[Rodolfox]

The bolt that attaches the upper control arm to the rear wheel carrier sheared off last Friday evening as I was slowly driving away from a friend's house. When I took the corner a loud metallic "ding" noise came from the rear of the car. I kept on going really slow and noticed the steering immediately became kind of "mushy" and less responsive. When I took the next corner the tail end felt like I was driving on snow.

Kept on going really slow and when passing through some rougher pavement a loud metallic banging noise could be heard coming from the left rear wheel. Stopped to take a look, but it was getting dark and I couldn't see much. A few blocks away was a service shop where I had gotten my brakepad sensors installed a few weeks ago so I decided to try to make it there where I could get a better look. When I got there the place was closing down, but we had a better look underneath and discovered that the bolt attaching the rear upper control arm to the wheel carrier has sheared off!!

I had to leave the car there and wait 'till Saturday morning to see what can be done. I've done some research today and found a part number for the bolt (see number 15 on attached image). My major concern is how to remove the remaining part of the bolt from the wheel base without ruining it!

My second concern is WTF?? Just bought the car and it only has 37k miles on it. Not something I would ever expect at this low mileage. And also! I could have F****g killed myself if this had happened at a high(er) speed!

Needless to say having this happen just as I was starting to get a feel for the car is a huge bummer.

Can this be the result of some idiot (i.e. does not know what a torque wrench is) having done work on my 37k mile suspension? Or is it just metal fatigue? I researched some on this forum, but couldn't find anyone with a similar thing happening (a stripped thread, but not a sheared off bolt!). Hoping for the best tomorrow, I would like to know what else I must check underneath in order to avoid something else like this happening down the road.

[Cloud9blue]

Never heard of this before. Usually the arms would bent way before the bolts would just snap.

You sure the car doesn't have an accident that you don't know about? Sounds like a improperly torqued bolt or damaged parts.

[ashmostro]

Do you have any upgraded suspension bits?

[Rodolfox]

Originally Posted by Cloud9blue

Never heard of this before. Usually the arms would bent way before the bolts would just snap.

You sure the car doesn't have an accident that you don't know about? Sounds like a improperly torqued bolt or damaged parts.

No, I had the car checked out at an authorized Bmw service before buying it. I'm guessing it could have been improperly torqued when doing an alignment?

Originally Posted by ashmostro

Do you have any upgraded suspension bits?

No, car is 100% stock.

[Timujin]

crazy sheet.

[feuer]

Originally Posted by Rodolfox

No, I had the car checked out at an authorized Bmw service before buying it. I'm guessing it could have been improperly torqued when doing an alignment?

BWM's are full of surprises, negative ones that is...
If something doesn't end up on the forum here doesn't mean it never happened.
Improperly torqued? Yes, but why? The eccentric bolts are on the toe arm and the lower control arm so it shouldn't be from an alignment. The upper torque arm and guide arm are free off adjustments.
Cross threading is very typical and happens to pretty much every other BMW e90.
This could have happen on the assembly line as well.
If it was cross threaded and forced to tighten the heat generated could have damaged the bolt.
Can you extract the bolt? Or you need to drill and tap new thread?
However, there might be something else wrong with the rear suspension that was causing the arm to carry excess load.
Check everything.

[Rodolfox]

Originally Posted by feuer

BWM's are full of surprises, negative ones that is...
If something doesn't end up on the forum here doesn't mean it never happened.
Improperly torqued? Yes, but why? The eccentric bolts are on the toe arm and the lower control arm so it shouldn't be from an alignment. The upper torque arm and guide arm are free off adjustments.
Cross threading is very typical and happens to pretty much every other BMW e90.
This could have happen on the assembly line as well.
If it was cross threaded and forced to tighten the heat generated could have damaged the bolt.
Can you extract the bolt? Or you need to drill and tap new thread?
However, there might be something else wrong with the rear suspension that was causing the arm to carry excess load.
Check everything.

I've been a BMW fan/owner for 20+ years and never seen something like this either. Like most of us here I believe they're great machines and a pleasure to drive. When properly cared for they last an eternity. Anywho... having this happen on a car I bought a few weeks ago is unsettling, to say the least. Grateful it didn't happen at high speed or in another situation that could've led to an accident and serious damage.

Update: Went to the service shop today to discover that the security bolt for the wheel lugs was missing so we weren't able the get the wheel off!
A guy with a 325i e90 LCI was there, too, and we tried his bolt on my wheel, but it was smaller and spinned. Ended up having to call BMW 24h Road Assist and pay 50usd for service, just to get the wheel off!! To make things worse, the guy said BMW doesn't sell the plug, but the whole set including the four bolts. He couldn't provide the cost. Will have to wait until Monday.

Still, got a better look at the damage and noticed the bolt sheared off almost flush. Mechanic said removing it wouldn't be an issue, gratefully, but would have to wait until Monday anyway.

I'll post an update when I have more news.

[glachhman2]

Happened to me before. Drilled it out and reattached with a grade 10 nylock nut and bolt. Been ok ever since.

[Rodolfox]

Originally Posted by glachhman2

Happened to me before. Drilled it out and reattached with a grade 10 nylock nut and bolt. Been ok ever since.

Any particular reason why you didn't replace with the OEM bolt? Should I do both bolts (left and right side) to be on the safe side?

[feuer]

Originally Posted by glachhman2

Happened to me before. Drilled it out and reattached with a grade 10 nylock nut and bolt. Been ok ever since.

Originally Posted by Rodolfox

Any particular reason why you didn't replace with the OEM bolt? Should I do both bolts (left and right side) to be on the safe side?

Exactly what I did just 2 weeks ago on friends e92 335i.
Again, if there aren't any posts here it doesn't mean this never happens.
I'm not here to bash the brand but BMW is not what is use to be. That is the honest true.
I started with e21's, had two, then e36, had two of those as well, now e90.
True, is pleasure to drive it, yes, but built lacks quality.
Anyhow, I didn't want to mess with the thread after I drilled it out so I drove the new bolt from the opposite side and used locking nut on the other side to fasten the arm.

[glachhman2]

Originally Posted by Rodolfox

Any particular reason why you didn't replace with the OEM bolt? Should I do both bolts (left and right side) to be on the safe side?

I wasn't able to get it out without ruining the threads. If you go this route you must use a nylock nut and grade 10 bolt or it will back out. I've been good for over 1 year. I even bought a used hub to swap it out but I didn't see the point.

[Rodolfox]

Originally Posted by glachhman2

I wasn't able to get it out without ruining the threads. If you go this route you must use a nylock nut and grade 10 bolt or it will back out. I've been good for over 1 year. I even bought a used hub to swap it out but I didn't see the point.

Got my car back today. They were able to remove the bolt without stripping the thread and replaced the sheared bolt with OEM part no 33306793891. Did a full alignment afterwards and everything seems ok. I even noticed that rear suspension was a bit softer/less noise.

Next maintenance is almost due so, I will wait and see what they have to say at the dealership about this when the car is fully and properly checked over. Will post any new findings here.

Thanks to everyone for their useful insights.

Happy driving!

[Formy]

OMG this exact same thing just happened to me!

I had the wheel bearing replaced 3 months ago, and last weekend the fwd bolt snapped resulting in the wheel no longer being central in the arch and the arm and remaining bolt jamming on the driveshaft.

I managed to drill the bolt and extract it from the hub without damage and now am waiting on a replacement driveshaft to arrive.