OEM Front Spacer Install for AHC Suspension

[TeCKis300]

Why:

1. More suspension travel to a full 10”, matching rear suspension travel. Spacer allows more droop travel by ~.75” than stock shocks allow.
2. More front axle payload capacity by pre-loading the front shock assembly for normal heights. This is because AHC relies on two sources for support: 1) AHC hydraulic pressure 2) Coil spring
3. Maintain payload capacity and AHC pressures for front axle sensor lifts.

How:

Spacer part number - 43136-60020

Installation mirrors suspension installation for non-AHC 200-series cruisers. With added steps to work with the AHC hydraulic line at the top of the shock assembly. This trades not having to deal with KDSS on LCs

A great video reference for 90% of the install once again provided by @OTRAMM


AHC specific steps

1. (optional) Get baseline normal ride heights at all 4 corners. Note these heights will not change with the spacer install, unless also performing a sensor lift with the spacer install. Always measure on a level surface, and after raising to normal position from low.
2. Set AHC to normal height
3. Lift vehicle
4. Fully release hydraulic pressure from front left and right front wheel accumulators via bleeders. Located forward between the frame rail and side steps on each side.
5. Follow video installation above.
   a. Tip – no need to untorque both lower control arm bolts to get enough droop of the LCA to release the shock body. I found releasing the forward bolt good enough.
   b. Caution – Do not hyper extend and damage the CV axle with. Be aware of the position of the hub carrier after removing the upper ball.
6. Before removing the shock assembly, remove AHC line at the top. The line is a slip fitting held in place with 2x 12mm bolts. Most of the pressure should be relieved, but wear goggles and use a towel around the fitting as it wiggled up and off.
7. Fit spacer. Note this side out marking.
8. Follow video for re-installation above.
   
   Connect AHC hydraulic line first after putting shock assembly in place to avoid contaminants.​
9. Follow norm bleed procedures of the AHC system. Make sure fluid level is correct in reservoir at normal height after all said and done. I used about 2 quarts for this install.

 

[dubyahard]

Do you need to turn off AHC before lifting, as when doing regular maintenance?

 

[TeCKis300]

The car should be off while doing the install. So turning AHC off doesn't particularly matter.

 

[AnyMal]

Thanks for posting this.

If you don't mind, i have a question for you specifically @TeCKis300.
This install is next on my list to dial in my LX and i have been thinking about things pertaining to your note in step 1.

From your experience, what do you think is the best method to slightly reduce rake after an LX spacer install. A sensor lift or a HOU lift?

As i understand it, a sensor lift would limit droop and travel but able to give a lot more height. A HOU adjustment would increase pressure for a max 20mm of lift but would also take you back to baseline damping force. Please correct me if im missing something else.

Cheers.

 

[TeCKis300]

Thanks for posting this.

If you don't mind, i have a question for you specifically @TeCKis300.
This install is next on my list to dial in my LX and i have been thinking about things pertaining to your note in step 1.

From your experience, what do you think is the best method to slightly reduce rake after an LX spacer install. A sensor lift or a HOU lift?

As i understand it, a sensor lift would limit droop and travel but able to give a lot more height. A HOU adjustment would increase pressure for a max 20mm of lift but would also take you back to baseline damping force. Please correct me if im missing something else.

Cheers.

Can you clarify what you mean by HOU?

 

[turbo8]

Height offset utility

 

[radman]

think of the physical sensor lift and the HOU as the same thing - HOU being a fine tuning of the gorilla sensor. HOU gives you .8" of play, so you would sensor lift the corners to get them close, then HOU to get them within .25" of each other. Or YOLO.

yolo = max out your sensor bracket and max out the .8 hou; however, several have indicated a harsher ride at this height.

 

[AnyMal]

Thanks radman, that makes it very simple.
Just say HOU and the Houston man himself shows up LOL!


I was under the impression that for each sensor value, there is a corresponding pressure the system is looking to achieve, hence why it will refuse to lift under heavy load.
You can see these kind of decisions taking place in other instances as well like front and rear / side to side discrepancies in height sensors. There is some level of control on top of just the sensors and my best guess is pressure. So in the case of HOU, what I imagined was happening was a remapping of the pressure curve to the height sensor voltage and the data list will show you the "equivalent" calculated height sensor reading. The AHC ECU uses its own logic and I was trying to see what would be best since it seems to not just be taking pressure into account but both height value and pressure simultaneously.

This is my basic understanding from the playing and poking around I have done. I know TeckIS and yourself have done a lot more.

@radman if you have done the shock spacer install, can you report if it in itself raised the front end at all?

 

[TeCKis300]

Thanks radman, that makes it very simple.
Just say HOU and the Houston man himself shows up LOL!


I was under the impression that for each sensor value, there is a corresponding pressure the system is looking to achieve, hence why it will refuse to lift under heavy load.
You can see these kind of decisions taking place in other instances as well like front and rear / side to side discrepancies in height sensors. There is some level of control on top of just the sensors and my best guess is pressure. So in the case of HOU, what I imagined was happening was a remapping of the pressure curve to the height sensor voltage and the data list will show you the "equivalent" calculated height sensor reading. The AHC ECU uses its own logic and I was trying to see what would be best since it seems to not just be taking pressure into account but both height value and pressure simultaneously.

This is my basic understanding from the playing and poking around I have done. I know TeckIS and yourself have done a lot more.

@radman if you have done the shock spacer install, can you report if it in itself raised the front end at all?

The control strategy of AHC is probably simpler than that. It keeps pumping fluid and raising pressure until the height target as measured by the height sensors are reached. Then there's a max fluid pressure / best effort the hydraulic system will allow for before giving up and leaning on the coil springs.

