broken control arm....

[brman]

A bit of a warning to other bmw owners - Recently I hit a pot hole pretty hard but could not find any damage despite close inspection of all the suspension and wheel. An MOT helped confirm all was well (or so I thought). Then at the weekend I was returning from a great weekend at goodwood when, on braking from about 30mph, this happened....

(front right control arm fractured)
Needless to say the lack of steering and braking made for an exciting few seconds but I am very glad it happened on a straight bit of road and moderate speeds!

This is a 2006 E91 btw.

[Triumph Man]

Jesus Christ!

Who was the manufacturer of that part?

[brman]

Triumph Man said:

Jesus Christ!

Who was the manufacturer of that part?

BMW, or rather whoever was BMWs OEM manufacturer (maybe lemforder??)

I don't think it can be blamed on manufacture, I could not see any faults in the material where it cracked. I think it is more a warning that ally suspension is likely to crack (then fail without warning) compared to steel which is more likely bend and be more obvious.
I think the worrying thing is that I did inspect it after hitting the pothole but I did not go as far as cleaning it thoroughly or using a crack detection spray. I suspect both would have been necessary to detect it.
Needless to say ALL the suspension arms are now going to be replaced.......

[bmwmike]

Did you track it at Goodwood? Surprised it didn't snap on track.

[brman]

bmwmike said:

Did you track it at Goodwood? Surprised it didn't snap on track.

No, last weekend was the goodwood members meeting. I don't think they would want me on track

I am surprised (and very relieved) it did not snap 30 seconds earlier when I was cornering fairly hard with a large drop down a field on my outside. In fact there have probably been many times since I hit that pothole where this failure would have really spoilt my day......

[bmwmike]

Quite. I guess you lose control of that wheel effectively?

Surprised a pothole could do that tbh unless there was some other weakness there already. Pretty sure I've seen another e90 with that type of failure on e90post btw

[brman]

Yes. It steered surprisingly well considering but when I touched the brakes all hell broke loose. I had to do a sort of cadence braking to keep it under control.
It could well be a stress crack that developed over time, hard to tell now.

[brman]

a follow up... I have replaced the arm and looked more carefully at the broken end. It looks like it has been fractured for a while and has been slowly getting worse.....

[AW10]

How many miles on the car? And original part or was it replaced somewhere along the way?

[brman]

AW10 said:

How many miles on the car? And original part or was it replaced somewhere along the way?

approx 120,000. I think original but cannot be sure as I have only had the car a few months. It is an OE part anyway (marked TRW and BMW)