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I have made an interesting, if not startling, discovery with regards to the Arnott replacement front air springs for the Allroad.
After the OEM's air springs failed on my vehicle I purchased the Arnott front air springs.
Over a period of 4 years and 50000 miles the vehicle has been through no less than 5 Arnott air springs. All the air springs failed suddenly. The car would be fine one day and the next day it would drop right down within a matter of minutes and the air springs would then need to be replaced. , i.e. no slow leak type scenario's.
When the last one failed I noticed that the vehicle was resting on the control arms and the vehicle was not driveable as the wheels would rub against the arches when the steering is turned.
The air spring airlines also got damaged in the process as they got pinched by the control arms pressing them against the fender.
This seemed strange to me as I did not experience this when the OEM air springs failed and was able to still drive the car to a workshop or home.
I ordered a new Arnott air spring and upon closer inspection established that the bump stop in the Arnott air sping is 40% shorter (60 mm long) vs the OEM bump stop (100mm long).
This explains why the vehicle was resting on the control arms as the Arnott bump stop is not long enough to support the load of the vehicle which is what it is supposed to do.
More alarming is the fact that the bump stop is a very important safety component that is designed to ensure the vehicle remains stable on the road when the suspension is under maximum compression. If during hard cornering the bump stop does not support the side under compression it can cause instability and an unpredictable behaviour of the vehicle which can cause the driver to lose control.
Even worse imagine a scenario where an air spring fails during high speed cornering resulting in the wheel rubbing against the fender. This can induce a sudden oversteer and resultant loss of control of the vehicle.
I also believe the sudden failures I have had are a result of the air spring having to do many more high compress cycles than it should due to the fact that it does not have an adequate bump stop to support it. See pic of failed air bellow reflecting the catastrophic failure!
I have enquired with Arnott about this alarming design fault. They have however not even bothered to revert with an explanation.
I sent the Arnott air spring back as it is clearly not fit for purpose.
I would be interested to hear what other peoples experiences have been on this.
Arnott does use a bump stop that is slightly smaller than the OE. During the original design we used the same size and material as the OE but the ride was a bit harsh.To fix this engineers changed the bump stop to a polyurethane unit that was a bit shorter but improved the ride quality significantly. We have sold these for well over a decade and typically this is not a problem.
Arnott Customer Support & the R&D team note that main reason for this type of damage is if the vehicle is driven in a deflated state for a period of time. Driving conditions, add-on modifications and mileage may also affect this. Regardless of the cause - we apologize for your continued issues - Please contact Customer Support for a warranty replacement.
We offer a Limited Lifetime Warranty in North America for all of our allroad products including GEN I & GEN II Air Springs, our new pre-assembled complete struts and the Arnott coil spring conversion kit which should eliminate future air suspension related issues on these 14+ year old applications.
You must really love your allroad to put up with five replacements, all of which I assume were covered by Arnott's warranty. I purchased one of their first coil spring conversion kits, and have never had to worry about suspension troubles again. Yes the ride height is a little lower (I would think they could fix that) but I don't really have a need for or miss the height adjustments.
Just a thought.
Arnott does use a bump stop that is slightly smaller than the OE. During the original design we used the same size and material as the OE but the ride was a bit harsh.To fix this engineers changed the bump stop to a polyurethane unit that was a bit shorter but improved the ride quality significantly. We have sold these for well over a decade and typically this is not a problem.
Arnott Customer Support & the R&D team note that main reason for this type of damage is if the vehicle is driven in a deflated state for a period of time. Driving conditions, add-on modifications and mileage may also affect this. Regardless of the cause - we apologize for your continued issues - Please contact Customer Support for a warranty replacement.
We offer a Limited Lifetime Warranty in North America for all of our allroad products including GEN I & GEN II Air Springs, our new pre-assembled complete struts and the Arnott coil spring conversion kit which should eliminate future air suspension related issues on these 14+ year old applications.
I have contacted customer support, however they have failed to respond to my e-mails re the defective design........ I live outside the US so the lifetime warranty does not apply. Total cost to me so far to replace the 6 airsprings is in the region of $3000!
