Thanks Barry,

It's always fun to take pictures and review what you've done later. And perhaps someone else might see such a project as just a little less "Black art".

Dave, now when you say the .028 shim, do you mean the solid spacer or the depth shim?

 

I've got a .031 in place for the depth to start. 

Do you think I should start at .028? Really not a big deal to change, since I have a removable inner test bearing in place!

Back at it after a vacation;

Made a set of locating pins that screw into the ring gear and help locate it correctly on the carrier. Cut some bolts down and slotted the ends for removal.

Made sure the mating surfaces were completely burr free. Ran a stone over the ring and carrier flanges, wiped them completely clean. Again, gently heated the gear and it went on like butter. Also heated the carrier bearings and they drove on with little drama.

Hint; If working on a posi, use a axle bolted to a tire and rim for a stand. Excellent when tightening in place and final torquing the ring gear. Will not work with a open carrier.

Degreased the ring bolts, used blue Loctite and torqued them to 45 Ft/Lbs.

A picture below of the godsend "super shims". They capture the smaller shims in two robust, interlocking outer halves. This allows even the thinnest shims to be driven in. I start with a deadblow hammer, then drive them in all the way with a small brass drift. Make sure the housing face has no burrs that would be "shaved off" when driving the pack in. To start I went with a .031 + .010 shim in each pack. I'm now at .028/.010 in one and .031/.010 in the other. The super shim empty measures about .205.

I make it tight enough that the carrier needs to be pried out. If you can pull it out by hand, it's far too loose.

 

After 5 tries starting with a .031 pinion shim and ending with a .038 I'm now here. Backlash .007. No good yet. The coast seems fair, but I can't seem to get the drive down into the flank of the gear. Will just keep trying. Might try more backlash at .038, or maybe even go down to .029 and see what happens. All fun. Thank god for the "Test" pinion bearing! I'll get her eventually.

Drive,

Coast,

Well, I did consider having the tubes welded, but decided against it since it's no DIY job. In fact, I bet there is very few people that can or are willing to even nickel weld steel to cast iron properly in my town. 

But you're right on, with it probably being inexpensive insurance, cheaper than having a failed tube! We'll keep our fingers crossed.

The honed out pinion bearing is definitely a good idea, problem is, with my setup, it put me at a .040 shim to even get anything resembling a good pattern. And that is apparently unusual. So, not trusting it, I decided on going with a .035 shim behind the final press on bearing. Wrong...

I should have trusted the test bearing .040. The pattern is the same between the test and real bearing at .035!!!

So now I have to find a shop with a quality press and clam-shell to press it off (hopefully not destroy it). Then I'll probably go with a .042 shim. 

Trust the honed out test bearing. Some gear sets can be fickle.

 

Cheers,

Nice!

Nice job Mark. That diff looks way to nice to be hidden under the car

She's finally back on the road! Road tested at 5pm today

The new drive seems very smooth so far. But I'm getting a random slow (brake drum speed) Shish, shish, shish, from what I hope is just a brake issue. It goes mostly away on braking or light turns. Sometimes gone altogether. The E brake cables are totally hanging down slack. Could that cause it? Lets hope its brakes, really sounds like it's brake drum timed and not the posi which I would assume to be quicker in time. I turned tight fast figure eights in the high school parking lot, no clutch clicking. Using Quaker State 80/90 non synth Posi gearlube with 3/4 bottle of GM positrack supplement.

Going real easy on the gear break in, so no booting er' yet, but I can tell you, I'll likely need another gear at some point! 2.73's to a 3.55's will do that, lol! It really revs now, but feels ready to run. She is definitely more lively on the get go. But I'm ok until the dream 4L80 shows up at my door.

Suspension wise...it's totally tight. I Love the feel compared to the old wasted elastomeric bushings. But obviously anything would be an improvement over 47 year old rubber .

I was a little concerned about the Delsphere joints up front on the new control arms being too solid...wrong. They impart no perceivable harshness into the chassis. Just make it feel tight and connected, even over sharp bumps, and overall much more compliant over uneven pavement! Rips into fast tight corners no sweat, smoother lean in and out and more predictable. Safer. The Hotchkis bar is certainly an improvement. Get the bar off the arms, makes sense to me. It all tells me it's time for new or better rubber on the back!

I haven't even dialed any rebound into the Ridetech shocks yet but we'll start at the bottom and work up. Looking forward to a gentle easy gear break in.

Can you tell I'm happy?

Thanks for watching!

Cheers, Mark

Old thread but I can't find what I'm looking for pertaining to this. Did you at one time post information on pinion seals and how the seals available for 12 bolts were the wrong depth? I have an NOS GM seal for my posi that I plan to put in my car. Not rebuilding the diff but I want to do pinion and axle seals. I think I saw where you posted the measurement for it and mentioned if you the wrong seal is installed it will hit bottom before the flange bottoms on the housing.

4SPEED427 wrote:

---

Old thread but I can't find what I'm looking for pertaining to this. Did you at one time post information on pinion seals and how the seals available for 12 bolts were the wrong depth? I have an NOS GM seal for my posi that I plan to put in my car. Not rebuilding the diff but I want to do pinion and axle seals. I think I saw where you posted the measurement for it and mentioned if you the wrong seal is installed it will hit bottom before the flange bottoms on the housing.

---

 There's a YouTube video that pertains to what you're talking about Carl.  Go to the 37:45 minute mark.

 

-- Edited by seventy2plus2 on Saturday 16th of January 2021 07:21:10 PM

cdnpont wrote:

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Not sure I ever covered that aspect. But I was just reviewing stuff in prep for doing a 12 bolt, and came across some important info on the seal height.

One of the few available, still correct to GM spec seals is the Rateck 6109. In this excellent image below, taken from the web, you can see this "correct" seal to the left, and a generic one that usually comes with a install kit.

If you do get one with your kit, and it looks like the red one, be sure to install it about 3/16" proud of the housing flange. Do not drive it down all the way flush. Otherwise the lip will be driven into the bearing inner race, and will not seal. I don't know why they still include this incorrect seal. Maybe that has changed since 2014.

 

 

---

 Wow  - this is REALLY good to know!!!

I also liked this hint:

Hint; If working on a posi, use a axle bolted to a tire and rim for a stand. Excellent when tightening in place and final torquing the ring gear. Will not work with a open carrier.

I would have never thought of that - I will definitely do this now!!

-- Edited by unruhjonny on Sunday 17th of January 2021 01:09:42 PM

Remember to put a light bead of ultra black around the seal shell before driving it in. And never forget some on the pinion splines as well.