This 1998 E39 540i Automatic is my daily driver. Recently it had begun to develop a nasty clunk over bumps coming from the front suspension, so I did a bit of research and discovered the most likely culprit would be the swaybar end links. It turns out you can look at the sway bar end links with the car sitting on flat ground and the wheels turned full lock in one direction or the other (depending on which side you want to check) rather than having to jack the car up in the air to get at it. The end links are located in front of the upright assembly.
I took a look at mine, and it turned out that the boot on the driver's side upper end was torn, so that was enough for me to order a replacement end link for each side of the car (figuring that if one is gone, the other is generally not far behind)
You can buy these parts from BMW however in Australia, BMW charge an "australian" tax and you generally pay 5x their normal value had you purchased them anywhere else in the world. As such, I looked into alternatives and soon discovered that the BMW parts are OEM by ZF's sub-brand Lemförder. The part number is 19387 02 009 (BMW part: 31 35 1 095 664 - search eBay for suitable end-links) - the parts fit either side of the car so you need two of the same part number to do the whole car. The Lemförder kit includes new nuts and washers, where some other brand kits do not.
Some of the guides on the internet state that you need to jack the car up to "unload" the suspension - this is not true, the swaybar is unloaded as long as the car is on level ground, it is only loaded if you were to jack up one side of the car at a time. To be honest, it's probably more comfortable to jack the car up and remove the wheels, but if like me you can't be bothered, it's quite possible to do it with the wheels on the ground.
What you need:
- New end links (duh)
- 16mm open end spanner
- 16mm socket
- Ratchet handle
- Breaker bar (or muscles)
Basically the process is as follows:
- For RHS of the car, with car on level ground turn the steering full lock to the right; for the LHS you will need to turn the steering full lock to the left.
- Use the 16mm open end spanner to hold the ball joint side of the end link (look at the new one if you don't understand what I'm talking about) - you can undo the top or bottom in whatever order you like, it doesn't matter.
- Use the 16mm socket and ratchet to undo the nut on whichever (top or bottom) link you have the spanner on. You shouldn't need the breaker bar to undo this unless the incredible hulk last fitted these parts to your vehicle (or if you are exceptionally weak ;)
- Remove the other end as well, then remove the end link.
- Install the new end link
- Install the nuts finger tight top and bottom; this prevents cross threading the nuts which can sometimes occur when using power tools. Note it's also recommended that you only use hand tools for this process to prevent damage to any mounts or to the end links.
- Note item 10 in the image above to ensure you install the washer (my original end links were missing this washer on both sides, and as a result the noise my car had was due to the RHS end link working loose at the top) - of the two nuts included in the end link pack, the top bolt is the larger of the two with the free-rotating washer.
- Tighten nuts using the open end spanner to hold the end links - ensuring you don't push the rubber ball joint boot off the end link (if you do, make sure you use a smooth/old flat head screwdriver or similar device to reinstall the ball joint boot)
- Tighten down as hard as you possibly can using the ratchet handle (unless you're the incredible hulk). If you're incredibly weak, you might want to use the breaker bar to help get these tight. Note they have to be quite tight to stop them making any noise.
- Go back to #1 and do the other side of the car
In my case it was immediately obvious as the loose end link was noisy even just pulling in and out of my driveway - the new found silence is amazing, having the new joints fitted has made the car feel a lot more stable at speed also.