leeleatherwood
Active member
After having the airbags and rear king shocks installed and put some miles on them, including a trip from San Jose, CA to Washington state, I have some feedback on this setup.
The current modifications:
King Y62 Patrol shocks with Remote Res and Adjuster.
Firestone Coil-Rite airbags
PRG 2" Coil Spacers
OEM Coil Springs
Removed factory Air Shocks. (replaced by the Kings)
For anyone not too familiar with the Nissan IRS suspension used in the 1st and 2nd Gen Armada's and QX56's/QX80's (Maybe R51 Pathfinders too), they use 2 different "springs" to support the weight of the vehicle. In this case, the majority of the weight is supported by the coil spring, and the remainder, but still large amount, is supported by the air spring inside the Air Shock.
The rear suspension also has 2 control arms. The coil spring sitting inside of a bucket on the rear control arm, with the air shock being connected to the front control arm.
If the air shock is removed, and replaced by a typical shock, something must be done to support the load that the air shock was supporting. If you do not, the suspension will squat all the way down. Even though the coil spring is supporting a majority of the weight, it is still not even close enough to support the vehicle by itself.
There are 3 solutions to this issue:
1) Replace the coil spring with higher springrate which is capable of supporting the vehicles weight.
2) Install airbags to use as helper springs.
3) Do both.
In my current setup, I have installed the Firestone Coil-Rite airbags to use as helper springs for the OEM coils. This "works", but it is not ideal.
The factory air ride pump does not seem to have an issue operating at the pressure required for the Firestone airbags to lift the vehicle to proper height. On the other hand, the air bags have a MUCH larger volume than the factory air shocks. It seems Nissan has programmed the air ride system to turn off the air pump after a set period of time, this is probably so that the pump doesnt burn itself out incase there is an air leak or something. So, in order to get the air bags to fill up, you will need to turn the vehicle on, let the pump run, turn it off, and repeat the process a few times. Because the air ride system "leaks down" over time, like almost any other air system, after sitting for a while you will need to perform this "air up" procedure. Not a big deal, but obviously not ideal. Alternatively you could install a switch to turn the pump on manually whenever required, I will do this myself when I get time.
The larger problem with this setup, is that In-Coil airbags are literally balloons, super thick balloons. Because of this, and because of the fact that they support so much of the load, in certain parts of the road like long whooping rises and dips it feels like the rear end is riding on one of those giant bouncy exercise balls. Not ideal.
The bad thing about using air as a spring, is that they are not linear, they are progressive. When you compress a gas (air in our case), the pressure increases as the volume decreases, and to make it worse, its non-linear. The more you compress it, the higher the "spring rate" will be. This makes it very hard to tune around, and very hard for a shock to control.
Normally, when these airbags are used, they are used as helper springs. As in they help the main springs, but the main springs are still capable of supporting the vast majority of the load. In this scenario, the "balloon effect" while still present, is far less pronounced for at least two reasons, 1) The airbag is simply supporting less load. 2) The main coil actually helps to control the air bag and "balance" the spring rate more evenly.
In our case, the coil springs (main springs) are not able to support the load, and since they are such a low springrate to begin with, you lose the ability for the main spring to help "balance" the spring rate. This leads to a very pronounced balloon effect.
From the beginning, I knew about this potential problem and I ordered some Dobinsons Y62 Patrol Medium Duty springs, they simply have not arrived from Australia yet. They should be here in a month or two last time I checked.
I believe the increased springrate will resolve the balloon effect in the rear end, I still plan on using the Airbags to adjust the ride height when the load changes.
The current modifications:
King Y62 Patrol shocks with Remote Res and Adjuster.
Firestone Coil-Rite airbags
PRG 2" Coil Spacers
OEM Coil Springs
Removed factory Air Shocks. (replaced by the Kings)
For anyone not too familiar with the Nissan IRS suspension used in the 1st and 2nd Gen Armada's and QX56's/QX80's (Maybe R51 Pathfinders too), they use 2 different "springs" to support the weight of the vehicle. In this case, the majority of the weight is supported by the coil spring, and the remainder, but still large amount, is supported by the air spring inside the Air Shock.
The rear suspension also has 2 control arms. The coil spring sitting inside of a bucket on the rear control arm, with the air shock being connected to the front control arm.
If the air shock is removed, and replaced by a typical shock, something must be done to support the load that the air shock was supporting. If you do not, the suspension will squat all the way down. Even though the coil spring is supporting a majority of the weight, it is still not even close enough to support the vehicle by itself.
There are 3 solutions to this issue:
1) Replace the coil spring with higher springrate which is capable of supporting the vehicles weight.
2) Install airbags to use as helper springs.
3) Do both.
In my current setup, I have installed the Firestone Coil-Rite airbags to use as helper springs for the OEM coils. This "works", but it is not ideal.
The factory air ride pump does not seem to have an issue operating at the pressure required for the Firestone airbags to lift the vehicle to proper height. On the other hand, the air bags have a MUCH larger volume than the factory air shocks. It seems Nissan has programmed the air ride system to turn off the air pump after a set period of time, this is probably so that the pump doesnt burn itself out incase there is an air leak or something. So, in order to get the air bags to fill up, you will need to turn the vehicle on, let the pump run, turn it off, and repeat the process a few times. Because the air ride system "leaks down" over time, like almost any other air system, after sitting for a while you will need to perform this "air up" procedure. Not a big deal, but obviously not ideal. Alternatively you could install a switch to turn the pump on manually whenever required, I will do this myself when I get time.
The larger problem with this setup, is that In-Coil airbags are literally balloons, super thick balloons. Because of this, and because of the fact that they support so much of the load, in certain parts of the road like long whooping rises and dips it feels like the rear end is riding on one of those giant bouncy exercise balls. Not ideal.
The bad thing about using air as a spring, is that they are not linear, they are progressive. When you compress a gas (air in our case), the pressure increases as the volume decreases, and to make it worse, its non-linear. The more you compress it, the higher the "spring rate" will be. This makes it very hard to tune around, and very hard for a shock to control.
Normally, when these airbags are used, they are used as helper springs. As in they help the main springs, but the main springs are still capable of supporting the vast majority of the load. In this scenario, the "balloon effect" while still present, is far less pronounced for at least two reasons, 1) The airbag is simply supporting less load. 2) The main coil actually helps to control the air bag and "balance" the spring rate more evenly.
In our case, the coil springs (main springs) are not able to support the load, and since they are such a low springrate to begin with, you lose the ability for the main spring to help "balance" the spring rate. This leads to a very pronounced balloon effect.
From the beginning, I knew about this potential problem and I ordered some Dobinsons Y62 Patrol Medium Duty springs, they simply have not arrived from Australia yet. They should be here in a month or two last time I checked.
I believe the increased springrate will resolve the balloon effect in the rear end, I still plan on using the Airbags to adjust the ride height when the load changes.
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The Odyssey is good for 400 cycles down to 80% discharge, so they work great as a starting battery and deep cycle.
