R180 diagnosis S3019500

[ToolBoy]

Hello to all. . . Purchased my little car after it was driven into the ground and then parked for 17 years so there was no shake-down drive to listen to rear end, trans, engine etc. I currently have everything  behind the transmission completely out and am cleaning up and spiffing up or replacing, shaft, brake, frame, stub-axle, wheel bearings, suspension components and  bushings, et. al. as I go. Removed R180 diff, cleaned it up and took to to a gear shop hoping there was a cheap and easy diagnosis to tell me if it seemed like it was in decent shape. I didn't see any metal or crap in the bottom or on the magnet when I drained it.  I was told by several gear places that little could be seen without tearing it completely apart. I have several questions for the old school or anyone that has been thru this. I don't want to needlessly dump 600 clams into it for P and L but also don't want to yank it out again a week after I think I'm done and ready to drive it. My questions are. . . Can anyone refer me to a good post with photos that addresses the whole deal. . . teardown, diagnosis, bearings, seals and reassembly.  Also wondering if with feeler gauges and some know-how I can determine is it definitely needs a major redo or not. Would also be good to know if the redo is definitely a job for the gear shop or can I handle it myself realizing I would surely need to acquire a bearing press. Gear place wants 300.00 for labor and I'd supply parts. Diff is 37/11 and car has 5 speed trans and also wondering if this is a good pairing. Thanks in advance. . . .

 

[ToolBoy]

. . . at the very least I want to replace the 3 seals and the gasket before reinstalling.

[Patcon]

You could check movement in the bearings at the output stubs and the input flange. With a dial indicator you could probably check backlash. Spin it by hand and feel for roughness. replacing the seals is probably a good idea

[Zed Head]

The FSM is a good starting point.  Here's a sample.  73 is a good one.

https://www.classiczcars.com/files/category/11-240z/

[ToolBoy]

Thanks Zed Head, I have FSM from '71 but '73 has better detail drawings so I downloaded. My goal is to know every nut and bolt of this car when I'm done but tasks like this make me nervous. Should I be able to tear this diff apart and get it back together?  Is a bearing press necessary at this point?  They're showing lots of "special tools"  I guess I can always take a box of parts to the gear shop if I can't figure it out.  

and Thanks Patcon. . . The input flange rotation is smooth when I spin it but if I rock it back and forth clockwise, c-clockwise there is 1/32 of play and the gears surfaces tap each other. The same is true for the output stubs (gears tapping from the other direction) and these also have 1/32 inch play in and out (toward and away from differential body). I don't currently have a dial indicator but will get one soon.  Should everything be seamless and tight or do they typically have a little play?   Thanks. . . 

[ToolBoy]

Just looked at FSM and sounds like thrust washer play?

[Captain Obvious]

My completely unsupportable opinion?

It's fine. Clean the grease off put it in the car and run it.  

[ToolBoy]

. . . would be the first thing in the car that wasn't completely worn out. . . But it seems like it might be ok. . . (with new seals) 

[Captain Obvious]

LOL. I hear ya.  

But looking back at your pic, you've already cleaned off the grease AND pulled the rear cover off, right? No chunks of metal came out? No missing or damaged looking teeth? Nothing looks blued from heat?

I still say Put it in and run it. If you're energetic, put new seals on the output shafts first. I think they're the easy ones, right?

[ToolBoy]

No metal in the gear oil or the magnet, gear teeth look good, nothing blued. . . Just found this video where a guy rebuilds one in about 3 minutes. . .  But I think mine's prolly OK

 

[ToolBoy]

. . . and then I'll put it in and run it. . . 

[ToolBoy]

. . . right after Christmas