TOWING: Airbags and AHC (1 Viewer)

[mrand]

hey guys
there are quite a few threads on this but none are definitive so I was hoping to get some clarity in one thread. Hopefully this will help many who are in my same predicament.

I have a LC 2006 with AHC and towing a heavy load. I'm looking to install airbags and hoping to continue to use AHC.
- is it possible to use airbags with the AHC system? Lots of differing opinions on this. But it seems many have done it and hoping they can speak up and bring clarity.
- I am considering airbags from airlift(part#60728)
- the big question is the OEM rubber stopper inside the coil spring (part# 48313).
*Some say to remove the rubber stopper (is that a safety concern if the airbag pops)?
*some say to leave it in (is there enough room for the rubber stopper and the airbag)?
*and Some say to cut it down (if so, how much...the airbag is variable in length based on PSI)

and lastly, my shocks are worn out and I'm replacing the shocks, bushing, washers, nuts...entire system. Should I also replace the coil spring while i'm in there. The vehicle is riding level now but I'm ok to baseline the entire system if that is advised.

Mine is a 200k LC....no rust, very good condition

here is a parts diagram to simplify this discussion
- many thanks everyone

 

[06 flstfise]

While I can not give any info on the AHC issue I thought that this was a good video to watch prior to installing mine.

 

[Snowrydr01]

I did bags with ahc to help keep my pressures in check since I had sagging springs. The added benefit was the ability to dial in the neutral pressures between daily driving with the family and long fully loaded road trips.

I removed my inner bumpstops so my bags could fit properly. I ran the lines independent so I needed a second hose kit, the original wasn't nearly enough.

 

[mrand]

Thats great info. Do you remember which manufacturer and model you went with?
Did you have any concerns about removing the bumpstops?
Do you (or others) feel it would make more sense to cut the bumpstops to a minimal height so there is some cushion for the entire shock system if the bags fail? I have some concerns just based on practical/what - if scenarios upon a failure and what that means for the entire shock system without a cushion....but you are the one with the experience (I've towed for years, but have 0 experience with airbags)

And thats helpful info about the second hose kit. Thanks for sharing your thoughts.

I'm hoping this thread can become the definitive AHC/Airbag thread for everyone that still has questions.

 

[06 flstfise]

I have the airlift system in my 05 LC. I did remove the bump stops as i found it easier to remove then to cut. I did use a step bit to open up the bottom plate and did line it with some tubing that i had laying around. I also took time to run the air lines up and out of the way and in any area that there could be contact i lined them with tubing to ensure that they wouldn't get sliced. I do have the advantage to having access to a lift any time i need so that made it easy to route lines. I have had no issues or concerns about the bags failing. I keep maybe 5psi in them to ensure they don't move when I am not towing or loaded down. I put my fill valve by the trailer wire connector. I am sure you have seen this thread in your search but another good reference.

Air Lift 1000 Install



@taco47001 installed with AHC so maybe he will chime in

 

[Snowrydr01]

Here is what i used.

https://www.amazon.com/gp/product/B001F15YYA/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B000CFO04U/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

A step bit is absolutely needed.

I had no worries about removing the bump stops. I would hope i could identify one rear spring operation at a different rate then another (because the were plumbed separately) well before a very unlucky suspension failure to the point of actually needing a bump stop from keeping the axle from laying on frame.

 

[mrand]

Thanks everyone this is so helpful.

Snowrydr01 - what year is your 100? Great to know that you have AHC and you have no problems. Do you turn off your AHC when you tow. There is obvious added benefit to leave it on assuming it doesn't throw the system off. Does it?

06FlstFise - thanks for the link. Somehow I missed that one. Great to know you also have AHC. Do you keep it on when you tow?
Also what tubing do you use to protect the lines. Another fantastic idea. Cheap but redundancy is key when towing. I love backups when a lot is on the line.

