BMW Drive Belts & V-Belts

Your BMW's drive belts are wear items, and will degrade and crack over time. Don't wait until you have a belt failure... don't get stranded! Replacing your BMW's belts, such as the alternator belt, power steering belt, air conditioning AC belt, or serpentine belt is a low cost insurance policy to preventing a break down -- or worse, engine damage. We recommend checking your belts every 10,000 miles. If your belts have excessive cracks, dry rot, missing teeth and/or grooves, are cause noise, it's time for new ones.

While also inspecting your serpentine belts, also check for wear or resistance in the pulleys. The tensioner pulley and deflection pulley are the primary sources for belt squealing. The rubber-isolated pulleys can also break apart, leading to total belt failure. We sell the tensioner and deflection pulleys for the M50 engine family used in the E34, E36, E39, E46, X5, Z3, and Z4.

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E9X M3 Performance Underdrive Pulley Kit

T#:593749

Part#: 10.00.011

In Stock

$ 349.00 USD

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$ 349.00 USD

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Free additional power to your M3’s rear wheels without sacrificing or compromising your BMW’s reliability. Machined from 6061-T6 aerospace aluminum, Macht Schnell Performance Underdrive Pulleys are strong as well as lightweight to limit parasitic drag from the accessories within a moderate level for maximum performance on or off the track. After machining and engraving, pulleys are then T3 hard anodized for additional strength, anti-corrosion & wear resistance. Our DualDrive design replaces the Crank Accessory & Power Steering Pulleys, resulting in an additional 9-14 HP and 7-9ft. lbs TQ gain for the M3. Gains are due to a reduction in power required to turn accessories; an increase in accessories lifespan due to lower speed will also result. All factory harmonics/balancing are undisturbed. Macht Schnell Performance Underdrive Pulleys have no negative effect on accessory operation and comes fully equipped with new belts. Already have this kit and need new belts? See T#14491 and T#14489 Performance Underdrive Pulleys Features: DualDrive design allows maximum performance, with minor effect on accessory speed Proper cooling temperatures are retained at proper levels on or off the track Maintains proper alternator speed, allowing sustained levels to sensitive control modules Machined from 6061-T6 aerospace aluminum T3 Hard-Anodized for maximum strength and corrosion/wear resistance No affects to crankshaft dampening or harmonics Simple bolt-on installation

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Water Pump/Alternator Accessory Belt Service Kit w/ Kevlar Reinforced...

T#:22097556

Part#: 6PK1548TKT

Ships on Aug 28, 2026

$ 129.99 USD

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$ 129.99 USD

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Eliminate your squeaking accessory belt pulley and cracked drive belt with this upgraded accessory belt service kit! This kit includes the ECS Kevlar Reinforced Accessory Belt, tensioner assembly, and your idler pulley. ECS Tuning's Red Kevlar Accessory Belts are both an aesthetic improvement and a performance alternative to a traditional belt. Kevlar-reinforced belts experience less elongation over time minimizing the amount of belt adjustment needed as well as offering a higher shock and impact resistance compared to OEM-style belts. Refreshing the rollers and/or tensioners simultaneously is a great way to ensure all vital components of your drive belt system are functioning optimally for years to come!

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