AHC 100 series vs 200 (1 Viewer)

Joined
Aug 18, 2019
Messages
693
Location
St Louis, MO
Seems like everyone thinks that we have "air" ride in LX. If people not technical or know, they don't even expect to hear it's actually hydraulic suspension.
Then I got curious about 200 series. They also have AHC and hydraulic suspension. But is it the same?

Watching this video couple things got me cuirous:
1. Battling lean in a corners
2. Battling nose dive on stops
3. Going to mid-low at high speed.

Do we have all that in 100 series?

 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
3,750
Location
Colorado
1 and 2 yes, 3 no. 1 and 2 are more effective in the sport modes. In comfort and normal, AHC rides pretty close to a standard suspension from a handling perspective, IMO.

I think the 200 system is a bit different in the approach used, but I don't know enough to help explain how.
 
Joined
Aug 18, 2019
Messages
693
Location
St Louis, MO
1 and 2 yes, 3 no. 1 and 2 are more effective in the sport modes. In comfort and normal, AHC rides pretty close to a standard suspension from a handling perspective, IMO.

I think the 200 system is a bit different in the approach used, but I don't know enough to help explain how.
Nice to know! #1 I did notice as sometimes I do put it in sport and it doesn't lean as much but I always thought it's simply because of firming up whole thing. Not because it detects actual cornering. It might be for #2 also.
 
Joined
Dec 6, 2016
Messages
249
Location
Brisbane, Australia
Seems like everyone thinks that we have "air" ride in LX. If people not technical or know, they don't even expect to hear it's actually hydraulic suspension.
Then I got curious about 200 series. They also have AHC and hydraulic suspension. But is it the same?

Watching this video couple things got me cuirous:
1. Battling lean in a corners
2. Battling nose dive on stops
3. Going to mid-low at high speed.

Do we have all that in 100 series?


The video at your YouTube link describes the AHC/AVS system in the LX570 (and possibly LC200 in some parts of the world but not known to me -- certainly AHC is not fitted to any LC200 model in Australia). The design objectives and principles of the LX570 system released around 2008 (?) has evolved further than the system used on LX470's since around 1998 (?) and on some later LC100's in some markets. The detailed LX570 AHC/AVS solution, meaning the hydraulic circuits and most of the components, are very different to the earlier LX470 version. Among other things, the ability to change the overall "effective spring rates" (not just damping rates) is part of the LX570 solution. Nevertheless, a well-maintained and fully functional AHC/TEMS system on an LX470/LC100 provides a far better ride and flexibility than the stock conventional suspension on the LC100 -- in my opinion -- but there are a lot of differing opinions on this subject!!

Anyway, if interested, see more information at the attachments included in the following link at Post #168 midway down Page 9:

 
Last edited:
Joined
Jul 23, 2008
Messages
165
Don't the 200s all have KDSS as well? That's a big part of controlling the lean and brake dive, not just the AHC.
 
Joined
May 20, 2019
Messages
1,111
Location
Las Vegas NV
Main diff between the 100 and 200’s AHC is the front, torsion bar and coilover. The 200s ahc’s reservoir is found at the rear while the 100 is found in the front. 100 doesn’t have the KDSS, 200 has the KDSS. 100’s version of the KDSS is the suspension mode “soft” allows the struts to free flow or fully extend easily on off camber situations while the 200 has that finer selectable option called the MTS aka craw control (loosen up the struts and hydraulic anti roll bars for full suspension articulation)
 

uHu

Bridgeburner
Joined
Nov 27, 2005
Messages
2,062
Location
Oslo, Norway
Seems like everyone thinks that we have "air" ride in LX. If people not technical or know, they don't even expect to hear it's actually hydraulic suspension.
Then I got curious about 200 series. They also have AHC and hydraulic suspension. But is it the same?
Watching this video couple things got me cuirous:
1. Battling lean in a corners
2. Battling nose dive on stops
3. Going to mid-low at high speed.
Do we have all that in 100 series?
Yes, we do have "Air ride". Well semi air, at least. Whether the suspension movement is transferred hydraulically or mechanically doesn't determine if it is "air ride" or not. If air bellows are placed directly over the axle, or connected via a hydraulic pipe, it still results in that gas (air) is holding the weight of the vehicle. (air is 78 % nitrogen, so air=nitrogen for any suspension application). Now, we do have steel springs in addition, so it's not a plain gas suspension, but enough to be able to do the damping (dynamically) on the gas/hydraulic part of the suspension load (which has to be done in a normal shock on a pure air suspension setup).
On the 100, the suspension is called AHC/TEMS, while on the 200 it's AHC/KDSS. The two are nearly the same, but a bit more refined on the newer version, and the big difference is the sway bar disconnects. Calling it Electronic Modulated Suspension, or Kinetic Dynamic Suspension doesn't change much.
The AHC/TEMS reacts to steering angle, brakes, accelerator, G-force, ABS-info (wheel spin), road condition via height sensors (bump and wash-board detection).

