AHC Lift With Full Range

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xirforever

xirforever

10 Year
Joined
Feb 19, 2012
Threads
9
Messages
86
Location
Dallas, TX
Guys, I have been doing some reading around but I can't seem to find anyone who has done what I'd like to do. Therefore, I'd like to get some options from the knowledge base here.

Let me start by saying, I really like my AHC. I know many don't, but I find it really convenient and a good piece of engineering. What I'd like to do is lift the vehicle 1"-2" all the way around without using the system outside of its normal operating conditions. And what I mean by this is by 'tricking' the system to make N a taller position. I am considering two paths to take, please give me some input on both.



OPTION 1
Adding rear spacers for the springs to get me 1" at the rear and still keep my globe pressures within spec. Obviously I'd adjust the bars on the front to do the same. (I will also have to adjust the sensors..) There are two things I don't know about if I go this route:

1. Will the system fail to go into H mode from a position that is already 1" taller than the standard N position?
2. My shocks will not rest in the intended position for the rest of its life, what are the negative effects of this?



OPTION 2
On the more extreme side, I am considering to engineer some spacers between my shock mounts and the shocks to get my range back at the intended position. With this route I will be able to lift more than 1" sense everything will be equal on the lift. This would look like:

All components would be equal in height
1. Shock spacers (x")
2. Rear spring spacers(x") (or possibly FJ80 springs)
3. Front bar adjustment to equal x", or purchase standard LC bars and do the same
4. Bump stop drops also equal to x"

This method I can choose X to be any height I want as long as it is within reason. This way my system can function as intended, I cover myself from bottoming out the shocks in a destructive way by adding equal length bump stops, and all should be good, right?

Please let me know what you guys think! Obviously option 2 is much more work than option 1, but the yields are far better.

Edit 4/7/15 - picture added
Option Comparison Chart.webp
 
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Many people have done as you suggest in option 1. As long as you do everything you said and bring the AHC pressure back into spec after the lift using techstream software, you should be good. I would add a differential drop to keep your front axles from wearing prematurely if you go more than 1 inch on the lift. Yes you will still have L N H

There has been talk of making spring spacers in several threads but I have not found anyone who has actually done it. Good luck and post up your results because this is on my list of things to do.
 
I could be mistaken, it happens pretty often, but I think the key to tricking the AHC is all about the height sensors. The other stuff helps keep pressures and range of motion at stock. Until you adjust the height sensors it will continue to find the original N. That being said I'm interested to see how this tracks out as I have thought about adding an inch or two with the AHC.
 
The problem will in any case always be the angles of the front suspension parts. There is no good way around it without a lot of work.

Just put on 33" instead of 31" tires, and you are 1" up. Go to 37", regear, body lift, cut some body-fat, move rear axle, and you're even higher. That's the way.

You could go to 34" tires, tweak 1/2" ahc lift, and you're 2" up. Compromise.

Why would you want a lift in the first place? Higher COG is not beneficial. What kind of driving do you do? (or is it for posing only o_O)

Here's one on 38":
getfile.aspx
 
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I have been pondering the exact same questions. I will be following this thread closely.
 
Thank you all for the responses!

Okay, it seems as though option 1 has been confirmed and option 2 people seem very interested in, with the two biggest obstacles being the diff drop (bolt on kit) and a suspension geometry concern brought up by uHu (valid point).

uHu said:
The problem will in any case always be the angles of the front suspension parts. There is no good way around it without a lot of work.

Just put on 33" instead of 31" tires, and you are 1" up. Go to 37", regear, body lift, cut some body-fat, move rear axle, and you're even higher. That's the way.

You could go to 34" tires, tweak 1/2" ahc lift, and you're 2" up. Compromise.

Why would you want a lift in the first place? Higher COG is not beneficial. What kind of driving do you do? (or is it for posing only o_O)

Here's one on 38":
getfile.aspx
Click to expand...

uHu, I believe the setup I desire are 33" tires and a 2" lift from option 2. I don't really want to go crazy with the setup and put 37's on it, but I'd like a little bit more than maybe just a 2 inch lift with half of it coming from tires. If I am going to go through the trouble of option 2, then I will do more than a very mild lift.

The reason? I used to trail my 4runner pretty hard before i upgraded to the LX, and I'd like to get back there. I am currently wrapping it in flat green to protect my paint from light tree scratches and I have only trailed it once so far and I don't plan to do any more until i finish the wrap. However, I also happen to appreciate the look of a somewhat more aggressive stance, so I won't lie, I like the look too. But being an engineer, I think I like the look for a different reason than most people lol.

So, with that setup in mind, can you please dive a little deeper into your comment about the angles of the front suspension? How bad would the situation be with a 2" lift? I know people on here are always buying the 2.5" lifts, maybe someone on here with one can post about it?

I took a really quick look at the top of the shock and it looks like Toyota is going to make this really difficult on me. I think I will have time more to take a wheel off tomorrow night and investigate further.

On the upside, if i do the lift maybe my poorly engineered EMS exhaust will stop rubbing on my drive shaft flange......
 
I'm thinking about fabbing up some 1-1.5" spacers up front for the shocks and then adjusting the front AHC sensor that same amount. That should give me a level ride and allow some 33"-33.5" tires. I should still be able to use the "HI" function on the AHC when I'm on the trail to give me that added little clearance.
 
I have used option #1 on 2 AHC Lexus/Toyota will no issues.

