[BoostaVita]

Dear friends, my front control arm finally caved in after 181k miles of service and needs replacement. After reading tons of DIY related thread, I am still nervous as heck. Please help me with some questions:

1. Is the front control arm located behind tie rod and in front of tension strut (upper control arm) for xdrive car?

2 Do I need to detach the whole headlight leveling module (rod and sensor) or just the headlight leveling rod before starting work? Do I need to order new headlight leveling rod?

3. Gonna get Pittman arm puller to drop ball joint part of the arm. What to use if the bushing end (end that attach to the subframe) is stubborn?

4. Is there enough space to get an impact wrench in to remove the ball joint and bushing nuts?

5. Do I need to get new locking nuts for control arm?

Thanks in advance. Please help my car join the 200k miles club.

[westchester335i]

Don't know much about control arms but I am sure someone can help you out here.

More interested in seeing how your car has held up with 181k miles. Are you tuned? What other mods do you have and what issues have you encountered ?

Thanks

[bhmax16]

It sounds like you're talking about the tension strut, which is essentially a lower control arm. Yes one end is attached to the subframe with two large bolts (one in each bushing end) and the other is attached to the ball joint which can easily be removed with a pitman arm puller.

You're not likely to have room to use an impact wrench for this job (and you shouldn't need one anyway). I replaced mine a few months ago and did it completely with hand tools.

You don't need to detach the headlight leveling rod or order any related parts. At least I don't recall needing to do so.

New locking nuts for the ball joint end may be necessary, but you could also just apply some locktite to the old ones and reuse them, which is the route I took. Torque spec on them is very high. They're not going anywhere.

It's one of the simplest steering/suspension related jobs you can do on our cars. Nothing to worry about.

[BoostaVita]

Thanks for the help. Gonna try it soon. Btw, car runs with only Cobb stage 1 aggressive, no other tunes or bolt ons. I dodge pot holes like a religion, drive behind grandmas before oil heat to about 200F, and keep up with maintenance (try to DIY as much as I can, thanks to this forum). This car is probably the most reliable car I've ever owned (20+ car owned). I love this car.

[BoostaVita]

Forget to mention the issues I've had: Mechatronic sleeve, and water pump. others are basic wear and tear items or preventative repair (thermostats and HPFP).

[BoostaVita]

Took a look yesterday and realized the part that need replacing is the wishbone (lower control arm), not the tension strut (upper control arm). On my car it does have a headlight leveling rod attached. Had to pack up cause I don't want to mess up anything. Can someone please help with wishbone install?

[bhmax16]

The wishbone looking piece (lower control arm) is known as the tension strut. I have never heard of the upper control arm being referred to as a tension strut, so what I mentioned in my first post still applies except for removal of the headlight level sensor linkage. If I remember right it detaches either by 1 bolt or a clip. If this doesn't make sense to you, go to realoem, get the front suspension diagram, and show us exactly what part you're looking to replace. The parts breakdown on that site shows how everything comes apart quite well.

[markus037]

OP, where are you located? Id be willing to give you a hand if you are local.

[BoostaVita]

Appreciate the help. I think I should stop thinking and start doing. BTW I live near Boston but thanks for offering though. Hope I don't mess up......

The E90 ball joints are not a tapered interference fit, you don't need any type of puller, you unbolt them and pull them out with your hand. (At least on E90 i not sure if xi is different)

When you say caved in do you mean the arm actually failed by fatigue or did the bushing or balljoint fail?

[BoostaVita]

The control arm fatigued, no leaking from bushing or ball joint.

Thats crazy post pics.

[BoostaVita]

you mean my mileage or the actual control arm? BTW, do you have to remove the leveling rod completely or just remove the end that attached to control arm?

you just pop the end off that attaches to the arm just use a flat head, and you can pop it back on with just your fingers its plastic.

[BoostaVita]

Thank you. I tend to overthink things...... You answered my main concern completely.

Also would suggest a rubber mallet to bang the bushing side of the arm out of the subframe, also its a little tight to remove the bolt on the bushing it will rub on the tierod boot but just push up on the boot as your pulling the bolt out and it will come out.


Remember to leave the bushing side bolt very loose and not torque it until the suspension is loaded (measure from the fender to the centerbore then use a 2nd jack to jack up the hub to that height then tighten use wood if you can), the ball joint side can be tightened at full droop to 122 ft lbs, subframe is 74 ft lbs + 1/4 turn, but I didn't do the 1/4 turn and its fine.

Your gonna have a hell of a time breaking the ball joint nut off unless you have an impact gun, it will rotate and you need to counter it with a T40-45 torx bit can't remember problem with that is you have to use a open end wrench 21MM and they are not very long so you have little leverage for breaking 122 ft lbs.

After its broken off then you can tighten it as tight you can get it with the 21mm open wrench and torx bit countering it, then put the torque wrench on it, the ball joint has little nubs that bite into the aluminum steering nuckle preventing it from rotating once you have it reasonably tight but only in 1 direction, so it will spin when trying to loosen with a breaker bar for example.

In other words if you don't have a impact gun to break the nut off the ball joints, don't waste your time, find a good indy shop to install them. I was about to give up borrowed by friends impact and had the job done in 45 mins, first time, including everything torqued to spec in the loaded position.


Remember to replace both arms, if your car has high miles a lot of guys sell low miles used arms on the forums after upgrading to M3 arms for cheap, otherwise get LEMFÖRDER arms from rmeuropean.com


Oh and if your replacing the lower wishbone the balljoint nut is impossible to get to with a impact without first removing the caliper (note all you need to do is remove the 25 ft lbs sliding pins and pull the caliper off, do not remove the 88 ft lbs caliper carrier as this is a waste of time.) You still will need a 6 inch impact extension and 21mm socket preferably deep.

[BoostaVita]

Greatly appreciate the detailed help. I don't think my car will travel very far without this forum. I am gonna give it a shot and will bolt at the first sign of trouble. I figure even if I can't do it, I will learn a bit more about the car's suspension anyway. Thanks again.