What are the symptoms ....

[slparry]

....of a worn ball joint on the duolever?

I'm guessing it's not a notchiness like worn head bearings would be?

[Costas]

The best to give you an accurate description in Brian.
Mine started to feel a little waving just before stopping bike at a traffic light. Coming hard and braking last moment the feeling of the front going left and right. Then when hard on the brakes the same waving reappear, again braking before a curve movement of the front was noticeable and the bike also seemed to open a bit its course at fast curves, it seemed that there was not enough road to make it through every curve.
My mechanic had developed a test to check on them. He lifts bikes front from the steering supporter and then with the duolever free of any wait moves it back and forth, left and right; if the joints is broken or need replacement then distinctive noise is heard sometimes even block during movement and the waving is obvious to any observer.   

[Phmode]

Having had two sets replaced within 800 miles (at 18,000 miles), I consider myself to be an expert (a has-been drip under pressure  )

The first sign of mine, both times, was a bad judder under HARD braking from HIGH speed. Definition of hard, a great big fistful but not quite making the ABS kick in. Definition of high, well above 70, so not really high then 

This didn't happen/wasn't noticeable at lower speeds or lighter braking.

At or about the same time I began to notice a LOW speed, LOW amplitude weave about the dead ahead position with no steering input, much like a set of head races on the way out. Low speed means about 50 and the 'width' of the weave is about a foot or less on the road.

I have heard of cases where only one of the above symptoms was in evidence, cases where neither were noticed by the rider (?) and cases where both were, like mine.

The acid test is to have your very attractive assistant hold the bike upright with the weight on the wheels while you grasp the bottom of the 'forks' and do a violent back and forth pull/push motion. You should feel the  play in the assembly. If you try this alone with it on the centre stand you can easily pull it off. If you try it with the brakes on, nothing happens apart from feeling the knock of the discs moving on the rivets.

If you can get it raised and chocked you can do the test by yourself. If you have it raised and chocked and have your very attractive assistant do the push/pull stuff, you can put your fingers up on each ball joint in turn and feel the movement; it is VERY distinct!

When mine went the first time I was convinced the judder was the front brakes but Bahnstormers showed me the play in the top joint and changed them both. I paid.

The second time, 800 miles later, I knew the judder was the brakes warping and took it back to them. They tried it and informed me the top joint had gone again. They had stock and set about changing them foc while I waited. Bad news was they stripped the thread in the bottom hole of the wheel carrier (forks). BMW was happy to pay for that at £400 but there were none in the UK.

Picked the bike up a few days later and a slight judder was still in evidence. New discs cured that and everything is still tickety-boo at 35,000 miles.

Brian (who has never changed his own but seems to remember Tom has)

[slparry]

I ask cos of late my steering feel has gone very light, I'm not sure if it's the steering dampener that's gone or the joints. Coincidentally Brian I also get a juddering that I'd attributed to a warped disk, but who knows

It's booked in at the end of the month for the rear wheel flange and the fuel strip so they're going to check out the steering dampener/joints.

I'm surprised BMW coughed for a new duolever arm cos of the thread issue Brian, I'd have expected them to say corrosion so not covered ?

[Niall]

To be honest, I hadn't noticed mine going. Chandlers said I had probably adjusted and got used to it over time.

I think it was a bit "weavy" and a bit vague which I'd put down to tyre wear

[Phmode]

Steve, my bike wasn't under warranty so the deal was based on my paying to have the joints changed the first time.

When they went the second time, the dealer had cleared it with BMW to give me new joints and pay for the labour too seeing it was only 800 miles since the first lot. When the thread stripped in the A frame they pushed BMW into agreeing to pay for that too.

Brian (who thinks it was a fair deal and one he found hard to complain about  )