Ford RS Sierra & Escort Cosworth YB Dayco Timing Cam belt Cambelt

Ford RS Sierra & Escort Cosworth YB Top Quality Dayco Timing Cam belt Cambelt

Dayco Timing Belt – Ford Cosworth YB – Later Parabolic / Curvilinear Tooth Profile

Premium Dayco timing belt suitable for Ford Cosworth YB engines.

This Dayco belt uses the latest available parabolic / curvilinear tooth profile design, developed to work smoothly with the fully rounded timing pulleys used on the Cosworth YB engine.

Earlier quality YB timing belts used fully rounded tooth forms, but the later Dayco parabolic profile is a more refined version of the curvilinear design. The tooth shape is designed so that each belt tooth enters and exits the pulley groove more progressively, rather than loading suddenly as it comes into mesh.

As the belt wraps around the pulley, each tooth has to engage, load, unload, and release. On a high-performance twin-cam engine such as the Cosworth YB, this happens under constantly changing camshaft load from valve spring pressure and cam torque pulses. A smoother tooth profile helps reduce the impacts and vibration that can occur as the belt teeth engage with the pulley.

The parabolic profile helps build contact gradually across the tooth flank. This can improve load sharing, reduce localised stress on the tooth, and help the belt run more smoothly at higher engine speeds. By reducing harsh tooth loading and improving engagement, it can also help reduce premature pulley and belt wear.

Another advantage of a refined curvilinear profile is how it manages air as the belt tooth enters the pulley groove. When a belt tooth enters a fully curved pulley, air can become trapped between the belt and the pulley valley. If this air is compressed and forced out suddenly, it can contribute to belt whine and running noise. A progressive parabolic tooth form helps the tooth enter and leave the pulley more cleanly, allowing air to escape more gradually and reducing harshness in the belt drive.

The belt construction is also important. Dayco timing belts use a tough wear-resistant tooth fabric, high-strength tensile cord, and a moulded tooth surface designed for consistent slip-free power transfer. The high-modulus glass fibre cord helps maintain belt length stability, which is critical for accurate cam timing over the service life of the belt. The tooth fabric also helps reduce friction as the belt meshes with the pulley, contributing to smoother and quieter running.

Key technical benefits:

• Later Dayco parabolic / curvilinear tooth design

• Designed for rounded Cosworth YB timing pulleys

• Progressive tooth entry and exit

• Smoother flank loading as each tooth comes into mesh

• Reduced tooth impact and vibration

• Improved load distribution across the tooth flank

• Helps reduce premature belt and pulley wear

• Helps reduce trapped-air noise and belt whine

• Wear-resistant tooth fabric for low-friction pulley contact

• High-modulus glass fibre tensile cord for length stability

• Moulded tooth surface for consistent slip-free drive

• Resistant to oil and engine heat

• Well suited to twin-cam engines with changing camshaft loads

• Suitable for standard, fast-road, and performance YB builds

A quality timing belt is critical on the Cosworth YB engine. This Dayco belt combines modern tooth profile technology with high-quality belt construction, making it a strong choice for servicing, rebuilding, or upgrading the timing drive where smooth running, accurate engagement, and reduced belt noise are important.