an air suspension - different ballgame, but for a system that can be used and abused for a decade plus in thousands of rigs with relatively few failures, I am really, really impressed with it and fall into the @nwfl4runner and @chalice camp - still gonna sends it!

Here are some extra thoughts for anyone trying to fall asleep in the Americas...

Are there some other cool options out there? Sure!
- Spool valves - I really like the Multimatic spool valve shocks in the ZR2 and ZL1-1LE. They perform great for their intended use and I love the fact that they are a mechanical, contained unit! But those are apples to oranges comparisons with AHC. Spool valve shocks are $ to replace compared to AHC shocks and globes, and while they can be built to respond reasonably well across a range of conditions (like the ZR2), when tuned to get the most out of them, like in the ZL1-1LE, a lot of people find them difficult to live with outside of their intended environment (i.e. track days and super twisty, smooth canyon roads for the 1LE are fun while daily driving, for most, is a pita). And you can't play with the height on the fly.
- Air suspension? I have only tried the Land Rover (D5) and Cayenne (958), and while they are nice on the road and okay for low speed crawling, from my admittedly limited sample size, I think the ride on lifted air sprung suspensions at speed, offload, is crap.

Twilight zone between a daily and a dedicated pre-runner
My other thought on the AHC as I looked at it more, and have started to ... explore the envelope a bit... If I can drive it across the country and take it on some fun desert roads up to 50 or 60 (Mojave at 50-60, not Baja whoops at 80), I am probably close enough to the limit of what I want to do in a street driven daily driver now than I am older and have a family. Now, would I pre-run an LC200 with a nice King 2.5 or 3.0 suspension and no cage?

- At the same speed as the AHC? Sure, and with good valving it will work better, off road, in that scenario, hands down. But I don't think I am going to enjoy a pre-runner setup as much on the trip to and from the desert, which is a few thousand miles each way. My only caveat on this caveat - with KDSS I imagine the ride on an LC200 set up for pre-running is markedly different than most other vehicles set up for whoops.
- At 75 MPH or more? Eh - I've already done that in vehicles that didn't have the same passenger cab strengthening from the factory BUT somewhere between 55 and 75, which may not feel much different ride wise with the right valving and build, I think the desert starts to move by your window more quickly and unexpected surprises can catch and role you with one mistake (or stroke of bad luck). I've been in a Raptor (great fun), Y62 Patrol (wasn't valved for it), a 150 series (slower than the Raptor but well set up), and a Hilux (not prepared but took a licking and kept on ticking) for a few hundred miles in total going between 60 and 80 mph on everything from smooth desert roads to rutted out 'paths' in the Himalayas and mild whoops in the desert (not bigger Baja or SCORE style stuff to be clear). While its fun for a short stretch on a road that you or a co-driver know, I wouldn't do serious pre-running at 75+ in a non-caged, street driven vehicle again after watching other people who are better drivers catch an unexpected whoop/drop/obstruction that rolls them and lands them on their roof.

Great post and I enjoyed the read geeking out on suspension hardware. I likewise enjoy digging into the technology used by various manufacturers, and there's a lot of pretty monstrous suspensions being employed by OEMs these days. Much of it integrated at a level beyond what the aftermarkets are capable of. Too bad OEM systems are tuned generally for the broad market and we don't have access to many physical or software dials to tailor them further. Not unlike our AHC.

Funny you touched on spool valves.

We don't generally talk much deeper here than "AHC", it's Lexus association, and perceived connotations of mall crushing. The reality is that AHC is Toyota's tour de force mic drop for its vaunted Land Cruiser. Available as an LC upgrade option in international markets. Just that in the US market for the 200-series generation, it's tied solely to the LX. The '06 and '07 LC of the 100-series in the US did have AHC as an option.

What's interesting is that the AHC damper employs some pretty hardcore tech, including spool valves. But unlike DSSV and other static suspensions that rely only on analog magic to sense, AHC goes full computer control for continuous adjustment and feedback. So it's not only optimal for unladen use, but has the ability to dial in damping for much broader loads and use cases. So no static compromise has to be made. It's tied into just about every major ECU (steering, skid, 4WD, ECM, main body) allowing it to preempt and tailor. Actively adjusting for things like steering or 4lo, and further compensating for feedback of height , acceleration, and yaw rates. That's just damping. Heck it has 2 auto selecting spring rates for the front axle... what other system is capable of that? And there's still more to geek out on if anyone's interested.

