Towing with AHC

[LandCruiserPhil]

In the past I towed our boat with 06 LC with AHC slightly lifted and 295/70-18's. Although we had plenty of power with the VVT the good amount of tongue made it bouncy and the AHC would go into limp mode if I hit dips hard in the road.

Fast forward 5 years to today with an 06 LX470 same set up but smaller tires and a new approach. Installed a set of Air Lift bags. Measured the normal ride height of the LX, turned off the AHC and hooked up the boat. Pumped the air bags until the same ride height was accomplished less 3/4". Now turn back on the AHC and let it pump the rear up 3/4". The results are a solid feel to the suspension and no chance of seeing limp mode again.

The thought behind my set up is the with the AHC off most of the tongue weight was taken on with the air bags. The bags are rated at a max. of 1000# at 35 psi and I ended up with 30psi to get the ride height where I wanted it. The PSI makes sense with an estimate 600#+ of tongue weight. The next thought was to let the AHC make up the additional 3/4" this would raise the damping level of the AHC.

There is no way with the bags inflated and the boat hooked up to read the AHC pressures so all this is just WAG'n it.

I was a little concerned with running a 30mm spacer Im at a less than ideal set up with the air bags. If anything I might add in a 30mm spacer to the coil pad down the road.

The results seem to give a firm feel but still maintain a Lexus ride without the bounce I had before using AHC. Time will tell if Im on to anything as boating season is here.

Thoughts?

 

[drwapenshaw]

I added aibags too. Works great with AHC, but instead of using height to determine my bag PSI, I used the techstream software and filled to keep pressures in spec. i dont understand why you had difficulty with that. I started with pressures normalized by inflating the bags before hooking up a trailer though. Then added more air as needed for the trailer. I LOVE the flexibility of the airbags.

Eta I would have to look it up from my previous post but I think 9-10 psi works well for no load on my 100 and then I have to go up to @ 22.5 psi for moderate load.

 

[drwapenshaw]

BTW I just looked at your pictures. I love the way your LX looks with the the roof rails and steps removed. I look forward to removing mine.

 

[LostAfrican]

Can you use the three height modes of the AHC to mount and unmount the trailer without having to raise and lower the trailer itself? If you have a camera back there you may be able to do it almost completely from the drive's seat! Trailering LX style.

Bonus step. Once mounted, raise LX to H to drain the boat faster!

 

[TeCKis300]

Can you use the three height modes of the AHC to mount and unmount the trailer without having to raise and lower the trailer itself? If you have a camera back there you may be able to do it almost completely from the drive's seat! Trailering LX style.

Bonus step. Once mounted, raise LX to H to drain the boat faster!

Ayup. I've even used AHC to help reduce the ramp angles of the trailer to unload a really low race car. AHC is really awesome with its flexibility. I've towed my rear motored porsche, with it loaded backwards on the car trailer. That easily puts over 1k lbs on the tongue. AHC handled it like a champ.

The key is the keep the AHC pressures within spec. That means it's super important that the regular mechanical spring is not worn and is holding up its share of the overall weight. By lifting via the AHC height sensors, a disproportionate amount of weight is put on the AHC system and correspondingly taken off the mechanical spring. The proper way is to augment the mechanical spring via a spacer and/or swapping out a longer/stronger spring in place of the lightweight AHC spring.

 

[nahtnoj]

Can you use the three height modes of the AHC to mount and unmount the trailer without having to raise and lower the trailer itself? If you have a camera back there you may be able to do it almost completely from the drive's seat! Trailering LX style.

Bonus step. Once mounted, raise LX to H to drain the boat faster!

Mine won't go to H with the trailer attached, but yeah, my trailer sits low, and last year it was parked in a field and had sunk in a bit. So I put the suspension in L, back under the trailer, raise to N, easy-peasy. I couldn't use the trailer jack because it was just sinking in...

I keep finding new uses for AHC. Such an awesome system.

 

[LandCruiserPhil]

Not sure how accurate my reading are because it will not go all the way down in low when the air bags have air.

