What are the Pro's and Con's of an AHC system? (1 Viewer)

[porkandcorn]

I originally posted a thread a month or so back, searching for adjustable valve suspension systems with electronic in-dash control for my 04 LC. I was wanting a great ride on the freeway, plus on the trails. Plus, I have a height restriction in my garage. With my rooftop tent, and the adjustability would allow me to sneak under when I'm home from the trails, whereas most 1-2" lifts would have me scraping my tent. As it turns out, that thread's user suggestions to just get a LC/LX with AHC were wise. I wasn't previously aware it existed. And when I was aware, I was simply having trouble accepting it was my perfect solution, due to not entirely understanding the system, and because of an emotional attachment to my LC of 15 years that does not have it. Saw the AHC demostrated on an LX470, and immediately got over my emotional attachment. I want that s***! Now my plan is to look for a 06/07 Silver LC w/ AHC, or LX470, and when I find it, will turn that into a full-blown overlander, knowing I can creep into my garage, and also having height adjustability to gain clearance on trails.

I've spoken with a couple outfitters and trusted Toyota mechanics, and the general concensus is that the AHC was designed to adjust for a heavy rear 'expedition' load, and so the weight of my planned storage drawers, cooler, swing gate, long range tank, etc, will eliminate the need for any suspension modifications or upgrades...

That said:

Does anyone have any experience or knowledge about the pro's and con's of an AHC system on the 100 series?
What modifications that can be made to the AHC suspension system (if any) to improve it, and what are the limitations of those modifications?
With a typical 'expedition' weight load, does AHC they perform as designed in all the modes (Low, Normal, and High)?

Thanks for your wisdom in advance.

 

[ramangain]

Seek out the excellent video posted by @suprarx7nut

 

[suprarx7nut]

I originally posted a thread a month or so back, searching for adjustable valve suspension systems with electronic in-dash control for my 04 LC. I have a height restriction in my garage at 8 ft. With my rooftop tent, and the adjustability would allow me to sneak under when I'm home from the trails, whereas most 1-2" lifts would have me scraping my tent. As it turns out, that thread's user suggestions to just get a LC/LX with AHC were wise. I wasn't previously aware it existed. And when I was aware, I was simply having trouble accepting it was my perfect solution, due to not entirely understanding the system, and because of an emotional attachment to my LC of 15 years that does not have it. Saw the AHC demostrated on an LX470, and immediately got over my emotional attachment. I want that s***! Now my plan is to look for a 06/07 Silver LC w/ AHC, or LX470, and when I find it, will turn that into a full-blown overlander, knowing I can creep into my garage, and also having height adjustability to gain clearance on trails.

I've spoken with a couple outfitters and trusted Toyota mechanics, and the general concensus is that the AHC was designed to adjust for a heavy rear 'expedition' load, and so the weight of my planned storage drawers, cooler, swing gate, long range tank, etc, will eliminate the need for any suspension modifications or upgrades...

That said:

Does anyone have any experience or knowledge about the pro's and con's of an AHC system on the 100 series?
What modifications that can be made to the AHC suspension system (if any) to improve it, and what are the limitations of those modifications?
With a typical 'expedition' weight load, does AHC they perform as designed in all the modes (Low, Normal, and High)?

Thanks for your wisdom in advance.

All this info is covered in the forum pretty well. Just have to spend some time reading. Here are my quick answers.

1. AHC can handle around 1000 extra lbs of weight over its "calibrated" weight. However, to maximize reliability, you want to calibrate it close to your heaviest load-out.
2. You "calibrate" by watching neutral pressures as you adjust the torsion bars and swap in and out rear springs/spacers.
3. The AHC hydraulic system supports a relatively fixed amount of weight. The mechanical springs (torsion bars up front and coil springs in the back) can be modified to an extremely wide range and are how you tailor the system to your needs.
4. Buying aluminum armor, where possible, helps keep the system closer to the factory intention regarding weight and improves ride and one would presume, longevity.
5. When buying an AHC vehicle, it's important to understand that most owners (and unfortunately most mechanics) don't understand the system, nor how to maintain or diagnose it. Plan on buying new globes unless they're already replaced recently. They last around a decade. Plan on the current pressures being out of spec high. Unless somebody has checked them in the last few years, they will almost always be off. Fluid is almost always too old as well. Fluids lasts around 30k miles/3 years.

Pros are variable height, sportier suspension in a comfier package than any of the common traditional setups can offer.
Cons are complexity. While I'm a believer that you can maintain the system without much added cost and that all complexity is worth it, it is inherently more complex. You need to be ok with that.

To understand how the testing and basic pressure maintenance works, check out my Youtube video on it.

 

[GTV]

The only pro I’ve experienced with mine is when I slam it on 33’s I get a little chuckle.

 

[Apex 153]

Decidedly non techy answer: In addition to being able to lower AHC to fit into the garage, it's sometimes convenient to position your hitch under a trailer in "L" and hit the "H" button. Obviously, engage the lock and connect the chains if moving more than a few yards, but great for a quick trailer reposition at the campsite or in the driveway without having to hop in and out of vehicle. Also a great way to justify a Dissent rear bumper if you don't lock the trailer and it pops off the receiver ball

 

[DanInDenver]

Slamming it into low low low as you roll up to the light
Then flexing to high before the light changes.

 

[ramangain]

Slamming it into low low low as you roll up to the light
Then flexing to high before the light changes.

