Need advice: AHC fix or delete (1 Viewer)

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Relative noob here, looking for some advice by those who been in my situation. I read a bunch of posts about AHC mods and OME upgrades.

07 LX470, 180k, been driving the truck for about a year and AHC has been fine until now. I have done only solo trips and no issues. I figure I have 850# over curb weight including my extras, gear, fuel and water, sliders, roof rack, drawer and fridge slide. I read here that factory AHC should be able to raise into H with 4 adults and 350# and I’m in that range until I take my family. But last week on first family trip with wife and child, truck would not move into H, and dropped noticeably (although the L light was not on, I believe it dropped to low mode). When unloaded, it went back into H and stayed there for about 25 mi of rough road. Back home, unloaded it will go into H but I am reluctant to test it far out, especially with wife and 3 year old. The main reason for this vehicle is getting well off the beaten path to remote camp spots with my small family. I’ve spoke to a couple mechanics and received a variety of options.

so, having read here a bunch about AHC tuning and fixes, including LC or king springs...... who here has been able to improve reliability of their AHC with a bleed, new rear springs and tb adjustment?

or, bite the bullet and delete then go with aftermarket lift?

Thanks in advance for your input.
jd
 
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I don't have the extra gear/weight that you have, but I'm really happy I decided to keep my system. I think most people that sort out their AHC are extremely happy with the reliability and comfort. There are a number of threads I've seen with people who move to aftermarket suspensions and complain about the stiff ride.

Is your extra 850 pounds a normal every-day load or something that only happens on trips? You may benefit from using air bags instead of stepping up to LC or King springs if that load is not normal and the vehicle just needs a little assistance every once in a while. I think the first step is to see where your pressures are with your vehicle loaded as you would regularly have it, then you will have a better idea of the next steps.

Unfortunately, I don't think most mechanics are familiar with the system and won't offer good advice.
 

ramangain

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If you'd like to keep AHC, you can try swapping out rear springs and front torsion bars for heavier rate units. I'd bet your issues would subside with beefier rear springs, spacers, and TB adjustment.
 
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First thing to do is make sure it's in spec. Plenty of posts here.

Fresh fluid is cheap. Get the pressure in line with what it should be, then decide.

I'm of the opinion it's a great system, do what you can to get it working correctly first and see if it works for you. Why throw it away without at least trying.

Mechanics probably won't know a thing about this...
 
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I don't have the extra gear/weight that you have, but I'm really happy I decided to keep my system. I think most people that sort out their AHC are extremely happy with the reliability and comfort. There are a number of threads I've seen with people who move to aftermarket suspensions and complain about the stiff ride.

Is your extra 850 pounds a normal every-day load or something that only happens on trips? You may benefit from using air bags instead of stepping up to LC or King springs if that load is not normal and the vehicle just needs a little assistance every once in a while. I think the first step is to see where your pressures are with your vehicle loaded as you would regularly have it, then you will have a better idea of the next steps.

Unfortunately, I don't think most mechanics are familiar with the system and won't offer good advice.
@YotaWagon thanks for this. 850 is the occasional weight. I figure that with drawers, sliders and bumper I’m probably rolling with 400 lbs over curb weight daily.
 
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First thing to do is make sure it's in spec. Plenty of posts here.

Fresh fluid is cheap. Get the pressure in line with what it should be, then decide.

I'm of the opinion it's a great system, do what you can to get it working correctly first and see if it works for you. Why throw it away without at least trying.

Mechanics probably won't know a thing about this...
Planomateo - this was my first inclination too. I (and especially my wife ;) ) like the ride quality and I would prefer to save some $$ by keeping a system.

re: mechanics- the neighborhood Toyota dealer refused to even look at AHC and a couple local specialty shops wouldn’t either. It just sounds like there is limited experience with some mechanics and some contradictory info out there. I’m not the most experienced mechanic so trying to get as much info as I can. I think I found a local guy and mud member who can give me a hand assessing pressures etc. thanks.
 