Both along with another lifted 100 series have never been equipped with diff drops. I have over 100K on lifted 100 series with no diff drop and no problems. FLame - on
 
I'm running Option #2 (more or less). I have 2" rear shock extensions, 30mm spring spacers (w/ 80 series coils), 2" lowered bumpstops, extended brakes line(s) & extended sway bar links. Basically, the rear suspension travel is no greater than stock but the shocks/dampers operate at roughly 40/60 up-to-down travel ratio with 2" of lift vs ~60/40. It definitely wheels better in the 40/60 configuration... less wheel lift.

I have 1.5" front shock extension brackets (equates to ~2" at the wheel) but have been apprehensive about using them... and the effect it might have on my steering rack due to the angularity of the steering arms/TRE when the IFS is fully drooped. We tried them before and at times, the front wheels had a very pronounced toe-in when one side was fully extended and one side compressed. I think .75" shock extensions (or a modified shock mount) would be more ideal.
 
hoser said:
I'm running Option #2 (more or less). I have 2" rear shock extensions, 30mm spring spacers (w/ 80 series coils), 2" lowered bumpstops, extended brakes line(s) & extended sway bar links. Basically, the rear suspension travel is no greater than stock but the shocks/dampers operate at roughly 40/60 up-to-down travel ratio with 2" of lift vs ~60/40. It definitely wheels better in the 40/60 configuration... less wheel lift.

I have 1.5" front shock extension brackets (equates to ~2" at the wheel) but have been apprehensive about using them... and the effect it might have on my steering rack due to the angularity of the steering arms/TRE when the IFS is fully drooped. We tried them before and at times, the front wheels had a very pronounced toe-in when one side was fully extended and one side compressed. I think .75" shock extensions (or a modified shock mount) would be more ideal.
Click to expand...

where did you get the front and rear shock extensions? Cost? Pictures? Why are you running 80 series springs out back and are the 30mm spacers for an 80 series spring?
 
I sourced the extension brackets from Japan many years ago. There are several companies that offer them, these were manufactured by Zeal. You can try asking @sonk76 , as he purchased them more recently from Japan4x4. The 80 series springs and 30mm spacers were to accommodate the extra weight. There are many options to get the desired ride height/AHC pressure. (non-AHC 100 springs, LC80 springs---two DS or two PS, as they are different in height, 10, 20 & 30mm spring spacers.)

60mm Rear Brackets (shows 4, only 2 needed) 5000 Yen/pr:

4WD07_P0647_04_S0424.webp


40mm Front Brackets, 6000 Yen/pr:

4WD07_P0645_07_S0424.webp
 
hoser said:
I sourced the extension brackets from Japan many years ago. There are several companies that offer them, these were manufactured by Zeal. You can try asking @sonk76 , as he purchased them more recently from Japan4x4. The 80 series springs and 30mm spacers were to accommodate the extra weight. There are many options to get the desired ride height/AHC pressure. (non-AHC 100 springs, LC80 springs---two DS or two PS, as they are different in height, 10, 20 & 30mm spring spacers.)

60mm Rear Brackets (shows 4, only 2 needed) 5000 Yen/pr:

View attachment 1055127

40mm Front Brackets, 6000 Yen/pr:

View attachment 1055128
Click to expand...

Thanks for the info. So in theory If I added these 40mm spacers to the front and adjusted the front AHC sensor then I would keep the factory ride quality but sit 40mm higher in the front correct? I would also still be able to go into the "H" and "L" AHC settings for the front correct? Right now my factory stance/rake is about 1.5-2" higher in the rear and I would much prefer a more level stance. Once the front bumper and winch are mounted my current rake will get a LOT worse. some shock spacers should be able to help that.
 
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No, I won't recommend the 40mm extension at the front at this time. Adding a front bumper and winch will not change the front height significantly. The AHC will compensate for the extra weight until the AHC pressure exceeds some preset threshold and at that time it will revert to LO. I don't think a bumper and reasonable sized winch would be enough to overload it. However, it will be putting extra stress on the system. And so...

If you want to bring the front up an inch, just adjust the front height sensors for desired height (typically 1" lower than rear). Buy $35 tech stream software cable and cheap old PC laptop, then crank front T-bars until you are 'in-spec.'
 
hoser said:
No, I won't recommend the 40mm extension at the front at this time. Adding a front bumper and winch will not change the front height significantly. The AHC will compensate for the extra weight until the AHC pressure exceeds some preset threshold and at that time it will revert to LO. I don't think a bumper and reasonable sized winch would be enough to overload it. However, it will be putting extra stress on the system. And so...

If you want to bring the front up an inch, just adjust the front height sensors for desired height (typically 1" lower than rear). Buy $35 tech stream software cable and cheap old PC laptop, then crank front T-bars until you are 'in-spec.'
Click to expand...

Will that approach affect ride quality?
 
The spring rate and damping factor will remain the same. Any difference in ride quality or feel will be due to suspension/steering geometry changes. Most people would find it acceptable or imperceptible.

P.S. No need to quote the post directly preceding your reply.
 
I'm going to assume there is some write up someone has done that walks you through the "tech stream" method and cranking on the T-bars? Looks like I need to do some research now that I have a good idea on what I want to do. Thanks for the info. Is there a good place to pick up the tech stream software and cable?
 
Thanks for the link. I'm at work so all of the links are blocked. When I get home I will check it out and get the tool ordered.
 
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