We gently lowered the new carrier assembly into the housing and placed carrier shims between the carrier bearings and the rearend housing. Their job is to place a preload on the carrier and keep pressure against the bearings while the shim’s thickness on both sides also determines the amount of ring-gear backlash. It’s important to note that the backlash can be adjusted by changing the shim’s thickness side for side. To decrease backlash, we could increase the thickness on the left side while reducing the thickness an equal amount on the right side. To increase backlash, we could do the opposite. With the carrier in, we torqued the main caps to 65 ft-lb and made sure it spun freely in the housing. Note: The carrier assembly may have to be installed several times before the correct backlash is determined.