# Control Arms



## 31st330i (Jan 11, 2002)

slilley said:


> Yes, those are the newer control arms in the pic above.
> 
> And yes, those also have the same problem with the bushings.
> 
> ...


thanks, Steve. that helps a lot. my car has the newer arms.

the bushings that are "just off the picture" I think are actually the lower ball joints. I'll have to crawl under the car and take another look.

so are the ball joints what is failing prematurly or the bushings at the bottom of the picture? or both?


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## Mystikal (Dec 20, 2001)

TD said:


> FYI, production for the 2001 330s did start in 06/00.


Funny, I asked that quesion in this thread..._last August!_


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## Nick325xiT 5spd (Dec 24, 2001)

The HACK said:


> The TSB is really for older E46es made before September of 1999. All E46es made after that has the upgraded control arm and control arm bushing.
> 
> It is not uncommon for the contorl arm bushing to wear down early, these suspensions, afterall, are wound VERY TIGHTLY.
> 
> You can check out BMP Design for upgraded URETHANE bushings that are stiffer and longer lasting. The side effect is that you'll feel more road vibration through your chasis and steering. That'll probably be my next project.


 Out of curiosity, how many people have installed urethane bushings in E46es? On bf.c, the E36 M3 guys strongly suggest stock bushings as the urethane/polyurethane bushings are apparently prone to on track FAILURE.


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## elbert (Mar 28, 2002)

31st330i said:


> the bushings that are "just off the picture" I think are actually the lower ball joints. I'll have to crawl under the car and take another look.
> 
> so are the ball joints what is failing prematurly or the bushings at the bottom of the picture? or both?


Both, which is part of the confusion. The TSB is actually for the ball joints. That has the symptoms of the wretched squeaking/moaning sound. Those are off the pic, as you stated.

There is no TSB for the control arm bushings, which are visible in that photo. It is right above the "33" part in the "my330i" and underneath the brace, in that particular view (when really it's above the brace).

I have been told that neither the ball joints nor the bushing are serviceable. The ball joints I can believe, I'm not so sure about the bushings.

I've had both fail, the bushing failure having the potential of being catatrophic.


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## 31st330i (Jan 11, 2002)

I wonder if I'm just lucky or if I don't hammer my car enough. :dunno: my car has 40K miles and these have never been replaced and have been checked twice by two different dealers.


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## elbert (Mar 28, 2002)

Nick325xiT 5spd said:


> Out of curiosity, how many people have installed urethane bushings in E46es? On bf.c, the E36 M3 guys strongly suggest stock bushings as the urethane/polyurethane bushings are apparently prone to on track FAILURE.


The irony is the E36-m3 bushings are the recommended replacements for E36 non-m3s! I found that out during my search for E46 urethane control arm bushings, but I haven't found any.

I had a control arm bushing fail which, believe me, is scary.


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## slilley (Feb 12, 2003)

31st330i said:


> thanks, Steve. that helps a lot. my car has the newer arms.
> 
> the bushings that are "just off the picture" I think are actually the lower ball joints. I'll have to crawl under the car and take another look.
> 
> so are the ball joints what is failing prematurly or the bushings at the bottom of the picture? or both?


IMHO, it's usually the ball joints that are failing...and the only fix is to replace the entire control arm. This is a well-known problem not only on the 3-Series, but also on the 5-Series from what I've read in Roundel.

The other bushing (the one at the bottom of the pic) is nothing special -- it's just a rubber suspension bushing -- so it's hard to imagine that this part alone would fail very often. More likely, the bushing will become compliant over time, which will allow the suspention geometry to change during cornering/braking. However, since the dealer replaces the control arm (with built-in ball joint) AND the other bushing together, he'll end up fixing either problem (bad ball joint or bad bushing) by replacing the control arm, so it's hard to say conclusively.

