Unless they tried to tighten or loosen the nut with the cotter pin in place I’m not sure how that could happen. More pics might help.

 

sorry, I cannot take pic as I dont have the car at home since the accident.
I wonder if it can be the hole of the spindle that is worn... and therefore, the nut could "stick" to it then turning ?

 

Did they use a steel cotter pin or aluminum one?

 

I guess the ones provided by ricks (lower ball joint was ordered there) but I cannot be sure

 

I don’t see how a new cotter pin would shear in that application.

 

With the amount of force it takes to separate a ball joint, I can't imagine it coming loose. Maybe when assembled the tech forgot to properly set the castle nut tight, and just put the cotter pin in. If there was play in the ball joint pin maybe the repeated pounding forced the castle nut to turn.

 

Tens of millions of cars on the road with cotter pins in castle nuts...failure is highly unlikely. Not impossible, but I'd think you would have a better chance of hitting the lottery once a month for the rest of this year than have one fail UNLESS improperly installed.

 

The shop asks me to bring back the car but I wonder how that can happen...


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than have one fail UNLESS improperly installed.

OP

from this side of the internet...the chances of your failure are more due to improper installation. They did not seat the ball joint properly into the A arm. IMHO, would be the most likely cause of your issue. I would have a close look at the other side if the same shop installed ball joints on both side (should have)

With that said, it is possible for the A arm to crack where the hole for ball joint is and that would loosen the ball joint and under stress and driving maybe the cotter pin fails under this movement, castle nut comes off and boom....although I suspect the install being more likely

Glad you and the children were not hurt, most importantly. The car can be fixed

 

I think Mr Good Pliers was absent on torque day.
That’s got to be a lack of appropriate torque applied, as was pointed out. It can be a real test of patience to un seat a properly torqued tapered joint.
In 42 years of doing my own I have never lost a castle nut. I have however over torqued every fastener at some point…..which is not a good idea either.

 

It can be a real test of patience to un seat a properly torqued tapered joint.

I used to use a pickle fork, I bought one of these, to remove a set of Proforged uppers so I could save them for a new set of a arms. Worth ever penny.

 

The cotter did not just fall out. Could not get sheared.

Was installed wrong or not at all.

 

Clement, I do not have a front spindle, but do have some extra ball joints, castle nuts. If the spindle is still good, and you need new ball joints, send me a message. I can send the parts to you, just cover the postage. I'm not far from Forbach. Can't help with the fender either.

 

Dang, that is a scary situation, Clement. At least everyone is OK... cars can be fixed. I agree with the others, though... that cotter pin should have never sheared off. Good luck!

 

As said more than likely was installed improperly. Perhaps castle nut was beyound the hole and cotter was sitting above the groove to where nut just backed off. Having been in the trades, I have seen many improper setups over the years.
Had a similiar situation on a brand new Ford pick up back in 93. Front end had a clunk when turning lock to lock. Ford decides to realign the front end and replace some parts. Picked up the truck on a Friday, and hooked up my 26' RV trailer for a 14 day 5k mile family vacation with my young son. That night while washing the truck I had this notion to look under front bumper, and noticed NO cotter pins on the tie rod ends, the holes were not even lined up with the nut. Grabbed my wrench to align and they were finger tight.Imagine the results that couldve been.

 

The only way I can see the cotter pin getting sheared off is if the ball joint and shaft are seized in the joint itself but able to spin free in the spindle, and the nut got turned by the spindle when turning the steering wheel. It would take a LOT of force.

 

Clement mentioned in his first post that this ball joint was just replaced so I don't think it could have been seized. Also if it were seized it would impede the movement of the control arm, and don't think that would go unnoticed. The mystery of the sheared cotter pin remains. Is there is a possibility the cotter pin was used more than once? You should always put in new ones because they'll weaken if they're reused. FWIW I like to use the stainless steel ones as they are much stronger than the tin ones.

How about this scenario?.........The tech begins to tighten the castle nut but gets distracted and goes for lunch break, comes back assuming the nut was torqued and puts in the old used tin/ lead cotter pin. When driving the car, there is linear movement of the ball stud because the taper is not seated in the spindle, and this caused the nut to be slammed on every time you go over a bump, so it makes it impact itself off. This would be my assumption.

 

Thanks everybody for all your answers. The shop is going to repair and check everything.
As the cotter was installed for sure (I have found the rest of the cotter but cut on both sides so the nut can go out), there was an improper installation and I agree with Green, to have enough force to shread the cotter, it is probably due to the spindle turning the nut somehow....
I think I will ask the shop to change the spindle on both sides in order to start with someting clean...
Now I have to wait for my car but as you all said, everyone is OK and the car can be fixed....

 

Im thinking tech didn’t tighten enough, went to lunch or a nooner, came back and put too small of a cotter pin in. Eventually tightens up nut with air gun that just creams the pin and stripped the threads which eventually worked loose.

 

^^ this

 

Whatever the cause, I would personally see to it that the shop takes responsibility to make things right, including the body damage.

 

I think jimsl78 has it right. Can’t imagine the nut backing off once the taper is seated tightly, cotter-pinned or not.

