66 GM 12 bolt 8.875 tear down and rebuild - Impala Tech
Transmission & Driveline Transmissions & Differentials

 
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post #1 of 9 (permalink) Old 12-06-2019, 11:53 AM Thread Starter
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66 GM 12 bolt 8.875 tear down and rebuild

I found a 66/67 12 bolt rear-end from a Caprice or impala. I think it was a 2.70 ratio open.

Inside was pretty rough so I gutted all bearing and gear. Except the caps..

I Kept everything just in case.



disassembly little power washing..

And done..



just need to remove the inner races and she'll be ready for a final clean and paint.

Next order pinion gears, LSD (posi for you OGs) and carriers and bearing/shim kit.

I have a newly rebuilt 454 with a mild street cam/flat tappet hydraulics, going into my 66 with a 700r4 tranny, so I'm thinking about a 3.55 ratio

These seem pretty reasonable.

https://www.ebay.com/itm/65-72-GM-8-...g/333123689421



$500 for the kit shipped.

Ted
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post #2 of 9 (permalink) Old 12-06-2019, 12:36 PM
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I can not comment on the quality of the product as I have never used them. I can comment on the ten minute phone support as being totally useless, and question the warranty as being limited to what the seller defines as an "accident". I can say if you buy the kit start out with your original shim pack and modify the shim pack as needed. Also you can hog out the old crush sleeve with a sanding drum to get a slip fit over your pinion for testing the shim packs as that is a lot easier than trying all new crush sleeves every time yo go to measure your pinion depth.

"posi" by the way is a contraction of the trade mark Positraction that belongs to Eaton. Everyone calls any limited slip rear end a posi today through common use (Kleenex, Asprin, and Xerox being similar trade marks that are thought to be generic, though still trade marked).

Big Dave
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post #3 of 9 (permalink) Old 12-06-2019, 12:55 PM Thread Starter
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using a sacrificial pinion bearing seems to be the way to go not to have to go through crush sleeves.


This guy is great on his explanation on how to set a new diff.

I'll even made a plate to test the pinion depth.

Ted
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post #4 of 9 (permalink) Old 12-06-2019, 01:25 PM
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Quote:
Originally Posted by brickwhite View Post

I'm admittedly skeptical of many things for sale on the internet these days, but, that price almost seems too good to be true. It's like, ....there must be more to the story that we're not getting up front.

Certainly those 2 brand names, Standard Gear and Yukon, are both well known and trustworthy, but just a similar center-section alone seems to be $600 at Summit Racing. (ex. YDGGM12P-3-30-1) And we all know the gear set could easily be $130-$150 on the open market.


I'm just not sure how those parts add up to only $500.


.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #5 of 9 (permalink) Old 12-06-2019, 01:47 PM
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Buyer beware. $500 seems too good to be true and I would be especially skeptical about it being sold on Ebay. You have basically no recourse in the event it is defective. I bought an Eaton posi, Richmond 3.73 gear set, and Richmond installation kit off of Summit and it was a little over $1100 all together. Less than half that price? Run the other way.

1968 Impala SS
496 Stroker
T56 Conversion
3.73 Posi-Trac
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post #6 of 9 (permalink) Old 12-06-2019, 03:04 PM Thread Starter
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he gets good reviews and the parts seem brand name.

The one that is $495.. may buy some Timken's instead of Koyo's but... they are the same company now.

On jegs the ring an pinion are $165 and the and the LSD from yukon is $500...

https://www.jegs.com/i/Yukon-Gear/80...P3301/10002/-1 IDK..

Ebay shows the part numbers....which matches jegs..

I'll post my findings when I order it.

With Ebay you can always get your money back...


12BC355 - YDGGM12P-3-30-1 - WK GM12P - OILADD


Richmond Excel Gear

The new Excel gears from Richmond are manufactured to meet the exacting specifications required by Richmond. Excel gears are Designed by Richmond engineers with more than 70 years experience in gear design and manufacturing. Each detail in the manufacturing of Excel gears has the Richmond stamp of approval. The gear design, tooling, material selection, heat treat recipes and quality requirements are specified by Richmond. Each gear carries Richmonds 1 year warranty against manufacturing defects.

Duragrip Posi LSD

The Yukon Dura Grip provides aggressive yet smooth traction to give you the confidence & performance you need. Get longer life and better traction with the heavy duty Yukon Dura Grip Positraction. The Yukon Dura Grip uses a nodular case and forged 4320 internals for added strength along with composite clutches for high performance and long life. All units are Rebuildable and many offer upgrades to increase aggressiveness for racing applications. Each unit carries a one year warranty against defects.

Recommended Oil: Standard 80/90wt (Non-synthetic) (with Posi additive)

Master Install Kit

Premium master install kit uses only the highest quality components including Koyo brand bearings. Included are carrier bearings and races, pinion bearings and races, pinion seal, complete shim kit, ring gear bolts, pinion nut, crush collar, threadlock, marking compound, brush, and gasket or RTV silicone.

Application: 1965-1972 GM 8.875" Chevy 12 Bolt Car Rearend (will Not fit Truck) (will Not fit Oldsmobile)

Cover Bolts: 12
Ring Gear Bolts: 12
Axle Splines: 30
Pinion Splines: 30
Package Includes the Following:

1- Chevy 12 Bolt Car 3.55 Ring and Pinion Set (Richmond Excel Gear)

1- Chevy 12 Bolt Car Yukon Duragrip Posi LSD (30 Spline)

1- Chevy 12 Bolt Car Master Install Kit (Koyo Bearings)

1- Bottle Posi Additive

Ted
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post #7 of 9 (permalink) Old 12-12-2019, 05:42 PM
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Garage
If you look at his items for sale, they are all differential related. Usually guys like that have a shop and have been doing this for years, they sell on ebay to increase sales.
I believe the posi unit was rebuilt by them that's how they can sell it cheaper. I bought similar kit from a different seller and had no issues with it. Quality parts and very helpful if you have to call them.
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post #8 of 9 (permalink) Old 12-14-2019, 09:15 PM
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Quote:
Originally Posted by brickwhite View Post
With Ebay you can always get your money back...

That totally made me LOL. :-D

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #9 of 9 (permalink) Old 12-15-2019, 10:29 AM Thread Starter
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I've used paypal and ebay and had no problems getting my money back if the item is not as described. Just have to be careful who you buy from. If they have no history or positive reviews don't buy from them.

Common sense is a must when buying on the internet folks..

When I order mine I'll post results... with pictures...and part numbers....

Ted
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