e36 M3 Rear Lower Control Arm Replacement

HIe36m3 · 06-20-2007, 11:32 PM

I tried replacing my rear lower control ams today to correct a negative camber issue as a result of new coilover suspension. I was able to remove the eccentric and nut on the rear spindle. Then I began to remove the bolt that goes through the final drive carrier. When I tried to pull the bolt all the way out, it hit the axle. there's about an inch and a half of space to get out a bolt that is over two inches long. So i tried to remove the mounts for the rear end and move it back, but it wasn't enough to remove the bolt all the way. The Bently Repair Manual says that once the bolt is out the arm should come out. It doesn't say anything about moving any other parts, such as the rear end. I also own the 101 e36 Project book, but it doesn't have anything about the rear arms. Neither does the Mitchell OnDemand version 6, if you're familiar. Does the M3 have a larger(beefier) rear end? I wouldn't be surpried if it did. But I still can't get the bolt out, so now what? Any help would be great. I'd love it if I don't have to remove the rear end. Thanks in advance for the help.

Jeron · Jeron's Garage

You have to lower the bracket. Here at the UUC instructions:
http://www.uucmotorwerks.com/CHROMOLY_ADJ_ARMS

dboyles · 06-22-2007, 07:43 PM

Loosen the diff bolts and you can just barely get enough room to get the control arm mounting bolt out. It's not a fun job, but it can be done.

HIe36m3 · 06-23-2007, 06:17 PM

thanks for the help. i took it out and changed em the other day. i just did it at work where i had a lift, beats the hell out of lying on cardboard.

hitmachine101 · 07-15-2007, 07:16 PM

I am about to tackle the same project and I do have a lift, how did you get those bolts out, did the differential need to be loosened?

sballard · 05-15-2008, 12:20 PM

I resurrected this thread because it looks like I will have to replace the Lower Rear Control Arm. Can someone point out which bolts I have to loosen to lower the differential to remove the upper bolt on the lower control arm? (I assume that it one of these for the differential carrier)

Thanks

Jeron · Jeron's Garage

Haven't done it but as I understand it, the problem is getting clearance to slide the inner bolt out. You should be able to loosen the 4 vertical bolts at the corners of the subframe (7 and 5?). The sub-frame with diff attached should drop down. Use a jack to support it.

dboyles · 05-16-2008, 05:05 PM

I'm drawing a blank on where the three bolts are in relation to the diff, but it's fairly apparent when you're under there (I believe there are 3 bolts). I had to unfasten one end of the rear sway bar and loosen the diff enough to get that bolt out to remove the control arm. In fact I think I completely unbolt the diff and support it with a jack.

I've never done it the way Jeron describes (unbolting the subframe and supporting it with a jack) - Jeron, is that pretty straightforward?

Jeron · Jeron's Garage

Like I said, I haven't done it, but I will soon. I need to reseal the entire diff on mine. I may go with an aftermarket diff cover(racing only part).

sballard · 06-11-2008, 04:49 AM

I am finally getting to replacement of the control arms. Amazing how BMW can make a simple task so hard to do.

I am trying to loosen the 4 bolts that will appear to lower the differential frame and the differential so I can get the freaking inner bolt of the control arms off. The rear two bolts of the diff/carrier (#7 in the figure) came off easily, but the front two needed a deep 18 mm socket which I didn't have. I put a wrench on one (#5 in the figure) and got it to move but the entire bolt and nut are turning the the rubber bushing. I'll try my impact wrench tonight, but I don't have a good feeling about this. I can't get to the top of this bolt to hold it. Any ideas? I'd really like to drive my car to work this week.

sballard · 06-13-2008, 06:14 AM

Well, I am nearly finished with replacement of my rear lower control arms. What an ordeal. I definitely would not have done this if I knew what I was getting into.

Just loosening the 4 vertical bolts in the figure I previously posted will NOT be all you have to do to replace the control arms. You will need all the room you can get in and around the rear drive. First, you will have to take off the anti-sway bar - probably the EASIEST thing I did. Then take off the muffler - again access. The objective is to remove the inboard bolts that hold the lower control arm - they are too long to remove and they bump against the differential (rear drive). Therefore, you will have to separate the rear drive from the rear drive carrier so that you can wiggle the two around enough to get the bolt out. Therefore you will need to unbolt the rear drive from the rear drive carrier - there are 3 horizontal bolts holding it in: one in the right lower front of the carrier and two in the upper rear of the carrier. Then loosen the 4 vertical bolts that hold the carrier to the body. You will need a floor jack to support the assembly but it will not fall to the ground because the rear drive is still connected to the drive shaft and the half shafts. This will allow you to wiggle the carrier separately from the rear drive. It took me about 45 mins of wiggling to get the bolts out. Believe it or not, putting it all back together was twice as difficult as taking it apart. It took just as much effort to get the lower control arm bolts back in when I installed the new arms. I’d swear that the bolts had gotten longer! I found that assembly worked best if I first bolted the carrier to the rear drive, then bolted the assembly to the body. Trying to align the bolt holes in the carrier and rear drive was a FPITA. It has to be perfectly aligned to work. On my first attempt, I stripped the end threads on the front horizontal bolt that connects the carrier and rear drive. I fortunately had a metric tap and die set (put this on your parts list!). I finally figured out that I needed to shine a light from one end and use a mirror on the other end to align the holes. Aligning the carrier bolts to the holes in the body was perhaps even more difficult but with hours of wiggling, jacking, cussing, and yelling I got it all bolted into place. I also snapped a rusty bolt on the rear bracket when I removed the muffler. The freaking bolt was welded into the bracket which was just another thing that made this job so much fun. Thankfully, I found a bolt in my bin that was close in size and used my MIG welder (also essential, it turned out) to weld it onto the bracket. By the way, bolting up the outboard ends of the control arms was no picnic either. You can’t just jack up the hub assembly. You have to pull the hub assembly up and out with you hands (it’s movement is opposed by the upper control arm) while pushing up the lower control arm up from the bottom. Then slide the bolt in. A real "three-handed" maneuver.

Essential items: 18 mm short and long sockets and stout wrench, floor jack, BF hammer, crowbar. Impact wrench was very helpful. As difficult as it was to crawl under the car and do this, I can’t see that it would be any easier with a lift because of all the pushing and pulling and wiggling.

It probably took me 20 hours to change 2 bolts for what unfortunately appears to be a "wear" item. The engineer who decided that a major suspension item should be stamped out of bendable sheet metal and installed so that you have to take half the car apart to replace it should be drawn and quartered at the next Octoberfest.

hafnertile · 02-05-2012, 05:08 PM

I just finished replacing the left LCA on my 2003 330I. Fearing for the worst after reading prior post on the matter I charged ahead only to find that indeed the bolt by the differential does not simply come out. I followed the thought that the differential must move and simply removed the rear bolt and loosened the two front ones that hold it in place. Using a screwdriver to pry the differential over a bit the LCA bolt popped right out! Putting everything back was a cinch. Thanks to all for the helpfull information.