And do you guys think I should replace my coil springs while I'm in there? I've already purchased new shocks and am considering the coils if someone with more experience can shed some light on it. My vehicle sits level, but the shocks are very weak and definitely worn out (200k miles). The coils are only $127 each, not cheap but could be worth it.

 

[mrand]

reason I keep asking whether you keep AHC on or off is bc airlift highly recommends I turn AHC off. They say it will compete with their system. But I'm not really sure why.

my hope is to only keep 5psi in the airbags as suggested when not towing (with AHC on)
and when towing adjust, to achieve a level tow (also with AHC on)

Can someone advise on this?

 

[BEG]

reason I keep asking whether you keep AHC on or off is bc airlift highly recommends I turn AHC off. They say it will compete with their system. But I'm not really sure why.

my hope is to only keep 5psi in the airbags as suggested when not towing (with AHC on)
and when towing adjust, to achieve a level tow (also with AHC on)

Can someone advise on this?

You can't turn AHC off. The springs/t-bars are designed to work with AHC and only support a percentage of the vehicle weight on their own. That being said, there's no competition between the two systems, that I can see. The AHC needs to be kept within a certain pressure range. If the vehicle + load/tongue weight causes the AHC to exceed that pressure, the air bags can be used as helper springs to boost the coils' load bearing capacity and put the AHC back within range.

 

[PADDO]

reason I keep asking whether you keep AHC on or off is bc airlift highly recommends I turn AHC off. They say it will compete with their system. But I'm not really sure why.

my hope is to only keep 5psi in the airbags as suggested when not towing (with AHC on)
and when towing adjust, to achieve a level tow (also with AHC on)

Can someone advise on this?

You realize that AHC will turn itself back on above 50mph (when at N, or at 19mph if at H), even if you started out with it turned OFF? And if you pull fuses to force the self leveling to stay off above 50mph then you also loose your adaptive variable suspension. Lots of people fit helper bags with AHC, works as intended. Dropping to L or getting back to N can be an issue with the bags too inflated as when you lower the vehicle you compress the bags progressively and they’ll tend to hold the vehicle up. Removing, or shortening, the inner cone buffer as individual installation instructions call for isn’t so catastrophic if you have a bag blow out as you’ve the additional frame rail mounted bumper that’ll buffer against the axle. It’s probably 3/4 in shorter then the cone buffer, but it’s still a buffer.

 

[Snowrydr01]

I dont really tow but with wife, 2 kids, big dog, rear full and roof box full my neutral pressures would be way too high. I use the bags so i didnt need to buy new springs. I would charge the bags while checking my neutral pressures to ensure that i am in the operating window for my AHC to last as long as possible.

I believe my daily pressure is 8lb to account for my 18yr old sagging springs. When i fully load, i break out tech-stream again and then add air slowly until my neutral pressures are where they should have been with the truck empty. and i note that number. When i arrive at my destination and unload i air the bags back down to 8, and when i load back up for the ride home i air them back up to what they were at and know itll be pretty close. This way i dont stress the AHC system and the truck operates as it was intended.

 

[mrand]

Just wanted to thank everyone for their gracious replies. Incredible information and very helpful. Bags are on the way and I'm going to the extra trouble of replacing entire OEM shock system and OEM coil springs. I'm know that is overkill but I don't want to take any chances and would rather start at baseline since I'm getting in there anyway.

 

[BEG]

Just wanted to thank everyone for their gracious replies. Incredible information and very helpful. Bags are on the way and I'm going to the extra trouble of replacing entire OEM shock system and OEM coil springs. I'm know that is overkill but I don't want to take any chances and would rather start at baseline since I'm getting in there anyway.

Check out the King springs for AHC. They're affordable and have a rate somewhere between the OEM AHC coils and the OEM conventional coils. They're a pretty yellow color too!
Regarding the OEM "shocks," the hydraulic rams (look like conventional shocks) rarely need replacing unless they're leaking badly. The globes (on the frame rails) do go bad after a while. Lots of OEM and aftermarket options available for these.

