[ChrisH]

In my case it was the bolts pictured here that broke causing the control arm to seperate. (there are actually 2, only one is pictured) These are the bolts you would remove if you were to pull your shims.

I have always suspected that they were not torqued on properly which should be a part of the PDI ritual then checked again at first service since it is an obvious problem. This ultimately led to them loosening then breaking.

According to the service manual, the bolts you showed (whether front or rear wheels) are supposed to be secured with a thread locker (Loctite or equivalent). However, when I removed the shims on my front wheels, I noticed that the bolts had NO thread locker. Apparently the factory doesn't always follow its own rules. When I put the bolts back, I did use thread locker. Maybe I'll remove the rear ones now and put them back using Loctite, just to be safe.

Of course, that doesn't matter if the heads pop off. Stronger bolts required?

 

[ChrisH]

Chris, yours broke because one backed off,the mount became loose and that excess load of only one bolt holding the mount. I check the torque on my outer upper A arms when I check the rear toe link, once a month. I have not noticed the upper A arm bolts getting loose, but I did locktite them after removing the shims.
Regarding the paint....yes, it is there to identify that the process was competed and checked, not as a referance to bolt movement.

Another way that the hub (shim) bolts might be breaking is if they come loose, even a little (a millimeter or two), the hub will shift suddenly as the car shifts side to side in during handling. The bolt will stop the hub when it reaches the head, which will cause sudden hard shocks to the bolt and could eventually snap it. The shock force can be much greater than if the bolt is tight because in the tight case, it picks up the load gradually due to the tire dampening the side to side onset of force a bit. Even if only one bolt is loose, the flange (that bolts to the hub) can shift at that bolt location (it twists around the tight bolt). Hence, I wouldn't be surprised if the slightly loose bolt breaks before the tight one does. If the bolt manages to get very loose without breaking (too far out for the bolt head to be hit with a shock), then I would expect the secure bolt to break first.

 

[ChrisH]

Those bolts require loctite whenever you realign the camber. I can't see how that bolt can walk out with proper loctite. I always wirebrush the old loctite off and clean with solvent prior to reinstalling with new loctite. With loctite, I believe the torque setting is not critical but I'm not positive. Anyone have the torque spec?

I agree the bolt shouldn't walk out if there is loctite on it. However, the point in one of my earlier posts was that the factory did not put loctite on the bolts in my car as they were supposed to. How many others don't have loctite on these bolts?

 

[ChrisH]

I haven't had this failure happen and it appears that this is not a design flaw but an assembly problem. For those that have had the problem, I think it would be interesting to see if those cars have VINs that are close together or not. If the affected cars were made during the same time frame, we could narrow it down to an assembly problem affecting only a small range of production dates. ...

Build date: February, 2005.
I didn't have a failure, but did notice that there was no Loctite (Permabond A130 in the service manual) on the bolts connecting the upper ball joint plinth to the hub carrier. The manual specifies that there should be. Hence, there is a risk of them coming loose.