2003 Disco air suspension let down

I have just returned from a 20,000 km caravanning trip to the top of Aus in my 2003 Discovery TD5, the trip went well until the last bit when the rear air suspension went down half way accross the Nullabor, using the Microsoft technique of turning everything of and restarting, up came the rear suspension, only to go down again twenty kms later, this repeated until we stopped for the night. Next morning all was well, up came the air bags and we finished up travelling another 1,500 kms without problem by reducing our touring speed to 80 kmh, with 100 kms to go to get home I increased the speed to 100 kmh and lo and behold, down went the air bags after 70 kms. I might add that when we have this problem, both bags go down simultaneously over a period of several minutes, there are no evident leaks in the air bags.

Can anybody shed some light on what could be causing the problem, the ball weight from the caravan is 185kgx and the car only had a Waeco plus odds and sods (not a lot) in the back. At the end of the trip the car had 80,000kms on the odo.

Brian

I believe that the nose-weight limit on the discovery is 150k, so you were well over that plus by increasing your speed would have the effect of increasing it further, try redistributing the caravan load, a target figure for the nose weight should equate roughly to around 7% of the actual laden weight.
hope this helps.
john