Front - 7.4
Rear 6.7
Accumulator 10.1

The road to the lake is twisty, bumpy, with lots of dips. It pulled the boat excellent and the ride was almost better than without the boat. Firm but not too firm, sway was a minimum and it was hard to tell we were pulling once at speed.

What ever the number represent does not matter too much at this point unless something blows up because Im very happy with the results.

 

[drwapenshaw]

Good numbers. Mine does go all the way down but I bet I could put enough air in to stop it as well. That is a big boat and 30 psi is a lot of force so it makes sense that it doenst go all the way down. Its really impressive when you look at it.

 

[LandCruiserPhil]

Good numbers. Mine does go all the way down but I bet I could put enough air in to stop it as well. That is a big boat and 30 psi is a lot of force so it makes sense that it doenst go all the way down. Its really impressive when you look at it.

The jury is still out until the wife experiences it. It will be interesting if anything chances when the boat and LX470 is loaded for a weekend outing. To me right now it rides better than my non AHC Land Cruiser with air bags.

It definitely has way more pulling power with a VVTi motor but water temps are hotter. Not sure on trans temp just yet but I will be testing the trans soon. I do have a condenser fan out of a 99 LC but not wired in yet. More on the heat issues in another thread.

 

[LandCruiserPhil]

After several trips down the bumpy and twisty paved road to the lake the new set up has been wife approved. The ride is excellent with a solid feel and not springy at all. Our last trip with 5 adults and all were surprised with ride quality. We received all thumbs up from all prior to beer. If you are towing or find yourself sometimes with heavy loads this set up is for you.

 

[ntsaint]

Which airbag setup did you use?

 

[LandCruiserPhil]

Air lift

 

[nnnnnate]

I guess I'm a little confused. Do you have rear spacers installed in addition to air bags or are you only using air bags?

We are borrowing my parents camp trailer to go to Oregon this summer and am trying to get my ducks in a row. The trailer specs say the hitch weight is 395# and max weight is just under 5000#. I have bought spacers (not installed yet) and planned to buy air bags to use in conjunction with the spacers to get the back end happy.

Also, what is the difference between pulse and electric brakes? I have the 7 pin connector on my hitch but no electric brake controller in the cab. I'm not sure if I need to find one to use though.

 

[LandCruiserPhil]

I guess I'm a little confused. Do you have rear spacers installed in addition to air bags or are you only using air bags?

We are borrowing my parents camp trailer to go to Oregon this summer and am trying to get my ducks in a row. The trailer specs say the hitch weight is 395# and max weight is just under 5000#. I have bought spacers (not installed yet) and planned to buy air bags to use in conjunction with the spacers to get the back end happy.

Also, what is the difference between pulse and electric brakes? I have the 7 pin connector on my hitch but no electric brake controller in the cab. I'm not sure if I need to find one to use though.

I use a rear spacer because I lifted/adjusted my LX by ~1" with stock height no spacer is needed. With that said I have 1" rear spacers and air bags.

 

[TeCKis300]

^You won't have a problem at all with those kinds of weights. The AHC system is not delicate and actually very capable and robust. Australians regularly modify AHC for even higher weight capacities, and run them through the outback hard.

One thing to understand is, like any normal sprung vehicle, if you load it up, it will sag. The AHC system works likewise outside of a certain threshold which is perfectly normal. Meaning, it's got a constant height capability within a certain weight limit (i.e. 1000lbs, I don't know exactly but it's at least that). When that's exceeded, it goes to a non-constant height mode like a traditional spring system. That is AHC will continue to support the 1000lbs, but the mechanical spring will take up the addition weight beyond that like a normal car by compression and lowering in ride height. The readout on the dash is two things, a height selector and height readout. It may say 'L' because it's telling you that the suspension is now being compressed - which is perfectly normal and not indicative of the system failing in any way!

Even more, the AHC system has dynamic dampening that no other system has. With all that added weight, it can adjust for more dampening. Which means the ride with all that extra weight is still buttery and has control to match.