The airspring ultimately was not designed to run a shorter bump stop. Running a shorter bump stop is a bit like suggesting one should underinflate tyres for a softer ride. It will work but we all know the dangers and damage done to the tyre by running them underinflated! Ditto for running a bump stop that is too short.
If the bumps stop was the correct length there would not be issues with driving the vehicle to the closest place of safety without damage
If the bump stop was the correct length there would not be damaged air lines due to the vehicle resting on the airlines where it should be resting on the bump stops.
If the bump stop was the correct length many of us users would not have premature failure and leaking of the air bag around around the lower connecting ring.
I never drove the vehicle as is suggested on deflated bags to then cause the damage. I parked the vehicle in the evening on level 2, came back the next morning to find the front completely deflated. It had failed so badly over night (whilst standing in the garage) that I was unable to even raise the vehicle at all the following morning
The bump stop is 40% shorter which is somewhat more than "a bit" as suggested. Note that this % is based on the full length of the bump stop including the portion integrated into the top support. If however you base the difference only on the active (protruding) portion of the bump stop the difference is probably closer to 60%.
I am seeing multiple symptoms (tyres touch fenders, airlines damaged, vehicle resting on control arms, multiple failure of airspring at bottom connection ring) on my side that all point to one cause and that is that the bump stop is too short.
You must really love your allroad to put up with five replacements, all of which I assume were covered by Arnott's warranty. I purchased one of their first coil spring conversion kits, and have never had to worry about suspension troubles again. Yes the ride height is a little lower (I would think they could fix that) but I don't really have a need for or miss the height adjustments.
Just a thought.
Hi B7JDS,
I am outside the US so my Arnott's were not covered by the lifetime warranty. Totals cost so far is in the region of $3000! In hindsight I should have just replaced with OEM's when the original OEM's failed. But as they say hindsight is an exact science!
I did consider coil springs. I however do enjoy the smooth ride of airsprings and feel the adjustable airsprings are a unique character of the allroad for me.
Hey gcpgcpo
Same here.
05 Allroad. Replaced front OEM air springs with Arnott's.
Exact same failure. Right one wouldn't inflate all of a sudden, following several years of successful usage.
Took it apart and found the band at the bottom off. I don't think I have the tools to reset it.
The parts are in good condition, just came apart.
I had leaky airlines back in 2017 after buying my AR used, and I lost all air in the front bags once while driving home. I could barely get back and needed a "30-point" turn just to get into the garage that was at a right angle to the driveway.
I always assumed my airbags are OEM but it sounds like one should still be able to turn the wheels fully with deflated front bags? This definitely was not the case with my car. At the time, I cursed Audi engineers for their p!ss-poor, short-sighted design. Maybe I should've cursed Arnott engineers instead ha ha!
I'm wondering though if it's possible both the Arnott Gen-I and Audi/OEM front bags cause steering restriction when fully deflated?
I have new Gen-I fronts in the house, so perhaps I'll compare them to the ones on the car when installing my winter tires here shortly to see exactly which bags I've been rolling on the past 6+ years and report back...
Regarding durability, whatever bags I have now are very well built as I use the car on a bumpy, rocky, muddy logging road regularly in the warmer months. They've started to leak down a bit on cold nights the past few winters but still hold air well overall. I believe I read "Continental" on one of my springs once years ago but maybe Arnott uses Continental bladders as well..?
Regarding ride quality, I will assume the bump stops are molded into the bottom seat of the air spring, which would explain how Arnott's choice to use a polyurethane seat affected the bump stop as well? If so, I agree that incorporating a 40% shorter bump stop than OEM specification is definitely a design flaw, and I sense the Arnott customer service department will be submitting a long overdue engineering change request to real quik lol!
Last edited by Adam's Dad; 10-25-2023 at 05:31 AM.
Reason: Addendum and corrections.
In addition to the bump stop observation and likely stating the obvious but the crimp clamp around the bag is not up to the task. Sadly the bag in this pic is still good but failed to hold between two adjacent high points of the band clamp. The clamp needs a re-design as well as a taller bump stop.
04-17-2019, 10:00 AM
Faulty air spring design
