8.2-8.5
 

What is the difference in the 2 diff and which is stronger can u tell the difference between the 2 externally??

8.2 was made in a couple of varieties and was used from '65 to '73. Its a piece of trash for anything but restoration work. Any serious HP will blow it up. There were several 8.5 versions made, you want the one from the Pontiac cars with whatever suspension and width you have.

The 8.2 had U-bolts and nuts to hold the ujoint on. The 8.5 uses straps and bolts that thread into the yoke itself. Both have 10 bolt covers, but one has a round cover and the the other had cutouts. Not sure which. I threw my 8.2 away when I blew it up and went Ford 9.

yup. 8.5 done right is 98% of a 12 bolt.

I have a 70 F-bird that will sport a 461 stroker with auto trans 2800 stall would like 355 gearin so I'd want an 8.5 will it fit in this car.... what years would i look for

Check out the 70-81 f bodys ,the 8.5 has a larger ring gear bolt compared to an 8.2.Plus if it is an original 8.5 it will have an S shaped spring in the carrier for the clutch packs.The early 8.2's in the camaro's will have a cover that looks like a 12 bolt cover,but it will have 10 bolts on it.

The 8.5" rears have little ears on the bottom, at the 5 and 7 o'clock position, that can be seen like small half-squares (triangles...wish I had a picture to show you).

They are VERY easy to tell if you know what to look for...you can even see them at night. Go to a car show or cruise night and look around. Most 1st gen camaros had the 8.2 (round covers, 10 bolts) and most GM rears from 71 and later had the 8.5".

The BOP rears had the cutout ears at the 3 and 9 o'clock positions...a bit stronger than the chevy version, I believe, because the axles are a bit stronger. But, make no mistake, they will grenade on you if you have much power with traction.

The 8.5's are pretty tough, like stated above.

As for your 70 F-bird...if it's an auto, it originally came with an 8.2 BOP (I think). You can get an 8.5 out of 71-81 F-bodies, or buy a new one for around $1800.

But, for piece of mind, you can get a 9" for a few bucks more, and be a lot stronger, or an S60...which is heavier, stronger, and probably overkill.

Lastly, I think the 9" has the best selection of gear ratios available.

8.2?
 

What is this a 8.2?

Karch is probably right as mentioned above about the 8.2 rear end.

I've got a built 8.2 10 bolt BOP rear that is original to the car on my 67 gto. It has custom moser axles, rear disc brakes, an eaton carbon fiber clutch posi, a TA Performance Aluminum Rear End Cover/Stud Girdle, and richmond 3.55 gears. I built it so that it could take more abuse than it could in stock form.

However, the down side is I built the rear end before I had an engine. Now I'm working on a 600 horse 461 EFI street motor, and I'm going to have to be uber careful with my rear. I'd replace it with a 12 bolt but I'm on such a tight deadline to get my car done, I'm just not going to push it or run slicks on the rear. Besides, I've gone too far backwards on my build, and I need to start making some progress. The other factor also boils down to MONEY. I've gone wayyy over budget and I'm running out of money, so I've just gotta eat it for now.

I don't think the factory BOP 8.2 rear end is all that bad, they've just got that weak point of a small ring gear. When built right they can do well. But you can't have ANY type of drag tire or slick...or you'll be asking for the thing to bust up in a million and a half pieces.

I'm just going to cross my fingers and sacrifice the fact that for now my car is not going to hook at all or get any traction if I ever want to take it out to LACR. Which may not be a bad thing, roasting the tires should take little effort :D .

Take care,
Bryan

My car has an 8.5 O type rear. It's a ten bolt but actually has 12 bolts on the cover. I have a photo of it on my computer at home. Looks almost exactly like the one above but with 12 bolts holding the cover and the two ears sticking out below at the 4 and 8 o'clock postions.
Check this out as well. The best page I've seen for identifying rear ends-
http://www.oldsmobility.com/10bolt-tech.htm

Is this an 8.5" ????

The Oldsmobilty link has a lot of errors & ommisions, there is better info avail.

Lastly, '67-70 Type "O"s were actually an 8.3" ring gear.
While the Type "O" is the ancestor of the corporate 8.5, it did not have the pinion support that the later 8.5 has.

I didn't know that. I've been referring that site for a while. What are the errors? Do they involve basic ID info? Maybe mine is not really an Olds 8.5 although I've been told by others as well as the above link that it is.
Where is the accurate info...Online... or in factory type manuals?
BTW, I have never been able to make sense of the "code" on mine.

Paul, just ck'ed my housing racks.

The pic you are showing, there are the pronounced "lugs" at 8 & 4 o'clock, that is a telltale that you have an 8.5. With 10 bolt cover, appears to be 8.5.

