Adding weight to stock AHC

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ohernia24

ohernia24

Joined
Mar 6, 2025
Threads
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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!!!!
 
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GVWR - 6860 (Door sticker or plate should have it, go by that number)
Curb Weight - 5590 (this is including the weight of gas/petrol)
Total payload left - 1270
PXL_20260322_070643112.webp


The AHC system should be able to handle that payload number.
So with that 1k + 140 you'd be just and under and should be fine.
 
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I agree. Driving an 06 LC with AHC and ran around a lot of forest roads and mild trails with stock suspension. When I added the ARB drawer set, I added the King KTRS-79 rear coils. That got me back in spec and was required for the additional towing of the Chaser as well.

There is a lot of good info in those springs here on the site.
 
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x8o8drifter said:
GVWR - 6860 (Door sticker or plate should have it, go by that number)
Curb Weight - 5590 (this is including the weight of gas/petrol)
Total payload left - 1270
View attachment 4107247

The AHC system should be able to handle that payload number.
So with that 1k + 140 you'd be just and under and should be fine.
Click to expand...
Good to know about the sticker, never would have known that. I sure appreciate the info
 
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RKRUGER said:
I agree. Driving an 06 LC with AHC and ran around a lot of forest roads and mild trails with stock suspension. When I added the ARB drawer set, I added the King KTRS-79 rear coils. That got me back in spec and was required for the additional towing of the Chaser as well.

There is a lot of good info in those springs here on the site.
Click to expand...
Good to know! A lot of my added weight will be near the front, and I don’t plan to ever tow with my LX. I’ll still have to look in some posts about them
 
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Rear Coil Springs - KTRS79 by King should help your rear end keep up the weight. Once AHC rear pressures go over threshold, it will set to LOW setting to avoid complete system failure. Front AHC can be mitigated by cranking your torsion bars to get the correct pressure but rear does not have that adjustability.
 
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To reiterate.
You should be fine IF the weight you said is how much weight you add. Find it a bit hard to believe the stock system couldn't handle the max stock load it can have.

I doubt you ride around most of the time with that weight, so IMO there'd be no point in throwing money at a non-existent problem.
Be the guinea pig and see/post what the pressures are with leaving everything stock.

The pressures right now, with the new bumper/slides/skid plate and the last one with all your gear and buds would be the best thing.
I bet the pressures will be fine for the first 2 and maybe a touch high for the last one.
But like I said, I doubt you'll be running that last weight a lot. So what tiny bit of life you'll lose in the system parts would far outweigh buying parts you dont need.

This is all assuming you are starting at proper/in spec pressures which I see no reason for not having right now.
 
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There is a maximum weight the system can handle before it drops to Low. That is for the front and the rear.
 
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OEMGUY0720 said:
Rear Coil Springs - KTRS79 by King should help your rear end keep up the weight. Once AHC rear pressures go over threshold, it will set to LOW setting to avoid complete system failure. Front AHC can be mitigated by cranking your torsion bars to get the correct pressure but rear does not have that adjustability.
Click to expand...
That’s the second recommendation on the King rear coils, I’ll look into those here soon. Makes sense to support the end with no adjustment.
 
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x8o8drifter said:
To reiterate.
You should be fine IF the weight you said is how much weight you add. Find it a bit hard to believe the stock system couldn't handle the max stock load it can have.

I doubt you ride around most of the time with that weight, so IMO there'd be no point in throwing money at a non-existent problem.
Be the guinea pig and see/post what the pressures are with leaving everything stock.

The pressures right now, with the new bumper/slides/skid plate and the last one with all your gear and buds would be the best thing.
I bet the pressures will be fine for the first 2 and maybe a touch high for the last one.
But like I said, I doubt you'll be running that last weight a lot. So what tiny bit of life you'll lose in the system parts would far outweigh buying parts you dont need.

This is all assuming you are starting at proper/in spec pressures which I see no reason for not having right now.
Click to expand...
It’d definitely be a rare occurrence to have near max weight. I definitely need to see where they’re at after the install of parts. I’d be happy to post what they are. Will be a few weeks til everything is installed.
 
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Only nearing upper weight limit, part time. Just flush and adjust. If then, seeing 9 grads or better H to L, your good.

Air bags are nice, if carry above max weight, part time.
King coils, are great, if above max weight, full time.
Kings coils & spacer are needed, if doing sensor lift.
 
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ohernia24 said:
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!!!!
Click to expand...
It has all been said by others in the previous replies in this thread -- succinctly summarised by @2001LC in Post #13 above.
The only specific mention in the FSM in relation to AHC weights for LC100 and LX470 is as shown in the extract below. This does not fully answer your question but it does give some guidance:

AHC Load Limits.webp

The KIng KTRS-75 springs are a good solution, widely used. In my case, with these springs fitted (in 2019), the Rear AHC pressures are slightly lower than the FSM-specified range when the vehicle is unloaded, giving a slightly firmer but very acceptable ride. The ride is made perfect by adding load or persons or in my case a couple of grandchildren. The advantage of the KIng KTRS-75 springs is that unless there is a fault somewhere, the "sinking feeling" of the AHC system at its limits is never experienced (except possibly in extreme overloads).

