Adding weight to stock AHC

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

ohernia24

ohernia24

Joined
Mar 6, 2025
Threads
3
Messages
52
Location
New Mexico
Forgive me for probably beating a dead horse here with this post, but I plan on giving my 06 LX a few new parts for looks and functionality when cruising some moderate trails.
- Adding 240lbs total: front bumper (100 lbs), sliders (120lbs), and skid plate (20 lbs)
- Removing about 100lbs: stock front bumper assembly (40lbs-ish?), stock running boards (30-40lbs), and also did some exhaust work so stock muffler and resonator are gone with a new Flowmaster in lieu of those (30-40lbs).

Netting only 140 more pounds.

I plan to flush the AHC fluid for new, as well as get tech stream and get my pressures within desired ranges after everything is added. I’ve seen the posts on how to properly do that.

My question is: If I’m hauling 4 guys with camping/hunting gear around with the new parts listed I’m around 1000lbs (I can’t find a definitive answer on gross weight for stock AHC I know it’s about 1000) so should I be concerned if going on forest service roads, etc. in a fully loaded situation?
The AHC is stock @175k and I’ve never had any issues or suspicions that it’s degrading, but just wanted some feedback if I should be concerned, take any other precautions, possibly add new springs, etc. Thank you!!!!
 
Sort by date Sort by votes
Upvote 0 Downvote
Jack90210 said:
Non-AHC springs are substantially stiffer than the Kings.
LX470 AHC spring rate = 95 lbs/in
King = 130
LX450 = 150
100 = 170

Info from this post in the thread Updating AHC system
Click to expand...
Just went through that thread, that's great to know. Thanks for sending that. Definitely need to get a baseline reading and go from there on if I even need an aftermarket spring
 
Upvote 0 Downvote
ohernia24 said:
Specific part number for those? Or just look up any LC 100 rear springs
Click to expand...
No specific number, I just got a used set of a non-AHC Landcruiser 100 series. They have been under the car for 9 years now.
With the additional weight on my car, it just works.
 
Upvote 0 Downvote
Finally bought a CReader Elite scan tool and was able to check AHC pressures (I can add a link if anyone is interested in the reader). Front was 8.3 and rear was 7.4. That was with a new bumper (check my new profile pic), but no sliders yet. Both a little high. I’ll probably adjust torsion bars once the sliders are on and hopefully get them close to spec. I’d imagine my rear springs are pretty old hence the higher back pressures. I think spacers might be a solid option for me to lower the rear. My accumulator pressure seemed to be right at spec though at 10.5. Will add new pressure readings once I get my rock sliders, those are still a few weeks away.
For normal specs reference
  • Front spec: 6.9MPa +/- 0.5
  • Rear spec: 5.6-6.7MPa
  • Accumulator spec: 10-10.6MPa
 
Upvote 0 Downvote
Hello ohernia24,
Once you follow the correct procedure and adjust your front torsion bars to get your front pressure to be 6.9 MPa, it may raise your rear pressure a bit.
Here's the correct procedure...

Perform AHC Height Check

Check Height at Normal Height at All 4 Corners (Level Ground, SUV Running, Full Tank of Gas):
- Front should be 19.75” Hub Center to Fender
- Rear should be 20.5” Hub Center to Fender

Adjust Torsion Bars to get the Front Cross Level
- 1 Complete (360 Degree) Turn on 1 Torsion Bar Bolt will raise / lower that corner ~1/8”
- The goal is less than 1/4” Difference

After the Front is Cross Level...

Perform AHC Pressure Test

SUV with a Full Tank of Gas.
SUV on Level Ground.
Disconnect Fluid Temperature Sensor (Optional…)
- On the side of the pump assembly, rear connector with 2 wires
- Center connector with 3 wires is the pressure sensor
- Forward connector with 2 heavier blue and white wires is for the pump motor

***Change Vehicle Height to L.
Wait 60 Seconds.
Change Vehicle Height from L to N.
Wait 30 Seconds after N is reached.
Read Front Pressure.
Front Pressure should be 6.9 MPa.