However, of the 3 cast versions of the '71-72 A-body housing, two of them lack these "lugs".

Examining the plug weld areas on each side of the center housing.

Most common '71-72 8.5 A-body hsg:
-2 plug welds outside of each side of the rear cover
-hsg has the two large lugs
-rear cover has cut-outs
A-9 housing ends

Least common '71-72 8.5 A-body hsgs:
-NO large lugs at 8 & 4 o'clock. What protrusions are there, are smaller & cupped, similar to the same casting area on some 8.2's, & all factory Chevy 12 bolts.
-One plug weld outside of each side of the rear cover. One hole on each side right inside cover for grease to flow through.
-ROUND rear cover. Using the cutout rear cover exposes the inner passage holes.
-A9 or A10 hsg ends.


-One version of the bolt-in axle '73-77 A-body rear uses a center cast housing, similiar to what you are showing above.

-One plug weld hole on each side
-Uses cutout rear cover
-As a '73+ A-body rear, the upper spring perchs are spread wider apart, the spring locaters are directly on top of the axle tubes, the lwr control arm brackets have inboard shocks. Last, rear is wider than previous A-body rears.

///EDITTED/ Which brackets are on this housing. What chassis car is it in? ///

If early A-body, you have ANOTHER less common version of the '71-72 8.5 A-body housing. That said, I'm betting you have another style of 8.5 r/e.

Greg,
Hello, I've given a disclaimer on the Oldmobility site info, since I first saw it. While it is a graphically neat site, it lacks the quality info that someone like myself who's built the 8.5 for a long time has run across. Not going to get that info w/o pulling a ton of cores/ assembling rears.

One of the omissions... for years, website article exspurts, & most recently an article in Carcraft, have stated "look for the big squared off casting lugs to ID the 8.5". Since some 8.5 housings lack this feature, not the best info. Also in an order to disquise an 8.5 & make it look like an 8.2 from the rear, many builders have reshaped the lugs on 8.5 hsgs to make them look like other 10 bolts, I've done this for years on the most common 8.5 A-body housing.

Here's a list of common 8.5 ID points.
-All 8.5 rears have twin cast ribs on the each side of the cast hsg. Similiar to 12 bolt Chevy hsg. These add support to the pinion bearing area. This pinion area is slightly longer on an 8.5, couple that with slightly longer pinion flange, & that is reason for 7/8-1 1/8" shorter driveshaft needed when swapping to an 8.5.
All original 8.5 r/e's used stamped steel straps & bolts to attach the u-joint to the pinion flange. One 12 bolt flange also used bolts & straps, but most 12 bolts & all 8.2 10 bolts used pinion flanges that used u-bolts, & nuts for u-joint attachment.

Mine has the lugs at the bottom. It has a smooth, almost round cover with cutouts on each side and 12 cover bolts. The ribs on the sides run parallel to each other.
8.5 'O' type?

Greg, yes it's a type "O" Olds rear, just not an 8.5.
The two ribs are also a type "O" attribute. If 12 bolt Chevy car hsgs did not have them 1st, one could attribute them to Olds.

Reply is below.
Too hard to read when spread out across the page.

What can't be upgraded into any 8.2 is support in the pinion area. Yes, one can buy an LPW or T/A Performance rear cover to preload the caps... add stabilty to the bearing caps, but the small pinion is still trying to raise up upon heavy torque loading, esp with suspension hooking up slicks. Higher torque manual trans combo's will often tear up an 8.2 first, while foot braked auto cars will soften the blow some (torque convertor) & last longer. I've picked up the pieces from a ton of blown up bolt-in axle 8.2 rearends, but without knowing whether the pinion was loose, one can't always say why the rear failed.

Have posted the following before, but few use the search function & sometimes it does not work...
Some history on GM 10 bolt rearends...
'64-66 Pontiac used cast gray iron 8.2 hsgs with 2 converging ribs per side. Buick used cast gray iron 8.2 housing with single rib per side. Lot of Olds A-bodys received the Buick 8.2 r/e as well. Pontiac version was stronger with the converging ribs. Still this rear became a warranty issue behind higher hp lowest gear ratio 4 speed cars, esp with slicks. Over the years have bought 4 pinion posi carriers from several '66 tripower cars that shelled their gray iron hsgs. All were hotrodded or raced. Have a nice set of 4.33's out of an early '66 car. Bought them from original owner of 4.33 tripower Goat. Only reason I can surmise they survived, is car owner pulled them & installed 3.90's shortly after buying the car.