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Bottom line, Land Cruiser style is more reliable than AHC and less costly to maintain. For those with heavily built rigs, going deep off road. You'd not want suspension failing and dropping to low on rocky terrain, bottoming out the vehicle.

Personally I really like AHC. The ability to change ride from Comfort to Sport, is so sweet. As is it's ability to change height, for various uses, including off-road hold in high and going into ultra high. How sweet is that!

A well tuned and maintained AHC, is very nice and rarely fails, when kept within weights limits. As globes deplete weight limit drops. You can boost weight limit, with King AHC coils and Land Cruiser T-bars. You loose only a little damping, as a trade off.

Over time the globes will deplete and need replacing. They are pricey to replace. Kuni Lexus just quoted~$5.5K (IIRC) on a 2007, for a full set. They wanted ~$1k per globe, just for the part. Cost is one reason AHC has a bad rep. Many convert to land cruiser (with or without lift) for about half that cost, of/when time comes for new globes. Others rip out, just because they hear it's "bad". Others are doing a heavy build, going for lift and reliability.

I recently installed a full set of globes, that came direct from Japan for client. He got the set to his door for ~$1K. He had King AHC coils and later put 30mm spacer on top of those. Slee build up the rig and recommended "rip out AHC". Adjusting was difficult with the spacer. Kings being stiffer already carried more weight. So just to bring pressure up to minimum in rear, it had to have a sensor lift. I max out T-bars and rake was off (front extra low) and pressure still high in frt. We then pulled spacer and installed Land Cruiser non AHC T-bars, to get back to near stock height. He has iron bumpers, winch, sliders, rack, box, camping gear and full load of passengers. He's getting armor next. I assume it's working well for him, as I've not heard back from him. Had it failed him, I'm sure he would have contacted me. I do wanted it back in my shop, to tweak out sensors. I kept ride height a little high, by about 3/16". I wanted to let it settle in, than re-adjust.

I'll be installing another set of AHC Kings next week, in a 2006. It's more or less stock weight. Client is interested in a mild lift. Will see! We may need to either keep stock height or add spaces with the King coils and add Land Cruiser T-bars. Then giving small sensor lift. Health of globes will be key. If globes weak, say 8 or 9 graduation after turning. Than a sensors lift will be problematic, even with King coils, spacer and LC T-bars. On other hand, if we see 11 - 12 grads, it should respond well to mild sensor lift w/full upgrades.

Some do a sensor lift without upgrades. Doing so means running with higher pressure. Running with higher pressures, shortens life of globes and may also reduce weight limit. It also gives a ride feel I don't care for, but to each his own.

Goal is to have pressure near or at lower limit, riding more on coils and T-bar and dampen with AHC. Thus saving pressure for when need to carry extra load. In doing the fast and easy axle to fender measurements. I find if sensors that have not been touched since factory, height is 19 3/16" frt, 19 15/16 rear. That height, along with 6.8Mpa frt and 5.8Mpa rear gives best ride IMHO. But that takes new OEM coils, spacer and new or very healthy globes in most cases to achieve.
 
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Bottom line, Land Cruiser style is more reliable than AHC and less costly to maintain. For those with heavily built rigs, going deep off road. You'd not want suspension failing and dropping to low on rocky terrain, bottoming out the vehicle.

Personally I really like AHC. The ability to change ride from Comfort to Sport, is so sweet. As is it's ability to change height, for various uses, including off-road hold in high and going into ultra high. How sweet is that!

A well tuned and maintained AHC, is very nice and rarely fails, when kept within weights limits. As globes deplete weight limit drops. You can boost weight limit, with King AHC coils and Land Cruiser T-bars. You loose only a little damping, as a trade off.

Over time the globes will deplete and need replacing. They are pricey to replace. Kuni Lexus just quoted~$5.5K (IIRC) on a 2007, for a full set. They wanted ~$1k per globe, just for the part. Cost is one reason AHC has a bad rep. Many convert to land cruiser (with or without lift) for about half that cost, of/when time comes for new globes. Others rip out, just because they hear it's "bad". Others are doing a heavy build, going for lift and reliability.

