View Full Version : Ball Joint Shearing

02-21-2013, 05:48 PM
Greetings everybody,

We have had this problem for quite some time now to no avail and i thought i would finally use some serious expertise for this. We use regular Hyundai Ball Joints for our Upper and Lower A arm in the front Upright along with Zero rake on both arms. The member is 1 x 0.062 " and is more than sufficient. An issue we keep having repeatedly is that every time we encounter a slightly big obstacle, our ball joints shear. We have never had an issue with A Arm or Upright failure. Its only the Ball Joint which shears off from the point where it contacts the upright. Any remedies as to how we can fix this ? Costs us way too much time and spares

02-21-2013, 07:03 PM
Welcome to the site Vladmir123.

If they are being used just like the picture the issue is simple.

You do not have the ball joint in right. You only have it on the threads. It NEEDS to be on the tapered part just below the break!

Take one of those ball joints and go put it in the stock spindle off the car it came off. See how it snuggles down in on the tapered part and you will know how it needs to go into your spindles.

You will need to have a machinist bore the spindles you are using out a little more at a taper to match that ball joints taper. The ball joint should be sitting so the rubber seal is touching the arm.

So in short you need a larger spindle hole thats tapered to match the ball joint. Its not in far enough!

02-21-2013, 07:29 PM
You need to figure the taper and buy the correct on of these: Speedway Tapered Ball Joint Reamer, 10 Degree - Speedway Motors, America's Oldest Speed Shop (http://www.speedwaymotors.com/Speedway-Tapered-Ball-Joint-Reamer-10-Degree,29005.html)

02-21-2013, 08:01 PM
Some ball joints only work in a planar movement, meaning they move in an arc and are not able to move in a circular motion. I have no clue if this is the case at all, but if you don't have them clocked to the arc of movement, that could cause issues.

I have to agree w/Nutz, though - looks like you need to taper the bore that you're putting them in and use the whole shaft body instead of just the threaded section.

Welcome to the site, btw. :)

02-21-2013, 09:33 PM
Thank you so much for replying.

So the spindle needs to have a bigger section to compensate for the ball joint sitting ? That makes sense as currently we have only line contact .. We worked through a knuckle and welded on a couple of extensions with tapered bores, and got this .. Do let me know if this is any better

02-21-2013, 09:36 PM

or is this the better way to go ?

02-21-2013, 10:04 PM
I vote for the second way to go. Your post number 6 in this thread.

02-22-2013, 10:45 AM
The threads of a ball joint are only there to hold the tapered part into your upright. The tapered part must take all of the load.

Is this how your suspension is assembled now?


If you just bored out this existing hole with a tapered reamer so that the ball joint tapered section is in the upright with the threads sticking out of the hole, it would solve your problem. Which is basically what is going in your last picture above. Of course this will also move your ball joint pivot points closer together, which will then change your suspension geometry.