Spontaneous Control Arm Bolt breakage :(

[carlover]

I was driving home from some errands yesterday when I experienced the titled problem.

I turned left out of a parking lot, no curbs, bumps or the like (except for reflecters in the road) with my throttle in the appropriate "enthusiastic" position when suddenly at about 30-35 mph I felt violent shaking from the rear followed by signifcantly increased resistance. It felt like a flat tire, so I pulled into the gas station across the street and found what you see in the pics. A bent brass colored bracket was found sitting on the diffuser tray (rescued it and put in in the car).

The wheel was found rubbing against the wheel well lining, and the car was not drivable (backing up pushed the wheel more firmly into the wheel well).

The car got towed to the dealer last night, and I went by to check on in it this afternoon. It turns out that the two bolts that hold the upper control arm to the wheel lost their heads. Yep the heads popped right off the bolts. WTF? It doesn't appear that any other mechanical damage was caused by this mishap, I'm just glad it didn't happen on an auto x course or on the highway.

Anyone else have this experience or have thoughts? Do you think the bolt could have been over torqued at the factory? If it matters, the car has 15 k on it. Never had slicks, never taken any damage to the wheels or suspension.

[Ian]

Wow; sorry to hear about this. Didn't you just have some work done on your car? Could this possibly be related?

[newman]

negative camber for the win...


but that sucks... However, a properly made/torqued bolt will fail at the fillet just under the bolt head. At least the wheel didn't flip the other way!

I'd replace them with grade 8 stainless.

[Thomasio]

I hope that this news makes it back to Hethel so that engineering is made aware.

Thomas

[R T]

Originally Posted by Thomasio

I hope that this news makes it back to Hethel so that engineering is made aware.

Thomas

Why? So they could deny there's a problem

[Randy Chase]

Mine did exactly the same thing two weeks ago. Much worse looking though. Pulled out the driveshaft.

[carlover]

Originally Posted by Ian

Wow; sorry to hear about this. Didn't you just have some work done on your car? Could this possibly be related?

I had some minor clam work done, nothing mechanical. I can't conceive how the two would be related. I've driven about 1500 miles since picking it up, and this is the first unusual thing that has occurred.

[Thomasio]

> Mine did exactly the same thing two weeks ago. Much worse looking though. Pulled out the driveshaft.

Perhaps this should be a sticky. People die when this stuff happens... makes me wonder about a recent tragic crash...

Thomas

[Randy Chase]

Originally Posted by Thomasio

> Mine did exactly the same thing two weeks ago. Much worse looking though. Pulled out the driveshaft.

Perhaps this should be a sticky. People die when this stuff happens... makes me wonder about a recent tragic crash...

Thomas

Hmm... my reaction when it happened to my car was that I was glad it happened at an autocross, and not during a canyon run the following day, when the outcome could have been much much worse. But I also thought it was possibly just my fault for not keeping the bolts properly torqued and checked. Mine may have backed out prior to breaking.

This is the first I have heard of another car having this happen. And it seems more attributable in this thread's case... to not being owner error (as it might be with me).

[Chris]

I had the exact same thing happened to me at the track, except my wheel folded over mid corner!

The car spun 90 degrees and I let the car roll backwards off of the track to get out of the other drivers way. Fortunately I did not hit anything and there was no body/frame damage. It was towed to the dealership and they replaced everything in the rear suspension under warrenty. I just pray it never happens again! I was actually glad it happened at the track and not on a highway off-ramp in traffic!

Everyone should pull off their wheels and check the torque on the 2 bolts that hold the upper control arm together. I had the mechanic put paint on the new bolts so I can visually confirm they are not moving.

Sorry to hear it happened to you, I don't think it is all that common.

[carlover]

Originally Posted by Randy Chase

Mine did exactly the same thing two weeks ago. Much worse looking though. Pulled out the driveshaft.

Holy crap! I guess I got off easy. Under what circumstances did your break? Did Lotus give you a hard time? Should I ask them to cover my rental?

[xtn]

I know of one other owner who discovered - not that the bolt heads had snapped off - but simply that the nuts had backed off. I'm talking about the two upper a-arm mounting bolts. One of his bolts was completely missing and the other had no nut on it at all.

[Chris]

Wow, since I typed my post I see that several others have had the same problem. Maybe it is more common than I thought.

[LarryB]

Think this is something like the rear toe links, we need to check on a fairly regular basis.

[codymac]

Originally Posted by xtn

I know of one other owner who discovered - not that the bolt heads had snapped off - but simply that the nuts had backed off. I'm talking about the two upper a-arm mounting bolts. One of his bolts was completely missing and the other had no nut on it at all.

The really sad fact being that this particular car had been through the dealer for:
- pre-delivery inspection
- first service
- pre-purchase inspection

And the issue ("safety" tabs not folded over) was never discovered.

[Seb]

Well 3 people....thats 3 too many. There really is no reason for these things to be happening. Especially since most have so few miles on them.

Like others have said, he is pretty lucky this didn't happen at higher speeds.

As for that being the cause to a recent tragic accident.... possible?

Sorry for the pic quality.... camera phone.

EDIT: More than 3 people now?

[carlover]

Originally Posted by Chris

I had the exact same thing happened to me at the track, except my wheel folded over mid corner!

The car spun 90 degrees and I let the car roll backwards off of the track to get out of the other drivers way. Fortunately I did not hit anything and there was no body/frame damage. It was towed to the dealership and they replaced everything in the rear suspension under warrenty. I just pray it never happens again! I was actually glad it happened at the track and not on a highway off-ramp in traffic!

Everyone should pull off their wheels and check the torque on the 2 bolts that hold the upper control arm together. I had the mechanic put paint on the new bolts so I can visually confirm they are not moving.

Sorry to hear it happened to you, I don't think it is all that common.

I guess I really did get off early. This type of thing scares me because it is so unpredictable.

As far as it not being common, I think the three of us all having similar problems under essentially normal driving circumstances makes it too common.

***Just out of curiousity, which side was the problem on? If we all have had problems on the driver's side I'm thinking this go indicate a significant design flaw. That said, I'm not sure it isn't a design flaw if it occurs on both sides....

Thanks for all the input.

Joe

[Chris]

Mine was passenger side. I have the whole thing on video both in-car and out, I will try to find the footage and post it for you.

[carlover]

Originally Posted by Chris

Mine was passenger side. I have the whole thing on video both in-car and out, I will try to find the footage and post it for you.

Awesome, thanks!

[MitchT]

I feel like putting safety wire, tabs and paint on all my bolts but I am parinoid about stuff falling off on the track. Nut and bolt the suspension before tracking.