AHC and adding lots of weight

[Wilsil]

I know there are several topics, but after going through lots of them I can't find the answers I am looking for as every one has a different setup.

What I am lookking for is the following.
My plan is to install the following items to my early 2002 LX470 while retaining the AHC:
- ARB Sahara bar
- ARB dual spare wheel carrier
- long range tank (182 liter)
- second battery, most probably in a battery box in the rear
- the car will be towing a Kimberley Kamper SportsRV Limited Edition
- 2 adults and 2 kids (kids still under 10)
- winch with preferrable synthetic rope in the future

The trips we will be doing will be remote, so fridge in the back, recovery gear etc.
With all this additional weight, I am pretty sure that the car will not go into Normal mode.
What is the way to go and remember I want to keep the AHC if possible. Or point me to the correct topic if I could have missed it.

 

[lexi4darin]

Wilsil, I don't have answers but to expand on your thread, I had a post a week back about the same thing.

My original post, "Any ideas as to how the LX would ride if I changed the torsions and coil springs over to LC parts (but left the AHC in place and functional)?

I'm planning on adding some weight to the car and would like to eliminate some of the swaying and squishy ride feeling of the LX in it's stock form."

Anyone with ideas on how AHC will handle and what's the deal with adding LC parts to the LX to compensate.

 

[Yukon LX]

For what i have now, i love my AHC. It is Cadillac silky on the highway, and gets fairly tight in sport mode. Everything in between can really fit what you need offroad for moderate use. However, it does not have a chance against the weight you are going to add. With your plans, it will sag hard at night and bounce back and forth as you drive it. I am one of the few who really like the system while it last, but i believe that is just too much.

FYI, i believe i am pushing it as is with an ARB comb, Sliders, tools and recovery gear in the trunk, no rear bumper(bare frame), third row removed, and a bunch of other crap bolted on and sitting in it.

As long as it lasts, it i good with me. However, i already have parts, work, and full instal sourced for when it dies.

 

[1loudLX]

Even if you add stock LC t-bars and springs to the equation to help lift the truck back up, the damping from the AHC shocks will more than likely not be enough to keep that much weight under control safely. I suggest replacing it all with less complicated(non-AHC) shocks, tbars and springs. Sure the AHC system is working now but what about when you're in those remote areas?

 

[Wilsil]

Agreed Loud.
I am not sure if the settings of my shocks are working. If I change the setting from comfort to sport I don't notice a difference.
However I like it very much when I hit the H button and the car moves up when I have an obstacle on the track.

 

[hoser]

Wilsil, Loud is spot on. With that much weight, it's not only a matter of springs but also damping. If one was really inclined to make it work, they'd probably add a secondary set of shocks in the rear in addition to different springs.

 

[jdlsantos]

Waoo, this site is incredible!

I am working on the same thing right now, let's see if my progress and comments, can help here.
I am not mechanical expert, and I am not good writing, so, everything here is susceptible to improve, and still under testing.

Problem: Tire size limited, weight capacity limited.
Root cause: LX stock Tbar & springs are too soft (weak)
Goal: Get the right lift to fit big tires, increase the weight capacity for expedition build, and keeping the AHC working for nice ride.
Solution: Improve the Tbar & springs properly rate for the expected weight keep the balance weight balance between Tbar & springs / shocks & AHC.

Gral info & assumptions
Play the scenarios with the stock weight truck and get the right lift to fit the big tires, and understand the AHC, the second step will be increase the weight until get the expected weight (for expedition stuff).

LX470 2006, tires 315-75-r16

The ACH work is relying X% of weight load on the springs/tbar and Y% on the shocks/AHC for a total of 100%, so, the idea is to replace the TBar & spring to increase the weight capacity of the truck but keeping the balance of weight load between the spring & shocks.

w/o AHC or shock intervention = means that one of the system bleeder is open in order to release the pressure and rely all the weight load just on the tbar & spring. (This must be with the truck off and never turn on during the procedure)

Lab # 1.
I installed OME TB and rear slee spring, I did following the standard procedure + adjusted the height sensors to the new normal height (1.52 volts), the end measures are (see below), from the center of the hub to the fender.
FR 21 ½
FL 21 1/2
RR 23 1/2
RL 23 1/2

Conclusion: bad ride on truck, too stiff and bumpy, the AHC still working in normal and high position. Tbar & spring getting all weight load and total weight is not enough to rely the right weight load to the shocks, + the height sensors were not set properly.

