2-2.5" AHC Lift Using King Coils & Shock Spacers

[DirtDawg]

OP, do your shock spacers squeak?

They creaked a little at first, I was assuming from just settling, but haven't really paid attention since. If they keep it up ill throw some anti-seize on the bolts and mated surfaces to quiet them down.

So the a-arm does not droop any lower due the compensation at the sensor?

Yes the front suspension will droop lower than stock due to the spacer and sensor lift, but so would any other lifted LC. The limiting thing in our front ends is first most the ball joints. they will stop suspension travel before you would literally pull your CV apart. But you really have other factors stopping down travel before it even gets to that point. The sway bar will limit down travel. If AHC is in operable mode it will limit down travel. This is essentially working the EXACT same way a sensor lift would, but instead of having constantly over extended shocks, we are getting some of that travel back by installing the front 60mm spacer.

 

[ChuckB]

This looks like a great option if you want to keep AHC! Any pictures in 'H' mode?

My pressures are a little off and this would be a great upgrade. Thanks for doing the legwork on this project.

 

[DirtDawg]

She's under the knife right now working on a new project, but once I get her back up and running I'll get pics in L and H mode.

 

[AimCOtaco]

Yes the front suspension will droop lower than stock due to the spacer and sensor lift, but so would any other lifted LC. The limiting thing in our front ends is first most the ball joints. they will stop suspension travel before you would literally pull your CV apart. But you really have other factors stopping down travel before it even gets to that point. The sway bar will limit down travel. If AHC is in operable mode it will limit down travel. This is essentially working the EXACT same way a sensor lift would, but instead of having constantly over extended shocks, we are getting some of that travel back by installing the front 60mm spacer.

My lifted LC does NOT have extra droop travel, if it did I would be very concerned about both the CV's and Ball joints ( despite running TC UCA's and a diff drop). I think this set-up requires limit straps to maintain long term reliability as I would not want to run a situation where the ball joints were the travel limiter. No mater how tough the CV is something will break if the deflection angle is more than it can handle. It will be interesting to see how this front set-up works long term. I recommend measuring total droop from the fender to the hub center to compare with conventional lift set-ups.

 

[DirtDawg]

My lifted LC does NOT have extra droop travel, if it did I would be very concerned about both the CV's and Ball joints ( despite running TC UCA's and a diff drop). I think this set-up requires limit straps to maintain long term reliability as I would not want to run a situation where the ball joints were the travel limiter. No mater how tough the CV is something will break if the deflection angle is more than it can handle. It will be interesting to see how this front set-up works long term. I recommend measuring total droop from the fender to the hub center to compare with conventional lift set-ups.

Please explain to me how your lifted LC, with what I am assuming is longer than stock shocks, has any less down travel than my LX with extended stock shocks (essentially the same thing)? All I did was extend the length of the stock AHC shock. It still has the same travel characteristics as stock form.

With a sensor lift and no spacers, the hydraulic piston in the shock runs in the bottom of the cylinder, people have complained of this setup bottoming out on the shocks over bumps, I wanted to avoid that. With the spacers, the piston runs more in the stock range of the cylinder. But once again, in either setup (LC or LX), the first limiter of down travel is the sway bar.

But in the end, guys have been running these spacers for plenty of miles with no ill effects or issues, so it's of no concern regardless. Now if I was running no sway bars, flexing out on the rockiest trail I could find, turning at full lock, flooring it, then yeah I'd be a little concerned then. But hopefully nobody's that stupid.

 

[ntsaint]

I've been wondering this ^ exact same thing...

 

[AimCOtaco]

Quite simple, when we lift the fronts of these 100's (regular shock/springs change) we use the same travel range and limits, we just change the resting ride height by adjusting t-bar pre-load. The wheel does not move up or down any more than it did before, the same affects could be achieved by unloading the front by say removing the engine. We don't end up with more travel or different limits, we usually do end up with much better dampers and stiffer spring rates.
By just spacing the a-arms downward I expect the additional droop to lead to component failure. On the upstroke you may or may not top out and kill the AHC shock thing but you are asking it to compress about 30 mm more (the height of the spacer) than it used to which may be fine or may not be.

Who's run this set up on the front for lots and lots of hard off-road miles that can chime in?

