I can tell u from my experiences with the 741 case that 3.55 and 3.91 had approximately .030 back lash from the factory to get the pattern acceptable cause they didn't give a dam where the pinion was installed. I have tried to set backlash to .010 but the pattern was whacked like yours. You will always have noise with those gears even if u set the pinion depth deeper. U need atleast a .020 shim for the pinion. Kim
I have also heard this from another guy that I know that has been building 8-3/4's for 40 yrs. I have only had one 741 unit and it had a ton of backlash. I didn't measure it but I know it had to be at least .020 from the feel
