how to replace front control arm

[sipman]

I have a bad ball joint. I can't tell if its the ball joint at the knuckle or the front pivot.
either way, I need to replace the arm with both ball joints attached. knuckle and bushing are easy but the forward pivot ball joint looks difficult. do I need to drop the subframe? and support the engine?

and are there different control arms for M vs. non-M cars?

[mtrhed]

Actually pretty easy to do. No dropping subframe or supporting engine. Inner ball joint goes through front subframe with a nut on top. I was able to do in my garage on jack stands. Don't remember anything that pissed me off about the job Replace both control arms! M part is different than other Z4 but also used on many e46 models. Noticeable improvement when I did mine.

[jdoublehcubed]

Look on Rock-Auto at their "suspension kit." I just stumbled across it, I want to say it was $250, and it came with 2 control arms, 2 LCABs, 2 sway bar end links, and 2 tie rods. Not OEM BMW but for suspension parts like this I don't see why a qualified suspension company (like Meyle or Lemforder) shouldn't be able to do just as well.

[Karacticus]

Inner ball joint doesn't take much more than a pickle fork and a bigger hammer.

The only real PITA I recall from the job is only being able to get about an 8th of a turn at a time on the inner ball joint nut. They were quite generous with the threads, so get comfortable, you'll be there a while.

[sipman]

I looked on rock auto and some arms are cheap and others are pricey. I might be imagining this, but I thought the ball joints where different on M cars than regular. Is that the reason for the price difference?

[The HACK]

Originally Posted by Karacticus

Inner ball joint doesn't take much more than a pickle fork and a bigger hammer.

The only real PITA I recall from the job is only being able to get about an 8th of a turn at a time on the inner ball joint nut. They were quite generous with the threads, so get comfortable, you'll be there a while.

Ratcheting gear wrench is a MUST for this job.

[mtrhed]

Originally Posted by sipman

I looked on rock auto and some arms are cheap and others are pricey. I might be imagining this, but I thought the ball joints where different on M cars than regular. Is that the reason for the price difference?

All metal vs some plastic I believe. I wouldn't skimp on control arms. I think I found M part, non BMW branded for a good price. They were Lemforder.

[GP20]

How do you tell when the ball-joints are bad? Did you hear any clunking noise? Or noticed any weird handling characteristic?

[Shipkiller]

///M part numbers.

Left control arm: 31122341297
Right control arm: 31122341828

[sipman]

Originally Posted by GP20

How do you tell when the ball-joints are bad? Did you hear any clunking noise? Or noticed any weird handling characteristic?

In my case, I slid into a rounded curb at a Skip Barber Skid School. That wheel was the one to impact the curbing first. I shortly after developed a noise when I would cross over those huge expansion cracks that ice has enlarged to a few inches wide. That or some washboard bumps would make a noise.

I then tried everything to see movement in one of the two arms and nothing would show movement. Sometimes, you need to jack the car by the control arm so you can pick the tire up off the ground, but not let the suspension sag. In that case, you might be able to see moving. Some people use pry bars to see movement or large channel lock to squeeze ball joints together.

What ended up working for me was to put the car on stands, and then I used a rubber mallet. I banged upwards on the control arm and it made a ton of noise. Like a 'clack' or the sound metal to metal makes. I then hit the other side and it was a solid thud indicating that the one side had play, and the other was tight.

[sipman]

Originally Posted by Shipkiller

///M part numbers.

Left control arm: 31122341297
Right control arm: 31122341828

thanks shipkiller,
but I'm still confused. rock auto shows no matching parts to those numbers. are the ones on rockauto different than M arms?

[Shipkiller]

Those part numbers are what RealOEM shows for an MC.

http://www.realoem.com/bmw/showparts...79&hg=31&fg=05

[mtrhed]

31122282121/ 31122282122 will get you the same part(not BMW branded) for less money. Lemforder is the manufacturer. ECS Tuning has them for $199 each vs. $246 each for the BMW branded ones.