Needless to say, I'm an advocate of the system. Sure, it'd be fun to setup a vehicle for fast Baja running. At a trade to better broader use. Though Baja setups are as much about weight, suspension travel, and other things that a balanced daily use 200-series isn't. For that, including durability, I have a hard time imagining better.

 

[Surfy]

h AHC (LX570), do you worry about it going out? Do you adjust your driving NOT to hit bumps or potholes at high speeds to protect the system?

I have a LX470 and used to have AHC para

I drive an european Land Cruiser 200, with AHC. I love to be able to adjust the dampers for comfort and the height of the rig during trails. It allows relaxed long term driving over bad roads and tracks, as well as highway driving.

I`m on the road since 10 Years, and did 110`000 km / 68500 Overlanding-Miles. I didnt try to drive slow - the system allows speed over bumps.

The different trip diaries with a lot of pictures you can find here: About us - https://vanlife.4x4tripping.com/p/about-us.html and too some threads here at ih8mud.

The AHC did never failed in the last 10 years. It is also no problem to get spares if necessary, too . I did had a talk with toyota in salta and lima in peru at example, both had ahc shocks on stock - if necessary, same in bolivia.

Surfy

 

[borfoo3]

Our streets are practically 70% potholes, and I drive my AHC LC200 just like I do with my extended travel KING equipped 4Runner with hydraulic bumpstops (i.e. aggressively).

Just to get this out of the way, AHC will never handle the high speed rough stuff like the KING does (or any high end shock setup). However, it is mighty impressive for a factory setup on how well composed the vehicle handles at various loads. Comparing the two is unfair, as one is a jack-of-all trades, master of none (AHC) and the other is a purpose built setup that sacrifices some ride aspects to excel in others (KING).


As for AHC breaking, there are two important points to consider:
1- Theoretical: AHC has more parts to give you the better flexibility and performance. More working parts = higher probability of something going bad. Plus there are more regular wear items (i.e. fluid, pistons, globes) that deteriorate faster the more abuse they see. So: we should expect it to need more maintenance throughout its lifetime if it is used aggressively. I know someone who runs his AHC LC200 VERY hard in the sand dunes, and he does new pistons (few started leaking) and fluid at ~60k intervals.

2- Real world track record: On the other hand, real world experience proves it is fairly robust system with many worry-free 10+ years cases. Even more if it is mainly street driven. It is more reliable than other dynamic suspension systems out there (I'm looking at you, Land Rover). Though, people who actually push AHC to its limits are a fairly small crowd to begin with.

Summary: If you use an AHC equipped truck aggressively, you should be prepared to keep it in tip top shape with more maintenance in order to enjoy it and NOT be worried.

 

[Madtiger]

The problem with AHC is not that it fails by doing things.

The problem with AHC is the maintenance…more like, how difficult it is to maintain. Sure, it is reliable in that it requires flushes every 60k miles. And if done correctly (and the metal line don’t rust), then it should last a long time (unlike other air/hydraulic suspension of other companies).

As can be seen on this forum with numerous posts, maintenance is (very) difficult. A wrong flush…such as not priming the pump…can be disastrous and $$$$$. Dealers have issue with doing it correctly (a member here had dealer screwed up and could not drive his LX for months!)…and unless you’re really handy mechanically, it can be a major headache. For that member who could not drive his LX for several months, Lexus dealer brought in ”AHC experts” after experts tracing the issue.

For an average Joe, AHC can become a dilemma. Too tough to do it alone in your garage…yet dealer can **** it up…and no 3rd party shop will even touch it. Maintaining AHC is not like changing your engine oil. There is no leeway for mistakes.

From a recent thread, the AHC pump can be clogged…and requires an extensive digging around by a great member here to know how to fix it. How many average Joe can do this? Heck, dealers don’t even bother to fix this! Thus, pump is on national backorder due to frequent “failures,” as noted by one dealer.

And then you have the issue with rusted metal line. Painful to trace to the cause. And once found, then you’re now force to reflush/refill the AHC fluid, which brings with it issues noted above.

AHC is a good system. Works great. It should not fail from off-roading. The problem is the long-term maintenance / cost for an average Joe. If you’re very handy, then it should be a good system to tinker with. If you’re not, then AHC presents a long-term potential risk.

