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DIY: Adjustable Lower Control Arm

55K views 34 replies 23 participants last post by  Hrvat 
#1 ·
Just finished installing Turner Motorsport rear adjustable control arms. The passenger side is very straight forward, the driver side is the challenge. Completed the driver's side in about two hours with sockets, wrenches and a crowbar.

I used two threads to help me with this project:
Subframe DIY http://forum.e46fanatics.com/showthread.php?t=521636
And a control arm DIY http://forum.e46fanatics.com/showthread.php?t=572194

As the attachments are no longer available in the control arm DIY, I contacted the OP so he could explain his approach further. What he conveyed was even though he loosened the differential, he still couldn't remove the existing upper bolt which is why he cut it or bent it. I could see why......you definitely need a helper with this project otherwise I am sure it will be a struggle to get that last 1/4 inch to get the upper bolt removed.

According to the OP, if you order an upper replacement bolt, you will get a shorter one even though the PN called out on Realoem is 80MM in length. Hex Bolt Part Number is 331 710 908 24 if you plan to bend or cut the existing bolt. Not necessary if you have a crowbar and a helper.

I followed the above DIY up to the point of cutting the upper bolt off. Concise DIY for the drivers side:

1) Jack up car as high as you can.
2) Remove wheel.
3) Mark and remove lower control arm bolt then remove it. (No need to mark it if you are replacing with adjustable control arms)
4) Remove four nuts from rear muffler hanger
5) For convertibles or M3's, remove structural "A" brace
6) Remove driveshaft support bracket (suspension reinforcement brace) in front of the differential. Thank "thefoxkazen" for his pic and subframe bushing DIY

7) Loosen the two bolts for the front differential until they are almost out. Do not completely remove them. Noted as B1 And B2 in this photo, thanks to the "foxkazen" again!:

8) Begin loosening the upper control arm bolt with an 18mm wrench. You will now see why the exhaust needed to be dropped as there isn't alot of room to get at this bolt. I found it easier to loosen the upper bolt by removing the lower control arm from the ball joint. Basically let the lower part of the control arm hang free so it doesn't bind or twist. Relieving the pressure makes getting the upper bolt loosened quite easily.
9) Support the differential with jack and completely remove the rear differential bolt
10) Slowly lower the jack
11) Now is the tricky part. The reason you left the two front differential bolts in is to support the unit. You need to pull the differential to the back of the car in order to get the upper control arm bolt out. If you are doing this on your own, you can follow the OP's advice and cut the bolt or bend it. If you have a helper you don't need to do either as the bolt will come out. Have your buddy uses a crow bar to pry the diff to the back of the car. While he is prying/ pulling the diff backwards, you can remove the upper differential bolt.

Great pictures are here to describe what needs to take place for this DIY, thanks to the foxkazen!:

http://forum.e46fanatics.com/showthread.php?t=521636

There is no need to remove the driveshaft, swaybar or the axle as described in other threads or Turner's instrcutions......
This is not that hard of a project, just alot of stuff needs to be either removed or loosened to get this bolt out.

Now for an alignment...these Turner Adjustable camber arms surely make the car feel rock solid!



http://www.turnermotorsport.com/html/detail.asp?PRODUCT_ID=TSU9940001
 
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#24 ·
James, I Too have these same arms and LUTZ Performance installed them but NOW I see they were "just" Installed and never Aligned or adjusted as to why I Blew BOTH Rear tires in just 5k miles.

Both tore the inner sidewall with ALL of its thread still in great shape.

The tires give off the appearance of no wear until you put your face on the ground and take a REAL LOOK underneath to see the Tires are only making contact with the ground on the inner portion of the tire tread.

$300 Tire gone in 8 months... frustrating waste!

so now i need my Rear aligned asap.

this is a Great thread btw OP thank you!
 
#8 ·
To get out the upper bolt of the lower rear LH control arm, I understand the brace in front of the differential and the three bolts supporting the differential (2 in front, one in rear) have to be removed, but does the driveshaft have to unbolted to move it back or over enough to slip the upper bolt out?
Do the 18mm bolts to the subframe bushings (were all the cracking problems are) need to be loosened or removed, too?
This simple '10 minute' job of slipping in and out 2 bolts to replace a broken lower control arm has turned into a nightmare;
I live in a Condo where we are not allowed to work on our cars in the carport, so I need the quick 'stealth' fixes!
 
#9 · (Edited)
NO.....do not remove the front two subframe bolts, only loosen them until they are almost completely out. You only remove the rear subframe bolt.

7) Loosen the two bolts for the front differential until they are almost out. Do not completely remove them. Noted as B1 And B2 in this photo, thanks to the "foxkazen" again!:

These are the only three bolts that you need to touch on the subframe.

You do not have to do anything with the driveshaft or the subframe mounts.
 
