LX AHC Off Road Suitability

[TeCKis300]

You bring up another good point: the effect heavy load has on the system.

So how long have you had your LX and how many miles of trail has it seen?

Is there any data out there on the suspension travel of AHC vs non? I know I picked up a considerable amount with the long Radflos over stock.

I've been on trails for sure but not a huge amount relative to the asphalt duty it's seen. I've have been on a rather varied mix and not once have I found the AHC system to be what holds the car back. On the contrary, I find it to excel at just about everything I've tossed at it.

Andrew are you towing a CT every now and then?
My system drops down to low when we go away for a trip with the Kimberley Kamper in tow.
That's even before will add a dual spare wheel carrier and a bigger fuel tank.

Don't be alarmed at the system 'dropping to low.' It's not necessarily in a low position (kneeling mode), just that it's telling you the suspension is riding at a lower position relative to 'N'. The readout serves two purposes: 1) mode selection and 2) actual position.

The system is constant height within a specific load capacity. Beyond that, it is best effort. Just like you would expect a normal suspension vehicle to ride lower with greater load, the AHC system will do just that outside of the normal load capacity. Nothing is wrong, it's just telling you where things are at.

I likewise have run into this towing this setup. Note that the Porsche is rear motored, so there's probably 1k+ of tongue weight here with another couple hundred pounds of wheels in the trunk. And AHC performed flawlessly even in 'L' even though it obviously is not kneeling mode low. I would hate to have done this dragging butt without AHC.

 

[Wilsil]

I am still in two thoughts of what to do: keep the AHC or replacing it with conventional suspension.
I love the AHC as you can lower it to get in the garage, but I also wouldlike to have some lift.

 

[MH_Stevens]

Seems the field really is split about even for or against AHC. So here the real question. Is the AHC on the LX470 a real alternative to a LC with a 2" lift?

 

[TeCKis300]

The only thing a standard static 2" lift is good at is looking tough and wasting gas. Seriously. And that can be solved with a slee override on AHC. That is unless you're talking about extra long shocks that give you more travel...and more compromise to the 95% other use cases.

Consider that you will be missing out on this:

During Lo Position:
When the vehicle speed becomes
higher than approximately
5 km/h (3 mph), the vehicle
height transfers to normal.
The normal vehicle height is
maintained even if the vehicle
speed becomes lower than 5
km/h (3 mph).

"During Hi Position":
When the vehicle speed becomes
higher than approximately
30 km/h (19 mph), the vehicle
height transfers to normal. The
normal vehicle height is maintained
even if the vehicle speed
becomes lower than 30 km/h (19
mph).

"During Hi Position with Transfer shifted in Low":
When the vehicle speed becomes
higher than approximately
50 km/h (31 mph), the vehicle
height transfers to a height that is
approximately 25 mm (1 in.)
higher than the normal vehicle
height. When the vehicle speed
becomes lower than approximately
20 km/h (12.5 mph), it
returns to the high vehicle
height.

Also on the topic of what the system does other than height control and explicit setting of the damping switch:
2) Thumping Sensitive Control
When the road surface condition does not require a damping force, this function controls the actuator
so that their damping force will not increase.
As a result, both flatness and a soft ride have been achieved.
3) Unsprung Vibration Control
If unsprung resonance is detected, this function controls so that the damping force will not decrease
below a certain level, in order to reduce the unsprung resonance.
As a result, excellent road-holding performance has been ensured without affecting riding comfort.

4) Speed Sensitive Control
To optimally balance the vehicle’s riding comfort and road-holding performance, the damping force is
increased along with the increase in vehicle speed, in order to ensure stability during high-speed driving.
5) Anti-Roll Control
During cornering, this function makes the damping force firmer, thus restrating the body roll speed in
order to provide excellent stability and controllability.
6) Anti-Dive Control
During braking, this function makes the damping force firmer to restrain the body dive, thus ensuring
excellent stability and controllability.
7) Anti-Squat Control
During acceleration, this function makes the damping force firmer to minimize the changes in the vehicle
body posture to provide excellent stability and controllability.
8) Damping Force Control
The actuator uses a 16-step step motor to generate a continually variable damping force. This provides
a wide selection of damping force and enables a smooth transition of the damping force.
As a result, a minutely controlled damping force that accommodates various types of driving conditions
has been made possible.

"Right-Left Wheel Communicating Function"
Normally, an oil passage remains open between the shock absorbers for the right and left wheels. This
enables the suspension to contract and elongate smoothly when the right and left wheels move gradually
at opposite phases and provides excellent road-holding performance while driving on a winding road.
When the driver operates the steering wheel, the oil passage between the right and left shock absorbers
closes according to that condition. This restrains the increase of the vehicle body roll during cornering,
thus ensuring the vehicle’s stability and controllability.

 

[Actualeyes]

Seems the field really is split about even for or against AHC. So here the real question. Is the AHC on the LX470 a real alternative to a LC with a 2" lift?

Certainly. AHC beats nonAHC with a 2" lift at least until major components have really failed. 3" or more starts to get difficult to achieve, but remember you entry and exit angles, diff clearance, wheel sizes all come into play in terms of real relevance.

If you always have heavy load onboard you will need to do minor mods with AHC (heavier coils/spacers plus heavier torsion bars perhaps) just like you need to buy heavy load carrying springs and shocks for nonAHC.

Mind you, actually there aren't many places that 2-3" lift (AHC or not) won't take you unless you are into serious risk or competition.

IME most 4x4 clubs have a range of vehicles including some stock and they mostly go the same places although sometimes take different lines.

And most folks do long distance driving before a shorter time wheeling and the AHC eats all but the most expensive adjustable systems for the hard top, and even they need to be adjusted for the load/terrain.