 

If this shop did in fact install the ball joint wrong, which appears to be the case, one should make it very clear to them that those kinds of errors can kill people. Fortunately, that did not happen. I would make that very clear to the shop

Whatever other work that shop may have performed is also subject to a check...ideally by another shop

IDK what kind of insurance OP has or if this does involve a claim...but the "why" the failure and subsequent accident occurred should be conveyed to the insurance company to recoup what they would pay if this were an insurance claim

 

A responsible mechanic practices due diligence, especially when it come to the safety of vehicles trusted to them for repairs.
Steering, brakes, and suspension are top of the list on things that need to be gone over and double checked every single time.
As far as being clear to the shop, don't mess around! .......they are the ones who are liable and if they choose to make a claim, it's their insurance who should handle this.
This isn't just a mistake, it's a dangerous example of NEGLIGENCE on their part, and if they care about their reputation, keeping their operating license in good standing, and their insurance rates down, they should be bending over backwards to accommodate you.
Copy your receipt and take lot's of pic's. Find out who the governing body (inspection / licensing authority), just in case they try to screw you and you decide to report this incident.
What is a Defective Mechanic Work Lawsuit?
Individuals may bring their automobile to a mechanic for repairs. Repairs are needed for many reasons. Individuals may sue the mechanic for defective mechanic work. Defective mechanic work, also called faulty repair work, occurs when a mechanic negligently makes repairs that result in vehicle damage or injury to people.

 

Mr. Clement,

You inspected the ball joint after it failed. Where did you find the broken cotter pin?

Was part of the cotter pin still inside the hole of the ball joint?
Did you find the round ring part laying on the lower control arm or somewhere else in your car?
Or did you see the straight pin part laying somewhere close to the ball joint?

The reason I am asking the questions is because you might have found the old cotter pin. It might have been cut by a pair of diagonal pliers and not disposed of properly. Maybe there was never a cotter pin installed in the new ball joint. You found the old one.

 

You might be on to something here. The cotter pin should have been gone miles before the nut fell off and the joint separated.

 

Just as an aside to this discussion…
General Dynamics taught me how to install cotter pins on 9+G aircraft,
while probably 90% of fasteners were safety wired, some used a cotter pin.
If you were on the flight line or hanger preforming maintenance and the dreaded Quality Assurance man “QA” came by, you better have had your technical order “TO” out,
and on the correct page with your two-man team, (We delt with explosives also. Ejection systems)
He would run the palm of his hand over the cotter pin, if it snagged on a leg or any part of the pin, you were doing it over and getting written up.
The purpose of this is keep the pin from potentially snagging on something like a wire...if something came loose or whatever...

not aircraft perfect, but Examples none the less...
Ideally the bottom leg should be right at the base of the nut.

 

The purpose of this is keep the pin from potentially snagging on something like a wire...if something came loose or whatever...

That is the way I learned how to do it.

My Detroit Speed subframe had specific instructions on how to tighten the lower ball joint stud. The instructions say to use RED Loctite on the threads, tighten to 20 foot-lbs, and then turn the castle nut an additional 180 degrees. After that, stick a cotter pin in the hole.

It is hard for me to imagine how the castle nut turned and sheared off the cotter pin. My old subframe was rusted through in many spots but the cotter pins were still intact.

 

I know aircraft standards are much higher and more critical. I learned in automotive world similar to the aircraft bends/cut off, but we would cut the top tang over center of the stud. Generally, theres no wires in vicinity of steering geometry.

 

You know 99% of the time even if the cotter pin was left off the joint would not separate. I would think the castle nut was never torqued. Without proper tools they can be a beocth to separate anyway. I have seen weird stuff happen but shearing a cotter pin and spinning off a castle nut is not included. Don't know how French law is but I see $$$$$.

 

Maybe 99.8%.

 

You know its amazing what people will do when putting a car or anything together, either deceitful or errant. When I bought my car the seller said everything was new or rebuilt. Long story short the motor failed so when I pulled the motor/trans and started to go through every nut and bolt associated that I touched.
The front end had no less than 5 different styles and lengths of cotter pins on new ball joints. I literally filled a shoe box with all the worn out nuts/bolts/ washers/hardware the guy put the car together with. I was destined to take the car apart and fix it right. I replaced all hardware with either American made or ARP hardware. I was blessed to say the least that I caught the errors before stuff failed.

 

You know its amazing what people will do when putting a car or anything together, either deceitful or errant. When I bought my car the seller said everything was new or rebuilt. Long story short the motor failed so when I pulled the motor/trans and started to go through every nut and bolt associated that I touched.
The front end had no less than 5 different styles and lengths of cotter pins on new ball joints. I literally filled a shoe box with all the worn out nuts/bolts/ washers/hardware the guy put the car together with. I was destined to take the car apart and fix it right. I replaced all hardware with either American made or ARP hardware. I was blessed to say the least that I caught the errors before stuff failed.

It seems the majority of these cars are owned by people with limited mechanical knowledge. Some of these folks with a fat wallet have a good "car guy" mechanic they can trust. While others are happy if it starts, drives and has shiny paint.