So, you can't call it hydraulic suspension, but you can say hydro-pneumatic suspension. There are really only two ways for a suspension system to carry the load in a springy way, either steel springs or gas (air) springs, or a combination of the two like on land cruisers. (Or rubber, like on the old Mini and on some light trailers). Air is springy (can easily be compressed) and spring steel is springy. Hydraulic fluid is not compressible, and a other steel parts of the suspension are not compressible, they both just transfer the load to the springy part.
 
Joined
Dec 11, 2018
Messages
213
Location
EU
1 and 2 yes, 3 no. 1 and 2 are more effective in the sport modes. In comfort and normal, AHC rides pretty close to a standard suspension from a handling perspective, IMO.

I think the 200 system is a bit different in the approach used, but I don't know enough to help explain how.
I believe we have a version of 3 too. The user manual states that height is changed at 50+ km/h, but I believe it was going higher, instead of lower.
Nearly all 100s in Europe have the AHC btw. Conventional suspension is the exception and there are barely any LX470s around here.
 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
3,750
Location
Colorado
I believe we have a version of 3 too. The user manual states that height is changed at 50+ km/h, but I believe it was going higher, instead of lower.
Nearly all 100s in Europe have the AHC btw. Conventional suspension is the exception and there are barely any LX470s around here.
Interesting, I don't think that's in the LX470 manual. Do you have a pic of it? I can run techstream on the highway to check if the sensors show height variations.
 
Joined
Aug 18, 2019
Messages
693
Location
St Louis, MO
There are really only two ways for a suspension system to carry the load in a springy way, either steel springs or gas (air) springs, or a combination of the two like on land cruisers.

Ok, let's bust another myth. One of the guys told me that shocks do "go bad" in AHC. Where my understanding is that it's very simple piston operation and as long as they don't leak - there is nothing to "go bad" in them. True or False?
 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
3,750
Location
Colorado
Ok, let's bust another myth. One of the guys told me that shocks do "go bad" in AHC. Where my understanding is that it's very simple piston operation and as long as they don't leak - there is nothing to "go bad" in them. True or False?
I think this "myth" of sorts comes from a mis-labeling or misunderstanding of the system. For AHC, the "shock" as a functional system includes the shock/ram, the lines going to the actuator, the actuator and the gas chamber (not air chamber, gas chamber). You could go further and say the wiring and the AHC ECU is a part of that system. In this sense, the "shock system" can absolutely fail and it can fail in many ways. I'm not sure we've seen anybody run into a failure in the shock/ram that was not a simple fluid leak.

I think it's fair to say you can assume an AHC shock/ram is functional and good if it is not leaking fluid. I would not say it's impossible for an AHC shock to have internal failure, but I would say that it would be extremely rare.
 
Joined
Aug 18, 2019
Messages
693
Location
St Louis, MO
I think it's fair to say you can assume an AHC shock/ram is functional and good if it is not leaking fluid. I would not say it's impossible for an AHC shock to have internal failure, but I would say that it would be extremely rare.

I am planning to overhaul rear suspension and have some surface (nothing major) rust on those. I was going to remove them, clean/paint and replace bushings. I just don't feel like paying $500 for pair if those are pretty much life time units. I know they can leak at connection but if it's all good there I see no reason why they won't last
 

ramangain

Clarksonian disciple
SILVER Star
Joined
Feb 6, 2020
Messages
2,211
Location
Atlantis - recently discovered in the Rust Belt
Ok, let's bust another myth. One of the guys told me that shocks do "go bad" in AHC. Where my understanding is that it's very simple piston operation and as long as they don't leak - there is nothing to "go bad" in them. True or False?
False. A leak is a sign that the "very simple piston operation" is failing.

NO piston operation can last forever. Seals eventually fail.

When a conventional shock starts leaking, the terminology is that the shock has "gone bad". Why would AHC shocks be any different?
 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
3,750
Location
Colorado
False. A leak is a sign that the "very simple piston operation" is failing.

NO piston operation can last forever. Seals eventually fail.

When a conventional shock starts leaking, the terminology is that the shock has "gone bad". Why would AHC shocks be any different?
I think the difference with an AHC shock vs a traditional shock is that the AHC shock itself does relatively little in the way of shock absorbing. The internal valving doesn't seem to wear out on AHC the way it does on traditional. There is apparently gas inside the AHC shock (per the FSM disposal instructions), but since the gas chamber (globe) does the majority of the shock absorbing I think there's less stress on that AHC shock than a traditional unit. Given a similar level of robustness to the design, that would make an AHC shock likely to last longer than a comparable traditional shock.

