Broken Rear Radius Rods?
 

Hi everyone, this is my first post here but not my first visit. Usually I can find a post that will detail a problem I am having but I can't seem to find anything on this issue.

I recently had to replace the rear airbags in my 2009 X5 35D, and took it to a mechanic to have the suspension calibrated after I got the job done (not sure why it needed it but it was done). After that visit I started hearing a clunking noise in the rear when going over bumps at low speed. I looked this up and people said it could have been the sway bar end links, however these parts on my car are tight.

So my questions are can these broken parts be the source of this clunking noise? What do the rear radius arms do and is the part shown in my photos the radius arm? How could something like this break? Both sides have the same broken part in the same way.

Thanks for any help,
Aaron

I suspect those are the radius arms; possible to take another pic with more in the picture?


By any chance, do you experience any side to side shimmy / sway / looseness from the rear?

I don't feel any looseness while driving. Not that I can tell at least. Everything feels fine as far as drivability, I just hear the clunking noise. I would record it but I'm in the middle of removing CBU from my intake so it will be a little while before it's running again.

I've included wider angle pictures of both sides.

OK, yes, those are (were?) the radius arms. I'm not sure of their specific purpose, but learned long ago that once one part of a suspension system is weak or broken, the additional stress causes other parts in the system to get weak or fail.


I'm not sure if missing radius arms would cause clunking, but a worn ball joint or bushing or end link or rear shock mount can. Pry or squeeze (with large channel lock pliers) all of the ones that you can see. If the noise is easily reproduced by bouncing the vehicle around in your garage, it helps a lot to have it up on ramps and have a helper bounce it while you look underneath at what is moving excessively.



I'll be going through a similar process to locate the source of rear end sway on mine. I can actually push on the rear quarter panel and the vehicle will oscillate side to side.

I will have to try this. Everything seems tight with the tires in the air but that isn't how it drives down the road. I'm just curious about how they broke in the first place. They are up out of the way of debris from the road. But maybe since they're cast aluminum a big pothole could do the job?

Maybe, but that wouldn't be my guess. I'd suspect metal fatigue, possibly from something else being worn and causing excess movement and additional stress on that part. I have some experience with metal fatigue issues in the rear end of E36 and E46 chassis cars. It's interesting though that yours are broken on both ends; I'd expect metal fatigue would break one side and the other side would dangle. I'd be interested in hearing from others who've had this problem. I'll check mine tonight. I'm actually hopeful that this is it, as it looks straightforward to replace.

Mine are OK. Will check ball joints and bushings this weekend.

Can you take a photo of yours? I'd like to see what they're supposed to look like if it's not a hassle. And just to clarify, the suspension needs weight on it to test the ball joints, bushings and so on right? Unfortunately I don't have a helper to bounce the car like you said. I'm not sure if I even need to test since this problem just started about a week ago and everything feels like it did when I got the car. I might just replace the rods and then see if the noise is gone.

Thanks for the help so far.

I'll snap a photo this weekend when I have it up on jack stands. In my limited experience sometimes the suspension needs to be loaded to make play more obvious, sometimes not. I've even replaced sway bar end links which I swear weren't budging with giant channel locks only to have a clunk go away.



If I were you I would definitely replace the radius arms first (looks easy) to see if the clunk goes away.

Not sure of the history of this vehicle, but was it taken off road with heavy use (rock climbing), involved in some sort of collision, dropped from a lift...?


For both sides to be broken at the same point suggests something more than a pothole, unless it was the width of the entire vehicle + sufficient speed. At least to me. :dunno:

I'm the second owner of the car. I know its not for offroad stuff like rock climbing but it has seen a dirt road or two. I always go slow on them. According to the dealership the previous owner was a doctor's wife so maybe she took it rock climbing lol...
I have a suspicion something happened to it at the mechanic I was told to take it to (he's the only one in my town that does BMW) because some of the plastic under panels have cracks and I have never applied enough force to crack them. The problem also started right after I got it back from him.
As for a collision, I'm not sure but the CarFax is clean. How fast would you have to hit something to make these break?

My mother-in-law took her Crown Vic to the dealership for something a few years back (less than 3 years old) and they let it roll off a lift with the door open. Yep, not a good sight. She ended up trading it in, to the same dealer, but still. Accidents/neglect can happen with even the best mechanics.

That's the only reason I bring it up. Your vehicle may have just had a odd occurrence, but it's really odd both are completely broken in nearly identical ways.

Yeah that's my thought. It might not have been the owner of the shop, he's pretty cool. Maybe it was one of the people working for him. I'm honestly not sure how it happened, but I've never driven it hard enough to break stuff. I've also heard if you drop it down with a jack too hard that the air springs could burst so I've always lowered it slow.

When the funds get here for the parts, I'll post again to tell if it's fixed or not.

Those parts should be cheap used from ebay. I doubt there is a big market for them. Should be over half the cost of new.

Or launching off a speed bump.

It would take a massive impact to shatter those parts..... amazing.

Doctors wife.... lying pieces of crap.... but seriously its the modern trope of 'old lady church sundays'...

I though I saw an open weld on one of the tubular members in picture #1, no?

I don't think it's a weld opening up. To me it looks like the steel is overlapping and it's only welded on the bottom.
I've let my parents and brother borrow the car but I really doubt they did any speed bump launches. I'm just going to stick with blaming the mechanic. I normally don't take it to anyone because this place is a huge help with DIYing.

I just looked closer at the photo and the part on the vehicle. It's just the rubber mount. Maybe it looks that way from the molding process.

Those are aluminum arms... could someone have put it on jack stands/lift in a bad location and snapped them? Would make sense that both sides are identical if that's the case.

That was my thought. Maybe the mechanic I took it to has a helper that isn't very good. I can't prove it was him though but I am fairly certain I'm not the one who broke them.

Are the front radius arms intact? Have they been inspected for cracks?

+1
Was thinking yesterday I would be inspecting/have inspected everything under the vehicle. Since the cause is unknown, there's a good chance something else is broken or weakened. Would be looking at all the suspension, motor mounts, etc.