If Front Pressure is Higher than 6.9 MPa, adjust Torsion Bars.
1 Complete (360 Degree) Turn of Both Torsion Bar Bolts will lower the Pressure by 0.2 MPa

After Adjusting Torsion Bars, Repeat Step ***.
If Front Pressure is now 6.9 MPa, the Front is Correct.

Read Rear Pressure.
Rear Pressure should be between 5.6 & 6.7 MPa

If Rear is not in Spec, purchase new rear AHC springs or coil spacers (30mm or similar).
Note: 30mm Spacers only decrease your rear pressure by around 0.5 MPa.

You only need to Install Higher Rate Rear Coil Springs (like King Springs...) if you're always carrying extra weight (like an Aftermarket Steel Rear Bumper w/ a Spare Tire Carrier).

Installing New Rear Coil Springs and / or Spring Spacers will not change the Rear Height of your SUV.
It will only change the Pressure in the Rear of the AHC system.

The AHC System supports part of the weight of your SUV (via Hydraulic Pressure), while the Front Torsion Bars and Rear Coil Springs support the rest of the weight of your SUV.
The more weight the Torsion Bars and Coil Springs support, the less weight the AHC has to support.
There is a happy medium as to how much weight each supports.

Note: You should also replace your AHC Fluid (if it hasn't been done recently), perform a Graduation Test (to make sure your Globes are healthy), and perform a Pump Test (to make sure your Pump is healthy).

I hope this helps.
Tom
 
Last edited:
Upvote 0 Downvote
Snow Wagon said:
Hello ohernia24,
Once you follow the correct procedure and adjust your front torsion bars to get your front pressure to be 6.9 MPa, it may raise your rear pressure a bit.

Note: Correct Procedure is:
- Cross Level Front via Torsion Bars
- Adjust / Turn Torsion Bars to get front to 6.9 MPa
- Read Rear Pressure and Make Educated Decision on How to Address (Which New Springs or Spacers)

30mm Spacers only decrease your rear pressure by around 0.5 MPa.
I doubt that's going to get you into the 5.6 to 6.7 MPa range.
This is most likely because your current AHC springs are old / tired and you've added a little weight.

If I were you, I'd buy new Toyota / Lexus AHC Coil Springs, since you've added very little weight.
There's a few threads with part numbers.
IMO, King Springs are going to be stiffer than you need, so I don't think I'd go that route.

Good luck.
Tom
Click to expand...
Thank you Tom! Much appreciated
 
Upvote 0 Downvote
I would not wait to adjust T-bars. Driving around with front 8.3 Mpa, is very hard on Globes and shocks (seal). Adjust T-bar now (clean and lube threads first) to bring down pressures. Tweak, when sliders added. Once front in speck. We'll often see rear Mpa, come down a bit.
 
Upvote 0 Downvote
2001LC said:
I would not wait to adjust T-bars. Driving around with front 8.3 Mpa, is very hard on Globes and shocks (seal). Adjust T-bar now (clean and lube threads first) to bring down pressures. Tweak, when sliders added. Once front in speck. We'll often see rear Mpa, come down a bit.
Click to expand...
Definitely. Will do that this evening. Thank you!
 
  • Like
Reactions: uHu
Upvote 0 Downvote
2001LC said:
I would not wait to adjust T-bars. Driving around with front 8.3 Mpa, is very hard on Globes and shocks (seal). Adjust T-bar now (clean and lube threads first) to bring down pressures. Tweak, when sliders added. Once front in speck. We'll often see rear Mpa, come down a bit.
Click to expand...
Was about to say the same.
 
Upvote 0 Downvote
Forgive me I’m still pretty new to these rigs. I’m wanting to spin bolt one clockwise for both the passenger and driver side? Using a picture from another user. Thank you all for the help. Figured it out. Will post results soon
1776526937514.webp
 
Last edited:
Upvote 0 Downvote
You must log in or register to reply here.

Share this page

Back
Top Bottom