LX AHC Off Road Suitability

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OregonLC

OregonLC

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So... for those with the LX (or LC's with AHC for that matter) who wheel with the stock suspension, how does it hold up? There are plenty of maintenance threads and conversion threads, but who here in earnest has built a truck around the stock AHC system? Maybe even with the Slee module or sensor relo.

Looking for performance feedback, both from a long-term maintenance perspective and from a trail performance perspective. Do trails quickly torture the system into failure? Does it over or under dampen washboards? How does an AHC truck RTI compared to non-AHC stock? Or in other words, how does the travel map out?
 
From what I have heard said, AHC is largely a gimmick to help granny into the truck, and the main reason many hard off-roaders prefer the LC over the LX. Unfortunately, as I am finding, being the market for a new used 100, the availability of used LCs compared to used LXs is about 1:5 (at least where I live in southern Califonia) so I may have to eat my words.
 
It's called the Sequoia effect. In 2001 the Sequoia came out and LC sales plummeted while LX sales continued on.

I'm completely enamored with our 04 on the road, just curious of real-world experience on the trail. If its durable, there could be a great vehicle made out of an 03-05 LX with 33s... And the A750 is pretty fricken sweet too. Green grass on that side there is.
 
AHC gets a bad rap from most on these boards. While some of it is deserving, as it's a potentially expensive wear item to maintain and repair, most of the other reasons are largely undeserving as it's a robust and capable system that is meant to increase the capability breadth of the vehicle without compromises. That is, it will do very well for on road manners, yet also provide clearance, articulation, and active dampening when the going gets rough.

I can't find it at the moment, but Toyota had a diagram that compared the capability of AHC vs non-AHC equipped hundy. It basically showed the AHC vehicle having more capability and on and off road. Now you can't have everything and eat your cake too, as the obvious trade-off is increase cost and complexity. Which brings me to my main point.

Half of the negativity against the system is due to second hand owners unwilling to cough up to maintain and repair what is ultimately a wear item. Not that it's not durable as there are plenty of anecdotal stories about it lasting over 200k. The other half is due to second hand owners trying to modify the system, or use it outside of its carrying capability, without truly understanding how to modify it to do whatever they are doing. Then they blame any fault on some contrived incapability or unreliability of the system.

Fact is, it's a tremendously capable system that can allow you to have the best of both on road and off road qualities (unlike an off road oriented suspension which biases the truck). I'll list a few.

1) By it's very nature of having a large fluid volume, it has more thermal capacity than any remote reservoir setup - great for those washboards.

2) The suspension is ACTIVE, so it has the ability to automatically dial in the right dampening for any particular wash board and load.

3) AHC will RTI higher (toyota supported fact) due to its smaller anti-roll bars and active height control.

4) AHC is constant height, regardless of load within its rated capacity. For example, if you toss in 4 people and gear on a standard non-AHC hundy, you'll already begin at a lower ride height relative to the AHC equipped hundy. Nevermind that the AHC can lift on demand.

5) AHC can have more lift than a statically lifted (stock non-AHC shocked) hundy on demand. Because the non-AHC truck has to compromise to leave some droop in it's setup. The AHC can go even beyond its on demand high position, when the ECU detects the need.


Sorry for my long winded reply, but I hate watching the herd mentality (eg. above) bash AHC on these boards , without a substantive reply.
 
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.
 
When I originally got my LX I assumed I would scrap the AHC right away based upon the feedback on this forum. However, I am finding the whole system to be very capable off road. Plus, one added benefit is that I can lower the LX to make it much easier for my old 115 lbs dog to jump in the back for when we hit the trails. My only complaint is that I would like a little more lift in the high mode, but that's just me. Currently, I have 161k on the original system and the only maintenance that has been done is the AHC fluid was changed once. Other than that the system has required zero maintenance. (Knock on wood). Plus, I am extremely impressed with the way it rides. The system feels like it's still new.

Now I still might scrap the AHC system one day, but I have to admit the system has won me over so far.
 
I keep looking for a reason to rip out the AHC and put a 2.5" lift on...haven't found one yet.
 
In my experience AHC is a superior solution over the regular suspension, provided you actually maintain it. From a durability perspective I feel like I've read more threads here with conventional shocks failing (not necessarily OEM) than AHC failures. AHC has parts that wear down and require replacement much like regular shocks.

Some of the best features of AHC have been me mentioned above. My own personal one is the ability to limit the compromise between higher lift for off reading vs lower rode height for regular travel (allows for optimization on CV angles, overall drivability, without giving up clearance angles off road)

The ideal upgrade solution would heavy duty ahc shocks with length extended to maximum limits of the truck.
 