You should lead the Mr. T marketing department

 

[medtro]

Pro: AHC is working

Con: AHC isn't working

 

[CanadianRockyCruiser]

AHC is awesome if it is properly maintained. The ride, and range of stiffness is great for highway driving and offroad. It isn't going to beat huge suspension lift offroad, but AHC is a nice jack of all trades. You get a 2" lift if and when you need it, on command. You get stiff highway driving suspension in sport mode. The system is very versatile and last a very long time compared to most suspension systems.

 

[kwon-offroad]

Comfort over washboards alone is worth it.

 

[Trunk Monkey]

I'd say it's a huge pro if it's working properly, as has been said. Con is that it's a complex system, can be difficult to diagnose issues without proper equipment (techstream), and subsequently expensive to repair if misdiagnosed or unable to DIY.

 

[J1000]

AHC rules. Cheap and easy to maintain. The biggest expense would be the globes when they finally wear out but they go 300k usually and $1500 to replace all 4 with OEM which is totally reasonable for the performance and lifetime and a DIY level project. OP your plan is a great one. I have probably over 1000 miles on dirt roads or trails this year plus towing a heavy trailer and love it. I wheel hard and it's never given me a problem yet but I'm also on top of maintenance and inspecting it regularly. If you are going to have a static load all the time like with a drawers system, swingouts, etc, then add heavier rear springs otherwise air bags compliment AHC very well.

 

[Shortpencils]

How tall is your tent?

With 33's, neutral height, Gamiviti rack and Alucab awning (11 inches total above roofline), I'm just at 7 ft.

AHC will cost you a helluva lot if you have to buy a new to you truck to get it.

 

[ScottyS]

I was in the same boat as you, OP. I also chose to stick with it for the reasons suprarx7nut details. I am close to having mine "set up", as I've gradually been adding weight to the vehicle and modifying stuff.

My modified config so far is not as dynamic as "stock" AHC with no cargo or armor, but it still is workable. I can go from L to N to H with a full load (and slight adjustments to my airbags), as well as keep pressures within spec even with cargo, armor, and a motorcycle on the back. This flexibility is what I was looking for, even if there is some trial-and-error + manual adjustment involved.

 

[silver02accord]

I had ahc heights and pressures dialed before adding aluminum skids, sliders, land shark reef drawers and loading it up with gear, fridge etc. Do I go back to the drawing board and check heights and pressures with the rig loaded now? Adjust torsion bars as needed(maybe have to add spacers at rear) to get as close to factory spec?

All this info is covered in the forum pretty well. Just have to spend some time reading. Here are my quick answers.

1. AHC can handle around 1000 extra lbs of weight over its "calibrated" weight. However, to maximize reliability, you want to calibrate it close to your heaviest load-out.
2. You "calibrate" by watching neutral pressures as you adjust the torsion bars and swap in and out rear springs/spacers.
3. The AHC hydraulic system supports a relatively fixed amount of weight. The mechanical springs (torsion bars up front and coil springs in the back) can be modified to an extremely wide range and are how you tailor the system to your needs.
4. Buying aluminum armor, where possible, helps keep the system closer to the factory intention regarding weight and improves ride and one would presume, longevity.
5. When buying an AHC vehicle, it's important to understand that most owners (and unfortunately most mechanics) don't understand the system, nor how to maintain or diagnose it. Plan on buying new globes unless they're already replaced recently. They last around a decade. Plan on the current pressures being out of spec high. Unless somebody has checked them in the last few years, they will almost always be off. Fluid is almost always too old as well. Fluids lasts around 30k miles/3 years.

Pros are variable height, sportier suspension in a comfier package than any of the common traditional setups can offer.
Cons are complexity. While I'm a believer that you can maintain the system without much added cost and that all complexity is worth it, it is inherently more complex. You need to be ok with that.

To understand how the testing and basic pressure maintenance works, check out my Youtube video on it.

 

[Shortpencils]

I had ahc heights and pressures dialed before adding aluminum skids, sliders, land shark reef drawers and loading it up with gear, fridge etc. Do I go back to the drawing board and check heights and pressures with the rig loaded now? Adjust torsion bars as needed(maybe have to add spacers at rear) to get as close to factory spec?

Yes.

 

[suprarx7nut]

I had ahc heights and pressures dialed before adding aluminum skids, sliders, land shark reef drawers and loading it up with gear, fridge etc. Do I go back to the drawing board and check heights and pressures with the rig loaded now? Adjust torsion bars as needed(maybe have to add spacers at rear) to get as close to factory spec?

Definitely yes.

I mean, not back to the drawing board, but you do need to redo your AHC tuning. Spacers in the rear sound like a likely need because much of that weight is in the rear.

 

[silver02accord]

Definitely yes.

I mean, not back to the drawing board, but you do need to redo your AHC tuning. Spacers in the rear sound like a likely need because much of that weight is in the rear.

Thank you, makes perfect sense. Will be interesting to see how much pressures changed to get it moving.

 

[porkandcorn]

Thanks for you input everyone. I know I don't need AHC, but in speaking with other AHC owners, and hearing comments on here, it's definitely something I'd like to have. It boils down to complexity vs. convenience.

 

[ramangain]

Well, top tip would be to sell your rig locally and buy elsewhere, perhaps FL, TX, or AZ. The 100 series prices in the PNW are outrageous. For instance, my rig can probably sell for 30% more in Eugene than when I was in Orlando.