get a 19mm socket or box wrench and torque the part circled in red clockwise and you will be able to slide the belt off.
let me tell you... it is a serious pain in the ass with the clam on. I had to remove the passenger side rear wheel and pull on it from below the car while my friend removed the belt from above.
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2005
BADA55 Lotus Elise
1993 Black BMW 325i
2000 Solar Yellow MR-S - SOLD
1987 White on White Porsche 944 Turbo - SOLD
1993 Maroon Lexus SC400 - SOLD