All BOP GM divisions realized as they got more & more warranty claims, the fallacy of the normal gray iron 8.2 rearend hsg for performance use... basically there was a lack of pinion support. Thus each division's engineering redesigned or designed versions of rearends to handle the increased torque load. HP & Torque were on the rise, witness the 10 bolt r/e improvements that came in '67 & 68.

-At that time, Pontiac went to nodular 8.2 housings on what I'll call "at risk" 8.2 A & F-body r/e' s. These HD Safe-T-Track hsgs are rare today, & for restorers, nearly each year was different hsg casting number. HD Safe-Track 8.2 rearends also received hot forged axles, not the standard (light duty) axles.

These nodular 8.2's were, however, deemed not strong enough when Pontiac coupled near 500 ft of torque 455's to 4spd & auto's in '70. Through '72, lower horsepower & higher ratio (2.56-3.36) Pontiac 8.2 r/es received the standard gray-iron housing. Putting $1200-1300 in a gray iron 8.2 & thinking one has a strong 8.2 Pontiac r/e, well it is stronger than how it was originally, but there still is weak point.

-During '67 model year Oldsmobile ditched the bolt-in axle 8.2 rearends & went to the Type "O" rear. 12 bolt cover-10 bolt guts. For at least a year this r/e was avail with a special hsg, carrier, & 31 spline axles. Have one with 3.91's out of a 4spd '68 442. It's a resto piece. Same for the alum center section '70 442 type "O's. While the Type "O" is strong, it is not as strong as a propperly built 8.5 or 12 bolt. What aftermarket parts are avail for the Type "O" are expensive. A restoration piece or a white elephant, whichever you see it. On regular 28 spline iron Type "O"s housings I get in partscars, I usually disassemble & cut the outer tubes off so I can remove the lwr control arm/shock brackets. Occasionally need the brackets.

-Buick brought out its own '68-70 Buick 8.2 10bolt for '68. These were used through '70 models. This oddball 10 bolt used a carrier with 12 bolt bearing on driver side of the hsg & 8.2 bearing on the rh side. Basically BUICK beefed up the 8.2 housing & changed the dimensions on the pinion. 4 different ratios of carriers. Not that easy to find low ratio gears for (3.64's). Again. more of a restoration piece.

-8.5 A-body rears were 1st cast in Feb of '70. Buick & Olds used these A-body rears in '71 & '72 applications. Pontiac & Chevy got on board for '71 with a c-clip version for the F-bodys. There was even a c-clip & bolt-in axle B series version for '71. All original '71 8.5 posi's I've removed are the Warner-Motive cone style. So far been able to tell, the first "S" spring 8.5 clutch type posis showed up in '72 models. '73 Pontiac Service manual still gives info on the Warner-Motive 8.5 posi carrier, though have yet to pull one out of a '73.

Hope this was not to much rambling, just trying to get to the substance. Time has been at a premium, wish I could have taken time to present it better.

Pinion head, that does worry me somewhat as even though I won't be running slicks...I'll have 600 foot pounds of torque motivating my hopped-up 8.2 rear.

FYI, I don't know if this helps or not...but am I better off since my 8.2 is the original 67 Safe T track housing??? It's original to the car and PHS verifies it. So are you saying my nodular iron rear will take more abuse than the other 8.2's?

I only went with 3.55 gears, so It's not like there's anything really radical out back.

Since I'm not going to put slicks on it, should I worry?

Bryan,
Automatic or manual trans in your GTO?
You mention your car had Safe-T-Track, only the HD Safe-T-Track 8.2's had the nodular housing & better axles. Not sure what your GTO started life as. The 3.55 geared HD Safe-Track rear for '67 should have an N on its original housing.

Suspension improvements coupled with todays lower profile wide tires allow for more traction than original biasplys. Eventually, the torque limit of even a well prepped nodular 8.2 A-body rear will be met, esp in a heavy 4 speed car. What that limit is, depends on how the car hooks up.

Last two Pontiac guys I've dealt with who were faced with similiar situation, ie, over 500 ft-lb manual trans performance A-body build, when faced with building their present nodular 8.2, or going with a strengthened 8.5 (30 spline HD Eaton carrier-Moser axles) chose the HD 8.5. One had already bought new Moser axles & a new Auburn Pro series carrier for his nodular 8.2. Each ended up selling off these parts along with their nodular housings. One of these cars is also set-up for extreme handling, & the sealed ball bearing axle bearings of his 8.2 were of no use. Another nice thing about the bolt-in axle 8.5 A-body rear its housing is set-up for tapered axle bearings, the best for side loading. Without knowing exactly what you want out of your car performance wise, it's hard to give the limit of the 8.2 rearend.