66 differential opinions wanted
 

I have a 66 8.2" rear differential that I want to put in my 67 GTO so I can run the tire and wheel combo I like.
With that being said do Y'all think it is worth the money to put a posi-traction unit in it? I have not gone through the thing yet so I don't know if I will need new axles but I plan on replacing the bearings and seals anyway. If I don't put a posi in what else should I check or replace before installing the unit in my car?

No brainer.... YES! And go with 3.36 gears too.

"No brainer"... I would not automatically go that far, you are speaking of spending at least a thousand upgrading a gray iron housing 8.2 bolt-in axle rear. Some folks idea of a "driver" would waste a gray iron 8.2 in relatively short order. What do you have in the car for an engine and transmission? Has the suspension been set up for much better than stock handling? Those questions directly appeal to whether any 8.2 10 bolt bolt in axle rear should have $$$$ thrown at it.

'ol P, it could be far worse going with something else. In all the years I've driven the old Pontiacs, that 8.2 rear never let me down... and that's without a posi rear. It's far tougher than some think. If he's going to race, then yeah spend the money. If it's just a ride to shows, cruise nights and on a trip it'll do fine. Yeah it's going to cost 'ol Phil some bucks but why go overboard with what you're suggesting. I can't see it or the expense.

I would defer to OPH on this one. He is very experienced in this area. Starting with an open 8.2, I would be more inclined to build an 8.5 rear. Much stronger and more bang for the buck. That said, I am running 8.2's in both of my GTO's, and have been for over 30 years. I blew up the one in the '65 in 1990 during an evening of abuse, and had it rebuilt for $940.....which was a lot of coin back then, but it's still doing fine. (Larry Woltzen of California Differentials did the work). If you drive hard and make a lot of power, I would use something else. For a basically stock or mild build, the 8.2 is fine. My '65 makes decent power, and is a manual with a 3.36 gear out back, and so far, the old 8.2 is holding up fine. I no longer side-step the clutch at 5000 rpm, however.

I am running a stock 400 with the stock TH-400 transmission. I think the 66 rear has a 27? or 29? gear in it right now so I would have to change out everything.
And, please forgive my ignorance but is it possible to replace the 8.2 ring gear with an 8.5 in the same housing?

Jeff, I'm not putting down OPH's experience. I'm just stating my :2cents: on what my experience has been with the 8.2s in all of my old Pontiacs. I still stand by my saying if the car is used on the drag by all means go with another rear. But if it's a street car you're not abusing, then I see nothing wrong with the 8.2. If it wasn't up to par back in the 60s, then Pontiac would have changed it or make it stronger. ;)

GT-182, Pontiac did make its 8.2's stronger, and Olds and Buick said no more to the gray iron 8.2 rears in '67 and '68. I'm not presenting to the OP that he has to change to anything. Simply asked a few pertinent questions, that will help identify his needs.

No can do on swapping 8.5 internals into an 8.2. If wanting to go 8.5 A body rear and run the wheel tire combo you mentioned earlier, the 8.5 housing can be narrowed 1/2" or 3/4" on each side dependings on what you need, then it can be assembled w new axles and whatever gears you'd like 2.73's, 2.93's, 3.08's, etc (much lower). Have narrowed a few before, as have others.

With the Pontiac 8.2 10 bolt and 2.78 or 2.93 gearing and what I'm now assuming is stock to moderately strong 400 and a turbo 400, you should be alright with the gray iron '66 Pontiac 8.2. You are going to be limited to using a high ratio used 8.2 Pontiac 2 pinion Safe-T-Track carrier and most likely having it reconditioned, if the gears you have are 2.78's. If the engine is considerably above stock torque production wise, the T400 is a switch pitch, or if the car has had considerable suspension and tire/wheel improvements for handling, the gray iron housing/ sealed bearing axle bearing 8.2 just does not make much sense.

What is involved in narrowing the rear end?
As far as the car, I don't know what HP the motor is capable of as I didn't do anything to it when I bought this car. It's a 69 400 block with 67 670 heads and stock log exhaust manifolds. Stock intake is from a 71 as is the Rochester Quadrajet. No serious upgrades to the suspension other than poly graphite bushings although I would like to add rear lower boxed control arms and sway bar. Transmission was rebuilt to stock specs.
Would this be a good kit to convert to posi-traction? It's available in different ratios.
http://www.ebay.com/itm/GM-Chevy-8-2...item339c2b6974

That would work Phil. But make sure you know the axle spline count for yours and the posi unit so they match to go together.

8.2 Chevy gears and posi carriers are not the same as used in the 8.2 Pontiac. Different front pinion bearing and different pitch axle splines.

The above stated, 8.2 Chevy gears and carrier can be adapted into an 8.2 Pontiac housing, along with the right front bearing, right seal, and the 8.2 Chevy yoke, then you would be up against having custom bolt in axles built with the correct pitch 28 spline axles that are used on 8.2 chevy axles. With the 8.2 chevy package from Quick Performance and new custom axles, new axle bearings, and a quality build fee, you're going to be around $1200, minimum, in a very unconventional gray iron 8.2.

My personal thought on spending on the the gray iron hsg 8.2, keep the outlay low, if you want to later upgrade to a strong rear, you will be lucky to get much out of such a deal. At the level of torque you're making, along with a stock T400, you could buy a nice pair of used '66 axles, have new axle bearings pressed on then either pick up a good used mid ratio 4pinion carrier, if the rear is a 2.93, or start watching for a used high ratio carrier, if the '66 rear is a 2.78.

Crap.... I didn't realize it's a Chevy unit even tho I read the EBay link. :o 'ol PH is right Phil.

If I were you I'd get one for a Pontiac. Less work and cost than getting the Chevy unit to go in. Instead of narrowing that rear end how about getting rims with the right back spacing? That would save money, time, and work too.

Out of all the BOP units this guy has I had to pick a Chevy one to post here! How about this one?
http://www.ebay.com/itm/GM-8-2-BOP-1...item33944f16ee

The 66 rear end I have is complete. I will have to take it apart to check the axles and bearings and hope that they are good. If the axles are good I will replace the bearings. If the rear is a 278 or 293 can I replace it with this 336 kit?
http://www.ebay.com/itm/GM-8-2-BOP-1...item33944f16ee

Yes, that is the one Phil... and the one I want to get someday. :rolleyes:

And check this out too.... http://forums.maxperformanceinc.com/...d.php?t=768569

I ahve already looked at that! But, thanks for posting it.

Another member sent me a PM about this unit. What do Y'all think of it?
http://www.summitracing.com/parts/pw...2801/overview/

I tried one of those 'PowerTrax' units and I did not like the 'clicking' sound it made. (67 Tempest)

I never even had it installed with an engine in my car, just pushing it in and out of the driveway the sound bugged me, so I went with a 'real' posi.

If you want to give the Powertrax a try, let me know, and we can work something out.

Please read up on these things, as I don't want you unhappy and blaming me for the noise they make.

Thanks for the input. It gives me something to consider.