The factory rack bar slider is a wear item made of black nylon. The design is minimal with only four small pads contacting the rack housing. The mold is also fairly loose in the rack even when new. After time and abuse the nylon will wear and stretch allowing play which causes bump steer by letting the tie rods shift up to 2 degrees but also affects the rack/pinion gear mesh since the rack bar is able to rotate. This is compounded by the low quality grease used by the factory which tends to be pushed out of the contact areas and dry out.
The team contacted SHG Motorworks who have designed a Delrin insert to replace the OEM part. SHG Motoworks have increased surface area, depth, hardness and tolerances have been reduced to just a few thousandths of an inch. The final design was derived after testing and exploring the limits of tolerances.
The video below clearly demonstrates the improvement between the OEM part (on the right) and the SHG Motorworks part (on the left).
When installed with a high quality, high temp rating silicone grease such as Ford Motorcraft XG3A, the team can expect safe, reliable and consistent steering throughout their races.