I recently installed a full set of globes, that came direct from Japan for client. He got the set to his door for ~$1K. He had King AHC coils and later put 30mm spacer on top of those. Slee build up the rig and recommended "rip out AHC". Adjusting was difficult with the spacer. Kings being stiffer already carried more weight. So just to bring pressure up to minimum in rear, it had to have a sensor lift. I max out T-bars and rake was off (front extra low) and pressure still high in frt. We then pulled spacer and installed Land Cruiser non AHC T-bars, to get back to near stock height. He has iron bumpers, winch, sliders, rack, box, camping gear and full load of passengers. He's getting armor next. I assume it's working well for him, as I've not heard back from him. Had it failed him, I'm sure he would have contacted me. I do wanted it back in my shop, to tweak out sensors. I kept ride height a little high, by about 3/16". I wanted to let it settle in, than re-adjust.

I'll be installing another set of AHC Kings next week, in a 2006. It's more or less stock weight. Client is interested in a mild lift. Will see! We may need to either keep stock height or add spaces with the King coils and add Land Cruiser T-bars. Then giving small sensor lift. Health of globes will be key. If globes weak, say 8 or 9 graduation after turning. Than a sensors lift will be problematic, even with King coils, spacer and LC T-bars. On other hand, if we see 11 - 12 grads, it should respond well to mild sensor lift w/full upgrades.

Some do a sensor lift without upgrades. Doing so means running with higher pressure. Running with higher pressures, shortens life of globes and may also reduce weight limit. It also gives a ride feel I don't care for, but to each his own.

Goal is to have pressure near or at lower limit, riding more on coils and T-bar and dampen with AHC. Thus saving pressure for when need to carry extra load. In doing the fast and easy axle to fender measurements. I find if sensors that have not been touched since factory, height is 19 3/16" frt, 19 15/16 rear. That height, along with 6.8Mpa frt and 5.8Mpa rear gives best ride IMHO. But that takes new OEM coils, spacer and new or very healthy globes in most cases to achieve.
2001LC- that is great info. Glad to hear some other clients have had success. I agree, if system pressure are in spec, beefier springs and tbar sounds like a good upgrade. Will be in touch.
 
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I have bumpers, sliders and a winch. I'm running land cruiser torsion bars and springs to get it in spec. Also running the sensor lift.

It took about 5 turns on the stiffer bars after the sliders and lift to get the front pressures back in. The rear is still way under spec with the LC springs and rear swingout. Once I'm loaded for a trip it's fine but the rear is stiff with no extra weight on.

I have about 3/4" rake and about 1.5 " lift over stock height currently. High mode still works , low mode the front goes down but those stiffer rear springs don't seem to allow it to go down all the way. In low the rear seems to sit at stock height with all the trucks weight resting on the stiffer springs. I'm cool with that since I've never needed low mode anyway.

I enjoy the AHC and will likely just replace the globes soon. I have 191k miles and everything still works and rides decent even after the lift and stiffer bars and springs.

With my setup now I think if my system failed I could at least crank it off the bumps in the front with the stiffer bars up front
 

hoser

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The main reason for this vehicle is getting well off the beaten path to remote camp spots with my small family. I’ve spoke to a couple mechanics and received a variety of options.
I'd suggest OE 80 series rear springs and possibly non-AHC front t-bars. If AHC should happen to fail, these springs can still carry your weight decently without driving on the bump stops. Your zip code suggests you are just 30 minutes from Slee.... no brainer, go there. They sometimes have low mileage "take-off" springs too.
 
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I have bumpers, sliders and a winch. I'm running land cruiser torsion bars and springs to get it in spec. Also running the sensor lift.

It took about 5 turns on the stiffer bars after the sliders and lift to get the front pressures back in. The rear is still way under spec with the LC springs and rear swingout. Once I'm loaded for a trip it's fine but the rear is stiff with no extra weight on.

I have about 3/4" rake and about 1.5 " lift over stock height currently. High mode still works , low mode the front goes down but those stiffer rear springs don't seem to allow it to go down all the way. In low the rear seems to sit at stock height with all the trucks weight resting on the stiffer springs. I'm cool with that since I've never needed low mode anyway.

