How to fix ripped out ball joint in indirect under seat steering recumbent

Question

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

One of them ripped out of its socket:

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:

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

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.

Answer 1

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.

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.

And this is a ball joint separator which levers the ball out.

Answer 2

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 and probably also in auto stores because the part is also used for example for the self-leveling suspension adjustment of Mercedes 1999 E320 cars. 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: 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: 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.