 

[DirtNap]

Umm everyone, I'm still in the market for a 570 to replace my Cruiser, for reasons similar to Lou Gill. So if you could talk up the risks/costs a bit, that'd be great, mmOK?

It is something to consider though. There was an article in Toyota Trails this year about the Rubicon, and the author's 570 AHC failed mid-trip , so it was riding on the bump stops. Made it out but it was tough. There was a lot of carnage on my of the vehicles though, so maybe it was super radical extreme sending it? (Haven't been on Mud much lately so this may be well documented by now)

 

[tbisaacs]

Umm everyone, I'm still in the market for a 570 to replace my Cruiser, for reasons similar to Lou Gill. So if you could talk up the risks/costs a bit, that'd be great, mmOK?

It is something to consider though. There was an article in Toyota Trails this year about the Rubicon, and the author's 570 AHC failed mid-trip , so it was riding on the bump stops. Made it out but it was tough. There was a lot of carnage on my of the vehicles though, so maybe it was super radical extreme sending it? (Haven't been on Mud much lately so this may be well documented by now)

That was @Ohnoitsbreaux and it wasn’t an AHC failure, it was an EVAP code that out the truck in limp mode.

 

[Madtiger]

That was @Ohnoitsbreaux and it wasn’t an AHC failure, it was an EVAP code that out the truck in limp mode.

But did this error affect AHC system causing it to fail/malfunction?

 

[DirtNap]

What I spend time worrying (fixing?) more is my German car components, OEM or not.

Side note, I watched a bunch of videos this weekend on the Ineos Grenadier. Was pretty pumped until I saw it was British engineered, had hopes when I saw Magna Steyr was doing g a lot of the engineering, but "noped" right out of there when they said they are using BMW motors. Expensive AND unreliable (per a BMW mechanic acquaintance).

 

[1world1love]

But did this error affect AHC system causing it to fail/malfunction?

It didn’t have anything to do with AHC.

I do think that Toyota could be taken to task for having a failure point that takes out so many other systems in the process.

 

[DirtNap]

But did this error affect AHC system causing it to fail/malfunction?

That was @Ohnoitsbreaux and it wasn’t an AHC failure, it was an EVAP code that out the truck in limp mode.

Thanks, I assume there is a thread on here somewhere? Why would the evap sensor cause AHC to be in low? (IIRC, it was at the lowest setting). Maybe not an AHC caused problem, but still one you may get if you have AHC?

 

[turbo8]

Thanks, I assume there is a thread on here somewhere? Why would the evap sensor cause AHC to be in low? (IIRC, it was at the lowest setting). Maybe not an AHC caused problem, but still one you may get if you have AHC?

I noticed if I get a fault code (gas cap was loose) I can't shift into 4lo. I'm wondering if that is just common for everyone or just people that have disabled the ahc system.

 

[Madtiger]

There are remarkably few stranded tow off trail stories for ahc (just a couple). Probably the same number as failed shock/spring/strut.

I have not heard/read of any stock LC suspension failing while off-roading that could lead to being stranded or risking more damage to vehicle. Stock shocks may overheat i guess if you do desert washboards. But struts breaking? I have not heard of any.

 

[tincan45]

The problem with AHC is not that it fails by doing things.

The problem with AHC is the maintenance…more like, how difficult it is to maintain. Sure, it is reliable in that it requires flushes every 60k miles. And if done correctly (and the metal line don’t rust), then it should last a long time (unlike other air/hydraulic suspension of other companies).

As can be seen on this forum with numerous posts, maintenance is (very) difficult. A wrong flush…such as not priming the pump…can be disastrous and $$$$$. Dealers have issue with doing it correctly (a member here had dealer screwed up and could not drive his LX for months!)…and unless you’re really handy mechanically, it can be a major headache. For that member who could not drive his LX for several months, Lexus dealer brought in ”AHC experts” after experts tracing the issue.

For an average Joe, AHC can become a dilemma. Too tough to do it alone in your garage…yet dealer can **** it up…and no 3rd party shop will even touch it. Maintaining AHC is not like changing your engine oil. There is no leeway for mistakes.

From a recent thread, the AHC pump can be clogged…and requires an extensive digging around by a great member here to know how to fix it. How many average Joe can do this? Heck, dealers don’t even bother to fix this! Thus, pump is on national backorder due to frequent “failures,” as noted by one dealer.

And then you have the issue with rusted metal line. Painful to trace to the cause. And once found, then you’re now force to reflush/refill the AHC fluid, which brings with it issues noted above.