I think that idea is backed up by all the folks we see on here with a well-functioning AHC system with 200,000, 300,000+ miles and original AHC shocks.

Devil's advocate: There's not a good way to test for an internally bad AHC shock. The FSM is vague. There's no testing for the shock that I see. It's a process of elimination and eventually the shock becomes the next item on the list. 🤷
 

ramangain

Clarksonian disciple
SILVER Star
Joined
Feb 6, 2020
Messages
2,211
Location
Atlantis - recently discovered in the Rust Belt
I think the difference with an AHC shock vs a traditional shock is that the AHC shock itself does relatively little in the way of shock absorbing. The internal valving doesn't seem to wear out on AHC the way it does on traditional. There is apparently gas inside the AHC shock (per the FSM disposal instructions), but since the gas chamber (globe) does the majority of the shock absorbing I think there's less stress on that AHC shock than a traditional unit. Given a similar level of robustness to the design, that would make an AHC shock likely to last longer than a comparable traditional shock.

I think that idea is backed up by all the folks we see on here with a well-functioning AHC system with 200,000, 300,000+ miles and original AHC shocks.

Devil's advocate: There's not a good way to test for an internally bad AHC shock. The FSM is vague. There's no testing for the shock that I see. It's a process of elimination and eventually the shock becomes the next item on the list. 🤷
I don't disagree. I think separating a leaking AHC shock from the idea it hasn't "gone bad" is false. It is an identical failure mode as a conventional shock. Seals wear out because it is a closed system and the net entropy change is non-zero.
 
Joined
Dec 6, 2016
Messages
249
Location
Brisbane, Australia
Seems like everyone thinks that we have "air" ride in LX. If people not technical or know, they don't even expect to hear it's actually hydraulic suspension.
Then I got curious about 200 series. They also have AHC and hydraulic suspension. But is it the same?

Watching this video couple things got me cuirous:
1. Battling lean in a corners
2. Battling nose dive on stops
3. Going to mid-low at high speed.

Do we have all that in 100 series?


Just to add to the conversation ….

After nagging Mrs Indrocruise for years about an entirely unjustifiable purchase, permission was received to buy a new top-of-line LC200 for Christmas – I just had to have the 4.5 litre V8 twin-turbo diesel (1VD-FTV). This will become a collector’s item here after the LC300 is released and as the legendary 1HD-FTE turbodiesel vehicles (now 14 to 20 years old) slowly fade away!

The LC100 with 1HD-FTE and AHC-TEMS (Toyota Electronic Modulated Suspension – forerunner of AVS) are quite rare in Australia – only marketed here for about 18 months from late 2005, maybe more common in Europe and elsewhere.

The new truck now requires a fit-out with the good stuff for back roads and trails. The old truck (15 years but only 210,000 kilometres = 135,500 miles) will be ‘inherited’ by the Perth branch of the family on the Western side of the Australian continent.

Kinetic Dynamic Suspension System (KDSS) came with the package on my new LC200. AHC-AVS never has been an available alternative in this market for LC200.

Sadly, nowadays for AHC-AVS, Toyota requires us to step up beyond the top-of-line LC200 to LX570 (5.7 litre V8 gasoline) for additional A$26,226, or, go to LX450d (same body with 4.5 litre V8 twin-turbo diesel minus large fuel tank, minus sunroof, minus third row seats) for additional A$16,686. This did not work for me. Maybe the numbers are different elsewhere in the world.

Anyway, best if ….
  • KDSS (as fitted to most LC200 except base model from 2007), and,
  • AHC-AVS (as fitted to LX570 and LX450d), and,
  • AHC-TEMS (as fitted to LX470 and some LC100 until 2007)
…. are not mixed up.

These three systems are not the same. Their mechanisms and components are different. The different labels are important because they mean different things. KDSS is not part of AHC-AVS nor vice versa.

Compare:

KDSS as used on LC200, although this video shows LC150 (Prado):


and

AHC-AVS for LX570 -- note differences with LX470/LC100:

https://www.youtube.com/watch?v=uynhbaiKDqQ

To be clear, KDSS is not fitted to vehicles which have AHC-AVS in any market. KDSS will not be found on a LX570 anywhere. KDSS was not even on the market at the time of the earlier AHC-TEMS on LX470/LX100.

