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1,881 Posts
Discussion Starter #1 (Edited)
Usual Disclaimer, do this at your own risk etc.

This is another DIY I was meant to post a few months ago and never got round to it, its for the Lower Control Arm or Wishbone as you***8217;ll see it called on sites such as RealOEM or BMWFans etc, this control arm is the smaller of the two that connects to the lower part of the hub and on the drivers side (UK cars, I***8217;m not sure if it***8217;s the same side for US cars) will have the headlight aim control arm fitted mid-way along. Generally speaking these arms tend to last a bit longer than the upper control arms but if you***8217;ve had to replace the uppers then its worth checking these too, the only problem here is that unless you have a lift they can be a little tricky to check all round the main bushing due to it positioning so a small mirror will help with your inspection.
When looking for defects on these they are just the same as the uppers, your looking for wear, tears and cuts in the main larger rubber bushing and the same for the rubber boot at the hub end which protects the universal joint, but you***8217;ll usually find these on the larger first as it takes the most amount of punishment.
There can be various tell-tale signs of these starting to give out and a quick search throughout the forum will list some of these but for me it was a light steering wheel shake after 65mph.

If you***8217;re a hands on type of owner and used to this type of work you***8217;ll want to allow roughly half an hour per side for this but if this is something you***8217;re doing it as an amateur and not attempted it before then double this time, the lower universal joint nut can be particularly troublesome if its badly corroded, this isn***8217;t too much of a problem with BMW parts and warmer climates but it can be an issue if you live in an area where the roads are regularly salted during the winter months.

So onto the DIY, this is very similar to the upper control arms, so similar in fact I***8217;ve just copied and pasted some of this from the other DIY.

Tools required.

Your choice of vehicle lift be it jacks and stands or a full lift (if you have access) but not ramps as removing the wheels gives you much more room to work.
Chocks for the rears wheels if using jacks and stands.
Breaker bar.
Wheel nut socket 17mm.
18mm sockets deep.
18mm socket shallow or spanner.
10mm socket.
8mm socket.
9mm spanner.
22mm socket deep.
22mm spanner.
T40 Torx (good quality), this could also be a 6mm Allen if your removing an aftermarket part.
Large Philips screw driver.
Torque wrench capable of 165Nm/121.7ft-lbs.

Larger nut and bolt that goes through the main bushing to the chassis.
Self-locking collar nut 33 32 6 760 668 M12X1,5-10 ZNS3
Hex bolt with washer 33 17 6 760 343 M12X100-10.9
The choice is ultimately yours, but I would advise replacing these along with the arms.

Control arms
Left wishbone 31 12 2 347 985
Right wishbone 31 12 2 347 986
The large 22mm nut used to secure the universal joint to the hub should come with the arm but check to make sure.
Although Lemforder is usually the ***8220;go to***8221; parts for this type of thing mine were actually TRW, still from BMW and stamped as such but considering these lower arms lasted 98,000 miles I might not be quite so quick to dismiss the slightly cheaper alternatives next time (if there is a next time).

Before doing anything, you'll want to measure your ride height (reasoning will be explained later), the standard height is listed in the "General Information" sticky on the main E63/64 forum under "Dimensions and Weight" but may not be a good enough representation for you considering this would be a from the factory height.
To do this attach tape measure to bottom middle of the wheel rim flange and measure to lower edge of wheel arch (obviously with the car on level ground), this will give you your cars resting ride height, do this on both sides as you'll probably find there's a slight difference, nothing to worry about so long as it's within the tolerances listed in the sticky mentioned above.
Next is to get your car up on the axle stands (remember to break the tension on your wheel nuts first) and take the wheels and front lower engine splash guard off.
Start by loosening the front wheel nuts and get the car up in the air then remove the front lower engine cover using the Philips screwdriver and remove the front wheels.

Using the 8mm socket remove the black plastic steering and suspension cowl (three of these bolts for each).

Next up, using the 10mm socket and 9mm spanner remove the headlight aim bar from the lower control arm (if doing the driver***8217;s side), I found many places recommend a 10mm spanner for the inner locking nut but mine was actually a 9mm and I couldn***8217;t find any reference in the service history for this being replaced before so can only assume this is still an original BMW part.

Next loosen only (don***8217;t remove yet) the 18mm bolt that goes through the main bushing, both nut and bolt are 18mm, you may need the breaker bar for this as it will be quite tight, you can now also loosen the 22mm nut on the universal joint, you***8217;ll only get so far with this before the spindle just spins round as you try to undo it, at this point you***8217;ll need the 22mm spanner and the T40 Torx to hold the spindle in place while its undone.
You may need some heat if it starts to get quite tight and the last thing you want is to snap the end of the Torx off while still in the spindle, you don***8217;t want to much heat, just enough to expand the metal a bit thus taking the pressure off the nylon inside the nut. I just used a gas soldering iron with a heating attachment rather than the soldering tip, even though the nut is quite thick it only required about 25 seconds of heat to allow it turn relatively freely.
Once this is undone you can slide the universal joint down and out of the hub, then fully undo the bushing bolt and the control arm is now free to be removed.

Take the new control arm and get the main bushing end in place first and fit the new bolt, beware when placing the vertical aim bracket in position, there a small tab on it that fits onto a lip on the chassis, it***8217;s easy to see and needs to be correctly fitted before tightening, go ahead and fit the nut but don***8217;t tighten it up yet.
The universal joint end may need to be moved around a bit in order to fit it to the hub but once in place you can go ahead and tighten it to 165nm or 121.7ft-lbs.
Next refit the front angle joint using the 9mm spanner and 10mm socket, tighten this one to just 10nm or 7.4ft-lbs.

Your almost at the finishing line now and this is the part where the cars resting ride height comes into play.
You can do this in one of two ways, either refit the wheel and jack up the hub assembly until the measurement matches what you took with your tape measure earlier (which is the route I took) or you can jack up the assembly until the suspension is compressed enough to the point where it just begins to lift the car off the axle stand, now technically, both methods take the car to its (theoretical) resting ride height but I wanted to make absolutely sure that before tightening the strut it was exactly as it was when the car was on the ground so used the wheel on method and measured it.
The reason for all this is that the bushing needs to be able to flex in both up and down directions as the suspension moves.
The way the bushing works is the centre spindle where the bolt fits through will not move once it's torqued up but the rubber will flex around it as the control arm travels up and down so if you tighten it with the hub assembly hanging down then technically you've already used up all of its "flex" in one direction and so will wear out very very quickly.

Once you***8217;re happy with the hubs height you can go ahead and tighten up the 18mm bolt/nut, torque this one up to 100nm or 73.7ft/lbs, once you***8217;re up to that give it a further 90 degree/quarter of a turn.
When you lower the hub you'll probably hear the new bushing creak, this is nothing to worry about, it's just the new rubber flexing.
Give the whole area a good clean up to get rid of all the salt and road grime.
If you only put a couple of wheel nuts on just to get the ride height measurement then go ahead and put the rest on, replace the splash guards and lower the car. Once down, do the wheel nuts up to 120nm or 88.5ft/lbs and take the car for a wheel alignment at your favourite Indy/Dealership/Tyre Store then it***8217;s time to go for a very well deserved fun drive, when you get back be sure to retorque the wheel nuts to be sure they've stayed at the correct torque setting.
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