It is also possible to experiment with a small "sensor lift" as a fine-tuning step to slightly increase Rear AHC pressures if concerned about excessive Rear AHC pressure reduction due to the KIng KTRS-75 springs -- but being careful not to excessively increase the Front to Rear rake of the vehicle.

However, 'ride comfort' is in the eye (or the backside!) of the beholder. Satisfaction about comfort for one person is not necessarily satisfaction for another. Seven years later, my King KTRS-79 springs are still in place, no regrets, and they are likely to remain there indefinitely.

In my case, at the time the King KTRS-79 springs were fitted, air-bags also were added inside the KTRS-79 coils to cater for very unusual and extreme loads. This proved to be 'overkill' -- it was done to accommodate the possibility of heavy towing -- but both KTRS-79 springs and air-bags are not needed in ordinary circumstances.

As mentioned by others, air-bags inside OEM AHC Rear coil springs are a good solution for occasional heavy loads. The air-bags can be kept at ~5 psi to hold their shape but do no work, and air can be added at say 10 to 20 psi via conveniently located Shrader valves and a bicycle pump (or similar) when the OEM coil springs require assistance.

All that said, if in doubt, my recommendation would be to replace the now 20 years old and possibly tired OEM coil springs with King KTRS-79 springs and be done with it.

AHC Rear Height Control Sensor.webp


AHC with Airbag Assist and KING KTRS-79 coils.webp
 
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IndroCruise said:
It has all been said by others in the previous replies in this thread -- succinctly summarised by @2001LC in Post #13 above.
The only specific mention in the FSM in relation to AHC weights for LC100 and LX470 is as shown in the extract below. This does not fully answer your question but it does give some guidance:

View attachment 4107890
The KIng KTRS-75 springs are a good solution, widely used. In my case, with these springs fitted (in 2019), the Rear AHC pressures are slightly lower than the FSM-specified range when the vehicle is unloaded, giving a slightly firmer but very acceptable ride. The ride is made perfect by adding load or persons or in my case a couple of grandchildren. The advantage of the KIng KTRS-75 springs is that unless there is a fault somewhere, the "sinking feeling" of the AHC system at its limits is never experienced (except possibly in extreme overloads).

It is also possible to experiment with a small "sensor lift" as a fine-tuning step to slightly increase Rear AHC pressures if concerned about excessive Rear AHC pressure reduction due to the KIng KTRS-75 springs -- but being careful not to excessively increase the Front to Rear rake of the vehicle.

However, 'ride comfort' is in the eye (or the backside!) of the beholder. Satisfaction about comfort for one person is not necessarily satisfaction for another. Seven years later, my King KTRS-79 springs are still in place, no regrets, and they are likely to remain there indefinitely.

In my case, at the time the King KTRS-79 springs were fitted, air-bags also were added inside the KTRS-79 coils to cater for very unusual and extreme loads. This proved to be 'overkill' -- it was done to accommodate the possibility of heavy towing -- but both KTRS-79 springs and air-bags are not needed in ordinary circumstances.

As mentioned by others, air-bags inside OEM AHC Rear coil springs are a good solution for occasional heavy loads. The air-bags can be kept at ~5 psi to hold their shape but do no work, and air can be added at say 10 to 20 psi via conveniently located Shrader valves and a bicycle pump (or similar) when the OEM coil springs require assistance.

All that said, if in doubt, my recommendation would be to replace the now 20 years old and possibly tired OEM coil springs with King KTRS-79 springs and be done with it.

View attachment 4107929

View attachment 4107933
Click to expand...
This is very helpful info I sure appreciate it. I think before buying anything aftermarket I'll see what the pressures are with a considerate load. Using your extract numbers... with my new parts and 4 guys (not 150 each more like 200 each....) I'm still about 300 lbs under. I think I've actually used my AHC in high mode 1 time? I have larger tires and I've never been in a situation where I had to actively use the AHC in its high setting. Also no towing for me. So I'm not too worried about load capacity in high the setting. I think the KTRS-79 will come into play if my pressure readouts are not ideal. Seems like a flush and T-Bar adjustment is within my needs for now, using all of the helpful feedback and previous posts so far.
 
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GTV said:
I have Kings as well. If you want it to sit level put a 10-15mm shim on the left side.
Click to expand...
This is usual for LHD vehicles (due to driver and fuel weighted to tbe Left side) --not needed for RHD vehicles ....
 
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