Ring and Pinion Setup

Refreshing a factory Ford 9" rear end for my truck and at the phase of trying to set the pinion depth. Reusing the original gearset on a new locking carrier. I set backlash to .009" and am trying to get a patten on the teeth to see if I should change pinion shims. The setup guides all show a pattern that is very obvious and easily tells you if the pinion should move in or out. Real life for me just shows yellow gear marking compound smeared everywhere and no indication if things are happy or not. Does anyone have tips for getting a clear reading from the teeth. I am putting compound on 2-3 teeth and providing drag while spinning the pinion. Tried applications from thick to thin and still couldn't tell much.

Looking back a few years on the forums for gear setup topics Knurled posted in one thread that a pattern for used gears wasn't going to work well since they have worn together. Anything to do in this case or just go with the shim size that it came with and move on?

It sounds like you might be using too much marking compounf but if you're reusing the gears its more important to put the pinion depth where it was than it us to get a good pattern.  Unless the old pinion bearings were really shot (in which case you shouldn't reuse the gears) the depth won't change significantly with new bearings.  I'd set the backlash and call it good.

Plus 1 on going with the original shims. If things weren't worn out changing the carrier shouldn't affect the pinion depth.

Pinion gears are very precision, so whatever the shims were on the factory pinion should be exactly right for the new one.

Less making compound, and add resistance to the ring gear so there is more pressure on the teeth.... as in, you should need a breaker bar to turn the pinion.  Use a wooden wedge between the ring and the housing.  On a C-clip axle like an 8.5 I will apply the parking brake about half way to get resistance.