Entire weight of car is on the front lower ball joint nut?

[bbjones121]

Is anyone else concerned that under heavy braking, the single nut under the A arm on the front ball joint is holding the weight of the car? I thought about welding in a safety support to catch the knuckle if it failed, but I haven't heard any issues from people who are driving their cars.

[Junty]

Ive now completed 10,000km (about 6000km) very aggressive twisty winding roads. No issues what so ever... Very happy with performance and handling. Now running 2.5L TD05 20G, MOTEC ecu and about 280KW at rear wheels. So it is a pure rocket ship. I've recently changed to a 3.9 final drive transmission - this is absolutely amazing...

[flynntuna]

Hope you and your family is safe and ok from the earthquake today.

[phil1734]

I don't know the exact size of the nut, but I'm guessing it's something like a M12 x 1.25, which means it should be good to around 10,000 lbs.

Per side.

And if you somehow manage to get the entire weight of the car onto one wheel you probably have bigger issues.

[turbomacncheese]

Ive now completed 10,000km (about 6000km) very aggressive twisty winding roads. No issues what so ever... Very happy with performance and handling. Now running 2.5L TD05 20G, MOTEC ecu and about 280KW at rear wheels. So it is a pure rocket ship. I've recently changed to a 3.9 final drive transmission - this is absolutely amazing...

Care talk about the difficulty level of changing the final drive, your driving experience with it, how it compares to whatever you just switched from (hard numbers or just driving feel), or anything related that is interesting and I haven't thought of?

Thanks

[6t8dart]

I have never heard of the nut failing...ever. The cotter pit is in there to keep it from unscrewing. Millions of cars across the world have used this system for over 50 years (or longer) and it has proven to be reliable.

The higher incidence of failure are welds in lower control arms. I have know 2 people with Mopars that have had their lower aftermarket welded control arms break, one Road Runner ended up in a tree at 35 mph. FFR's design is race car technology, not street driven passenger car. They require regular inspection and maintenance. I made a conscious decision to use the Mustang lower control arms, lower ball joint, and spindles, they are proven technology. Although I still need to keep an eye on the uppers. That's a lot of separate parts.

[bbjones121]

I have never heard of the nut failing...ever. The cotter pit is in there to keep it from unscrewing. Millions of cars across the world have used this system for over 50 years (or longer) and it has proven to be reliable.

The higher incidence of failure are welds in lower control arms. I have know 2 people with Mopars that have had their lower aftermarket welded control arms break, one Road Runner ended up in a tree at 35 mph. FFR's design is race car technology, not street driven passenger car. They require regular inspection and maintenance. I made a conscious decision to use the Mustang lower control arms, lower ball joint, and spindles, they are proven technology. Although I still need to keep an eye on the uppers. That's a lot of separate parts.

Are you sure that millions of production cars have the weight of the car on the ball joint nut? Typically they have the weight on the strut and spring i thought.

[Coolspot]

Some production cars are this way, Corverte to name one.

My concern would be that this ball joint was not initially designed for that purpose, but given the weight of the 818, it should be OK.
Keep in mind this is not a production car and you should keep an eye on every nuts and bolt on this car.

[6t8dart]

Are you sure that millions of production cars have the weight of the car on the ball joint nut? Typically they have the weight on the strut and spring i thought.

Its true that a lot of cars are struts now, but there are still quite a few (most Trucks) and most older pre-80's cars are double A arm. Both technologies are pretty reliable.

[bbjones121]

Its true that a lot of cars are struts now, but there are still quite a few (most Trucks) and most older pre-80's cars are double A arm. Both technologies are pretty reliable.

I usually have seen the a-arm on top of the lower knuckle arm so that the weight of the car is pushing down into the ball joint. The 818 front a-arm sits below the knuckle arm, thus the weight of the car is pulling the ball joint apart. I see that a Corvette does this also, so that is a little reassuring.

[Frank818]

I see that a Corvette does this also, so that is a little reassuring.

Can what a Corvette does be seen as reassuring? What year Corvette?

[bbjones121]

Can what a Corvette does be seen as reassuring? What year Corvette?

I think all modern years

[phil1734]

I'd guess somewhere around 30% of all cars on the road do this Frank. It's seriously not an issue.

Just a few I'm aware of: All F-bodys, all G-bodys, all S-10s and Blazers, Mustangs, Miatas, Jeep Liberty, Pretty much every Honda built before 2000...

And those are just the ones in my pay grade. I'd assume that as you get into BMW, Mercedes, Porsche, etc. that even more models do this.

[bbjones121]

I'd guess somewhere around 30% of all cars on the road do this Frank. It's seriously not an issue.

Just a few I'm aware of: All F-bodys, all G-bodys, all S-10s and Blazers, Mustangs, Miatas, Jeep Liberty, Pretty much every Honda built before 2000...

And those are just the ones in my pay grade. I'd assume that as you get into BMW, Mercedes, Porsche, etc. that even more models do this.

That seems high. Those all have the a arm below the knuckle held to it with a nut?

[phil1734]

Yep. Most have the ball joint in the control arm going up through the knuckle to a nut, but it's the same (assuming the spring also acts on the lower control arm.)

Pretty much anything with double wishbone suspension does. Since the brunt of your road forces go through the lower control arm it's already beefy enough to take the additional load of the spring system, which is good because if you had to stack a spring on top of the upper control arm you'd have an unpackagably tall suspension. (Did I just make up a word?)

In fact, the only exceptions to this that I've personally encountered was an early 2000's Silverado (Ball-joint in lower control arm going down through knuckle) and the E30 which runs the spring directly to the knuckle.