What is a uniball joint?
When building vehicles for the racetrack, you keep hearing the term uniball. But what is a uniball anyway, what is the difference to a normal ball joint and why do you even use a uniball joint?
Modern multi-link axles in particular need joints to allow the individual links to move. In the production car, these joints have to fulfill a wide variety of tasks with regard to freedom of movement, comfort and service life.
Two types of joints are primarily installed in the production car:
- Rubber joints
- encapsulated ball joints
Rubber joints offer very good damping properties to increase driving comfort. Thanks to a complex structure, the elastic properties of the joints can be precisely influenced during driving. In racing, rubber joints are a disadvantage because they deform strongly, especially in connection with semi-slicks or slicks, and thus convey a "spongy" driving experience. The sometimes very high temperatures during racing also have a negative impact on the rubber mounts.
Cutaway model of a ball joint of the rear axle on the BMW M2 / M3 / M4:
Encapsulated ball joints are significantly less elastic than rubber joints. They are mainly used where increased articulation angles are required. The encapsulation makes them relatively robust against external influences. The plastic insert, which is located between the inner and outer part, is relatively thick and therefore still has an elastic behavior.
Cutaway model of a Uniball joint:
With the Uniball joint, there is only a very thin friction layer made of PTFE between the inner and outer parts. Elastic deformations can practically not occur here. Due to the complex manufacturing process, Uniball joints are extremely precise and durable. The service life in racing operations exceeds that of ordinary ball joints many times over. The disadvantages of uniball joints are their susceptibility to corrosion and their high price. We no longer recommend operation in salt and snow with open uniball joints. For operation on the racetrack, however, the advantages clearly outweigh them.