When building vehicles for the racetrack, you hear the term uniball again and again. But what is a uniball anyway, what is the difference to a normal ball joint and why is a uniball joint used at all?
Especially modern multi-link axles need joints to allow movements of the individual links. In the production car, these joints have to fulfill a wide range of tasks in terms of freedom of movement, comfort and service life.
In the production car, two types of joints are mainly installed:
- Rubber Joints
- encapsulated ball joints
Rubber joints offer very good damping properties to increase driving comfort. Due 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 significantly, especially in connection with semi-slicks or slicks, and thus give a "spongy" driving experience. The sometimes very high temperatures in racing also have a negative impact on the rubber bearings.
Cutaway model of a ball joint on the rear axle of 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 shows 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 production, Uniball joints are extremely precise and durable. The service life in racing exceeds that of ordinary ball joints many times over. The disadvantages of Uniball joints are the susceptibility to corrosion and the high price. We no longer recommend operating in salt and snow with open Uniball joints. For use on the racetrack, however, the advantages clearly outweigh the disadvantages.