I put new bearings and races in the rear end and set the preload on the pinion bearings at about 20lb-ft. I then shimmed the carrier and torqued the main caps at 60lb-ft. Everything turned fine until I torqued the mains. This makes sense, as it is making everything tighter, but I can barely turn the ring by hand, I have to turn the pinion yoke to rotate the gears.
Is this normal?

Backlash is about 0.012. These are my used/orginal 273 GM gears which I am re-installing temporarily due to the 3.73 breaking.

 

Yes that is normal. By turning the pinion you have gear reduction to the ring gear. By turning the ring gear you are trying to overdrive the pinion gear.

 

To be more precise, turning the pinion requires 47in-lb according to my meter. My gear paint sucks and is hard to see but I'm pretty sure I'm on very much on the toe coast side and pretty well centered on the drive side. I can't find a gear pattern interpretation document anywhere that has a picture of that scenario.

 

That seems too tight to me. I'd remove the ring gear and double check the rotational torque for the pinion. It should be 15-25 in-lbs (less if you were reusing old bearings).

Once this looks okay, reinstall the ring gear with 0.005 of bearing preload on each side. You can do this by taking up all the slack in the bearings, then adding 0.005 on each side.

Make sure everything is clean and there is no debris on the caps or on the bearing surfaces, as this may cause the bearing to 'crush' and increase the rotational torque.

 

but isn't the 15-25 with JUST the pinion? I think he's saying when he's driving the ring-gear he's at the 47in-lbs; which would be about right.

 

97FormulaWS-6, you are right...15-25 should be JUST the pinion. I was unable to get a good pattern with the stock pinion shim, so I am having a shop owner who knows how to do this come over and show me how to do it right. He has honed a out pinion bearing and nut for quicker assembly/disassembly during setup.

A side question, do you guys know if our gears are "face-milled" or "face hobbed?" (See link below) I have my own opinion but it is not completely clear to me what that diagram is showing relative to my ring gear when I hold it in front of my face.
http://www2.dana.com/pdf/5717.pdf

 

I have no idea how you can say that is 'about right' when there is no spec for it. My point was he needs to take the ring gear back off and inspect the pinion gear preload because that has a torque-to-rotate spec, where as the ring gear does not. Knowing the torque-to-rotate of the whole system does not tell you what the preload is on each individual component. You could have inadequate bearing preload on the pinion and excessive preload on the differential bearings or vise versa.

You need to assure the bearing preload is correct on the pinion bearings first. Once this is correct, you can set the differential bearing preload as I described in my previous post.

 

Matt, it was stated in the first post that the pinion bearings preload was 20lb-ft....i meant 20in-lb lol

I don't get to work on this very often anymore so tonight I am starting over and hope to have an acceptable gear wear pattern. When it is right, I will measure the force needed to turn the pinion with main caps torqued and everything properly shimmed.

I believe it will end up being "about 40-50 in-lb"

 

Just to update this thread in case somebody stumbles upon it in a future search:
The rear end is assembled now (except for the lube). I ended up setting the pinion bearing preload at 15 in-lb, and the total torque required to spin the entire ring and pinion assembly was 17 in-lb.

The reason I measured 47in-lb before could only have been caused by my main caps being installed upside down (chamfered edge in). I believe I read on a website that was how to install them--don't believe everything you see on the internet! I noticed it was wrong when I pulled the carrier out and one of the carrier bearings fell apart, making it obvious they were in fact crushed (just as MatLT1 suggested was the case). After flipping the caps right side up, the install went much smoother and the pinion can be spun much more freely.

These gears have 85-90k miles on them (they are original) and I was unable to get an acceptable gear pattern with smaller than a 0.009" backlash, so that is where it is set. Hopefully it lasts a few hundred miles before I buy/install the 9" next spring.

Thanks for the help