We get requests of this nature on an almost daily basis. Airbags (more accurately called air springs) are incredibly robust and reliable devices, and usually last at least a decade if treated well. In fact, we had a call earlier this week from a customer who had one of our kits 24 years ago, and just got an advise on his MOT that his bags were showing signs of perishing – but it still passed! Needless to say he was happy it lasted so long.
Most busses, coaches and a good proportion of lorries/trucks have air suspension, so it has to be reliable. This is well tested technology which when correctly installed and correctly used will last 100,000 miles with no issues.
Several issues can cause premature failure:
- Abrasion – coming into contact with any metal part of the vehicle.
- Abrasion – coming into contact with foreign matter – road impact/damage.
- Deflation - Leaving the Vehicle with no air in it for extended periods of time.
- Overextension - Extending the bag beyond specs (after bump or if jacked when pressurised).
- Cracked End Cap – suspension designed to run too low on bag without internal bump stops (most bags) or using bolts that are too long in plastic End Caps.
We have seen customers who have experienced all of these issues, but touching metal is by far the most common. To be clear none of the listed issues are normal but also they are also very much not warranty claims!
Bags/Springs do wear out and fatigue, but this usually starts to manifest itself as tiny cracks which run up and down the bag, usually starting at corners. Its caused by the extension and then deflation of the bag over hundreds of thousands and sometimes millions of cycles. They start as tiny cracks but grow as the bag is used. Initially these cracks are only in the outer layer (all our bags are multicore) but eventually they will start to leak. They get progressively worse, and so should be dealt with when they become visible. If left the bag will not hold air, and the compressor may try to make up for it and work beyond its duty cycle, also failing.
Bags are made of rubber and have similar construction to tyres, which can be repaired. Therefore you must be able to repair air bags, right?
To repair a bag you would need to get inside so the pressure was pushing the repair into the bag. If you repair from outside it would be pushing your repair off, which would likely last only a few seconds. Most bags have crimped ends which means you cannot get inside at all, as the crimping machines and crimps are not readily available. BUT the biggest issue is that bags extend a lot in height – far more than tyres, and up to 100% on some common bags. Tyre type repairs would not tolerate this type of motion.
Sorry to say, bags cannot be repaired. To be fair most of the calls we get refer to worn out OEM struts and bags, because OEM replacements can get pretty pricy, and customers are looking for a lower cost alternative than replacement. Much of the time the OEM bags cannot even be removed fro the strut. For aftermarket systems, the key is to deal with whatever caused the failure (usually touching something) and only then replace the bag.
Please call us on 0800 772 0315 or send an email to ENQUIRIES@AIRRIDE.UK if you need help with your vehicle although please note our location in central Norwich.