Is an AHC Mod necessary?

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1meancruiser

1meancruiser

10 Year
Joined
Mar 5, 2012
Threads
53
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444
Location
Southern California
I have a 2006 LC with AHC. I'm running Metal Tech sliders (210 lbs), front brush guard (60 lbs), and I am looking at adding a roof rack (70 lbs).

I'm planning on a 350 mile trip to Yosimite this summer and there are 6 of us going, total weight of passengers and luggage will be right around 1,000 lbs. Again, not including 270lbs of sliders and brush guard, and a rack weighing 70 lbs which I don't have yet, and may have for the trip.

Will the AHC hold up? Should I traded out the AHC rear coils with 80 series coils given my daily driver will only be 270-340lbs or so above stock? lastly, should I consider air bags for the AHC coils in the back?

The LC is 7 years old and has 39k miles on it currently, any advise will be much appreciated.
 
artwerks said:
Here is some info for you that I've been reading recently. I've been wondering the same things myself as I have an '03 LX with almost 140k miles and I'm looking forward to sliders, winch bumper in the front, spare tire carrier bumper in the rear, etc... and I want to keep the AHC if I can.

https://forum.ih8mud.com/100-series-cruisers/604577-definitive-list-ahc-maintenance-items.html

Good luck ;)
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Thanks! I recall seeing this thread sometime back. I scanned through it again and couldn't find anything definite on using 80 series springs. I'm not crazy about air bags as everyone I've discussed it with says they will not last.
 
You will definitely want to do something about this. AFAIK the AHC going to LOW is a failsafe based on pressure, not wear (aside from the amount of spring lost on T-bars and Coils) which means if anybody is having issues w/ weight and AHC, it makes sense for you to respect it as well.

My AHC is much older @ 130k and 13 years, but it finally went to LOW for the first time after adding winch + bumper + sliders (same as yours), so like 300+lbs.

It is very sensitive to that front load vs distributed between the wheels.

My AHC neutral pressures were at 10.5 mpa, which is 40% over what it should have been. It took 13+ cranks on the t-bars to get it in spec.

I'd take care of your AHC since it should have so much life left on it. I'm looking for stock LC springs myself, for when I get my rear bumper installed.
 
Mine still rides in N with bumpers, rack, winch, sliders, loaded drawers, empty aux tank and wife, dog and I in it. However add 45 gallons to aux tank or load it up and I ride in L. But this happened when newish when two buddies and I would go on a hunting trip completely loaded. And that was when I didn't have a single mod yet.
 
You'll absolutely want to adjust the springs and re-calibrate the AHC neutral pressures for several reasons:

1) You added additional static weight reducing weight carrying capacity.
2) The stock springs will definitely have sagged to put the AHC system just out of spec with the neutral pressures high even for an '06, and again reducing the weight carrying capacity.
3) You'll get better ride quality in terms of dampening with the system in spec.

In terms of dialing things back, I think you can get away with tweaking the torsions up front and adding a 10-15mm trim packer in the rear. I'd shoot for the low side of all neutral pressures to maximize carrying capacity. With the added weight needing more spring preload, you might also want to run the dampening setting one step higher than normal.

In an overweight condition, running the system at L height (note not L mode) is still completely viable and safe. It's what any standard spring based system would be doing anyways. Just that the AHC system attempts to be constant height within its normal capacity range. When it needs, it will ride lower transferring more weight onto the standard springs to keep the AHC springs operating within a functional pressure range. Just that everyone freaks out because we have an indicator that serves two purposes - AHC mode and suspension height. Usually the mode selection and resulting height correlate. When laden, the height readout indicator may tell us the very normal fact that a heavily laden car will compress the springs and ride lower in Normal AHC mode.
 
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Guys, thanks for a lot of helpful information. It look like i'll be buying the techstream kit. Is there any way to get a pressure reading from my OBDII diagnostic tool instead of buying the techstream tool?

Also, have any of you done the 80 series coil conversion? i'm looking into the trim package as well.
 
1meancruiser said:
Guys, thanks for a lot of helpful information. It look like i'll be buying the techstream kit. Is there any way to get a pressure reading from my OBDII diagnostic tool instead of buying the techstream tool?

Also, have any of you done the 80 series coil conversion? i'm looking into the trim package as well.
Click to expand...

I've run both the spacers (20mm) and the 80 series coils. Both helped the system to cope with the extra weight. The new coils continued to be able to help where the spacers were not enough. ...

...now I'm contemplating adding a single 10mm spacer to the 80 coil as I keep on adding weight.
 
sonk76 said:
I've run both the spacers (20mm) and the 80 series coils. Both helped the system to cope with the extra weight. The new coils continued to be able to help where the spacers were not enough. ...

...now I'm contemplating adding a single 10mm spacer to the 80 coil as I keep on adding weight.
Click to expand...

Can you tell me at what approximate weight you went to spacer, then 80 coil, then coil and spacer?

Also, which spacer brand did you get, I was looking at Ironman at 15mm or 30mm but no 20mm?
 
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