Ball joint taper

[SR240DET]

Im no engineer, but i was curious of the purpose for the taper on the LCA and tie rod end ball joint. I see that maby the taper allows for a tight fit so it takes the load off or lessens the load on the threaded portion, but I also see the taper being more beneficial for manufacturing.

thoughts?

[discosteak]

It allows the two parts to fit together without play. having play in these areas would allow your alignment to change while you are driving and that would not be good

[SR240DET]

Originally Posted by discosteak

It allows the two parts to fit together without play. having play in these areas would allow your alignment to change while you are driving and that would not be good

I know the question was kind of vague, and I am aware of how the fitment works.

I was asking If the taper on a ball joint when bolt up to a spindle is superior in strength over a non taper set.

[GSXRJJordan]

"Strength"? The force the joint can take without "breaking" or generating play is much more than the force the ball-joint can take without generating play.

The taper is there because these are items that can't be press-fit because of their location (on the car) - a reamed/tapered joint is the next best thing.

That being said, aftermarket LCAs don't use tapers, they use heim joints (spherical ball bearings) and bolts through them, with a nut on the end. I've always assumed that's because good heims can take much more force without generating play than a standard ball joint, but it may just be for ease of installation.

All of this assumes you're talking about the taper on the bolt, and not the taper of the LCA ball-joint to the arm.

[SR240DET]

Originally Posted by GSXRJJordan

"Strength"? The force the joint can take without "breaking" or generating play is much more than the force the ball-joint can take without generating play.

The taper is there because these are items that can't be press-fit because of their location (on the car) - a reamed/tapered joint is the next best thing.

That being said, aftermarket LCAs don't use tapers, they use heim joints (spherical ball bearings) and bolts through them, with a nut on the end. I've always assumed that's because good heims can take much more force without generating play than a standard ball joint, but it may just be for ease of installation.

All of this assumes you're talking about the taper on the bolt, and not the taper of the LCA ball-joint to the arm.

Thank you for the answer geared towards more of what I was trying to get at. I think the question I am asking is not quite specific for the answer im looking for.

Just for the sake of getting a definite answer;

For set up A lets just say we have a Lower control arm that is going to bolt up to a spindle. We have a traditional ball joint with a tapered bolt on the lower control arm and a bolthole on the spindle reamed to fit the taper on the ball joint. A stock setup basically.

Setup up B doesn’t have a hole on the spindle that is reamed for a tapered bolt its just a straight thru hole. Assuming a properly sized and type of shank is used with the proper spherical bearing to replace the old ball joint used as well.

Now the question is does Set up A have any strength benefits over setup B because of the taper on the ball joint bolt? Through research from what little information that is available to me all I can gather is set up A is more economical for manufacturing and ease of installation.

I hope I was more clearing in the question this time around. Thanks for the help so far.

[SR240DET]

Some more research tells me so far that Method A is more economical for manufacturing


Can anybody else confirm?

[anotherblusi]

A few things come to mind. With motion, you would want it localized at the ball joint only. This means that the spindle must not be allowed to move on the ball joint bolt. With a straight design, the spindle and ball joint would need to be pressed together, and would require a bearing separator of sorts.

A taper design would increase contact surface area, not require a press for installation, and doesn't necessarily need a special tool for removal.

The taper design would also resist higher shear loads than a straight design.

[SR240DET]

Anotherblusi! thank you so much for that answer.

[GSXRJJordan]

Originally Posted by anotherblusi

A few things come to mind. With motion, you would want it localized at the ball joint only. This means that the spindle must not be allowed to move on the ball joint bolt. With a straight design, the spindle and ball joint would need to be pressed together, and would require a bearing separator of sorts.

A taper design would increase contact surface area, not require a press for installation, and doesn't necessarily need a special tool for removal.

The taper design would also resist higher shear loads than a straight design.

A castle nut/cotter pin on the bolt that's fit correctly (torqued) will hold just as well in my opinion. By industrial standards, the weight of a car (even under 3g or 4g load) is not anywhere near the tensile strength of decent hardware. I believe this is why all aftermarket control arms come with heims/bolts, instead of standard tapered ball joints.

Thinking of sheer force, it's true that a taper would be superior, but I can't think of any time (except for a collision with a curb/etc) where you'd see loads like that. And again, it'd have to be 4g's or so before you'd come close to maxing the heim, and a bunch more before you snapped a 10.9 M12 or M14 bolt.

[anotherblusi]

Originally Posted by GSXRJJordan

A castle nut/cotter pin on the bolt that's fit correctly (torqued) will hold just as well in my opinion. By industrial standards, the weight of a car (even under 3g or 4g load) is not anywhere near the tensile strength of decent hardware. I believe this is why all aftermarket control arms come with heims/bolts, instead of standard tapered ball joints.

Thinking of sheer force, it's true that a taper would be superior, but I can't think of any time (except for a collision with a curb/etc) where you'd see loads like that. And again, it'd have to be 4g's or so before you'd come close to maxing the heim, and a bunch more before you snapped a 10.9 M12 or M14 bolt.

I tend to think most aftermarket companies these days use rod ends simply for marketing purposes. Yes, quality rod ends will be stronger than an equivalent ball joint, but they cost a lot more, break down faster, and tend to allow less angle. From the manufacturers stand point, ball joints are cheap, reliable, and allow greater suspension travel without binding.

Another thing to note is that ball joints and rod ends are different in there axis and range of motion. This means that it really depends on the application where one type will work better than the other.