Quick Belt Finder!
This tool is based on known GM fitments only. For other vehicles, use Dayco's official belt lookup.
Find It Manually — The Traditional Method
If your Mechman alternator uses the smaller 1.75" (46mm) pulley, you'll very likely need a slightly shorter belt — usually ½" or ¾" shorter — to reach proper tension and run the alternator at full potential.
The ideal belt keeps your factory spring/tensioner in the same position as your OE belt did. Too loose and it slips; too tight and you get premature wear. The factory tensioner marks are your best confirmation of correct belt length.
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Open the Dayco Quick Belt Finder
Go to the Dayco Quick Belt Finder. (Works best in Google Chrome.)
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Enter your vehicle
Input your Make / Model / Year / Engine — or even just your license plate number.
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Select the correct belt
Many applications list two belts: one for the main drive and one for an A/C accessory. Choose the belt that turns the alternator.
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Note the factory belt length
You'll see your factory belt dimensions. Find the value labeled "Effective Length (in):"
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Adjust by half an inch
Subtract ½" from that effective length (or add, if a longer belt is needed). This is your new high-output alternator belt length.
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Look up the new size
Use the Dayco Belt Dimensional & Identification Guide to find an available belt matching your new length.
Example
Popular GM truck & SUV belt part number applications