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There are two ball joints involved in the steering mechanism of my under seat steering recumbent.

One of them ripped out of its socket:

Picture of broken part.

The dirty grey-green part inside the end of the bar is made of rubber and is supposed to hold the steel ball on the handlebar. The rubber part has the number "010-0000-017-008" on top and "12" on the bottom. The metal piece surrounding it has an "R" stamped in. According to a comment the same part is used for the self-leveling suspension adjustment of Mercedes 1999 E320.

Here you can see the intact mechanism:

More zoomed out picture.

And here an overview with the whole bike visible, just for better illustration of why that problem is even bicycle related. :)

Even more zoomed out picture.

I tried pushing it back on by hand, then using pliers but in vain. Possibly there are larger pliers which can apply more force, but I already applied quite a lot.

Just for the curious, how this happened: The part where the ball joint fastens to the handlebar can be moved along the handlebar. I moved it out, this means that small movements of the handlebar result in much larger movements of the fork, so the steering is more responsive and smaller curves are possible before the handlebar hits the thighs. This also means that there is nothing preventing the fork from turning more than 90 degrees especially when no thighs are preventing the handlebar from turning, for example when pushing the bicycle by the seat. That's what happened, the fork turned so much that because of the steering axis angle pushing forward resulted in a force turning the wheel even more, until the ball joint snapped and the front wheel pointed backwards.

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    Have you checked with the supplier? They may have relevant advice about a repair or replacement – Criggie Jul 28 '18 at 10:22
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    @Criggie I have, but they didn't respond on Friday and don't work Saturday, so I thought maybe someone here could help me first. :) The steering damper is a good idea, if I find a way to mount one (or maybe ask the manufacturer too) I will. – Nobody Jul 28 '18 at 10:27
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    I have a length of cord hanked up on/in some of my bikes. Handy for tying down loads, but I once used it as reins, tied at the bars and the middle held in my hand at the saddle. Made walking a lot nicer. Or just ride and don't walk :) – Criggie Jul 28 '18 at 10:40
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    I talked with a guy from the manufacturer on the phone. Apparently it's hard but possible to put them back together, but quality would suffer. He thinks the reason it ripped out could be that the attachment ring in the handlebar is slightly turned, the screw bearing the ball should have a right angle with the rod. I'll put in in an answer once I've received the replacement and fixed it. Maybe also try assembling the old one again. – Nobody Jul 30 '18 at 15:42
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    Oh my goodness... This is the exact plug in my Mercedes 1999 E320 wagon. That's how I found this thread. It's used for the self-leveling suspension adjustment. Mine has ripped out due to deterioration. – GuitarPicker Sep 28 '18 at 1:15
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What you have there is a ball joint (sometimes called a tie rod end) on a push rod (or track or tie rod) for indirect steering.

I'm astonished it could pop out that easily - Normally they're very secure.

Here's what a car one looks like when exploded. Yours will be similar but much smaller and lighter.

http://image.fourwheeler.com/f/47147002+w660+h440+q80+re0+cr1+ar0/154-1307-03%2Bheavy-duty-custom-steering-built-for-abuse%2Bball-joint-exploded-view

I think you need a replacement ball joint. These are the same as ones used in car steering systems, and they are unserviceable. You generally cannot disassemble them without destroying the seal - all you can do is grease them via a grease nipple, if they have one.

The old parts should unscrew from the track rod end (there may be a clamp or retainer screw) and from the fork's arm. On a car, you use a Ball Joint Splitter to get the ball part out of the arm. The hole has sloped sides for an inference fit once tight, just like the sides of a square taper are sloped. In the exploded pic above, the slopey sided bit is clearly visible between the ball and the threadded part. Yours will likely be too small for a car tool.

This is a Ball joint fork - hammered in. enter image description here

And this is a ball joint separator which levers the ball out. enter image description here

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It's possible but hard to put it back together: Use lots of force and push the sleeve straight onto the ball.

  • Put it on loosely.
  • Add some lubricant if necessary. Some is probably already there.
  • If you've got sufficiently large pliers, wrap a cloth around the parts to protect them from scratches and push them together.
  • If using your hands, wrap a cloth around the parts lots of times to cushion them and increase the size of the area you are pressing against. It's probably fine to just press on top, but I tried opposing the force from the bottom to keep stress to the handlebar mount low.

But quality will suffer from putting it back together. The seal isn't perfect anymore and it could more easily pop out again.

Replacements are available from the manufacturer of the bike. The female parts unscrew from the rod, they are identical on both sides. The male parts should also unscrew. I'll add more details on replacing them once I do. Right now the reassembled one seems fine.

Prevent it from happening again:

  • According to the manufacturer they should really never pop out like that, it's very unusual. Possibly the reason was that the handlebar mount was (slightly) out of alignment. It's important the ball part has a right angle with the rod or equivalently the flat part of the handlebar mount is parallel to the rod. The alignment in the picture is pretty good: Illustration of previous paragraph. The red lines are supposed to be parallel to the parts they are drawn on and have right angles.
  • Setting the steering up to be less sensitive will improve steering behaviour in free handed (i.e. no hand at handlebars) pushing and make such an accident during pushing extremely unlikely. And while riding it pretty much can't happen in any circumstances anyway.
  • An M6x50 bolt will fit nicely through the slit of that part next to the fork where the ball joint is mounted: Fork mount with slit. Put it in from below using a washers on both sides of the slit and a nut on top. Wrap the thread with insulation tape or any other rubbery tape or shrink wrap it (possibly several layers of shrink wrap) so it doesn't scratch the frame. It acts as a steering limiter. Mounted at the outermost point it limits the steering to the largest plausibly useful range.

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