Ride Pro e2 and PSI

[66Chevelle]

Application:
05 Suburban

System:
Ride Pro e2/Level Pro/Big Red Valve, front Shockwaves, rear double convoluted bags

Questions:
1)When PSI increases in one front corner the other front corner's PSI decreases. And when the PSI decreases the other increases. Same thing happens for the rear. Is this normal???

2) I'm seeing a big difference in PSI from side-to-side. Example, the FL is about 130 PSI while the FR is 100 PSI and both front fender measure the same to the ground. Same in the back, RL is 30 and RR is 50. Why is this??


Thanks!

[darren@ridetech.com]

1. Yes, this is normal. Increasing the psi on one side will decrease the weight on the other side causing the psi to decrease.

2. It is normal to require a little more pressure in one side that the other to achieve the same height. This can be multiplied when inflating one side first then the other as the suspension is put in bind. 30 psi is excessive tho. But I notice that your LF and RR bags have the higher pressure. I bet you could get the same fender to ground measurements if your were to slightly decrease the psi in the LF and RR and slightly increase the psi in the RF & LR. This is referred to as cross loading. If the frame is rigid enough, it's totally possilble to completely deflate two cross corners and fully inflate the other two cross corners but still have the car balance out a level. But of course, your spring rates will be all jacked up and the car will drive really bad. This is why even when using height sensors we still use air pressure sensors.

[66Chevelle]

Thanks, Darren.

What is an acceptable PSI difference? What can I do, if anything, to make the PSI's closer?

[britt@ridetech.com]

PSI difference depends on the vehicle. Typically you'll have 10psi, maybe 15. However, I cannot give you a concrete number.

Bottom line, pressure determines spring rate. So if you have 30psi difference from side to side you'll have different spring rates as well. This will cause the vehicle to handle poorly as it traverses bumps in the road.

How to mitigate:
-lower the vehicle to near zero pressure
-raise the fronts as a unit
-raise the rear as a unit
-modify pressure slightly to attain proper height
***when you inflate one corner it affects the pressure and height of the other 3 corners. So you want to raise and lower the fronts and rears at the same time as much as you can. This keeps your pressure side-to-side as close to each other as you can get it.***

[66Chevelle]

Thanks, Britt, I'll give it a try.

[66Chevelle]

I raised the rear as a unit and was able to get within 10 PSI but not the front - not even close. In order to get the front within 10 PSI the FR is about a full inch higher then the FL! For some reason the FL jumps in PSI in comparison to the FR.

Ideas? :)

[britt@ridetech.com]

Pressure can be affected by many things: a bench chassis, more weight, suspension bind, etc.

One easy one to check for is bind in the front:
Let's say the RF is loose and easy to lift. . .but the LF has the control arms too tight and is difficult to move. . .this will cause the air pressure to be higher on the LF side as the air spring has to lift the weight of the vehicle as well as overcome the bind (the bind actually creates a "false load", meaning it adds more resistance). This resistance can cause the pressure to "jump" as the force from the air spring overcomes the bind.

Put the truck on jack stands, let the air out of the front, remove the tires and manually move the suspension. It should move freely even by hand (though it is a little difficult you can move it by hand). If you can't, loosen the a-arms and try again.

More weight is easy to check as well. . .you just need a set of scales (or a buddy with a set of scales):
If you can weigh each corner that will tell you how much the air spring has to pick up.
If one side is radically heavier than the other it's going to take more pressure to raise.

The twisted chassis is a little more difficult:
If the chassis is not square it will never get similar pressures side-to-side.
I've seen a lot of cars that are no where near square. (I saw a 72 Chevelle that would literally bend the frame and drop the front suspension over an inch if you put jack stands just under the front door opening!)

[66Chevelle]

Update:

I supported the front on jack stands and tried to move both RF and LF control arms, but neither would budge, so I unbolted the swaybar and lower shockwave mount from both lower control arms. This allowed me to move the arms. Both sides moved with the same amount of resistance so I bolted everything back up and set it on the ground.

Now get this, after simply unbolting and re-bolting the components the LF aired up to the same height and with the same pressure as the RF! I'm thinking maybe the swaybar was putting the LF in a bind? Not sure but all is good now.

Also, thanks guys for an awesome product! The 5100 lb suburban rides great with your setup!!

[britt@ridetech.com]

Suspension bind is an odd thing for sure!

Good to hear you have it going correctly.