Lab # 2.
I re-indexed the OME TB in order to drop the front end to 21" both sides w/o AHC or shock intervention, also installed stock 80 series springs on rear getting 20” w/o AHC or shock intervention, and re-ajust the height sensor at 2.33 volts.
FR 21 7/8
FL 21 5/8
RR 23 5/8
RL 23 1/2

Conclusion: The ride is so nice, like stock but noisy by the MT tires. The tbar & spring are giving me 21” on front and 20” on rear, and the shocks & AHC are giving me almost 1” more on front and 3.5” more on rear, so, I guess that the weight load is balanced. The AHC still working on all 3 position (Hi, normal, Low) and the suspension control still working on all position (comfort, sport, etc)

The good news is that the height sensors are adjusted properly, and this is the hard part of the lab, I need to take the pressure on the AHC system now, and see if I can put the weight on, or if is necessary to replace the springs for others stronger, and crank little big the tbar.

Technically I should be able to see the system pressure through the AutoEnginuity, but I can’t those specific sensors.

Special tools used:
Multimeter, 3 bateries AA, wires c/alligator, AutoEnginuity scan tool.

My thoughts, I am not sure if is good idea to use the AHC for an expedition truck, because if the system get toasty in the middle of the trails, will be very bad, also I don’t know how reliable is this system under this stress conditions, honestly, I am doing all those test for funny and for enjoy the AHC for awhile, but I know that at the end, I will install the standard suspension.

 

[Wilsil]

Wow, that is a lot of work.
I know that Daz in South Australia has done it on a couple of LX470s, but I think that the best will be to go to conventional suspension. Especially with all this weight and the mileage of the car: 227,000 kms (141,051 miles?)

 

[Kigiin]

I have front/rear bumpers, sliders, winch with rope, FR roof rack, 45 gallon FR aux tank, and loaded drawers - still using AHC. Even with another 25 gallons of gas in jerry cans plus a passenger I don't have a problem.

The truck does ride in low fully loaded - well it's not really low just not normal height. But it did this 10 years ago when 2 buddies and I loaded it up for hunting trips.

 

[jOnathN]

AHC ride quality

Wilsil, if you cannot tell a difference in ride quality between position 1 (full soft) and position 4 (full sport) then your hydro springs (aka globes or spheres) are almost certainly shot either front or rear (maybe both). If you load a lot at the rear and/or two it's probably the rear. If you have a lot of miles it may be both.

Swapping the globes is not cheap but it is trivially easy* and the difference in ride quality is amazing.

Even with completely flat spheres the ride on my 2004 was better than a non-AHC LC and with new spheres at the rear it is as good as my old Range Rover was on air...magic carpet ride.


*replacing the spheres requires a 36mm fan clutch wrench (to loosen the spheres), a 10mm wrench (for the bleed plugs), and a hose/bucket (to catch the bleed fluid). Best to spray a little PBlaster around the day before. Very, very easy.

 

[Wilsil]

Probably the best ay is to change over to conventional. As some said: it is more reliable but in the bush.
How much lift gives the Sleed 2.5" system over Normal?

 

[1loudLX]

You can dial as much lift as you want in the front, that's the advantage of the torsion bar setup. In the rear it's just a matter of picking your desired spring. For me I have Slee 2RHs, lots of load capacity without too much lift. The best way to pick your rear spring is talk to someone at Slees and tell them your intentions with the truck and expected load out.

 

[Wilsil]

I better talk to someone local.
There is a limit to the front lift with IFS.