 

[DirtDawg]

Quite simple, when we lift the fronts of these 100's (regular shock/springs change) we use the same travel range and limits, we just change the resting ride height by adjusting t-bar pre-load. The wheel does not move up or down any more than it did before, the same affects could be achieved by unloading the front by say removing the engine. We don't end up with more travel or different limits, we usually do end up with much better dampers and stiffer spring rates.
By just spacing the a-arms downward I expect the additional droop to lead to component failure. On the upstroke you may or may not top out and kill the AHC shock thing but you are asking it to compress about 30 mm more (the height of the spacer) than it used to which may be fine or may not be.

Who's run this set up on the front for lots and lots of hard off-road miles that can chime in?

@hoser has run these spacers for 10 years and 60k miles, including some hard off roading. Other members have recently picked up on these and started running them. I understand why you think there might be a concern, but ultimately the AHC is versatile enough to be able to accommodate the spacers. I can still go into H and L mode, I can still go down to my bump stops (checked this when bleeding), without anything binding. And as far as down travel, I rely on my sway bar to properly work and limit that. Here's a link to the group buy/info article: AHC Spacers - Possible Group buy

 

[AimCOtaco]

^^^ Gotcha, the fact that you can hit the bump stops without binding is very good, sounds like the uptravel side is fine.
I understood that @hoser was using shock extensions on the rear but didn't know he was running the fronts as well, is that indeed correct?
Is there a different type of sway bar on the AHC equiped trucks? The standard style front sway bar does not limit travel. I'm not trying to rain on anybodys parade, I'm really trying to understand how this is all ok up front as it's so different from the norm.

 

[DirtDawg]

^^^ Gotcha, the fact that you can hit the bump stops without binding is very good, sounds like the uptravel side is fine.
I understood that @hoser was using shock extensions on the rear but didn't know he was running the fronts as well, is that indeed correct?
Is there a different type of sway bar on the AHC equiped trucks? The standard style front sway bar does not limit travel. I'm not trying to rain on anybodys parade, I'm really trying to understand how this is all ok up front as it's so different from the norm.

This is meant to be an informative post, you aren't raining on anyone's parade. I really don't understand what your concern is though. Everything is good on the compression side, the sway bar limits down travel (even if it wasn't there, I believe the shocks could reach full extension without issues). And the restriction of down travel is all relative to the vehicle, sometimes it's the shock, sometimes it's the sway bar. I found that my front end would drop an additional 1" with the sway bar detached. Even though the geometry is the same, the LX and LC suspensions are both very different systems, so it's not good to compare the travel characteristics of both. Under normal driving situations, the AHC keeps the suspension in the neutral zone, and off-road the system still limits travel.

Hopefully @hoser can chime in and verify. But regardless, multiple people are running those spacers from the thread, with what appears to be no complaints.

 

[bamabrock]

Quite simple, when we lift the fronts of these 100's (regular shock/springs change) we use the same travel range and limits, we just change the resting ride height by adjusting t-bar pre-load. The wheel does not move up or down any more than it did before, the same affects could be achieved by unloading the front by say removing the engine. We don't end up with more travel or different limits, we usually do end up with much better dampers and stiffer spring rates.
By just spacing the a-arms downward I expect the additional droop to lead to component failure. On the upstroke you may or may not top out and kill the AHC shock thing but you are asking it to compress about 30 mm more (the height of the spacer) than it used to which may be fine or may not be.
Who's run this set up on the front for lots and lots of hard off-road miles that can chime in?

I dont see how the damper is compressing 30mm more than stock. Wouldn't the modification to the front sensor to trick the setup into thinking the new height is actually the original height ending up with the same amount of lift as the amount afforded by the bracket keep the AHC damper in the same operating cycle? Since the non-ahc uses the torsion bars only to set the resting ride height and the AHC equipped rig uses the lighter rated torsion bars in conjunction with the AHC damper, the only issue I see is not adjusting the torsion bars but I dont think they matter as much since most of the ahc suspension is set by the damper

 

[ihadmail]

Installing these spacers without adjusting the sensors will not grant any amount of lift.

In AHC equipped vehicles: the sensors control height by varying the amount of hydraulic fluid pumped into the actuators (what replaces standard shocks). The addition of the AHC spacers alone would simply raise the inner piston of the actuator to a higher position when in N mode, resulting in less possible up travel.