I enjoy the AHC and will likely just replace the globes soon. I have 191k miles and everything still works and rides decent even after the lift and stiffer bars and springs.

With my setup now I think if my system failed I could at least crank it off the bumps in the front with the stiffer bars up front
BDG- your solution sounds in line with my situation and 2001LC’s experience. Great reference point. Thanks
 
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I'd suggest OE 80 series rear springs and possibly non-AHC front t-bars. If AHC should happen to fail, these springs can still carry your weight decently without driving on the bump stops. Your zip code suggests you are just 30 minutes from Slee.... no brainer, go there. They sometimes have low mileage "take-off" springs too.
Hoser- good idea re: take off spring from Slee. I have spoken with them a number of times including recently for this matter, they were advising delete above other options. I respect their reasons and expertise but wanted to suss out all the options.
 
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Hoser- good idea re: take off spring from Slee. I have spoken with them a number of times including recently for this matter, they were advising delete above other options. I respect their reasons and expertise but wanted to suss out all the options.

Although, my wife tells me it rides like s*** now hahahah. I told her don't drive it then.
 

hoser

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Hoser- good idea re: take off spring from Slee. I have spoken with them a number of times including recently for this matter, they were advising delete above other options. I respect their reasons and expertise but wanted to suss out all the options.
If reliability is paramount, I'd say delete AHC too. But I think for your vehicle's weight, I'd just go with it. My LX100 is about 1k lbs over stock in equipment alone. I should probably go to standard suspension because I can't get enough suspension damping when fully loaded. Modifying the damping force actuators for increased suspension damping has crossed my mind but I need some donor parts for research.
 
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Sounds like it might be functioning correctly - 4 occupants (165 lbs) + 331 is max to go into high. So if 991 is exceeded may not go into high.
 
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Sounds like it might be functioning correctly - 4 occupants (165 lbs) + 331 is max to go into high. So if 991 is exceeded may not go into high.
Yes, exactly. I am within that range until I bring my wife. I can’t hardly suggest that she’s the “extra weight” :) that would just be dumb on my part.
 
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Are you using techstream to check pressure values? I'm in Denver and by no means an expert but have successfully fixed my faulty AHC.
Have a techstream ready computer and experience and relative competence in trouble shooting AHC issues.
 

suprarx7nut

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Relative noob here, looking for some advice by those who been in my situation. I read a bunch of posts about AHC mods and OME upgrades.

07 LX470, 180k, been driving the truck for about a year and AHC has been fine until now. I have done only solo trips and no issues. I figure I have 850# over curb weight including my extras, gear, fuel and water, sliders, roof rack, drawer and fridge slide. I read here that factory AHC should be able to raise into H with 4 adults and 350# and I’m in that range until I take my family. But last week on first family trip with wife and child, truck would not move into H, and dropped noticeably (although the L light was not on, I believe it dropped to low mode). When unloaded, it went back into H and stayed there for about 25 mi of rough road. Back home, unloaded it will go into H but I am reluctant to test it far out, especially with wife and 3 year old. The main reason for this vehicle is getting well off the beaten path to remote camp spots with my small family. I’ve spoke to a couple mechanics and received a variety of options.

so, having read here a bunch about AHC tuning and fixes, including LC or king springs...... who here has been able to improve reliability of their AHC with a bleed, new rear springs and tb adjustment?

or, bite the bullet and delete then go with aftermarket lift?

Thanks in advance for your input.
jd
Your approach here is EXACTLY the same as it would be for traditional suspension - you need to adjust/replace your springs. You're currently over weight and with or without AHC, you would need to change springs.

Check pressures with techstream and adjust from there. Easy.

Keep AHC unless your rig is rusted to hell. A conversion is an absolute downgrade, IMO. There is no "upgraded" lift when you delete AHC unless you're talking huge money custom coilovers or something. AHC is very reliable when it's given a small amount of attention.

 

ramangain

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How does that old adage go .... everyone's opinion is correct as long as it is the same as mine. Right?
 

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