 

[lexi4darin]

Wilsil- you can life the front however you want. The IFS limit I would guess you are referencing is the stress on the CV joint and the diff. Most guys on Mud are lowering the front diff to counter act the extra stress a lift would place on these parts.

 

[TeCKis300]

Even if you add stock LC t-bars and springs to the equation to help lift the truck back up, the damping from the AHC shocks will more than likely not be enough to keep that much weight under control safely. I suggest replacing it all with less complicated(non-AHC) shocks, tbars and springs. Sure the AHC system is working now but what about when you're in those remote areas?

With AHC being an active system, it's likely that it has enough dynamic dampening range to handle a heavier load. The trick will be to keep the system sufficiently cool as it attempts to handle the heavier load. Given it's layout and fluid volume, it wouldn't be too hard to add some passive heat sinks.

I think we often forget that AHC is not just height control, but a very sophisticated active dampening system. It should offer significantly better performance (body control, sway, roll, etc) than a passive system under just about all conditions when setup right.

An augmented and well tuned heavy AHC setup is very possible with good durability. Like any other wear item, changing the globes and fluid should just be looked at as regular service intervals.

I commend jdlsantos for tackling this lesser road traveled.

 

[lexi4darin]

I'm hoping to add a winch, sliders, and a drawer system. So ill add a lot less weight than OP'er. I thought LC tbars and springs would help compensate the weight but also add to an improved and flatter handling loaded and especially unloaded. When I am loaded down, I'm no where near the weights of other truck on mud.

 

[00N8]

An augmented and well tuned heavy AHC setup is very possible with good durability. Like any other wear item, changing the globes and fluid should just be looked at as regular service intervals.

I commend jdlsantos for tackling this lesser road traveled.

What is the general miles when the globes should be changed? Like the OP I can't really tell the difference when I switch the suspension modes around. How much are they to replace? When I had my fluid changed it was black and nasty.

 

[jOnathN]

>What is the general miles when the globes should be changed?
As early as ~75k miles (?) but most of the "I'll swap out my AHC when it dies" discussions on 'mud are truck over 100K. I'd say if you are either at 100K (wear and tear) or 10 years (rubber aging) they probably need replacing.

>How much are they to replace?
About $500 each via the internet. Beno or CDan can match and may even be cheaper. One aftermarket maker also (LX 470 Suspension Accumulators | Nitrogen Globes | Land Cruiser Damping Globes) but their track record on 'mud is mixed.
Try changing out just the rears first...that's the end of the truck that gets abused the most. The fronts may last longer. At ~120K my rears were completely flat but the fronts are still tolerable (not great but not killing me).
Also need about 2 quarts of hydraulic fluid. AHC uses a mineral oil (NOT brake fluid). Toyota's official AHC fluid varies from $40-$70 a can depending on the dealer. I've read at least one note that LHM+ is an equivalent substitute (internet) - Castrol, Motul, and pthers make LHM+. Pentosin CHF (very similar mineral oil) probably also works; most of the euro cars with active suspensions use that (e.g. citroen, MB).

Changing just the fluid will help too, is very easy, and is a good idea just to prevent corrosion and crap buildup in the pump/etc.

 

[00N8]

Ouch, $500 a pop? I can see why everyone just pulls the system out and puts in normal suspension. I got the fluid all flushed already, I'm not sure how to diagnose if the globes are trashed or "flat" as you say. Are they diagnosed visually or in another manner?

 

[TeCKis300]

I'm not sure if it's a difference of perspective, but I always find it interesting that people balk at the price for globes.

Granted, it’s pricey relative to standard suspension components. In the world of high end automobiles, or high end suspensions and coilovers, it’s par. What you get in return is something that is quite unique in flexibility and capability. With rather few compromises *if* setup correctly. That’s the thing though, is that you can’t just slap 500lb+ of static additional weight without augmenting it as jdlsantos has done. A service life of 100k+ miles and 10+ years is solid in my book. Guess I’m just use to coilovers for sports cars that are $2k+ with rebuilds every 50k miles.