ARP 251-2803 Pro Series Flywheel Bolt Kit M10x1.0 Ford Cosworth YB Sierra Escort

Vehicle Fitment

• 1986-1992 Ford Sierra RS Cosworth (Cosworth YB 2.0L 16V Turbo I4, RWD)
• 1987-1988 Ford Sierra RS500 Cosworth (Cosworth YB 2.0L 16V Turbo I4, RWD)
• 1992-1996 Ford Escort RS Cosworth (Cosworth YBT / YBP 2.0L 16V Turbo I4, AWD)
• Compatible with any engine build using the Ford Cosworth YB 2.0L 16V 9-bolt flywheel configuration

Fitment Notes

• Designed for Cosworth YB engines using a 9-bolt flywheel - confirm your flywheel uses 9 bolt positions before ordering
• Do NOT use washers - these bolts are engineered for direct installation without washers; using washers will void ARP's warranty and may cause failure
• Flywheel bolt holes must have adequate chamfer to clear the underhead radius of each bolt
• Use ARP Ultra-Torque assembly lubricant on threads and under bolt heads for accurate torque readings - do not use engine oil or thread locker

Features

• Forged from aerospace-grade 8740 chromoly alloy and heat-treated prior to thread rolling and machining for maximum material integrity
• Rated at 200,000 psi tensile strength - substantially stronger than OEM Ford Cosworth flywheel hardware
• Flat 12-point head design provides better socket engagement and more accurate torque application than standard hex-head bolts
• Larger-than-stock shank diameter improves flywheel register and reduces rotational movement under high-boost, high-RPM clutch loads
• Threads rolled after heat treatment for superior fatigue resistance under repeated clutch engagement cycles
• Reusable fasteners - do not stretch or deform under rated load unlike OEM hardware

Specifications

• Part Number: 251-2803
• Material: 8740 Aerospace Chromoly Alloy
• Tensile Strength: 200,000 psi
• Thread Size: M10 x 1.00
• Underhead Length (UHL): 1.150 in.
• Head Style: 12-Point (Flat)
• Socket Size: 5/8 in. 12-Point
• Finish: Black Oxide
• Washers Included: No - not required, do not install with washers
• Quantity: Set of 9

Included Components

• 9x ARP M10 x 1.00 Pro Series 12-Point Flywheel Bolts
• 1x ARP Ultra-Torque Fastener Assembly Lubricant

Product Description

The ARP 251-2803 is a Pro Series flywheel bolt kit designed specifically for the Ford Cosworth YB 2.0L 16V turbocharged engine, covering the Sierra RS Cosworth, Sierra RS500, and Escort RS Cosworth. The Cosworth YB is one of the most celebrated rally and performance engines in European motorsport history, and any serious build or clutch service should include replacement of the flywheel bolts. OEM flywheel hardware is not engineered for the sustained high-boost, high-RPM operation that these engines are frequently subjected to in competition and modified street applications.

This ARP kit replaces all nine bolts with 8740 chromoly fasteners rated at 200,000 psi, with a flat 12-point head for accurate torque application using a 5/8 in. socket and a larger shank diameter for improved flywheel register alignment. Install without washers using ARP Ultra-Torque lubricant included in the kit.