 

[Actualeyes]

Andrew are you towing a CT every now and then? My system drops down to low when we go away for a trip with the Kimberley Kamper in tow. That's even before will add a dual spare wheel carrier and a bigger fuel tank.

Of course. You've got too much load on and even without the CT your neutral pressures are too high.

Adding the fuel tank and wheel carrier will exacerbate it.

But it is inexpensive and butt easy to put on new heavier duty rear coils and ratchet up the torsion bars until you are in spec and then the CT will go on and off no issues.

When you're on the hardtop you will love yourself for not deleting it.

When you need lift you put it on H.

If you really want it to look lifted you adjust the height sensors to give you yet another 1-1.5" (although diff drop might be in order as with other lifts on IFS cruisers)

Call me to talk it thru perhaps.

BTW I have towed much heavier ball weights than a KK with my setup which has dual wheel carrier rear bar, and LPG tank and front bar and winch.

 

[Actualeyes]

Great minds think alike

Yes, but saying that your AHC is shot, what does that mean? And it's not that hard to understand, just different.

Lots think their AHC is shot because of how it is performing - that does not mean it is shot. That means it needs maintaining but quite simply a DIY job that really big suspension upgrades are not for most people. It may be shot, but probably isn't IME.

 

[Wilsil]

"During Hi Position with Transfer shifted in Low":
When the vehicle speed becomes
higher than approximately
50 km/h (31 mph), the vehicle
height transfers to a height that is
approximately 25 mm (1 in.)
higher than the normal vehicle
height. When the vehicle speed
becomes lower than approximately
20 km/h (12.5 mph), it
returns to the high vehicle
height.

Haven't noticed this.
I have read somewhere that when you are stuck, the system can go up another 0.5" or so? Haven't noticed that either.

Thanks Andrew.
I will give you a call one day, when I find the time.
It sounds good to me if I could solve it with HD torsion bars and coils.
First I will see if I have a 30mm socket (or borrow one from a friend) and turn up te torsion bars to get the pressure back.

 

[MH_Stevens]

OK, so agreed capability is accetable off road, how much is the dealership cost to replace the AHC system, that forces many to go back to fixed suspension?

 

[Actualeyes]

OK, so agreed capability is accetable off road, how much is the dealership cost to replace the AHC system, that forces many to go back to fixed suspension?

Don't ask. They would take a fairly uninformed approach, sometimes not even doing the basic maintenance first and certainly not adding heavier coils/TBs or helper air bags. Their knowledge is limited.

The price of OEM parts (just like other similar brake, AC etc parts) is inflated - that is how they get to be toyota stealers, and their apprentices learn on the job at your expense while you pay them too dollar.

With ih8mud help the system can be kept going pretty well in my view.

The major components are:
* pump - this is repairable but the stealer won't do it. He will only replace it. Needs some modest know how... But not too hard a job
* accumulators - easy replacement job and rumor has it the OEM ones can be got for about $700 for a set... Stealers would be $1800 up
* dampers - only OEM but you don't need to replace them all. There are a few examples of leaks but very few. You could pick up second hand ones from folks who delete AHC (cruiseroutfitters say)
* valves - perhaps a bit more finicky job but very few examples of failure to go by
* computer - even I will probably not stump up for that

But if it's working there's no need to feet these costs - you can see how well it is working by the difference between H and L in the reservoir, and the neutral pressures. Leaks in the dampers is visible and warns of impending replacement.

And the real cost of replacement is quite high... Usually understated here. And shockers still probably have significantly shorter life than AHC components (my gut feel).

 

[MH_Stevens]

As it happens I got a LC so I'm out of this thread now!

 

[sonk76]

So Sonk I take it that you're running AHC with your 34's sans problems?

Sorry for late response: yes, running sans "problems" (just like the 35's I ran were fine). That said, my setup, much like EVERY* setup that doesn't severely restrict the maximum shock compression and/or front turn radius, will make contact with tires to frame/body in EXTREME articulation/turning scenarios...

*I'm sure someone may be able point out a setup that doesn't EVER have contact with tires in the 35" range... I just haven't seen one.

 

[TeCKis300]

*I'm sure someone may be able point out a setup that doesn't EVER have contact with tires in the 35" range... I just haven't seen one.

This is more a characteristic of the suspension geometry than it is of the spring/damper (whether AHC or not). Limiting the stroke to avoid contact is a non-ideal solution as we all want to maximize suspension travel.

That said, I would like to see the aftermarket create some sort of damper upper mount lowering kit. That way we get more usable droop travel, while eliminating potentially unused upward travel when used with 34/35" tires. Still need to lower the bump stops as you don't want to rely on the shock limiting the travel.

 

[OregonLC]

This is more a characteristic of the suspension geometry than it is of the spring/damper (whether AHC or not).

I think this is one of our core questions that hasn't yet been answered: is there any difference in travel between AHC and non? On the LC there doesn't appear to be any part number difference with the AHC on the 2006 MY. However, do we know that the travel is the same between AHC and non? Does the AHC mechanism consume any of the throw? Or does the external nature of the system buy additional stroke?

The more I travel and read the more I've began to rethink the best strategy for an Expo 'Series 100'. Wondering if to do it again that maybe the LX (AHC) with 33s or maybe 34s and a 1" BL wouldn't be the best combo of ride, capability, economy, etc.

But back to the question: what is the delta in travel between AHC and non. And for that matter, would be nice to catalog the travel of the various aftermarket offerings.

 

[Wilsil]

The front shocks in my LX are also being used in the LC100 VX according www.toyodiy.com
Same for the rear shocks LC100 VX (http://www.toyodiy.com/parts/xref?s=48510-69127&mU=on&mE=on&mJ=on&mG=on)

Not sure if these models have AHC.