Refresh AHC or Aftermarket Suspension?

[lasquintanas]

Hey all! I recently picked up an '06 100 series and the AHC works fine but the rear shocks are shot. The truck has an ARB front bumper and a 4x4 Labs rear bumper with dual swing outs (spare tire & jerry can). So obviously heavier than stock. I like the idea of keeping the AHC working as I know the on road ride quality would be nicer.

Question is, with the aftermarket bumpers on, is that too much weight to sink money into new OEM rear shocks + an AHC refresh? The consensus online seems to be to upgrade to an aftermarket setup which would probably be cheaper depending on how much of the AHC needs work. I daily drive it and while it will see off-road time, it will spend most of it's time on road and don't want to sacrifice too much ride quality.

Bonus advice: If I did go aftermarket, I like the Ironman Stage 3 FCP because of it's relatively low maintenance and value. Would love to know how you're liking your Ironman FCP setups compared to stock.

Thanks guys.

 

[GTV]

There’s probably nothing wrong with your rear “shocks” (actually hydraulic rams) they’re just over pressure and weeping. Change the fluid, correct the pressures and they’ll be fine. Search “ABC’s of AHC”.

 

[mmbirtcher]

I have a 2006 as well with the AHC. Just a rack and belly armor so far, but rear with swing-outs is in my future for sure. I plan to keep the AHC as there is no better riding or handling suspension when dialed in. King springs is what you might need to handle the consistently heavier weight in the rear and adjusting the front torsions should take care of the front. Replacing the rear "shocks" should the last thing. If you don't have TechStream, try to get it or a friend with it to read pressures and other suspension info. It can sound complicated but there's lots of knowledge here and IMHO the AHC is worth it.

 

[Ironman4x4America]

AHC is amazing and I would highly recommend keeping it as long as possible. There is no better feeling than a LC100 with dialed AHC!

But be very aware of the added weight from accessories and how it will affect the vehicle handling. There is a point of no return where added weight exceeds what the stock suspension can support. That's when you will need to swap to heavier coils in the rear and some uprated torsion bars in the front.

Another note with the torsion bars. They are a nice adjustable system to help with weight, to a point. The stock torsion bars can be adjusted but eventually you will run out of down travel and the vehicle will not feel very nice. That's when an uprated torsion bar is recommended. It will support more weight without having to be cranked up a ton, sacrificing down travel. I see a lot of 100's/LX470's with the torsion bars so over cranked that they have very little down travel and handle like a dirty gas station toilet. Its important to try and find that balance of lift, weight support, and down travel in the front. It's best to shoot for a minimum of 65mm of front down travel. This can be achieved and maintained with 2" of lift typically. When you start to push beyond 2" and go more towards 3" you will be really withdrawing alot of down travel and pushing CV angles. Then you start going down the rabbit hole of chasing issues and that gets very expensive.

Lastly, I always suggest getting measurements and keeping a spreadsheet of vehicle data as you build it. With the cruiser on flat ground measure from the center of each hub, straight up to the bottom edge of the fender, record that data. With corner measurements you will see how the vehicle sits today, how much rake or sag it has, and how much list or lean it might have. Any time you change up something in the suspension get your before and after measurements. Any time you add or remove significant weight get your before and after measurements. This will give you precise visibility of how the vehicle is affected by changes in weight or suspension adjustments, and helps you make good decisions on what specific issue might need to be addressed. Also, get some axel weights on a lonely country road truck scales. That will be good info to track and help with suspension setup decisions as well as other upgrades like brakes, etc...

Hope this info helps! Just keep it simple and get rid of weight! Weight causes problems!

Holler if you need anything or have questions.

-Miller

 

[jsloden]

The breaking point for ahc is usually rust. As long as yours is rust free keep it. If the lines are rusty, dump it. If it's in good shape all you should really need is heavier rear springs. One you get the pressures dialed in the rear "shocks" should stop weeping.

 

[jaewastooshort]

if you're still on the OEM rear springs you'd likely be seeing pressures too high on the rear even with a stock setup. If you're using a metal bumper on the rear you almost certainly need a stiffer spring to get your rear AHC pressure in spec. The King KTRS-79 (stock height, increased weight) worked well for me at stock height to get my pressures back where they needed to be. I will probably be pulling them soon and posting them for sale in favor of some increased height springs as I'm doing an AHC spacer/sensor lift, if you're interested.

 

[lasquintanas]

Thanks for the help everyone!

I decided to keep AHC. I ordered new globes from IMPEX for an unreal price thanks to everyone here. Turns out the truck already has stiffer springs (OME 862). I assume these are ok to keep instead of adding the King springs? Should I add the Slee rear 30mm spacer if I have those OME springs already?

 

[GTV]

if you're still on the OEM rear springs you'd likely be seeing pressures too high on the rear even with a stock setup. If you're using a metal bumper on the rear you almost certainly need a stiffer spring to get your rear AHC pressure in spec. The King KTRS-79 (stock height, increased weight) worked well for me at stock height to get my pressures back where they needed to be. I will probably be pulling them soon and posting them for sale in favor of some increased height springs as I'm doing an AHC spacer/sensor lift, if you're interested.

AHC pressure will rise over time as the torsions/coils age. Even a stock weight/height vehicle would benefit from coil spacers, Kings are the next step up.

I’m on Kings as well with stock AHC bars up front. I try to keep things as light as possible but I still have skids, sliders, 40g tank and a bike rack with swingarm 99% of the time. Only a 3/4” sensor lift to match the diff drop. I use a 30mm spacer on the left and a 5mm spacer on the right coil to level it out and add a little more AHC margin. I can’t remember the exact pressure numbers as it’s been a few years but I believe a steel rear bumper would push me over the recommended figures.

I plan on going back to my OEM springs (I too like the extra length) and adding airbags to augment the AHC.

 

[GTV]

Thanks for the help everyone!

I decided to keep AHC. I ordered new globes from IMPEX for an unreal price thanks to everyone here. Turns out the truck already has stiffer springs (OME 862). I assume these are ok to keep instead of adding the King springs? Should I add the Slee rear 30mm spacer if I have those OME springs already?

Those springs are not designed for AHC and are way too stiff. Which is odd considering the leakage from the shocks/rams, they could actually be worn.

You really need to read techstream so you know what your pressures are. Until then everything is a guess.

 

[lasquintanas]

Those springs are not designed for AHC and are way too stiff. Which is odd considering the leakage from the shocks/rams, they could actually be worn.

You really need to read techstream so you know what your pressures are. Until then everything is a guess.

Ok good info thank you! I'll pick up some King springs!

 

[Jlx470]

Thanks for the help everyone!

I decided to keep AHC. I ordered new globes from IMPEX for an unreal price thanks to everyone here. Turns out the truck already has stiffer springs (OME 862). I assume these are ok to keep instead of adding the King springs? Should I add the Slee rear 30mm spacer if I have those OME springs already?

How were the gloves from IMPEX? Are the Oem parts? And how much were they? Thanks

 

[menancyandsam]

FYI, you don't need Techstream to read AHC presures. Many OBD readers can, my icarsoft reader does so. I believe it has to Toyota/lexus specific model.

 

[juicemode]

I read ACH data from my phone using OBD fusion. Very affordable data tool.

 

[lasquintanas]

How were the gloves from IMPEX? Are the Oem parts? And how much were they? Thanks

Globes are still on the way. But I've replaced the OME rear springs with King springs w/30mm spacer and it's already a world of difference.