RAPFIX Racing Caterham Quick Release and Top Shaft
Steering Wheel: Competition use (PCD50.8mm with 3 holes)
Vehicle mounting method: welded and bolted (PCD50.8mm with 3 holes)
Main structural material:
Plug = Chrome Molybdenum Steel SCM435
Socket = Aluminum alloy A7075T6
Sleeve = Aluminum alloy + Stainless steel SUS420
Ball = Steel SUJ2
Dimensions: approx. 90 mm
The SFI Foundation (SFI) is a non-profit organization established to issue and administer quality assurance standards for professional performance and competition equipment. The SFI Foundation has been serving the automotive aftermarket and motorsports industry since 1978. Its service to the industry is a system for developing and administering a variety of standards, certifications and testing criteria for use in motorsports.
How it happened
Developed as the ideal form of quick release hub for competition. The Rapfix series has already recorded sales of over 20,000 units as a detachable hub for commercial sports steering wheels, and has established itself as “Rapfix” with its unique ball lock system. Based on this technology, we have achieved a compact and lightweight design exclusively for racing vehicles.
Pulling the sleeve frees the steel ball in the socket and releases the socket from the plug. The pulled sleeve is held in place and does not need to be pulled again for insertion. The major advantage is that it can be inserted at any angle and automatically joins with the steering wheel (socket) when the angle of the steering wheel (socket) and the steering shaft (plug) are aligned, eliminating the annoyance of the pre-RAPFIX quick release where the shaft cannot be inserted unless the TOP is precisely aligned. The steel ball has been greatly reduced. The unique technology also eliminates rattling and ensures secure steering force transmission because the steel ball always maintains pressure on the plug. This rattle-free and smooth connection is effective even after a certain amount of wear and tear on the product, which greatly contributes to the driver’s severe steering wheel operation. Furthermore, RAPFIX Racing uses a new “Cam Lock” mechanism to ensure that the plug and socket are fully bonded and that radial loads are locked in place for absolute reliability on the racetrack. Together with the ball lock, this ensures safety.
Developed for use in competition vehicles. The plug is made of chrome molybdenum steel SCM435 for easy welding to the steering shaft and the sleeve is made of SUS420 liner for light weight and high strength. The socket is made of super duralumin and special plating for durability. A protection cap made of Delrin plastic is attached to the tip of the plug for hard use. The tip of the plug is not likely to damage the socket even if it is roughly inserted, and can be easily replaced if the protective cap is damaged. A bolt type plug that can be bolted to the steering shaft (PCD50.8mm with 3 holes) has been added.
Tests are conducted in accordance with the NAPAC standards (*1), which are the product standards for the Japanese aftermarket.
As a result of these tests, both the flexural and torsional tests demonstrated that, although a slight permanent deformation and increased rattling occurred at the specified load, it was still able to be attached and detached afterwards, and that it did not break but did not become impossible to steer even under heavy loads. We also tested how much load the coupled plug and socket might release if a strong tensile force was applied to them, and the test was completed with the fastening screws to the steering wheel breaking first, without breaking at 3754 kg (3.67 KN). It was confirmed that the quick release function could work after the test was completed. Since the standard weight of the driver according to the Japanese Industrial Standards is 55kg, this means that it can withstand approximately 68G of impact in the tensile direction.
In terms of durability, even after 10,000 attachments and detachments, it was confirmed that the steering wheel can be steered and attached and detached without increasing the rattle, and that it does not break.
(*1) Regarding the transmission of steering force through steering wheel operation and radial force, the steering wheel was tested in a torsional test at 29.7 kg-m (291 N-m) with no breakage under static load. (194 N・m) without fracture under static load.