Thread: RRC / P38 EAS AirBag Pressure

Just guessing but suspect Toyota would use say 3-5 bar but as it's LR probably 200 Bar🤣Just to make it easy

I think it’s a max of 160psi - not 200bar which is about 3000psi!

off the top of my head

45-55 PSI highway
60-70 PSI normal
80 PSI high

- happy to be corrected I recently rebuilt my p38's EAS several times after arguing with the valve block

Originally Posted by jsp

off the top of my head

45-55 PSI highway
60-70 PSI normal
80 PSI high

- happy to be corrected I recently rebuilt my p38's EAS several times after arguing with the valve block

None of this makes sense to me .... Maybe I'm just slow

The height or travel type should make no difference to pressure I would have thought. The only thing that will change the pressure is the cars weight. it doesn't matter what height the car is sitting at, the pressure should still be the same (there will be just more air in the bags .... but the pressure of the air will be the same).

So someone with bullbars, winches and lots of heavy stuff fitted to there car will certainly be running higher suspension pressures.

seeya,
Shane L.

Originally Posted by DoubleChevron

None of this makes sense to me .... Maybe I'm just slow

The height or travel type should make no difference to pressure I would have thought. The only thing that will change the pressure is the cars weight. it doesn't matter what height the car is sitting at, the pressure should still be the same (there will be just more air in the bags .... but the pressure of the air will be the same).

So someone with bullbars, winches and lots of heavy stuff fitted to there car will certainly be running higher suspension pressures.

seeya,
Shane L.

Hallelujah!
Finally someone who understands air bags, they are in fact equivalent to air pistons.
The cross section of the air bag is essentially constant at all heights as each bag must support a quarter of the cars weight for a balanced car for example, so the pressure must remain the same for the upward force to be constant and support the car.
Changing heights consists of either adding air to raise or venting air to lower.
When raising the compressor ups the pressure during the raise only, to force more air into the bags, and as expected more pressure will push the car up, but once the car is up and the compressor cuts out, the pressure will be the same as before.
The pressure will need to change though when the weight changes as when passengers get in and the airbags would drop unless the compressor makes up the difference.

An air bag is NOT the same as a tire where the volume is constant and the pressure is variable.
An air bag has constant pressure and the volume is variable.
All this is pneumatics 101 but so few understand it.
So well done Shane!!!

Yep I got the numbers wrong,

I just ran the 2000 P38 through its heights a few times -

access - just under 40 PSI
highway - just on 50 PSI
standard - high 50's bordering 60
High mode - low to mid 60's.

I only have cheap dial gauges on the front bags, chasing a weird height control issue which clears up after the car has warmed up.

Originally Posted by jsp

Yep I got the numbers wrong,

I just ran the 2000 P38 through its heights a few times -

access - just under 40 PSI
highway - just on 50 PSI
standard - high 50's bordering 60
High mode - low to mid 60's.

I only have cheap dial gauges on the front bags, chasing a weird height control issue which clears up after the car has warmed up.

Just to clarify, my system is disabled at the moment, and I am pumping up individual bags x 4 via a backup system/schrader valves as an interim step to simulate urban running. I'm finding that anything much over 50 starts to lift the bags, so that expectedly is consistent with the advice here. Cheers

Originally Posted by jsp

Yep I got the numbers wrong,

I just ran the 2000 P38 through its heights a few times -

access - just under 40 PSI
highway - just on 50 PSI
standard - high 50's bordering 60
High mode - low to mid 60's.

I only have cheap dial gauges on the front bags, chasing a weird height control issue which clears up after the car has warmed up.

If it works under the same principle as hydraulics. "access" height (or low in the case of Citroens) should really be zero psi .... as the car is resting on its lower bumpstops. ie: no weight is being held by the suspension system. standard and highway should be the same (though I imagine on the highway pressure may possibly be higher --how much downforce would a brick shape object generate ). High would probably depend on how much the suspension tightens/binds as it lifts. In the Citroens, they actually throw full system pressure at the suspension ..... so she is really pressed hard against the top bump stops (with probably 2800psi in the suspension). Does the air suspension just throw tank pressure at the bags to push the suspension up as high as it'll go?

Its a crying shame they didn't use hydraulics rather air bags. Hydraulics are enormously superior .... pretty much never wear out and have no fragile bags that can be staked (they also ride much better).

seeya,
Shane L.