A warning about replacement lower wishbones
 

I thought I best share this, as this for me was a serious safety concern.

Some time back, I put the A8 through its MOT and got its usual list of replacements needed, which included the lower suspension wishbone arm due to a perished boot.
As you may know, you cant buy the ball joint by itself - you replace the whole arm.

As you always do, you trust the garage, who ordered a none Audi replacement, and fitted it, along with a steering trackrod end.

The garage at the time was a well known "fast attachment" garage (work it out and yes, I was an awful numpty for ever trusting them).

About 8 months later, I started getting odd problem. The ABS warning light was coming on and the steering wheel was off centre.
So I took it down to my now regular garage and asked them to look at it.
Well... what they told me, turned me sheet white.
Firstly the Trackrod had been fitted, but not tightened up at all. It was loose, and the reason the ABS warning was going off was it was unwinding itself - the wheels were not straight anymore and with a sharp shock, the front wheel could have broken loose of the steering on that side.
However they also found, the replacement wishbone was also loose. It had been fitted correctly, but it seemed whoever had fitted it, put a Nylock nut to hold the ball joint in place.
The garage repaired the trackrod and did a full laser wheel alignment on the car which stopped the ABS light and the steering wheel went back to straight.
Sadly though this nylock was a different issue entirely. The nylock was due to the wear and motion, unwinding itself, which then loosened the arm.
There didnt seem to be any way of retaining the nut tight.
The solution was a old trick we used to back when I was doing classic VW.
Double nutting. This is fitting two nuts to the thread, then cross tightening the nuts against each other locking them in place. With a little bit of thread lock too, this fixed the issue and I checked it later.

Then the next year, the garage had to do the other side for the MOT.
Same situation and the parts came in from... well ... a European motor parts company that is well known in the UK.
When it turned up, same as the other side. No locking method - just a nylock.
They fitted it and thread locked it.

Roughly 4 weeks later, after driving down the motorway to take my daughter to her riding lesson, we finished, up, pull out of the car park and drove down the country road when suddenly and without warning, there was a bang, and the car went nuts... couldnt drive or steer it properly.
Pulled in to to a carpark, got out, and found the front wheel was at a very odd angle in the wheel arch - checking it, the wishbone had fallen off.

In short, the nylock nut provided had fallen off some time back and the suspension was floating free - terrifying to think a hour before, I had been doing 70 on the motorway.
The garage was mortified, and needless to say they repaired it and made it bullet proof. However that was also a catalyst for them to cease their trade with said auto parts supplier too.

When you replace these wishbone arms, be very suspicious of arms supplied with Nylock nuts for the main ball joint.
Nylock nuts are designed to hold a bolt fast so it doesnt spin unless you provide enough leverage to make it move. Its not a fully locking item.
So when you are dealing with a major stress point on a car, nylocks are not suitable.
On older cars they used to use castle nuts with split pins, so you could tighten the item up, and then with the split pin, lock it in place... physical mechanical locking.

What worries me is twice, I could have ended up having a serious accident thanks to poorly designed replacement parts. And I am talking about the kind of accident that would do lots of damage and possible threat to life. Imagine what would have happened if that suspension arm had failed at 70... the Wheel getting smashed in to the wheel arch, followed by either spins, or even rolling the car.

Anyhow... thats the warning...

I'm not sure the genuine parts using anything different to a nylon locking nut - maybe a nut with a serrated underside to bite into the surface a bit?

Worrying, nonetheless!

For information, the oem nuts are all 'washer attached'. That is, the washer is part of the nut and doesn't spin. It has also got a serrated bottom that bites into the arms or mounts when tightened to oem torque. The nuts are steel coated with a corrosion inhibitor so there is reduced bi-metal effect. Personnaly, unless it's oem, Febi Bilstein or Mahle don't use them. Nylock nuts won't cut it with the constant pressures of your suspension.
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Sadly I have to agree with Conan on this.
In fairness, the replacement wishbone itself is very good quality and does what it says on the tin. However, the fitting kit that came with it was an after thought, and a dangerous one at that.
Inside the pack you get a standard nylock nut, and a selection of standard washers. Its like someone went to a standard parts bin, grabbed the nearest stock items they could and ran with them.

If trading standards got involved in this, they would deem the part to be dangerous and defective, however these are being sold as replacement items off the shelf and probably worth noting that in all likelihood, the same philosophy is being employed across various cars from this manufacturer.

The saddest thing is, most mechanics today get a part in, its supplied with a fitting kit and they dont question it. If the parts supplied with those items, then they have to be safe. Which is why I found out the hard way.

If you are having a garage repair your A8, make 100% sure they are fitting a part that comes with the correct fittings - thats all I can say, or get OEM or trusted Aftermarket parts like Conan suggests.

For lower arms (the meaty ones) I'd only fit OEM on mine - partly because the 20" wheel from factory fitment is different to the others, but mainly because the non-genuine alternatives are few and far between. Meyle HD don't make one for it, although they do for 18" wheels.

Mine are still factory original at 13 years/65k miles

I have fitted 2 sets of after market arms with no issues at all and 100k miles, i replaced nuts and bolts for genuine from TPS the first time i reused the ones i took off and the nuts on the upper arms came loose, they are slightly oval to become locking and are one use only in my opinion. 2 others get cut out unless they have been replaced in the past.

Sounds like a good tip. I didnt realise you could get genunine replacement fittings from TPS. As I said, the arms themselves are good quality and do exactly what they say they should do and I guess the fitting kits from TPS didnt cost an arm and a leg. Worth remembering.