Quality pays off when it comes to rod ends in your race car.
When looking for rod end choices for a new project or to update used ones, the quality of your rod end bearing is based on the application. Start by asking yourself the right questions about rod ends anywhere from a simple throttle linkage to high-stress rod ends on your front and rear suspension.
Observe the machine work done in each rod end. “Apparently similar bearing life can vary widely,” advises John McCrory with Aurora Bearing Company. “This may be due to design and manufacturing control, and often attributed to the composition and installation of the PTFE liner.”
He continues, “This liner is wearable; for example, there is a big difference between aftermarket brake pads and proper high performance brake pads. The same longevity applies to PTFE liners from different bearing manufacturers.
Judge by yourself
First, look carefully at the end of the rod. Examine the machine work that has been done in each component of the unit. You can also feel the stroke; is it smooth or rough? Same thing with the ball, smooth or rough? Either way, the smoother the feel and surface finish, the better.
If you are looking for a rod end that is not teflon coated, you can hold the ball firmly and shake the entire rod end. We feel the games between the ball and the body. Does the rod end vibrate or does the bearing stick in the race? It’s a good sign if the assembly seems to fit precisely.
If a teflon liner is present, carefully check for any damage to the teflon liner. Are there gaps and missing pieces? It should be a continuous, snug liner around the circumference of the ball. Unlike a rod end that is not teflon coated, the tolerance between the ball and the housing must always be very “tight”. When moving it manually with your fingers, it should take reasonable effort.
Calculation of rod ends
An informative catalog of rod ends, such as Aurora Bearing’s, includes specifications for “static radial load capacity”, to which McCrory offers more definition.
“This load capacity is defined as the amount of load, applied either radially or along the axis of the threaded portion of the rod end,” he says. “Tension loading will cause the part to break or fail. Axial loads, which are loads passing through the axis of the ball, are generally recommended at around 10% of the number of radial loads.
What rod end force do I need?
For racing, these bearings are often divided into two categories: the first is suspension joints and the second is linkages, such as steering. The secondary or control linkages include the throttle, clutch, brake, and shift mechanisms. Joints in these applications are often low specification industrial/commercial grade rod ends.
“Race car suspension and steering have to use a liner rod end,” says McCrory. “These quality rod tips use a carrier fabric for strength, along with a polytetrafluoroethylene (PTFE) component for lubricity. This type of PTFE coated rod end provides optimum rigidity, strength and friction characteristics at an economical price.