Suspension modification and AHC

[arbetrader]

Hi all, I did a basic search on this but didn't find exactly what I was looking for here...

I'm thinking about purchasing a 200 series - likely an LX as they don't sell landcruisers in my country. I really liked the AHC system in my old LX, but I tow a travel trailer a few times per summer - that has a tongue weight of about 750lb plus 6-7 passengers. The 24ft trailer weighs about 6500lb wet/loaded. Yes, I know I'm overweight. Please try to resist the urge to tell me to get a 3/4 ton - I know both sides of the argument already, trust me.... I'm far more interested in doing this safely and reliably than doing this for legal limitation reasons.

I was considering the possibility of purchasing either OME or Dobinsons springs (rear) coilover (front) and put something like firestone airbags in the rear coils and use them only when towing. The plan would be to disable the factory ahc system when I tow, and rather fill up the firestone air bladders to level out the difference, and ride on E rated tires. I have a very high quality EQ and anti-sway hitch to boot.

I'm currently doing this already with my 2008 Toyota sequoia with air suspension. I do not have any aftermarket airbags though, so all the weight is just on the factory airbags, however I have upgraded the shocks/struts to bilstein 5100s already. So far so good, but I'm sure it's weighing in on the system.

I figure if there's a way to have the best of both worlds (to keep AHC when I'm unloaded) but turn it off (or somehow completely bypass it's functionality while towing), and rely on aftermarket heavier rear/front springs as well as aftermarket airbags to level, and a quality EQ hitch coupled with quality tires - what are things to think about this type of setup?

1. Is there a way to fully bypass the AHC while towing? (the point is to keep pressures neutral with the weight on the tongue) Implications?
2. I'd likely be riding on 275/70/18's.
3. Once I install the heavier suspension it will invariably give the vehicle a bit of a lift, unless I use LC springs, or? I'd be keeping it quite minor, maybe 1" to avoid needing a diff drop kit, but might consider that if I go higher. I'm guessing I wouldn't have to mess with the ahc sensors would I?
4. Anytime I'm not towing I would empty out the airbags and run with AHC, although how would this be affected with dobinsons or OME aftermarket springs? Could I just adjust the sensors and re-adjust the pressure in the ahc system?

Any other thoughts on this would be appreciated. Anyone else done this?

 

[grinchy]

You can increase AHC capacity a little with spacers to increase effective spring rate. there Have been some heavier springs discussed, but they were use for armored, always there weight. Haven’t seen any AHC equipped running bags, but I don’t know why it wouldn’t work. No reason to switch off the ahc, it would adapt to the new bag effective spring rate. Cheap enough to try it out . . . thoigh many have had some trouble getting to the top nut on the rear shock.

 

[TeCKis300]

Hi all, I did a basic search on this but didn't find exactly what I was looking for here...

I'm thinking about purchasing a 200 series - likely an LX as they don't sell landcruisers in my country. I really liked the AHC system in my old LX, but I tow a travel trailer a few times per summer - that has a tongue weight of about 750lb plus 6-7 passengers. The 24ft trailer weighs about 6500lb wet/loaded. Yes, I know I'm overweight. Please try to resist the urge to tell me to get a 3/4 ton - I know both sides of the argument already, trust me.... I'm far more interested in doing this safely and reliably than doing this for legal limitation reasons.

I was considering the possibility of purchasing either OME or Dobinsons springs (rear) coilover (front) and put something like firestone airbags in the rear coils and use them only when towing. The plan would be to disable the factory ahc system when I tow, and rather fill up the firestone air bladders to level out the difference, and ride on E rated tires. I have a very high quality EQ and anti-sway hitch to boot.

I'm currently doing this already with my 2008 Toyota sequoia with air suspension. I do not have any aftermarket airbags though, so all the weight is just on the factory airbags, however I have upgraded the shocks/struts to bilstein 5100s already. So far so good, but I'm sure it's weighing in on the system.

I figure if there's a way to have the best of both worlds (to keep AHC when I'm unloaded) but turn it off (or somehow completely bypass it's functionality while towing), and rely on aftermarket heavier rear/front springs as well as aftermarket airbags to level, and a quality EQ hitch coupled with quality tires - what are things to think about this type of setup?

1. Is there a way to fully bypass the AHC while towing? (the point is to keep pressures neutral with the weight on the tongue) Implications?
2. I'd likely be riding on 275/70/18's.
3. Once I install the heavier suspension it will invariably give the vehicle a bit of a lift, unless I use LC springs, or? I'd be keeping it quite minor, maybe 1" to avoid needing a diff drop kit, but might consider that if I go higher. I'm guessing I wouldn't have to mess with the ahc sensors would I?
4. Anytime I'm not towing I would empty out the airbags and run with AHC, although how would this be affected with dobinsons or OME aftermarket springs? Could I just adjust the sensors and re-adjust the pressure in the ahc system?

Any other thoughts on this would be appreciated. Anyone else done this?

What you're looking to do is not so far off from plausibility or reality. Short answer is that this is very possible to do. And may be less difficult than imagined.

So I understand right, and I'll make some assumptions here
1) 750 lbs tongue weight
2) 7 passengers, 150*7=1050 lbs
Total payload = 1800 lbs

Good news for you is that I'm running in this ballpark of weight. AHC in the 200-series is more capable with payload weights than it was in the 100-series and doesn't really flinch at this level. While still providing a well controlled, damped, and comfortable ride. I likewise don't care for HD trucks and IMO the 200-series offers so much more luxury and comfort for trips.

So you have some reassurance, here's my weights which I've verified on a scale
1) 1200 lb tongue on an 8000lb trailer
2) 6x passengers (2 young kids, 4 adults) = 700 lbs
3) 100lbs gear
Total payload = 2000 lbs

You don't really need any mods to make this work. If you like, you can augment AHC so it can more reliably get in to high mode while bearing this weight with spring spacers front and rear, particularly for example when the rig is on a downhill slope and the trailer tongue weight increases that much more. Airbags can work just as well if you'd like additional support. It's been a proven strategy on the 100-series although I'm not really aware of anyone needing it for the 200-series yet.

This thread may help you with additional setup information

LX570 Tow Report

Got some miles under my belt now towing my current setup: '09 LX570 with '07 Airstream 27FB International Ocean Breeze. Wanted to give a report for others attempting to tow things in the same weight/length range. LX570 mods: 33" AT Load Range E tires (Falken Wildpeak AT3W 305/55/20), 1"...

forum.ih8mud.com

To answer your questions anyways
1. Is there a way to fully bypass the AHC while towing? (the point is to keep pressures neutral with the weight on the tongue) Implications?
No need or way to do this. AHC is integral to the suspension (shocks) and needs to be there to support and provide damping.

2. I'd likely be riding on 275/70/18's.
I previously ran 305/55R20s that measure the exact same overall diameter at 33.2". No issues. I'm running 35s now.

3. Once I install the heavier suspension it will invariably give the vehicle a bit of a lift, unless I use LC springs, or? I'd be keeping it quite minor, maybe 1" to avoid needing a diff drop kit, but might consider that if I go higher. I'm guessing I wouldn't have to mess with the ahc sensors would I?
Again, no need for this because of how robust AHC is already. I have OEM front spacers and 20mm worth of rear spring spacers to help maintain payload capacity as I sensor lifted .75" front and .5" rear.

4. Anytime I'm not towing I would empty out the airbags and run with AHC, although how would this be affected with dobinsons or OME aftermarket springs? Could I just adjust the sensors and re-adjust the pressure in the ahc system?
You can try airbags if you'd like, but may not need at all.

 

[Mago]

Upgraded AHC suspension..