I'm pulling the diff on my 80, for other reasons to numerous too list. It's leaking quite impressiveley from the pinion and the yokes, so I'm thinking a rebuild, or at least a re-seal would be a worthwhile project. I've got the GM shop manual and I'm not too worried about the actual procedure, but the biggest hurdle is the amount of special tools used.
Now, I can make my own case spreader without too much fuss, but the "arbor" tool for measuring the pinion depth seems a little more "precision" than I can knock together myself ... Is there a good source of these types of tools that anyone knows of? Expensive I'm sure, but I'm just curious.
Or has anyone got any tricks from previous rebuilds, for getting by without all the tools? There seems to be quite a bit of info about people diy building the older cast iron diffs out there, but less so with the 80-82 ally units. Someone must have done this work on their 80-82 car?

Cheers!

 

Anyone?

 

i had to get my diff side seals replaced a little while ago. the only part i was game to tackle was removing it, i got a mate who rebuilds diffs to do mine cost me two cartons of beer after i payed for parts. i helped him drink it to

 

I replaced the bearings, seals, ring, and pinion in the DANA 44 from my '80.
If you are not replacing the ring and pinion, it will be simple. The gears are already shimmed properly.
Upon dissassembly, measure the shim packs and simply re-use or replace them with the equivalent thickness shim pack.

Even if you were to replace your ring and pinion, you would not need the "arbor" tool. In my research, I found that it is best to use "marking compound" to determine the proper gear mesh.

The Corvette Forum archives are currently not available but when they return, search for a post I made in regards to the differential rebuild titled:
"I have completed setup of the 3.73:1 gears in my DANA 44"
Here is a "cut-n-paste" of the text from that post:

I used the following parts:
Rear end rebuild kit 80-82 PN# 5542 ($89) http://www.bairs.com/
SPICER DANA ring and pinion, 3.73:1 ($141) http://www.tomsdifferentials.com/
4 - GM gear lube PN#1052271 ($5.10 each)
1 - GM additive PN#1052358 ($5.03)
1 - GM Gear Marking Compound PN#1052351 ($3.38)

I used the following reference material:
- GM Shop Manual for 1980 Corvette ST364-80 Section 4B "Rear Axle".
- SPICER DANA Ring Gear and Pinion Tooth Pattern Interpretation (included with gear set).
- Yukon Gear & Axle Installation Kit Instructions.http://www.ring-pinion.com/yukon-instructions.pdf
- Randy's Ring & Pinion "Tech Library" http://www.ring-pinion.com/home.html

I used the following tools:
1- 10-40 in/lb. Torque wrench
1- 16-80 ft/lb. Torque wrench
1- 50-250 ft/lb. Torque wrench
1- 1" Micrometer
1- Bearing puller
1- GM gear marking compound PN# 1052351
1- 18" Pipe wrench (for holding yoke while tightening pinion nut)
1- Bearing race installer (home made)
1- Big hammer
1- Differential housing holding fixture (home made for use with engine stand)
Obviously quite a few other tools were used but this is a list of the essentials.

My final specifications vs. reference specifications:
Pinion Pre-load - The GM manual called for 15 to 35 in/lb. and the Yukon guide called for 14-19 in/lb. My actual results were 18 1/2 in/lb.
Back Lash- The GM manual states "Backlash tolerance is 0.005" to 0.009" and cannot vary more than 0.003" between points checked. The Yukon guide showed 0.006 to 0.010". My actual results based on the four locations that I checked were .007, .006, .006, and .005 .
Pinion depth / Gear contact pattern- The GM manual specifies the use of Pinion Depth Gauge Tool but the DANA SPICER instruction says to use the GEAR CONTACT PATTERN METHOD and not to use the gauges. Below are pictures of the contact pattern on my gears along with comparison charts. The pictures are not real clear but let me know if any of you see a problem with the pattern on my gears vs. the reference guides. I was fortunate in that I started out with the original shim pack values and the contact pattern looks just fine to me. The only real trouble I had was trying to find an acceptable shim pack combination for the pinion pre-load but at least that bearing is not pressed on!

Due to wear on the differential shaft from the inner yoke shafts, I have ordered a new one. This will delay completion until it arrives via UPS. Combined, the wear on both sides of this shaft was equal to .025". Replacing this shaft should eliminate a considerable amount of the .014" (left side) and .015" (right side) inner shaft yoke play that I had in the beginning.
I have decided to just clean up the ends of my yoke shafts and re-use them as they are. I was going to test the hardness on the ends of the shafts but the guy who runs that particular lab at work was off all last week. I'm also not replacing my clutch pack because it still works fine, I'm too darned cheap and I don't have the required tools.

