Upper Control Arm Outer Bolt Snapped

[MrStabby]

It was an allen key head high tensile bolt, and snapped through the thread. There is some shear loading on the thread, so it makes sense if it were to break that it would break there. Brittle fracture. I'm assuming its not the factory part.

For a replacement I'd like to get something tougher, that is, more ductile and less brittle. Would simply moving to lower grade bolt achieve that? I don't see how you could get the shear loading onto the shank unless the bolt shank was perfect length. Too short and it will get shear loading, too long and the nut will bottom out.

[GTSBoy]

The odd extra washer can help with a too long bolt.

[Duncan]

before you blame the bolt, are you sure it never hit anything hard?

I'd put another 8.8 grade bolt in, and keep that bush well lubricated. Assuming it's not a custom setup the bolt is in double shear so the actual load on the bolt is not unreasonable - I would have thought the subframe was much more likely to bend or crack.

(I said bush, and lubricate, in the same sentence)

[MrStabby]

(I said bush, and lubricate, in the same sentence)

Giggity! Agree about the load on the bolt - its just a pivot so has next to no strain along its length, its all shear.

@GTSboy - good call - i might be able to space it out so its all shank.

[Duncan]

furthermore, these control arms have 2 flanges with a lubricated bush between them, and the standard bolt has a long shank. And only 1 nut, on the end.

I hope that helps

BTW read your sig again, it has good advice