The draw length of a bow - the distance between the shooter's brace hand and shooting hand when at a full draw - must be matched specifically to the shooter. With the exception of the Mathews Mission series, Mathews bows are designed draw length specific, and do not provide for setting adjustment. While the Mission series draw length can be changed with a setscrew on the cams, you will need to replace the cams to change the draw length on other models of Mathews bows.
Locate the graduated marks on the cam of the bow. The marks will be numbered 1 through 4 or 5, or A through D or E, with each mark representing 1-inch of draw length adjustment.
Remove the setscrews in the cams with a screwdriver. You do not need to release tension from the bow limbs, string or cables to change the draw length with adjustable cams.
Rotate the adjustment wheels on the cam, one mark up to increase draw length or one mark down to decrease draw length. For example, if you wish to decrease the current draw length of the bow by 1 inch, and the cam is set to mark "C" or mark "3," rotate the wheel to mark "B" or mark "2."
Apply thread sealer to the setscrews. Reinsert the screws in the cam and tighten the screws. If you wish to change the draw length by more than the adjustment wheel allows, change out the cam.
Clamp the bow in a bow press according to the bow press manufacturer's instructions. Engage the bow press, compressing the limbs of the bow until all tension is released from the bowstring and cables.
Slide your fingers under the bow cables and pull the cables out of the grooves in the cams.
Remove the camshafts. The bow's cams will be held in place, at the end of the bow's limbs, by a nut or circlip attached to the end of the camshaft. Remove the nut from the camshaft with the wrench. Remove circlips from the camshaft by inserting the pins of the circlip piers into the holes at the ends of the circlips. Spread the circlips with the pliers and pull the circlips off the camshaft.
Pull the camshaft out of guide at the end of the bow limb with your fingers. If the shaft sticks, use the tip of a small Phillips screwdriver to push the shaft from the guide.
Remove the old cams from the limbs with your fingers. Insert the new cams, specific to your draw length, in the same position and orientation as the original cams.
Replace the camshaft and reattached the nut or circlip back onto the end of the camshaft. Insert the bow cables into the grooves on the new cams.
Release the bow from the bow press.