Inversely, adjusting the sensors without adding the AHC spacers will result in the resting height of the inner piston at a lower position when in N. This results in less possible down travel. Many users of the "adjust sensor to trick truck into raising itself" method have reported issues with bottoming the actuator piston out in the actuator body after the lift without adding the spacers.

Now, when I discuss up and down travel, I don't mean the suspension system as a whole, I mean the travel ability of the linear actuator only.

 

[LandCruiserPhil]

Awesome write up! Just a heads up, you will likely experience premature CV failure if you don't install a diff drop from increased drive angles and changed geometry.

Wrong not required.... I have over 90K (160K total) and counting on a lifted 100 WITHOUT a diff drop that has been wheeled. I have owned 5 100 and LX470 and only 1 had a diff drop with upper long travel arms. Never a CV failure or boot replacement on any.

FWIW 21" fender to center of the hub is my set up

 

[ihadmail]

With my neutral ride height (fender to hub center) at 21.75" my suspension looks like this on the ground:

With the front tires off the ground, without restarting the truck, my measured height was 24.75" and looks like this:

I failed to mention, my lift consists of 2" height achieved by sensor lift, slee diff drop, Japan 4x4 AHC actuator spacers, SPC upper control arms.

 

[LandCruiserPhil]

They creaked a little at first, I was assuming from just settling, but haven't really paid attention since. If they keep it up ill throw some anti-seize on the bolts and mated surfaces to quiet them down.

Yes the front suspension will droop lower than stock due to the spacer and sensor lift, but so would any other lifted LC. The limiting thing in our front ends is first most the ball joints. they will stop suspension travel before you would literally pull your CV apart. But you really have other factors stopping down travel before it even gets to that point. The sway bar will limit down travel. If AHC is in operable mode it will limit down travel. This is essentially working the EXACT same way a sensor lift would, but instead of having constantly over extended shocks, we are getting some of that travel back by installing the front 60mm spacer.

Given the arm is the limited factor on front droop what good does the shock spacer do? If anything it could limit the compression of the front end.

Also have you had it aligned for caster?

 

[ihadmail]

From left to right:
AHC actuator in neutral at standard height
AHC actuator in neutral at lifted height
AHC actuator in neutral at lifted height with AHC spacer

Red is actuator body
Blue is the allowable travel range of actuator body
Yellow is the piston that moves inside of the body
Grey is the AHC spacer

 

[DirtDawg]

Given the arm is the limited factor on front droop what good does the shock spacer do? If anything it could limit the compression of the front end.

Also have you had it aligned for caster?

Not really sure what your asking with your first question.. Not sure how the arm could limit compression. But yes it was taken to the alignment shop the day after modifications took place.

 

[DirtDawg]

I dont see how the damper is compressing 30mm more than stock. Wouldn't the modification to the front sensor to trick the setup into thinking the new height is actually the original height ending up with the same amount of lift as the amount afforded by the bracket keep the AHC damper in the same operating cycle? Since the non-ahc uses the torsion bars only to set the resting ride height and the AHC equipped rig uses the lighter rated torsion bars in conjunction with the AHC damper, the only issue I see is not adjusting the torsion bars but I dont think they matter as much since most of the ahc suspension is set by the damper

This is exactly what I have been trying to say the whole time.. I guess you put it in better words than me

 

[Wilsil]

Your post made me to check on the AHC pressures.
Front 9.8 and rear 9.8.
Time for an ajustment and to get the non-AHC springs in.
I am guessing that the rearbar made the change. ☺

 

[syche]

Hi All.

This is very interesting, i was actually thinking to do the bottom bracket extension for the front only, not to lift but to gain down travel. I am planning to lift my AHC by 20 to 25mm max up front

I was planning 20 to 25mm but this one is apparently 30mm. I was worried that a 30mm extension would bottom out the shocks on full bump compression like when you take a washout a bit over speed and hit the bump stop a bit hard.

Doesn't the top arm fool with the shock at full drop? Are the drive shafts not binding at full drop without the diff drop?

A pics at full drop of the top factory arm would be great to see how much space is left between the shock and the arm.