Regards,
Steve


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## 31st330i (Jan 11, 2002)

slilley said:


> The other bushing (the one at the bottom of the pic) is nothing special -- it's just a rubber suspension bushing -- so it's hard to imagine that this part alone would fail very often. More likely, the bushing will become compliant over time, which will allow the suspention geometry to change during cornering/braking.


yes, after looking at the bushings (bottom of pic), I came to the same conclusion (that it seems unlikely that the rubber bushings would be that big of a deal). remember that I was a former dealership tech for a copuple of japanese makes 12+ years ago.

so I'll be on the lookout for bad ball joints from here on out.


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## Guest (Sep 25, 2003)

31st330i said:


> and the 31st 330i was produced in 6/2000.


 As was the 146th 330i (my former car).

And Mystikal, :rofl: I didn't even notice.


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## The HACK (Dec 19, 2001)

31st330i said:


> I wonder if I'm just lucky or if I don't hammer my car enough. :dunno: my car has 40K miles and these have never been replaced and have been checked twice by two different dealers.


I drive the crap out of my car and at 70K miles I have yet to have either the ball joint or the control arm bushing fail. Seems to me driving style does not affect the failure rate, but BUILT DATE.

Both SergioK and my car were built within 4 weeks of each other and his ball-joint just recently went at ~72K miles. We both track our cars and have fairly similar driving styles and miles. He's probably got 2-3X the number of track days I have though. Seems to me cars built between 9/99-9/00 have very small failure rates on these control arm bushings. My wife's car, built in May 2000, also does not show any signs of wear on the control arm bushing.

Too bad that Jason guy doesn't hang out here, otherwise we can certainly use his expertise in tracking the actual failure rate of these control arms. Perhaps BMW got a bad batch along the way? Some of these bushings/ball-joints are failing at an alarming rate.


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## slilley (Feb 12, 2003)

The HACK said:


> I drive the crap out of my car and at 70K miles I have yet to have either the ball joint or the control arm bushing fail. Seems to me driving style does not affect the failure rate, but BUILT DATE.
> 
> Both SergioK and my car were built within 4 weeks of each other and his ball-joint just recently went at ~72K miles. We both track our cars and have fairly similar driving styles and miles. He's probably got 2-3X the number of track days I have though. Seems to me cars built between 9/99-9/00 have very small failure rates on these control arm bushings.


I'm sure it's dependent on a lot of factors; my 323i was built duing 9/99, and the left control arm needed replacement at 35K miles, while the right one lasted until 55K miles (just out of warranty, dammit!).

According to a BMW tech I spoke to, there is alot more control arm failures in the Northeast (where the roads are bad and potholes are everywhere), while there are significantly fewer control arm failures in states with nice, smooth roads.

All I know is that I drove my previous car (Integra GSR) significantly harder than my BMW, and never had to replace one suspension component in 100K miles. Of course, that car weighed a lot less than the 323i.

One other thing to be aware of: bad ball joints don't always make noise. Unless you have a BMW tech that is specifically looking for play in the wheel, most corner garages don't think to check for such a failure. I often wondered how bad the car would get if I didn't replace them -- but would never risk driving a car for an extended period when I thought a critical component was slowly failing.

Regards,
Steve


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## james330x (Apr 14, 2002)

I just made a service appointment because my control arm ball joint was loose on the passenger side. They are apparently replacing the entire control arm, which in agreeement with what others have said, and seems to be a common problem. The dealer actually has tons of these in stock just for this purpose. My car has 22k miles on it. 

PS> Is there anyone that can provide a quick and dirty primer for non tech heads like me on the control arm, and it's various components like the bushings mentioned above. I'm a little lost as to waht's actually going on down under!


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## elbert (Mar 28, 2002)

slilley said:


> The other bushing (the one at the bottom of the pic) is nothing special -- it's just a rubber suspension bushing -- so it's hard to imagine that this part alone would fail very often. More likely, the bushing will become compliant over time, which will allow the suspention geometry to change during cornering/braking.


No. The bushings get brittle then crack. The increased compliance is not the material becoming more elastic/softer, but rather the material shifting around due to the cracks.

