Well I have only cleaned the front belts once on a car I owned a couple of years ago,my belts had a few stains on them from I think coffee,they were like it when I bought the car,I pulled both belts out and used two mole grips to stop them going back,it was all I had maybe some other clamp would be a better choice,I used a can of fabric cleaner and a small scrubbing brush and I kept wiping the excess of with a damp cloth,most of the belt came up fine but a couple of stains needed to be gone over again,I left the belts out overnight,they were still a little damp in the morning so I got a hair dryer on them they cleaned up well .