Arnott Air Bags any one had problems with them?

Datatek said:

I welded up a frame to put mine in to test it so that it couldnt extend beyond normal ride height 50 to 70 psi on the car took mine through normal settings so 100psi is pushing it anyway. I think what you did is likely to be destructive

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People think because the stored air is at 140 psi that is the working pressure of the bags. It is not, it is the service pressure, to allow quick inflation in use.

I have got a pressure gauge on the car which shows the tank pressure.
Starting from an empty tank the car starts to lift off the bump stops at about 6.5 bars or 100psi.

dave4x4 said:

I have got a pressure gauge on the car which shows the tank pressure.
Starting from an empty tank the car starts to lift off the bump stops at about 6.5 bars or 100psi.

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Good for you, but there is not 100psi in the bags when they are inflated. More like 55 to 60 psi at standard height depending on the loading. Have you ever thought that the ECU may only open the inlet valve at a certain pressure? Try blowing a tyre up to 30 psi from a tank holding 35 psi of air see how long it takes to do it, if it ever does. Higher pressure gives faster flow you could do it in seconds if the tank pressure was 150 psi.

wammers said:

People think because the stored air is at 140 psi that is the working pressure of the bags. It is not, it is the service pressure, to allow quick inflation in use.

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Exactly, how much air pressure do you need to put in a tyre before the car starts to lift - ie it's now air pressure supporting the car. 8psi? 10? It's exactly the same physics at work. At 140psi the tyre would either explode or be rock hard - not exactly what you need from an air spring!

Wammers wrote:

Have you ever thought that the ECU may only open the inlet valve at a certain pressure?

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The ECU does not monitor the tank pressure to my knowledge. How can it ? there is no pressure measurement device just a high pressure switch.

I also have a manual switch box (from Rover Renovations) to operate the valve box without the ECU. As I said the car lifts at about 6.5 bars when I manually open the inlet valve and the 4 corners. Much less than this in the tank the car won't lift.

StuckAgainSteve wrote:

Exactly, how much air pressure do you need to put in a tyre before the car starts to lift

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An air bag works on a different principle. It has a piston which only starts to move when the force acting on it overcomes the weight of the car. Anything less than this pressure the piston won't move and the car won't lift. The spring rate is determined by the cross sectional area of the piston.

dave4x4 said:

Wammers wrote:


The ECU does not monitor the tank pressure to my knowledge. How can it ? there is no pressure measurement device just a high pressure switch.

I also have a manual switch box (from Rover Renovations) to operate the valve box without the ECU. As I said the car lifts at about 6.5 bars when I manually open the inlet valve and the 4 corners. Much less than this in the tank the car won't lift.

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You are obviously doing something strange, the measured pressure in the rear air bags for normal height is aroung 50/55psi. The ECU does know when the tank is full and pressure is up as it has the pressure switch, however mine will start to lift long before the compressor cuts out on pressure, it just does it very slowly and in stages. The ECU knows the rate of lift from the height sensors so can stop inflation if the rate of lift is too slow allowing pressure to build before lifting some more.

dave4x4 said:

StuckAgainSteve wrote:


An air bag works on a different principle. It has a piston which only starts to move when the force acting on it overcomes the weight of the car. Anything less than this pressure the piston won't move and the car won't lift. The spring rate is determined by the cross sectional area of the piston.

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Bollocks, the piston has nothing to do with it other than to determine the amount of air displaced on an inflated airspring when the axle moves in response to a bump. Changing the piston shape changes the rate of displacement and thus the spring can be made to have a rising or even a falling rate on compression. Physics is Physics, the only thing that supports the car is air pressure just like a tyre in a static situation, the piston only comes into it on compression at a fixed level of inflation.

dave4x4 said:

Wammers wrote:


The ECU does not monitor the tank pressure to my knowledge. How can it ? there is no pressure measurement device just a high pressure switch.

I also have a manual switch box (from Rover Renovations) to operate the valve box without the ECU. As I said the car lifts at about 6.5 bars when I manually open the inlet valve and the 4 corners. Much less than this in the tank the car won't lift.

