Idler Pulley Set with Auxiliary Idler Bracket
2003-2004 Mustang Cobra
This convenient kit is offered to simplify the process of outfitting your supercharged Cobra with complete set of heavy-duty idler pulleys and our billet idler bracket. The kit includes our durable and proven Cobra auxiliary idler bracket with hardware, (1) billet pulley to mount on the bracket, and (3) billet idlers to replace those found on the factory supercharger drive.
The bracket is the same extreme-duty idler bracket listed under PN MCI-90 (shown elsewhere in this section), and the idlers are the precision-machined, hardcoat-anodized billet idlers with bearing covers, also listed in this section.
This idler kit, in the standard configuration, ships with (3) 100mm idler pulleys and (1) 90mm idler pulley. This pulley combination is by far the most popular, and works exceptionally well for nearly all applications. The 90mm pulley matches the original idler pulley size, and this pulley should be installed in the OEM location in the center of the engine, in line beneath the supercharger pulley. This 90mm pulley serves to maximize belt clearance as the belt goes up over the supercharger pulley and back down again, and is necessary for this reason. The 100mm pulleys should be installed in the remaining positions: on the provided auxiliary (snub) idler bracket; on the driver's side of the engine; and in the crank idler position, adjacent to the alternator. The benefit of the larger 100mm size is to maximize belt wrap at all contact points, to reduce speed at the pulley bearing, and most agree that the larger 100mm pulleys look better.
This idler pulley kit is available with either single or double-bearing pulleys. The single-bearing pulleys closely match the original pulleys in width, and with our proven billet construction, high-load, high-speed bearings, and hard-coat anodizing, can be considered a permanent solution to failure-prone OEM pulleys. The double-bearing pulleys stack two of these heavy-duty bearings in the pulley bore, to spread the side load from the belt over twice as many bearings. These pulleys are appropriate for severe-duty, high-load applications, or for installations converted to a 10-rib drive belt.
Each of the components in this kit are available separately, and are listed elsewhere in this section. Additionally, this kit can be ordered with any combination of 90mm and 100mm idler pulleys upon request - please feel free to contact us.
Note: With regards to the double-bearing option: Our double-bearing idler pulleys are used in both 8-rib and 10-rib applications, so these pulleys are 1.75" wide at the belt surface. When used with the Cobra's stock-style 8-rib belt, there will be .25" of unused belt surface on the pulley, forward of where the belt rides. This is mentioned for informational purposes only and there is no fitment issue with these double-bearing pulleys in the Cobra application.