11 Most experts say that using shims with the same thickness as original will set the new gears up correctly about 60 percent of the time. At the very least, the old setup will get you in the ballpark. The pinion is shimmed under the main bearing on Toyotas, which has a stout press-fit. Since we were fresh out of a bearing puller and we were determined not to guess at the shims' thickness, we broke out the cutoff wheel and cut the bearing off the pinion. The trick is to cut as deep a groove in the bearing as possible without hitting the pinion, then knock the fire out of it with a chisel to split the bearing and relieve the press fit. It worked...sorta. More on this later.