For the sensor lifts that can be achieved stock, I wouldn't worry about compromising too much droop travel. The suspension has pretty great travel. That's further mechanically enhanced by installing spacers.

To your question about whether spacers change height of the vehicle - no, it did not change at all until I did the sensor lift.

 

[TeCKis300]

yolo = max out your sensor bracket and max out the .8 hou; however, several have indicated a harsher ride at this height.

I've heard a number of times that people experience harsher rides. Something I've not experienced. I would chalk this up to a combination of things that cause the accumulators to bottom out. Combining large sensor lifts with heavy builds/payload is probably pre-loading the accumulators too much so they don't have much remaining volume for suspension travel. It could be that some examples are further challenged as their accumulators are worn with less nitrogen pressure/volume. I believe the cure could be the pre-load the coil spring (shock spacer front / spring spacers rear, or airbag, or higher rate springs) to assist the globes to support load and maintain travel.

 

[AnyMal]

I've heard a number of times that people experience harsher rides. Something I've not experienced. I would chalk this up to a combination of things that cause the accumulators to bottom out. Combining large sensor lifts with heavy builds/payload is probably pre-loading the accumulators too much so they don't have much remaining volume for suspension travel. It could be that some examples are further challenged as their accumulators are worn with less nitrogen pressure/volume. I believe the cure could be the pre-load the coil spring (shock spacer front / spring spacers rear, or airbag, or higher rate springs) to assist the globes to support load and maintain travel.

Has anyone ever ventured as far as to look for upgraded globes with a larger charge chamber? Do you think AHC pumps would refuse to cooperate?

 

[tbisaacs]

FWIW my maxed-out front sensors still ride like a cloud even with a steel bumper/lights/winch. There are a couple of folks here who have made custom brackets to exceed the adjustment range of the stock sensor and my assumption is those rode poorly due to lack of droop.

 

[AnyMal]

FWIW my maxed-out front sensors still ride like a cloud even with a steel bumper/lights/winch. There are a couple of folks here who have made custom brackets to exceed the adjustment range of the stock sensor and my assumption is those rode poorly due to lack of droop.

Are you talking on your coopers or what?
Cloud ride was my entire goal going into the fitment and im lost now

 

[tbisaacs]

Are you talking on your coopers or what?
Cloud ride was my entire goal going into the fitment and im lost now

I’m not sure what you are asking sorry. I’m no longer running coopers

 

[TeCKis300]

FWIW my maxed-out front sensors still ride like a cloud even with a steel bumper/lights/winch. There are a couple of folks here who have made custom brackets to exceed the adjustment range of the stock sensor and my assumption is those rode poorly due to lack of droop.

I believe that for the few that have done it. There's equally some that aren't jacked up as high that seem to comment on a harsh ride so their situation may be a bit different. We also know that there been stock height rigs that exhibit ride issues. Could be a spectrum of different and related issue, and sometimes for different reasons.

 

[AnyMal]

I’m not sure what you are asking sorry. I’m no longer running coopers

Hey, didn't get this notification for some reason.
I went with a 17" wheel and 33" P originally for ride comfort but it compromised too much at a good PSI. Now i feel stuck with a 17 in an inappropriate offset when i really wanted 18s so im kind of going back to the drawing board. Ive now decided to YOLO and sensor lift since im reverse engineering the AHC system. More below.

I was just wondering what the biggest contributor was since your build thread is too glorious and you've done so much for me to pinpoint.
Do you think that your ride comfort while AHC lifted is somewhat attributable to your heavy build? I am bone stock and empty, no third row either.
The LX is outfitted for a GVWR of 7,300+ lbs and im at 6,000 so there is naturally an over-sprung effect.
Fully stock my ride always improved the more i loaded it up and same with my 470.

Im currently trying to tune in a sweet spot with the stock springs up front, upgraded rear spring, and AHC sensors maxed.

 

[AnyMal]

In the spirit of consolidation Im continuing my original question to @TeCKis300 in the general AHC sticky.

@radman and Teck, I am more confident than ever there is indeed a difference between the two procedures and i think I'm beginning to understand how and why.
Sorry for the cliff hanger, ill see yall on the other side.

 

[tbisaacs]

Hey, didn't get this notification for some reason.
I went with a 17" wheel and 33" P originally for ride comfort but it compromised too much at a good PSI. Now i feel stuck with a 17 in an inappropriate offset when i really wanted 18s so im kind of going back to the drawing board. Ive now decided to YOLO and sensor lift since im reverse engineering the AHC system. More below.

I was just wondering what the biggest contributor was since your build thread is too glorious and you've done so much for me to pinpoint.
Do you think that your ride comfort while AHC lifted is somewhat attributable to your heavy build? I am bone stock and empty, no third row either.
The LX is outfitted for a GVWR of 7,300+ lbs and im at 6,000 so there is naturally an over-sprung effect.
Fully stock my ride always improved the more i loaded it up and same with my 470.

Im currently trying to tune in a sweet spot with the stock springs up front, upgraded rear spring, and AHC sensors maxed.

Weight might have something to do with it but I did the sensor lift almost right away in the front. I put ~30k miles on this adjustment with no extra weight. Also worth noting that I'm also running marshmallow sized falkens, just a hair smaller than @radman and @TeCKis300.

However the biggest improvements to ride hands down was fluid flush plus 4 new accumulators.

 

[radman]

@radman and Teck, I am more confident than ever there is indeed a difference between the two procedures and i think I'm beginning to understand how and why.
Sorry for the cliff hanger, ill see yall on the other side.

difference between the procedures? What do you mean..

 

[AnyMal]

difference between the procedures? What do you mean..

Im writing a rather long post to the AHC sticky about all of this right now. We should keep that discussion there since AHC stuff is absolutely scattered.