Thread: SLS airbag pressure

Originally Posted by Pedro_The_Swift

I did find left to right required differing pressures for the same height,,
yes I know that sounds stupid,,

Not at all, my left and right also vary around 5psi.

Originally Posted by Freightdog

Not quite, the tyre is fully inflated at low pressures, the air bag is not.

Funny, if I drop my tyre pressures down to 18psi then my vehicle is low enough to just get into my garage with the roof rack on. At 35psi it is too tall. A tyre's shape changes on the pressure - the pressure effects it's roundness, as at low pressure the sidewall will bulge out and the contact patch on the ground flattens out and is enlarged, at higher pressures there is less contact patch at the circumference takes a more round shape and the sidewall will straighten up.

Originally Posted by Freightdog

This is why I am having trouble understanding what you have measured.

My measurements are taken using a high pressure tyre gauge. I have a schrader valve fitted in each of the air bag lines to enable me to inflate the airbags in the event of a compressor failure.

Originally Posted by twr7cx

I have a schrader valve fitted in each of the air bag lines to enable me to inflate the airbags in the event of a compressor failure.

good job!
I have a push in joiner and extra hose on each side
schrader valves in the coin tray

Originally Posted by Pedro_The_Swift

good job!
I have a push in joiner and extra hose on each side
schrader valves in the coin tray

I can't take all the credit for it. Phil (DiscoWhite) originally fitted the schrader valves in the engine bay. However, the pipes ran near the exhaust and were eventually burnt through. So I shortened them and remounted them on the side of the air compressor box - much shorter lines so much less change of getting damaged.

A tyre's shape changes on the pressure - the pressure effects it's roundness

This is true, however when you half the pressure in a tyre the surface area in contact with the ground doubles. Thus the tyre is able to support the same weight.

However AFAIK the surface area of the air bag that is in contact with the vehicle does not double, in fact it stays the same. What this means is if the pressure is halved, the bag should only be able to support half the weight.

It appears that this is not the case with your experience, so now I am intrigued as to what is actually going on.

I have a couple of truck valves which I need to manually screw into my air bag lines to manually inflate. A bit of a hassle but it will get me out of trouble.