While it seems relatively straightforward (and it is, once you do it), I found that I had a fair number of questions when replacing the front lower control arm. (The straight one.) It was more difficult than I thought to find a tutorial on what would be involved so I thought I’d try to bring my thoughts together here in case it would benefit anyone else.
Tools I used:
Jack
Jack stand(s)
18mm socket/wrench X2
16mm socket/wrench
10mm socket/wrench
#2 phillips screwdriver
13/16” wrench
7/8” socket/wrench
T-40
12mm 12pt triple square
Rubber mallet
3lb hammer
Steps:
1. Remove wheel (18mm) / jack up car/support w/ jack stand
2. Loosen corner of plastic under tray for side you’re working on. (You can remove the entire thing if you are doing both sides, but isn’t really necessary. I found that I was fine removing the two 10mm screws closest to the wheel I was working near and then loosening one or two of the screws that attach the back of the front tray to the plastic covering for the cross brace. That should give you enough room to get to the bolt attaching the control arm to the sub frame.
Time to start on the control arm itself. I would suggest LOOSENING everything before removing any of the bolts completely as this will make it easier to break everything else loose.
3. The easiest place to get started is probably the bolt in the middle of the control arm that is attached to the strut. Both the bolt and nut are 18mm.
4. Ball joint. There are two ways to approach this:
a. Reuse existing ball joint. This means you’ll have to take off the nut on top of the ball joint. Due to the axle and other stuff attached to the steering knuckle, there is very little room to work here, so a socket almost definitely won’t work and you’ll have to resort to a wrench. 13/16” worked for me, but it might really be 21mm. (I didn’t have a 21mm wrench or socket to check with.) Anyway, assume you can get the nut off successfully, you still need to separate the ball joint from the control arm without damaging the ball joint boot. This means you probably can’t reasonably expect to use a pickle fork or ball joint separator. I have read that it’s possible to do with a lot of hammering, etc. Good luck to you if you want to go this route. However, I decided that it wasn’t worth the hassle… for one thing, it’d be basically impossible to install the nut back on correctly since there wouldn’t be room for my torque wrench. Plus, if you are this close (and you need to replace the control arm anyway), then why not just replace the ball joint as well? Which brings us to method 2:
b. Remove the ball joint from the steering knuckle. The ball joint is held in place by a pinch bolt in the steering knuckle. (16mm) Remove the bolt. I would suggest giving the steering knuckle a few good whacks with a 3 lb. hammer to loosen things up, but probably isn’t necessary. Another thing I found helpful was putting a jack under the control arm and putting some pressure on it. Then pry between the area the pinch bolt was holding closed with something – large screwdriver, pry bar, crowbar, whatever. Just don’t overdo it as you don’t want to be replacing the entire steering knuckle if you break it. Using this method, the ball joint popped out pretty easily for me.
5. Control arm to sub frame bolt. You can loosen this bolt up just fine without doing too much; HOWEVER, to actually get the bolt out past the inner tie rod end, you have to turn the steering wheel. If you’re working on the right wheel, turn the steering wheel all the way to the right. This extends the tie rod all the way out, making the tie rod boot as flat as it’s going to get. This will give you enough room to slide the bolt out. The nut is 18mm. The bolt is 12mm triple square (12pt). You can get the nut pretty loose without messing with the bolt side too much, but once it starts to spin, you have no choice but to secure it somehow. (And you’ll need to do this to tighten it up anyway.) I found that I could get the 12mm triple square in there and then just throw some vice grips on it.b. Remove the ball joint from the steering knuckle. The ball joint is held in place by a pinch bolt in the steering knuckle. (16mm) Remove the bolt. I would suggest giving the steering knuckle a few good whacks with a 3 lb. hammer to loosen things up, but probably isn’t necessary. Another thing I found helpful was putting a jack under the control arm and putting some pressure on it. Then pry between the area the pinch bolt was holding closed with something – large screwdriver, pry bar, crowbar, whatever. Just don’t overdo it as you don’t want to be replacing the entire steering knuckle if you break it. Using this method, the ball joint popped out pretty easily for me.
6. Now that everything is loose, start taking out bolts. You may find that using a jack to support the steering knuckle or control arm is helpful in taking some weight off of the bolts you are trying to mess with. Once the bolts are out, remove the control arm.