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Don't think that is correct, think the pressure switch works from resistance, don't think it is just an on off switch. It works between on at 120 psi +- 7psi and off at 140psi +- 7 psi. The sensor can detect a falling or rising pressure. Well according to Land rover it can, but what do they know. "The compressor is activated when the ECU detects a falling pressure below 120 psi +- 7 psi". How does it do that with an on off switch? It will lift at 100 psi but only slowly as explained earlier. The ECU won't open the inlet valve until a pressure is detected. If you manually switch the valves at 100 psi, when it starts to inflate the bags the pressure will drop in the tank fairly rapidly. It then can only continue to be inflated by the volume of air coming from the compressor which is not great. That would give a slow rise to height. 140 psi is used so the excess volume can be used to raise the car quickly to ride height. But there is nowhere near 140 psi going in the bags. Just as when you blow a tyre up from a 200 litre storage tank on a 150 psi garage compressor, it inflates rapidly to 30 psi but you don't use the entire amount of air stored in the tank. You just use the volume of air needed to inflate the tyre to 30 psi.

Did any one else have a similar experience? *In November I bought a new-to-me '05 HSE. *It is an Arizona car purchased via eBay (12th rover bought from eBay)*from a dealer in Memphis. *I live in New Hampshire. *When I bought it, the salesman told be he just had the front right air bag replaced. *Get the car and is it a great rig!!! *The first time the temperature dropped - PSSSSSSSSTTT. *The air bag blew. *I called the dealer I bought the truck from who put me in touch with the local LR dealer (Bluff City Land Rover - AWESOME PEOPLE - Roger is parts is the best!!!) where he had the bag replaced. *Bluff City told me that it was an after market Arnott air bag. *They replaced the part for free including shipping. *I had to cover the labor - no big deal. *12 days later, the temperature drops again. *You guessed it PFFFFFFTTTT - same air bag goes. *I call Roger at Bluff City. *He can't believe it but sends me ANOTHER Arnott Air bag. *Per warranty I cover he labor. *I ask Roger to put me in touch with the manufacturer because I think they should cover the labor for a bag that lasts 12 days even though that is not what their warranty says. I call Marvin at Arnott in Florida. *He explains their warranty policy to me but says that he will take a look at the part when he gets it back and he will talk to to the owner of the company to ask him if he will cover the $233 labor bill. *I patiently wait 10 days for Marvin to call me back. *In the mean time, every morning that the temperature drops below 30 degrees fahrenheit, the THIRD ARNOTT PIECE OF CRAP air bag fails. *I get a suspension fault error. *The RR goes down to the bump stops - fun ride. *Once the temperature goes back above 30 degrees I can shut the car down, reset the EAS and it goes back to normal function. *Arnott is a Florida company. *The clearly have no clue that their product fails in cold weather. *NOR DO THEY CARE!! *After waiting 10 days for Marvin to call me back, I give up and call him. *Shocker - I get his voicemail and he doesn't call me back. *I call again the next day and I go on permahold - i give up and hang up. *For some reason he calls me back - I missed the call. *Finally, we connect. *He tells me that he spoke to the owner of the company and the will not pay the $233 in labor to replace the air bag that lasted all of 12 days. *I asked him if he looked at the defective part I sent back. *The answer was NO. *He said that he has a "pallet" of defective air bags and core returns and he could not find mine. *SHOCKER AGAIN *they have so many of these JUNKY bags that they are returned by the PALLET!!! *Furthermore he tells me that the LR dealer should never have honored the warranty as I am not the original owner of the car when the part was installed. *My point of view is different. *I am the first titled owner of the car after the part was installed. Nevertheless - shouldn't a manufacturer stand behind a part that only lasts 12 days? *I had no gripe paying for labor on the first one that lasted a WHOPPING two months!!! *I guess if you live in a warm climate and you want a cheap piece of crap air bag then buy this stuff. *If you live anywhere where the temperature dips below 30 degrees you will be ver unhappy with the product. *You will be even less happy with the lack of customer service that ARNOTT provides. *Ironically, the owner of the company is Arontt. *I thought the just called them that because the ARNOTT any good.*

Yours is an L322 I presume, I have a P38 with Arnott Gen 2's, they seem quite happy at minus 16C here.

I think you have issues with the supplier, things in life are never perfect unfortunately, that's why customer services are there to sort things out, no matter how bad a product or how good, there will always be problems with it, and if you have good customer service and its sorted out, then its never much of a problem, you have been unlucky let hope it changes

If it's always the same airbag failing, could be you have another issue that's causing it to fail.

Yea seems strange 3 bags all exploding on the same side