 

[BJJCruiser]

Check out the King springs for AHC. They're affordable and have a rate somewhere between the OEM AHC coils and the OEM conventional coils. They're a pretty yellow color too!
Regarding the OEM "shocks," the hydraulic rams (look like conventional shocks) rarely need replacing unless they're leaking badly. The globes (on the frame rails) do go bad after a while. Lots of OEM and aftermarket options available for these.

The king springs on eBay look to cost less than factory ones. I'll be getting a set soon.

 

[Snowrydr01]

I used the bags because i couldnt decide what to do with my suspension. I go back and forth with removing the AHC so i didnt want to spend the money on new AHC springs to bring pressures back in range. The bags let me help the springs and if i decided to go LC suspension they would fit in them too so i wasnt out any money.

 

[mrand]

ok I'm still confused on one thing. Can you guys check me on my thought process
My '06 AHC landcruiser has weak shocks. I've towed for years and you can push on the back end and tell its been worn out over the past 200k miles.

so thats why I'm installing airbags of course for safe towing

I was going to replace the shocks myself and Toyota parts tried to talk me out of it. He said its not easy on an AHC LC because of the hydraulic components and other complications. Lots of things can go wrong unlike simpler non AHC shocks. He recommends the dealer does it or a qualified shop. He has no skin in the game, since he works in parts and is willing to take the parts back. Just a nice guy trying to help. But I'm not fully convinced

2 questions:
1. I'm handy but have limited shock experience, is this something I can do myself or is it complicated as he says on AHC system?
2. my intention of replacing OEM shocks is to get the vehicle back to "factory" condition...for times when I'm loaded down with other equipment in the cargo/on roof. I don't want to rely on airbags as a replacement for shocks but rather as a supplement when towing to level the rear end of the vehicle with heavy loads. Toyota parts says it could be other issues in addition to shocks (specifically the accumulators)

at this point I am scheduled to have shocks replaced by Toyota Monday morning and then install the airbags myself. Knowing the above context, is this a good move? It just seems practical to me that if I stand on the rear of the vehicle I can instantly tell the shocks are weakened. Also, the vehicle is fine during regular driving and doesn't bounce or anything. It just feels like an old station wagon in the back end. 200k miles and I would think those shocks are worn.

a bit confused and would love to hear from someone who knows the truth
thank you guys and value your expertise

 

[BEG]

The actual shocks (globes) are located on the outside of the frame rails, screwed into the actuators. They're pretty accessible. Replacement is similar to replacing a set of brake calipers, or any other hydraulic component (relieve system pressure, remove and replace, refill and bleed). You'll probably deal with some stuck bleeders, and you'll need to either use a strap wrench or source a thin 36mm wrench (Ford fan clutch wrench works, IIRC). It would be a good time to flush all of the AHC fluid.

I will say that if the vehicle doesn't drive poorly, I would hold off on that kind of investment. At least until you tackle the easier stuff. Make sure your AHC pressures are correct (might require adjusting the torsion bars, possibly installing a rear spring spacer or new springs), flush the fluid and see how it feels. That might be all you need.

 

[Snowrydr01]

Do some more research, it sounds like you are thinking of shocks in the conventional sense. On an AHC vehicle what looks like shocks are more similar to hydrolic rams the dampening happens somewhere else in the system. The globes mentioned above is usually the RnR part.

 

[mrand]

yes I already have the OEM hydraulic shocks in hand. (see parts diagram below)
just wondering if this will help my weak rear end suspension. Some say yes, others say no. Not sure what I'm missing

 

[Snowrydr01]

yes I already have the OEM hydraulic shocks in hand. (see parts diagram below)
just wondering if this will help my weak rear end suspension. Some say yes, others say no. Not sure what I'm missing

View attachment 1655529

Unless it is leaking I would say no, all it does is turn the up down movement of the suspension into moving fluid, the dampening and rebound are not controlled by that piece like a normal shock