KDSS is a passive system – it cannot be driver-controlled – there are no knobs or buttons in the cabin to adjust it. It is a cross-linked hydraulic system that only affects the sway bars and responds very well to road or trail conditions. In a LC200 there are other great driver-controlled features such as Multi Terrain Select (MTS) and CRAWL which work very well but these do not vary KDSS – see more at Toyota Land Cruiser 200 Series 2019 off-road review: VX - https://www.carsguide.com.au/adventure/toyota-landcruiser-200-series-vx-75406

Active Height Control (AHC) along with Adaptive Variable Suspension (AVS) is a full blown electronically-controlled hydropneumatic suspension system – probably the most fit-for-purpose of its kind among heavy 4WD vehicles – which continuously in real time will match road conditions by self-adjusting settings for damping, effective spring rate (on LX570, but not LX470), roll resistance, dive resistance as well as self-level to its driver-selected operating height and also allow operating height selection by the driver within the specified speed and weight limits of the system. The system uses many sensors and inputs – including wheel speeds, wheel-to-body heights, steering angle, brake operation, AHC pressures and temperature – to optimise suspension performance (provided that components are in good condition and correctly adjusted in the first place). Accelerometers, pressure sensors and height sensors also detect and respond to braking, acceleration, dive, squat, cornering, body roll, etc, etc.

The KDSS wheel articulation is excellent, although my new vehicle is yet to be put through its paces off-road. I am told that it is far better for body roll, dive and squat than a non-KDSS vehicle with conventional suspension – but it ain’t anywhere near AVS nor TEMS.

On good roads, my new LC200 is good but my 15 years old LC100 with AHC-TEMS wins.

Compared to the new LC200 with KDSS, the older LC100 with AHC-TEMS shows less pitch, less squat, less body roll. It is very fast and flat through winding roads with the comfort switch set at Sport2 – maybe “Porsche-like” is oversell but you get the idea. If too fast and a wheel is lifted, then there will be a few ‘beeps’ from various control units as a reminder to ease back. I kept the AHC-TEMS on the old LC100 in very good condition. I found that I used the AHC height control only a few times a year on long trips and back roads where more clearance occasionally was required, or, for lowering when small or impaired persons were coming on board. On the other hand, TEMS was used every time the vehicle moved – because its 16 steps of automatic damping variation are always “ON” (unless the system is disabled or in a 'fail-safe' state due to unresolved faults). The comfort selector was varied on any highway trip when the road surface was good and a stiffer damping ‘map’ (or range) and flatter cornering was desired, or, on back roads when corrugations (washboards) were unpleasant and a softer damping ‘map’ gave a far better ride.

The attachments from Toyota also may be helpful.
 

Attachments

  • AHC-TEMS for LX470 and LC100 - General Description and Diagrams.pdf
    319.4 KB · Views: 20
  • AHC-AVS for LX570 - General Description and Diagrams.pdf
    634.4 KB · Views: 13
Last edited:
Joined
Dec 11, 2018
Messages
213
Location
EU
Amazing post! That KDSS video was great. I never looked into details of how does it work, but it sort of looks like a mini-AHC covering a subset of it's functions. Cool.

I have seen the AHC-TEMS pdf in the past, but couldn't find it. It covers what I thought was "3. Going to mid-low at high speed." - apparently does that when AHC is in High and transfer is in Low. But this is strange. I am 90% sure, that even in low range, going too fast drops to N. Can you guys confirm that?
On the other hand 50+ km/h in low range with the diesel is very high revs.
 
Joined
Dec 6, 2016
Messages
249
Location
Brisbane, Australia
Amazing post! That KDSS video was great. I never looked into details of how does it work, but it sort of looks like a mini-AHC covering a subset of it's functions. Cool.

I have seen the AHC-TEMS pdf in the past, but couldn't find it. It covers what I thought was "3. Going to mid-low at high speed." - apparently does that when AHC is in High and transfer is in Low. But this is strange. I am 90% sure, that even in low range, going too fast drops to N. Can you guys confirm that?
On the other hand 50+ km/h in low range with the diesel is very high revs.
Hi @Moridinbg,

The words are plain enough and I agree with your reading:
LX470-LC100 AHC-TEMS Speed Sensing Function.jpg


For those wondering, the source of this Toyota document and the above diagram is as follows:
https://lc100e.github.io/manual/, then follow Index Tabs:
New Car Features > CHASSIS > Suspension > Active Height Control Suspension and Skyhook TEMS

Personally, I don’t recall using or having the need to use the Transfer Case in Low Range at speeds around 50km/h (31mph) given the torque available at lower speeds with 1HD-FTE (and this engine would be screaming in that condition), so I cannot offer any useful observations from memory.

Observations in actual ‘field tests’ by IH8MUD volunteers would help clarify this situation with both the 2UZ-FE (gasoline) engine and the1HD-FTE (turbodiesel) engine -- in case there is any difference in the way this works with these different engines, although I could find nothing about such differences in the FSM.

Unfortunately, I cannot help further at the moment -- ‘my’ LC100 now is in Perth, Western Australia, and I am about 3,600 air kilometres (2,240miles) to the East in Brisbane, Queensland, Australia – and local COVID travel restrictions mean that we won’t be meeting up any time soon. And I know your rebuild is still in progress.

Observations from others would be good .....
 

Users who are viewing this thread

Top Bottom