 

Doopsvette, I'm keen on payment in beer - I always try and get my friends to pay me in cans if I ever do any work for them Either that or cigarettes, but not everyone is a dirty smoker like me

Miker, well you've pretty much covered all that I'd hoped for mate, cheers!
I've actually got your main thread from the archives now, and have just saved it!
Having had time to think about this, arbor tool or not, I reckon i can easily make (or have made) a bar that would fit in the carrier bearings and give a reference for measuring the pinion depth. I work in a University Engineering dept, so all the measurement tools are at my disposal, and the machine tools. But, as you can say from experience that the marking compound is the way forward, then any measurement would just be done for a "second opinion", i suppose. Plus, marking gives you results you can actually see as you make changes.
Good point about the pinion depth being already set if I'm reusing gears (I hope to I will be, no nasty surprises please!)
I guess the back lash would be the only "shim adjustment" that might be necessary due to wear on the teeth, or is that negligible?

Just a couple more questions, if you don't mind...
Do you have an electronic copy of the spicer dana instructions? I can get to all the other literature you mentioned, via the web. But assuming (well, bloody hoping!) I don't need replacement gears, then the only thing I won't get to read will be those instructions. It would be nice to have a second view from the GM book.
Also, you mention the special tools for taking the clutch assy apart. I might try and fab something up for that, but looking at the pics inthe shop manual it's hard to see what that tool actually does. From having it all in front of you, can you tell us what the score is there? Do you think it would be "easily" make-able with a helf decent skill on the machine tools?
And finally (!) did you need to make a spreader for the casing (didn't see it in your list) ? That doesn't actually look too hard to make.

Sorry if the questions are coming a bit too thick and fast, but you seem to have done a good solid job on this...
Cheers!

 

First I would like to say that I have only done this job ONCE so I am far from being an authority on the subject but I'll share what I know along with some worthless opinions!
I've "heard" that it is not advisable to re-use differential gears because they need to re-mesh into exactly the same wear pattern as before. However, this may not be of any concern with our 80-82 DANA 44 rear end because it uses shims instead of a crush sleeve for seating the pinion depth. With that being said, I would not be afraid to reuse the old gear set.
I certainly believe you could fabricate an arbor tool but it is not necessary in my humble opinion. One reason being that you are not changing gears, thus all dimensions "should" remain stable as long as you use shim packs of equivalent thickness. It was a guy from either Tom's Differentials or Bairs' that told me gear marking compound is the only way to see the "true" contact pattern. They felt like there is too much room for measurement error using the arbor tool. I have not used the arbor. It might work great for all I know.
Gear marking compound is cheap, easy to use, and there are visual aids available for comparison.
For re-using the same ring and pinion, I would be tempted to use the marking compound to check the gear mesh pattern BEFORE removing the gears. AFTER re-installing the gears, verify that the mesh pattern is similar to what it was originally.
I feel that it is NOT ADVISABLE to make any "shim adjustment" when reusing the old gears. The new shim packs need to be EXACTLY the same thickness as the old ones were to ensure the gear mesh pattern remains similar to original. (sorry for repeating)

No, I haven't scanned the whole document, just the part shown in that old discussion thread. If I can locate it, I'll gladly scan it and email a copy of it to you.
I'm certain that you could fabricate your own tools for rebuilding the clutch assembly. No problem!
I simply used two pry bars. I placed a pry bar into each side of the case and spread it a bit while someone else removed the carrier. (very low tech!)

I really like to help others whenever I can.
This sure would be a good time for you to install a new set of gears to improve acceleration. I'd highly recommend the 3.55:1 ratio. It would be acceptable for use with a 3 speed automatic or 700R4 / 2004R.

Keep us updated as you progress.

Mike
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Hey mike - the very fact that you've done it once means you have infinitely more knowledge than me, so I'm happy - But don't worry I wont be blaming you if I stuff it up

Well, one step ahead of ya with the gears - I'm already running 3.55's from a previous owner
And she shifts alright with that rear end. BUT I've always found the top end a little "stressful" - which is why I hope to put in a 200 4r in the next few months (blew up the 350 only a fortnight ago - broke a halfshaft uj, hence the strip down - got a bit carried away with my socket set )
I can totally see where you're coming from with the idea of the marking compound being a more reliable method, there's just more margin for error with whole bunch of stacked measurements that the arbor tool would require. Being generally interested though, I think a metal bar, cut on the lathe to the exact diameter of the carrier bearings could be a ten minute job, and then you've got a way of checking the dimension as you first disassemble... OK, I'd be happiest to rely on the marking compound method, but I don't think you can ever have too much information.

If you do find the time to scan those other instructions, that would be excellent, but since it's not already at hand, please don't break your back over it.

As far as the clutch removing tools go, I'm still struggling to see (from the GM manual) what the tools exact purpose is... The way I see it, you need to compress the clutch and pinion gear, up into the carrier, so you can roll the little gears out. Is that right?

I wasn't sure if the pry bar method would be allow a good enough "stretch" but if you succeeded, that's good news.

Well, some parts to be ordered then! And some heavy shipping costs to the UK to be paid too! I will keep you informed, should be an interesting little project..
Cheers
Theo