If only all those people that chucked AHC understands what they're missing...

In general, I'd say it's good to throw in spacers as that will bring back some of the constant height capability due to the suspensions mechanical springs age (imagine those non AHC trucks that have the same age issue dragging their rear ends now). 30mm spacer rear. And 3.5x turns to each front torsion bar to bring it completely back into spec. So instead of 1000lbs of constant height capability, it will have 1300lbs of constant height performance (again, ballpark) If you want more, there are upgrade springs and/or airbags for more.

~5600lbs and 850lbs tongue. Tows beautifully. I have it in 'L' in this picture for my kids to get out, but it never dropped to L when I didn't want it to.

 

[nnnnnate]

Thanks for the replies and what you said about the "L" in the cabin is really interesting. I took some scouts on a trip outside Moab last year and towed my home built offroad trailer loaded with water, fuel, and gear. I built the trailer last spring so I hadn't had it out much and this was really the first extended towing I had done with the LX. I got a little nervous when the dash was showing low because I thought that meant my AHC wasn't doing great but checked my pressure numbers when I got back and found them to be okay but not horrible.

On the trip I figured I had loaded up the tongue too much and that was causing the AHC to drop. I've got room for 6 fuel/water cans on the front deck of the trailer and loaded up a few other heavy things up front in the box as well. I didn't necessarily notice that it had actually dropped into low but was worried none-the-less about it.

I'll be the first to admit that I don't know a ton about towing but its the tongue weight that is going to make the rear end squat right?

I don't necessarily want to lift the whole rig but would like to get back to OEM factory specs which is why I bought the spacers. I think I was told they were 25mm rather than the 30mm that are common to see purchased here. They might be older Slee stock that I bought from Cruiser Outfitters but I still need to measure them.

I'm fairly certain this thought process is flawed but I was thinking that when I added the spacers to the rear the AHC sensors would recognize the change in height and adjust down on its own. Thats not accurate is it? I hadn't planned to turn the torsion bars but I guess I will need to.

Thanks again for the help.

 

[bhicks]

If you put spacers in the rear and don't adjust the sensor then the AHC will adjust the ride height back to stock. You will just have more weight on the springs and less on the AHC. Your pressures will decrease a bit but your ride height will not be affected. this is what happened on my LX. I eventually raised the rear about 1.75" which then put too much load on the AHC so I added the OME 10mm trim packers in conjunction with the MAF 30mm spacers and my pressures were back to almost stock. Once I removed the 3rd row my pressures were identical to the pre spacers stock set up. the new BIOR rear bumper going on is going to mess all that up again and I will have to figure out something new to get the pressures back to stock. Probably some non AHC coil springs will get me close.

 

[bozncsurf]

If you put spacers in the rear and don't adjust the sensor then the AHC will adjust the ride height back to stock. You will just have more weight on the springs and less on the AHC. Your pressures will decrease a bit but your ride height will not be affected. this is what happened on my LX. I eventually raised the rear about 1.75" which then put too much load on the AHC so I added the OME 10mm trim packers in conjunction with the MAF 30mm spacers and my pressures were back to almost stock. Once I removed the 3rd row my pressures were identical to the pre spacers stock set up. the new BIOR rear bumper going on is going to mess all that up again and I will have to figure out something new to get the pressures back to stock. Probably some non AHC coil springs will get me close.

Have you checked out the King springs from Australia .. apparently they are the oem height but stiffer?

 

[bhicks]

Have you checked out the King springs from Australia .. apparently they are the oem height but stiffer?

I already have a set of 80 and 100 series stock rear springs. I will start with those and see how my pressures look. I will probably have to either remove the trim packer or the 30mm spacer to get it dialed in.

 

[bozncsurf]

I already have a set of 80 and 100 series stock rear springs. I will start with those and see how my pressures look. I will probably have to either remove the trim packer or the 30mm spacer to get it dialed in.

Good stuff. Could you keep us updated with your findings? I know others have successfully used the 80 springs but they arent the easiest things to source if you're looking for an un-abused / beat to death pair.