7. I decided to install the ball joint on the new control arm before trying to put anything back on the car. Mostly because trying to install the ball joint nut is an immense pain in the ass, but also because I could use my torque wrench to tighten it appropriately this way. As I mentioned above, the nut on the ball joint in my car was around 13/16” or 21mm. The NEW ball joint’s nut was 7/8”. The ball joint stud used a T-40 bit on BOTH. You’ll need this in order to keep the ball joint from spinning as you try to tighten the nut. You can use a regular wrench to tighten the nut, but I much preferred my open socket, just for ease of use. Once the nut is snugged down pretty well, you can switch to your torque wrench. I did some research and it seemed like the appropriate torque numbers depended on the type of nut that was used for your ball joint. In general, it looked like that number was between 100 and 110 NM (74-81ft/lbs).
8. Before trying to fight the control arm back into the car, disconnect the sway bar end link from the strut (the top one). Trust me; I fought with this for a while. Amazing how much easier everything became once I took 2 minutes to remove this one bolt (16mm) Doing so relieves some of the tension on the strut and you can move things around enough to get the control arm back in place fairly easily.
9. I worked inside out for installation (leaving everything loose until everything was in place). Get the control arm bushing in place at the sub frame. (Make sure the control arm is INSIDE the strut fork at the bottom and the bottom of the ball joint is on top of where it needs to go on the steering knuckle.) It took a little bit of wiggling, but by holding the bolt with the vice grips, I was able to get the bolt started. Once it was in to the bushing/control arm, I tapped it with the hammer to get it through. (You may find there isn’t really enough room to do it that way. Just have patience and keep at it. Try wiggling the bolt while you twist the control arm with your other hand. It may just be a matter of them not being lined up quite right.)
10. Next, put the bolt through the strut fork/control arm/bushing. This one is pretty simple. Just adjust the height of the steering knuckle/assembly so it matches up pretty close with the strut fork. You can use a pry bar or something similar to make sure the fork is in the correct placement over the bushing. Something else that might help is straightening the steering wheel a bit to line things up better. (Just be careful to not straighten it too much – the ball joint is sitting higher than it normally would and is pretty close to the axle boot.)
11. Ball joint time. Now that the two control arm bolts are in (but not tightened down), try to align the bottom of the ball joint with where it goes into the steering knuckle. If it’s way off, you may need to adjust via the steering wheel. Again, just be careful. Once it’s close you can try adjusting the ball joint so that it sits on top of where it needs to go in. Try to line it up so that it sits pretty flat. You can then use a jack to put a little weight on the steering knuckle (pushing up a bit.) Again, be careful not to overdo it, as this will force the ball joint into the axle boot, which you don’t want. At this point, I just pried at the pinch bolt location a little bit while tapping the steering knuckle on different positions with the hammer. Little by little the ball joint just sort of fell into place. With the ball joint in place, reinstall the pinch bolt enough to keep the ball joint from moving out of place when you move the jack.
12. Tighten the bolts! …but first things first. While the ball joint doesn’t matter too much, the bushings in the control arm are designed a specific way and you HAVE to tighten the bolts while they are under the correct load. (That is, the weight of the car.) Otherwise you will have a severely shortened lifespan. The easiest thing to do is to put a jack under the steering knuckle and jack it up until the car starts to lift from the jack stand.
13. Torque specs:
a. Control arm to subframe: 80 Nm + ¼ turn
b. Control arm to strut: 90 Nm
c. Sway bar end link (upper bolt): 40 Nm + ¼ turn
14. Lower car back on to jack standb. Control arm to strut: 90 Nm
c. Sway bar end link (upper bolt): 40 Nm + ¼ turn
15. Reinstall screws/bolts for plastic under tray.
16. Reinstall wheel
Another tip that might help out - at some points I found it helpful to pop the tie rod end out of the steering knuckle to give me some more room. This isn't really necessary, but I knew that it should be pretty easy to get out because I just replaced it not long ago. If you are in the situation (or you're replacing it at the same time) then keep that in mind.
**Disclaimer: I bought my car used, and it had some passenger side front end damage early in its life, which is the side I did the work on and thus based this write up on. While everything SEEMS to be stamped with the Audi rings, I don't know how close to OE the parts involved are. (For example, the ball joint is stamped with CZ WD3 TRW on the bottom. TRW is an aftermarket parts company, to my knowledge.) Bottom line, if some of the bolt/nut sizes don't match up exactly, you have my apologies.
Anyway, I hope someone gets some help from this.
-Tony
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Originally Posted by meph137
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