AHC is a good system. Works great. It should not fail from off-roading. The problem is the long-term maintenance / cost for an average Joe. If you’re very handy, then it should be a good system to tinker with. If you’re not, then AHC presents a long-term potential risk.

I have to disagree with regard to maintenance being difficult. It's actually quite easy. The real problem the fact that it's not a standard system with broad understanding like traditional suspension. Jay Leno had a great line when talking about his old Citroen (The great AHC grandfather).



I think the same principles apply with regard to the modern AHC. "Clem" jumps in and drops all four corners pours in new AHC or brake fluid (Same thing right?! ...It's hydraulic!) from a dirty old funnel.

It's just different....that's all.

 

[tbisaacs]

Thanks, I assume there is a thread on here somewhere? Why would the evap sensor cause AHC to be in low? (IIRC, it was at the lowest setting). Maybe not an AHC caused problem, but still one you may get if you have AHC?

Yes - starting here: Official LX570s Picture Thread - https://forum.ih8mud.com/threads/official-lx570s-picture-thread.1006565/post-13622296

 

[Madtiger]

It didn’t have anything to do with AHC.

I do think that Toyota could be taken to task for having a failure point that takes out so many other systems in the process.

It did not…but it (somehow) caused AHC to be slammed down to the lowest point, which is the last thing that you want while in the middle of nowhere.

EVAP error would not cause a regular suspended vehicle to bottom out.

 

[TeCKis300]

I noticed if I get a fault code (gas cap was loose) I can't shift into 4lo. I'm wondering if that is just common for everyone or just people that have disabled the ahc system.

Common for everyone. The despised "Moab CEL." I've been there when I was deep in the Death Valley backcountry. Fortunately, my transfer case was stuck in 4Lo the morning after boondocking, which is what I needed for the next 15 miles anyways.

It's unfortunate, but I believe it's a federal emissions requirement that when emissions CEL occur, that they have teeth, and not just an idiot light that does nothing. At least we're not diesels that will put the vehicle into progressively more serious limp modes.

The workaround is easy though. Reset the ECU either with a OBD-II tool (I left mine at home). Or temporarily pull the battery which is what I did after I got out of the technical section.

Nothing to do with AHC.

 

[TeCKis300]

I have to disagree with regard to maintenance being difficult. It's actually quite easy. The real problem the fact that it's not a standard system with broad understanding like traditional suspension. Jay Leno had a great line when talking about his old Citroen (The great AHC grandfather).



I think the same principles apply with regard to the modern AHC. "Clem" jumps in and drops all four corners pours in new AHC or brake fluid (Same thing right?! ...It's hydraulic!) from a dirty old funnel.

It's just different....that's all.

Hah, a friend that lives nearby has this car. I've helped him troubleshoot it a few times. It's interesting the parallels this has to our LX (little). They're forever leaking/dripping the magic LHM fluid that comes in a green bottle. He always has one in the trunk of the car.

The only parallel is hydraulic lift really. If you want to talk about nightmare, the Citrogen hydraulic system runs the suspension, steering, brakes, and transmission.

 

[1world1love]

It did not…but it (somehow) caused AHC to be slammed down to the lowest point, which is the last thing that you want while in the middle of nowhere.

EVAP error would not cause a regular suspended vehicle to bottom out.

I don’t disagree, but the same code will affect other key drivetrain components on the LC as well. By your logic, that would make the whole 4wd system in the LC suspect.

Don’t get me wrong, I think the disabling of AHC is crazy, but that isn’t the only system affected.

 

[grinchy]

One moral of that other story is that with computers making ill informed decisions based on sensor input (EVAP as an example), that taking a laptop with techstream on a serious trip is just as much a required spare as a CV or other rare use but critical item. Sensor failure can scupper a vehicle just like a mechanical failure can, and sometimes worse (multiple linked systems disabled). It is something more and more modern 4x4 are going to require.

 

[Madtiger]

One moral of that other story is that with computers making ill informed decisions based on sensor input (EVAP as an example), that taking a laptop with techstream on a serious trip is just as much a required spare as a CV or other rare use but critical item. Sensor failure can scupper a vehicle just like a mechanical failure can, and sometimes worse (multiple linked systems disabled). It is something more and more modern 4x4 are going to require.

Honest Q…can Techstream bypass that EVAP canister issue?