#10 ·
Just got done changing out the broken lower rear control arm at 2 a.m. last night, 5 hours before I had to report for shoulder surgery (I find I need three arms to work on a car, not just one!). Removed the bolts for the Rear muffler brackets (x2), sway bar, and the cross brace in front of the differential. Most nuts are 13mm or 18mm (<not incl. in most tool-kits-make sure you have one!). The front two bushing-bolts on the differential were also removed, and a jack put under the differential to move it up and down and loosen things up. Once I stuck the wrench on the rear bushing (21mm), I realized with 120+ ft-lbs of torque there was no way I was going to break that loose while working with only a few spare inches of room under a car on low jack-stands (in stealth condo-carport repair mode, since we aren't allowed to work on our cars here). Fortunately, just cranking on it was enough to twist the loosened differential so that I could get the lower inner control arm bolt out (only took three full evenings of messing with it! Finding this DIY yesterday sure helped!). Putting it all back together after putting in the new lower control arm took an hour, but was pretty much straightforward.
IMHO it is stupid that the BMW engineers didn't make the bracket 1 cm longer so the bolt would clear the axle-joint. Those guys may be good engineers, but they sure have no common sense, and certainly don't work on their own cars. Sliding out two bolts and replacing a simple straight bar that is dangling in the breeze should be a 10 minute job.
BTW- Goods News (which is rare with this recently-purchased Used car): No subframe cracks and bushings looked to be in pretty good shape in the totally-stock 323Ci (for now) with 137k on it.
 
#12 ·
IMHO it is stupid that the BMW engineers didn't make the bracket 1 cm longer so the bolt would clear the axle-joint. Those guys may be good engineers, but they sure have no common sense, and certainly don't work on their own cars. Sliding out two bolts and replacing a simple straight bar that is dangling in the breeze should be a 10 minute job.
The rear control arms are definitely not the German's best work but overall our cars are well thought out and easy to maintain.

The bad thing is you look at and think it will be so easy until you can't get that one bolt out.:banghead:

A brief review:

Between the addition of these control arms and the installation of the Powerflex RTAB's ( http://forum.e46fanatics.com/showthread.php?t=678004 ) the car is transformed to a whole new level! The car is so tight and handles so well, it's going to take some getting used to. The car's limits are beyond my driving skill at this point!
Let us know if your RTABS start squeaking. My UUC RTABS now have a noticable squeak when going over bumps which is mildly annoying.
 
#13 ·
Thanks for this DIY, it turned out to be super helpful when i installed my rear adjustable ca's. I didnt cut the bolt though i just unbolted everything like the instructions indicate and it worked out just fine. I live about 30 mins from the closest dealer so i just used the parts i already had. anyway, not a bad job...though it kinda sucks that the bolt won't just come out. all in all id say a 3 hour job with some standing around time factored in.
 
#33 ·
thanks for this diy, it turned out to be super helpful when i installed my rear adjustable ca's. I didnt cut the bolt though i just unbolted everything like the instructions indicate and it worked out just fine. I live about 30 mins from the closest dealer so i just used the parts i already had. Anyway, not a bad job...though it kinda sucks that the bolt won't just come out. All in all id say a 3 hour job with some standing around time factored in.
+1
 
#15 ·
most of it!, though i did hand a friend the flat bar so that he could pry the diff back while i stuffed the bolt in. Though i guess if you cant get any help it seems possible to let the loosened diff rest on a floor jack, and then when you are ready to move the diff pull the floor jack toward the back of the car.
 
#16 · (Edited)
Just installed my SPC adjustable control arms. Thanks so much for the write-up. I was able to do the job all by my self. I started with the driver's side first, since it was going to be the hardest. I loosened everything up and tried to pry back the diff. It moved back a little, but not far enough. It was pretty hard trying to pry it back with one hand and trying to remove the bolt with the other. Then, I remembered reading a post about lifting the diff up. So, I jacked up the diff a little and the bolt came right out. Everything else was easy after that. (Took about 3.5 hours.) Now, for new tires and an alignment. Thanks again!
 
#22 ·
I would Like to add something to this DIY thread if thats ok. Once you have the new control arms in and you place everything back into its place. the bolt that goes through the bushing end.... make sure to just snug this up at first until everything is in and tires are back on the ground.. you will need to torque the bolt with the vehicle at ride height. Torqueing the bolt to spec while the suspension is hanging will pre-maturely wear the bushing out. Just a tip. This basically goes for any bolt going through a bushing more or less.
 
#23 ·
just want to say thanks to this thread I was able to get my rear adjustable control arms in. Though the write up was a little confusing at first but going through the walk through over about 3 times and going back to the car after figured it out and was able to get it all done. Started with the driver side and then moved to the passenger. Took me about 3 and a hour hours. Now time for an alignment.
 
#27 ·
I am trying this right now and I am not sure where to pry the differential backwards. Can someone please help!
 
#28 ·
11) Now is the tricky part. The reason you left the two front differential bolts in is to support the unit. You need to pull the differential to the back of the car in order to get the upper control arm bolt out. If you are doing this on your own, you can follow the OP's advice and cut the bolt or bend it. If you have a helper you don't need to do either as the bolt will come out. Have your buddy uses a crow bar to pry the diff to the back of the car. While he is prying/ pulling the diff backwards, you can remove the upper differential bolt.

It's been a long time, try to just pry/pull/gain leverage to get the diff where you need to in order to get that bolt out. Pry on the most solid areas you can find avoiding axle shafts etc
 
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