Originally Posted by nobb

I wouldnt go as far as to call these aftermarket parts counterfeit. But the fact of the matter is that Toyota has engineered their front IFS systems in these trucks poorly with little tolerance for error.

When an aftermarket manufacturer reverse engineers a part, they don't have all the design parameters and specs that an OEM would have. So the result is they take a copy of the OEM casting and try to mimic the internals without understanding the actual operating requirements that the original engineers designed for. The likely result is a substandard part. There are many parts of a vehicle in which using a substandard part does not affect safety or normal operation, in which it would be fine to save money and use an aftermarket part. Unfortunately, the lower ball joints are not one of such parts.

Originally Posted by nobb

While owner maintenance is crucial, IMO, Toyota is to blame for this one. There are several other vehicles from other manufacturers that also have this design flaw like the Jeep Liberty. Toyota should offer a recall for ALL vehicles with this failed design because IMO...this is a lawsuit waiting to happen. But they wont because this design affects so many of their older (and best selling) trucks and would be too costly. This includes: 3rd gen 4Runner, 1st gen Tacoma, early model Sequoia/Tundra, and Land Cruiser Prado J90 series.

Most IFS systems have dual ball joints, upper and lower. But what makes our lower ball joint design flawed is the fact that they are in tension, which is a non fail safe design. The proper design from an engineering perspective is to load the ball joints such that they are in compression. Most newer vehicles, including newer Toyota trucks, use this fail safe, ball joint in compression type design. The difference between these two designs is that in a fail-safe compression type geometry, wear on the ball and socket may cause play, but the natural compression forces pushes the ball in the socket and prevents the entire wheel from tearing apart. The ball would have to be extremely worn for the wheel to be at risk of coming apart dangerously. In comparison, with a tension type design, wear on the ball and socket causes the ball to naturally pull away from the socket, thereby tearing the wheel apart. Even small amount of wear makes this design risky.

I suspect Toyota made a half assed design decision by copying the IFS geometry from the first generation Toyota trucks. You'll notice that the ball joint arrangement is very similar. BUT, you don't see the wheels falling off these older trucks because they use a torsion bar suspension in which the load from the torsion bar rests on the upper control arm, then through the upper ball joint (in compression), and finally to the wheel hub. The lower ball joints in the older trucks merely act to keep the wheel hub assembly in place and have little load bearing responsibility. With our 3rd gen 4Runner suspension design, the strut is connected to the lower control arm. That means the load of the vehicle is carried from the spring, to the lower control arm, through the ball joint (in tension), and finally to the wheel hub. In this design, the lower ball joint not only has to keep the wheel hub in place, but it also has to support the load of the vehicle through tensile force. THIS IS A POOR DESIGN. You basically have the thread of the ball joint and a ball stud that is maybe 1/2" in diameter, supporting the ENTIRE FRONT END of the vehicle under tension.

You may notice other vehicles having a similar ball joint design in which the lower control arm hangs below the wheel hub with a ball joint in between. But usually, the coil spring/strut is connected directly to the wheel hub and not to the lower control arm. This may be a similar design, but it is acceptable and not as much of a concern since the lower ball joint does not bear weight.

The key here is how the load is supported. If the load is supported directly by the wheel hub, then it does not really matter how the designer arranges the ball joints. However, if the load is supported by the control arm (upper or lower), then the ball joint has the extra responsibility of being load bearing, in which case, the proper engineering choice is to have them under compression loading.

Originally Posted by 42s on u

As a side note, if you get Toyota parts, get the Tacoma version instead of the 4runner. Taco stuff has a little more beef to it.

Note the shank difference on the tie rod ends

Originally Posted by TheeMikeB

As for using Tacoma parts, I understand this effects the turning radius on the 4runner.

Originally Posted by Nelsonmd

The casting is probably not the failure point for most LBJ's, I think it's usually the ball.

Originally Posted by 42s on u

how so?

Originally Posted by TheeMikeB

It's been discussed on here on a few threads. Something to do with the LBJs coming into contact somewhere during the turn, thus Messing with the radius. Do a search and you should find it.