In my case, the bushing broke apart completely and fell out of the carrier, so the control arm had nothing to hold it in place in the aft portion. This allows the wheel to deflect significantly while braking, turning, hitting bumps. I could literally lift my wheel upward with my bare hands. It is a big deal.


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## The HACK (Dec 19, 2001)

elbert said:


> No. The bushings get brittle then crack. The increased compliance is not the material becoming more elastic/softer, but rather the material shifting around due to the cracks.


Probably why New Englanders report more of the bushing failure than So. Cal residents...The freezing cold winter combined with quick warming can cause the rubber components to get brittle over time.


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## elbert (Mar 28, 2002)

The HACK said:


> Probably why New Englanders report more of the bushing failure than So. Cal residents...The freezing cold winter combined with quick warming can cause the rubber components to get brittle over time.


Yeah, I'd have to agree--that's the best explanation I've heard so far.


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## SergioK (Aug 14, 2002)

The HACK said:


> Probably why New Englanders report more of the bushing failure than So. Cal residents...The freezing cold winter combined with quick warming can cause the rubber components to get brittle over time.


I have an appointment to bring my car in on Monday to have them check the control arm bushings. Let's see what the damage is.


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## brave1heart (Jan 7, 2002)

Wow, I had not checked the board in about a week and am amazed to find out about the lower control arms being such a common issue, as I just had mine replaced this week out of warranty (53K miles on the car). It cost ~ $750 parts and labor. I first started noticing the creaking noise coming from the front passenger side after I get off the track and the problem kept getting worse over time. The dealer told me that they could not re-use the control arms because the ball bearing at the end of them had to replaced and they cannot be removed from the control arms. I have ~ 10 track days and 15 autoX events on the car so I figured it's not totally surprising but am amazed to find out that some of you have the same problem with a lot fewer miles and track days on your cars. It's an expensive repair - make sure to get it done under warranty if you can. On an unrelated issue, I also had to replace the driver side front and rear bearing hub assemblies (dealer told me that only 3 lug nuts were holding each wheel :yikes: :yikes: :yikes: ) and between these and a couple of other maintenance items, I am 2 grand poorer just a couple of thousand miles out of warranty...Hopefully the two days at Mont Tremblant next week will help erase the memory of that bill


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## blkonblk330i (May 14, 2003)

The dealer replaced my front control arm bushings about six months ago during Inspection 1 and I didn't even know anything was wrong with it.


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## jsc (Sep 3, 2003)

The HACK said:


> I drive the crap out of my car and at 70K miles I have yet to have either the ball joint or the control arm bushing fail. Seems to me driving style does not affect the failure rate, but BUILT DATE.


My 323Ci was a May 2000 build, the creaking started (faintly) at 50,000km (30K miles) and the suspension sounded like an old creaky door when the temperature was above 25 deg C (77 deg F), when both control arms were replaced at 58,000km. Interestingly there was no noise at lower temps and no noticeable difference in handling.

Perhaps (as you also posted) it is more related to temperature fluctuations, as Calgary sees some of the most extreme temperature fluctuations of any city in the world (although my car has spent at least 90% of it's life in heated garages). We have very little salt on the roads in the winter here, so it probably wasn't a factor in my control arm demise. The two dealers here are quite familiar with control arm replacement.

May be the failure is relatively random or just has a massive MTBF spread (generally indicative of poor quality control)?


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## jsc (Sep 3, 2003)

jsc said:


> May be the failure is relatively random or just has a massive MTBF spread (generally indicative of poor quality control)?


Just to elaborate, the MTBF (Mean Time Between Failure) for each batch of control arms may vary a lot, or the standard deviation of failure time for all arms may be high. Often rubber components may have significant property changes from batch to batch, pointing to perhaps more variation in failure due to the rear bushings. Normally machined, forged or sintered components such as ball joints are far more uniform in dimension and material quality.

It would be interesting to determine the number of failures due to the rubber bushing vs the ball joints on a control arm, perhaps then a better pattern may emerge.


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