Monday 4 January 2010

Guide: Changing Front Lower Control Arms on BMW E34

One of my to do items for the BMW was to change the control arms, as the wear in the bushes/ball joints was becoming very apparent.

The symptoms are basically wobbling / vibrating of the front end of the car, not just through the steering wheel but you could feel the whole car shaking from side to side. It started at just certain speeds on the motorway, about 50 - 60 mph, which then progressed into bad vibration under braking.

It all came to a head finally at the most inconvenient time (of course) when setting off to drive home for Christmas to visit family. It just started vibrating & wobbling at nearly all speeds and felt very unsafe. So had to limp home and use the Audi, I unfortunately, but fortunately, still have.

So I got hold of new control arms from GSF which included the upper and lower (or front and rear I would have labelled them) left and right control arms. I was expecting them to come complete with bushes and ball joints, which they did all except one joint and of course that was the big bush in the rear control arms. So I had to buy them separately then rush around on New Year's eve trying to find a garage that was open and able to press these bushes into the arms for me. Eventually found a nice little garage (TS Motors, Watford) with a helpful mechanic who said come back in an hour and they were done.

Set about changing them the following day. As expected, I was met with all the usual difficulties of working on old cars: seized bolts. It was cold and I wasn't really in the mood so when the last bolt I needed to release rounded off I gave up, swore and put it back together and swore I would never work on a car again.

When I inevitably calmed down and thought about it later, I decided to attack the job again the next day. I went and invested in a little butane blow torch and it was definitely something I wish I had done a long time ago. It made the job so much easier. The bolt that was seized/rounded I got out by hammering an under sized socket onto the bolt and applied a lot of heat. Finally it gave way.

Changing the arms is actually rather straight forward if it wasn't for the frustration of stuck fasteners. These are the basic steps I took:

  1. Usual safety is paramount first. You will need to chock the rear wheels to be doubly safe as you need to jack the front of the car. Put it in gear too and put handbrake on... No way those rear wheels are moving now.
  2. Remove wheel, brake caliper and brake disc.
  3. The spring is always placing the joints of the suspension assembly under load, even when fully off the ground, so this needs to be relieved. I jacked the hub up to compress the spring, then clamped the spring compressed using a couple of spring compressors. I had to modify them in the end as they were too long to fit in the limited space in the turret, but got there in the end with a set up as shown below.

  4. Next I went round all the bolts I would need to remove to 'crack' them off, to ensure they would all come off. This includes:
    • 3 bolts under the 'tie rod lever' or 'mounting plate'... the plate under the strut that the tie rod and two control arms join onto to.
    • 1 nut on the lower or rear control arm ball joint mounting to the tie rod lever.
    • 2 bolts at the end of each control arm attaching the arms to the vehicle
    • 1 bolt on the ball joint of the tie rod
  5. With all these bolts loosened and the load from the spring removed, you can remove the bolts through the bushes at the vehicle end of the arms, the three tie rod lever bolts and the tie rod ball joint, this whole assembly can come off, as shown below. A ball joint separator may well be required (I recommend you get one before starting) to remove the ball joint from the tie rod end.
    The reason for having to remove the tie rod lever is because the front/upper control arm ball joint nut is hidden underneath the strut.
  6. Now remove the old arms from the tie rod lever. This is much easier if you have a sturdy bench and big vice, but if like me, then standing on it in various ways to get the ball joint nuts off is required. Use a ball joint separator tool to remove the ball joints from the lever. Also the blow torch helped out.
    nce the arms are off, I like to clean things up with some WD40 and wire brush etc, just to remove excess rust/crud from components to be reused.
  7. Assemble the new ball joints onto the tie rod lever, torquing up the nut as required. It may be easier (I found) to tighten the as best you can, then final torque can be applied when it is back on the vehicle. BUT BEWARE, the front/upper ball joint is not accessible when back on the bottom of the strut so you must torque this up before re-assembling on vehicle.

  8. Assemble this assembly back onto the vehicle loosely. Just hand tighten everything in place: the three tie rod lever bolts and the two bolts through the bushes on the vehicle. Do not torque the vehicle nuts and bolts up yet.
  9. The bolts through the bushes on the vehicle end of the control arms need to be tightened up with the arms in the position they will be in when the car is at rest on its wheels. So at this point either jack the hub up to the correct height to simulate this or put the wheel back on and lower the car onto the wheel. Using the wheel method makes access to the bolts very difficult unless you have the front wheels on ramps or are lucky enough to have a pit.
    ighten the bolts with the hub in the correct position.
  10. Then torque up the remaining bolts/nuts: 3 on the tie rod lever, and the ball joint if necessary.
  11. Refit the tie rod ball joint, brake disc, caliper and wheel. Job done.

1 comment:

  1. Jon, great article! The other day our car broke down in the middle of nowhere and my husband was totally clueless as to how to fix things up. He should've read this! By the way, you've got a great blog, please keep up the good stuff! Cheers, Patty