Front ball joint nuts and bolts keep failing.

[Vlad01]

I know this is an old thread, but when I bought all the bits to rebuild my whole suspention ground up, I noticed the pissy M8 screws and thought not way this will hold.

I googled to see if anyone had broken these bolts and the results are shocking.

there are a couple of problems.

1 the aftermarket joints do not have the mating surfaces machined perfectly flat like the originals.(after market ones rock about on the arm) The joint mainly relies on friction of the 2 surfaces being clamped.
2 the surfaces are painted. They can not be painted period! The friction is reduced and the clamping force reduces over time as the paint squishes and migrates out of the joint.
3 the bolts don't provide enough clamping force to allow for the friction join to work correctly without moving about under high load.

I am personally having my control arms and new joints modified by an engineer to fit class 10.9 M12 1.5 pitch bolts with all steel class 10.9 locking nuts. My engineer is having them machined flat, nut and bolt head seating areas spot faced 90º to the holes and the holes for the bolts machined just right for a snug fit of the bolt shanks to effectively pin the ball joint to the arm so I have a shear and fiction joint combined together for extra strength.

I ordered these special M12 short bolts with class 10.9, fine thread and shank from Wurth. No bolt supplier stocks such bolts. not that class, shank or metric fine thread.

I will post the results once they get done by my engineer.

Its an absolute joke they supply such crap hardware with the ball joints.

 

[VR38]

Not only is it disappointing, and FFS it can't be that hard to supply a bit of quality, but it also sounds quite dangerous.

 

[lowandslow]

Nyloc on nuts won't stop them coming loose. All it's there for is to stop the nuts falling off.

Replace those bolts with some 12.9 unbrakos with bulk loctite.

 

[Immortality]

Fairly sure standard nyloc nuts aren't a high tensile nut. That is half the problem. You would be better of using a proper high tensile nut with loctite.

As Vlad mentioned, if the mating surfaces aren't flat then the joint will never last.

 

[delcowizzid]

Ive lost count of the number of balljoints ive fitted with the supplied bolts be in the hundreds never had one fail

Sent from my C8660 using Tapatalk 2

 

[VR38]

FWIW I too have never had one come loose.

 

[Vlad01]

well its a combo of many things.

I have even had rear control arm bolt come loose and even bushes come out due to rough roads and wheel hop in the wet.

So naturally those M8 bolts will break straight away on my roads.

I got my new Wurth bolts and dropped off the arm at the engineer today.

We had a slight change of plan too. We decided to go for 1 central pinning M12 bolt and leave the 2 outside ones M8 size, however I will replace the M8 with shanked 10.9 class M8 from Wurth and steel locking nuts. All other machining and spot facing still stands as the current modification plan.

We are leaving the 2 outside holes as is because we feel there isn't enough material to safely drill any bigger on the 2 outside ones.

It will be a few weeks before its done.