So Sonk I take it that you're running AHC with your 34's sans problems?
 
My second hand 2005 LX470 with 115k miles on it AHC was maintained but acting up (rough ride sometimes other times not). Instead of dumping big $$$ in the AHC I had Slee install OME. I personally like the ride feel and looks of the LX with OME. The OME cost less then messing with the AHC. The service manager and one of the service writers at my local Lexus dealer that own LX's switched to OME because of the long term cost issues with the AHC.
 
So how much is the Slee OME? Would you do this preemptively or only when a problem develops?
 
Join the Reprobates Club

I also am in the Reprobates Club - those of us who are recalcitrant enough to go against the Tide of Mud Opinion and maintain and even enhance our AHC system rather than "delete" it.

I have found that AHC goes every where I want to go (including extreme off-road expeditions in Australia) and makes the journey very comfortable.

The LX has front bar with winch, rear bar with dual wheel carrier and a 100l LPG tank - quite a lot heavier than stock.

I run standard non-AHC LC100 rear coils instead of standard coils and this allows the AHC to work well, and have the same load carrying capacity as the out of the factory AHC equipped vehicle. Besides this, all I have done is crank torsion bars (easy) and replace AHC fluid (also easy).

All my AHC components are working well at 90K miles and 10 years old.

You're welcome to join the Club!
 
Just spoke with a guy I know who's LX AHC needed replacing at 140K miles.
 
MH_Stevens said:
Just spoke with a guy I know who's LX AHC needed replacing at 140K miles.
Click to expand...

Remember there's a lot of ignorance and because it is somewhat unconventional many mechanic shops or 4x4 shops don't understand how it works or know how to maintain it. They have a vested interest in deleting it and replacing with after market coils, torsion bars and shocks that they understand.

Even toyota and to some extent Lexus stealers don't know enough about it and just RnR the major components until they "fix it". They perceive a manufacturer's liability to advise to make mods to increase the carrying capacity, say - even though it's possible. They often won't even put techstream on a vehicle to read the neutral pressures because they don't understand what to do about it (generally). They're not used to adjusting torsion bars except to raise vehicle heights and don't understand.

Parts through stealers are exorbitantly expensive and there are few after market options (just spheres really, but even OEM ones can be obtained at similar prices).

But here the darkness of ignorance has been lifted ... We know the maintenance options. We can avoid the expense of expensive service by stealers and extend the life of the very capable system. Like most things they don't last forever... So perhaps there is a point where major investment is unavoidable, but perhaps it is not as often or as early as some believe it is.

The question for someone that thinks it needs deleting is:

1. Are you a hardcore off roader that needs extreme articulation, lift and can sacrifice on road stability?
If not:
2. What is the AHC fluid level difference? (H - L) - if within spec then continue. If not you may have failed system components - spheres, dampers, pump, valves. [this can cost money to source the parts and may be time to think about after market options]
3. What are the Neutral front and rear AHC pressures?
- adjust/reindex torsion bars until front in spec
- consider heavier rear coils or helper airbags to bring rear into spec

Or if you just can't apply your mind to a new technology or sheepishly follow the uninformed go right ahead.

Cheers,
Andrew
 
SWUtah said:
Around $2k includes the OME install and removing the old AHC components and the interior dash light and console switch. That is about what Lexus charges to replace the globes. No more problems 2" lift with diff drop.
Click to expand...

Just did the same thing at 150k. My AHC was shot, and I mean almost undriveable. I planned to do this from the day I bought it with 118k and perfectly functional AHC. I wanted a conventional suspension which was easy to work on and maintain. I should be good for the next 150k with maybe a change of shocks at some point but no flushing, worrying about how many grduations between high and low, and no more expensive parts to worry about having to replace. If you adjust the height sensors I think you can expect the system to degrade faster than normal. LX with OME feels like a 4x4.
 
So the cost and maintenance is one issue, but to the performance: is there any data out there on articulation? I'd love to see a back-to-back RTI of a stock LC vs a stock LX.
 
sonofshin said:
Just did the same thing at 150k. My AHC was shot, and I mean almost undriveable. I planned to do this from the day I bought it with 118k and perfectly functional AHC. I wanted a conventional suspension which was easy to work on and maintain. I should be good for the next 150k with maybe a change of shocks at some point but no flushing, worrying about how many grduations between high and low, and no more expensive parts to worry about having to replace. If you adjust the height sensors I think you can expect the system to degrade faster than normal. LX with OME feels like a 4x4.
Click to expand...

Great minds think alike ;)
 
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.
 
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