SADEV Primary Shaft ST66 Dog-ring Gearbox – Clio 2 Gr N (F1903001)

Failure to Replace a Worn Primary Shaft Risks Mechanical Catastrophe

The primary shaft is the first line of defense for your competition transmission. In your Renault Clio 2 Gr N's ST66 SADEV dog-ring gearbox, it is subjected to extreme shocks and torsions during aggressive gear changes. If you keep a primary shaft showing micro-cracks, stress marks, or damaged bearing surfaces, you are jeopardizing the integrity of the entire gearbox. A failing part means not only a forced stop during a race but potentially the destruction of the gears and the casing.

The Consequences of a Defective Primary Shaft

• Loss of Structural Reliability: The primary shaft supports most of the shaft bearings. If it is warped or its surfaces are pitted, it generates extreme vibrations that reduce the lifespan of all gearbox components.
• Accelerated Bearing Wear: High torque and the poor rigidity of a damaged shaft subject the bearings to abnormal loads. Clicking or excessive play in the bearings is a warning sign of major failure.
• Shaft Nut Damage: Poor retention due to shaft wear can compromise the correct tightening of the shaft nut and cause it to loosen, leading to axial play that is fatal to the entire gear set.

SADEV Primary Shaft F1903001: Designed for Competition

The SADEV primary shaft (P/N: F1903001) is forged and heat-treated to withstand the toughest stresses imposed by the ST66 dog-ring gearbox. Optimiz Access, an expert in sports mechanics and authorized distributor, ensures you access to the best quality for your:

• Renault Clio 2 Gr N (ST66 Gearbox)
• Renault Clio 2 X65 Cup
• Renault Clio 3 X85 Cup
• Renault Megane N4
• Twingo R2

Overhaul Questions for the ST66 Transmission

When should I consider replacing the primary shaft?

During every complete gearbox overhaul, the primary shaft must be inspected on a test bench. Any sign of deformation, bluing (overheating), or abnormal wear on the splines or bearing surfaces justifies replacement. This is an investment in the longevity of the transmission.

Which products should be checked or replaced along with the shaft?

It is imperative to replace the shaft bearings located on both sides of the shaft. Furthermore, the shaft nut must always be replaced during reassembly to guarantee the correct tightening torque. These complementary products are available at the bottom of this page.

Our Service: Expert Installation and Quality Parts

Specializing in sports vehicle maintenance since 2010, we offer fast delivery of this shaft and, at our facility in the Hauts-de-France region (near Lille, Arras), the expertise for the professional installation and precise shimming of your SADEV gearbox.