Completing my first Diff rebuild. Looking for a second opinion, I believe I need a thicker shim to move my pinion in a bit more. I've been looking around the internet and its seems subjective what is nominal and what is good, but I'm sure this is a shallow engagement. Lash was set prior to checking these patterns.

I also had a wierdism. When I put int a new crush tube from Mazda, and torqued the flange nut, the outer bearing would not seat fully and the pinion shaft would move in and out ~1/8" with 130 ft/lb on the nut. I re-assembled with the old crush tube, which was visibly shorter than the new one side by side, I got a tight assembly with between 10-12 in-lb of drag after subtracting the oil seal, with my flange nut torqued just over the 94 ft-lb

 

I agree, it does look a bit shallow. I've only done 2 with a lot of reading other forums and youtube, and I'm told the coast pattern should be paid more attention to on a used a gear set.

A new crush tube takes a lot more than 130 ft/lb to crush. I don't know why it's made with the extra 1/8" or so to begin with. Stick with the used one as long as it gives a good oil seal drag value.

 

kind of got a little crazy with the grease so it's kind of hard to tell if it's shallow, Or the grease is being pulled back over it as it's gushing out.

You only need 4 or 5 teeth covered for a pattern. Or use foot powder spray. This works very well,

 

Ok,

I had it all together, there was an imperfection in one of the teeth which caused a popping sound every rotation of the pinion at the same spot and the ring gear would 'jump' just a bit, so I took the opportunity to replace the 4.10 with a brand new 4.44 from Mazdatrix. Also had a bit more of an a-hah moment and made sure I used the same pinion depth spacer which originally came with this particular housing.

Also when I re-installed the NEW pinion with the crush tube which was new during my last pinion install in this housing, all the numbers worked out perfectly; my total drag was ~11 in-lb with the pinion nut tightened to 104 ft-lb, oil seal drag was between 0.5 - 1 in-lb.

Thoughts on the pattern, still looks slightly shallow to me, but better than the used 4.10 gearset in my first post. Also, the bright white grease is my check, there is a more faded chalky white material that looks like what Mazda used when checking the gears during manufacturing.

 

Sorry, I accidentally responded to the wrong thread. This can be deleted.

 

I set up a couple of these -- a Toyota 8" and an FB RX-7. I have the good fortune of living a few miles from an old school ring and pinion shop. In both cases, I took them to the shop and they corrected my work. If you live near a ring and pinion shop, it might be money well spent.

 

I've done a number of R&P swaps. Pinion spacer usually always depends on the dimensions of the differential housing. So, usually its best to stick with the original pinion spacer. Your pattern doesn't look too good to me. As elwood wrote, "If you live near a ring and pinion shop, it might be money well spent." I agree.