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Discussion Starter #1 (Edited)
So, I started on this project about 3 months ago, and just haven't had the time to finish it up. I exchanged posts with some of you about making a post that brakes down all the feasible First Gen rear end swap possibilities -- that is, ditching an 8.2 for "better" rear ends -- and things to consider before making the leap. As you can see, I didn't make it too far. But rather than this going to waste, I thought I'd go ahead and post it for additions and corrections.

DISCLAIMER: I don't know ANY of this from first hand experience. I compiled the vast majority of this information by sifting through old posts. I'm in no way trying to take credit for the expertise of others -- I justed thought it would be worthwhile to have everything located in one post -- maybe a sticky?

For ease of use, I attempted to have set fields of info for each swap, e.g., pros, cons, potential donor cars, what has to be modified, etc.

Here's what I have:

8.5
Potential donor cars: The 71-81 Camaro rear axles are 1" wider than first gens, which is why you can't just grab one and throw it in your first gen. But 68-79 Novas had the exact same rearend dimensions as first gen Camaros. Thus these Nova rearends are the widely proclaimed to be the"bolt-in" swap for 1st gens. However some Pontiac Ventura, Buick Apollo & Skylark and Oldsmobile Omegas and 77-79 Cadillac Seville also got the 8.5.

Drive shaft: you'll probably have to shorten it anywhere from 1/2" to 1 1/2". But this will vary based on type of yoke used and yoke position. Cost: anywhere from $70-150, depending on your location.

Suspension: if you have mono-leaf, they can be reused on the Nova 8.5. If you're going from mono-leaf to multi, or vice versa, there may be some fabrication required. One source says Buick Skylarks had coil springs and control arms; another says 75-79 Skylarks are X bodies w/ multi-leafs, w/ either 7.5 or 8.5. Buick Apollo is multi leaf.

Axles: If using 77-79 Seville, you'll have to change the axles from 5" bolt pattern to 4 3/4", or swap in the axle from a 8.2.

Brakes: 8.2s brakes bolt on to Nova 8.5. 77-79 Seville had rear discs.

Posi: 71-79 Trans Am are purported to have posi units that will fit the 8.5.

Gears: 86-92 GM trucks and vans often have 3.42s that will work with the posi units mentioned above.

Pros: inexpensive and lots of them around. They were "the universal rearends for millions of GM cars … from 1971 through 1996… [R]ing gear diameter is only .375 inch smaller than a [the more expensive] 12-bolt" -- How to Build a Bulletproof, Posi 10-Bolt for $400 of Less!, Jeff Smith, Chevy High Performance. Useful article here.

Cons: you can't brag about having a 12-inch.

12 bolt
Potential donor car: First Gen Camaros, of course; possibly some late 60s Impalas
Driveshaft:?
Suspension: if going from mono-leaf, you'll need a multi-leaf conversion kit, and you may have to clear out some space in the holes of the spring eye brackets.
Brakes:
Pros: Almost universally regarded as the strongest rear end available for a First Gen.
Cons: Getting hard to find and increasingly expensive.

Ford 9-inch
Potential donor car: (Broncos?):
Driveshaft:?
Suspension:
Brakes:
Pros: Cheap and readily available. If you switch out gears a lot (going from track to street maybe), the gears are supposed to be easier to swap in and out compared to GM rearends.
Cons: GM purists will give you grief for having F.O.R.D. parts on your car. Lots of moving parts equates needing more horsepower to turn it, compared to 12 or 10 bolts.

Truck 14 bolt:
Potential donor vehicle: Blazer.
Drive Shaft:
Suspension:
Brakes:
Axles: will have to be narrowed and have a set of 5 lug axles installed.
Pros?
Cons: lots of mods required,

Ford 8.8
Potential donor cars: 95-01 Explorers.
Drive shaft: ?
Axles: have to be re-drilled for 4 3/4"
Suspension:
Brakes: they're set up for disc.
Pros: Traction Lock differential; 31 spine axles; extremely close to first gens 59 1/2" width.
Cons: clutches, bearings and rotors usually need to be replaced; 2 1/4" offset might be an issue.

7.5
The consensus seems to be "don't waste your time." Sounds like it's possible, but not worth the time, because they're not very strong rearends, and for the cost of the modifications, you could buy/build something that fits and is much stronger. However, there was at least one TC member who liked this set up, so if you insist…

Potential donor cars: 90s Camaros/Firebirds
Drive shaft?
Axles: the axle tubes are smaller than a first gen, so they'll have to be replaced.
Suspension: they're coil springs, first gens are leaf (unless modified), so that's more fab work to do.
Pros: cheap and easy to find
Cons: lots of mods required to make it work.
 

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Good work, Zac!

Off the top of my head, so some of the years might be wrong:

68-79 Nova rear could be any of the following: 8.2, 8.5, 7.5 or 12 bolt.

68-71 were 8.2 or 12 bolt
72-74 were 8.5
75-79 were 7.5 or 8.5

they are all the same overall length with the same spring perch spacing as 1st gen Camaro

12 bolt donors - include the 68-71 (72?) Nova

2nd gen Camaro - in addition to being wider also had different perch spacing compared to a 1st gen

1st gen firebird - I know they fit a first gen Camaro. Something tells me they were all 10 bolts but better than the 8.2 Non c-clip axles perhaps?

anyway - good project. That's all I have.
 

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To add to this a bit. I bought my 69 with a 12 bolt under it... out of a 70 Camaro. So yes, it's 1" too wide and if you want to run the widest rubber like a 275/45/17 or some combination you can forget about it without air shocks, which I have...and hate. There just is not a backspace combo that will work without going to custom wheels.

So, I bought some Alloy USA axles for the correct width 69 and am having Murray's Custom Rods here in Fort Worth narrow it accordingly and totally rebuild it side to side. I'm also installing a Hotchkis suspension while I'm at it.

I'll be in it for about 1000.00 but will have new axles, bearings, seals, girdle/cover, welded tubes and new gears. Bullet proof and new.
 

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Discussion Starter #4
Al, do you know if there something weird about the 67 12-bolts? Don't remember what it is, but a friend mentioned it once and he was turned off by the 67 12-bolts because there was something screwy about them.
 

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Also, the 1971 - 1981 Camaro 8.5 rear had another problem. The 2nd Generation Camaro 8.5 rear will not bolt into a First Generation Camaro unless it is modified. The perches are not in the same location as the First Generation Camaro. You would have to remove the perches and re-weld them to bolt the rear into a First Generation Camaro in addition to shortening it as you have already mentioned.
Also, most, but not all Seville rears had disc brakes. The ones equipped with drums have the correct bolt pattern of 5 x 4 3/4.

The 1968 and 1969 Camaro had staggered shocks in order to counteract the wheel hop problems associated with the 1967 Camaro.

Zac, nice job. Hopefully one of the Moderators will make this a Sticky.
 

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Discussion Starter #9
Thanks, C-n-C and Al, for the props and input. This is a learning experience for me, so your input is much appreciated. Hopefully this will save a few people from some key strokes in the search page.
 

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First gen Firebirds have a BOP (Buick, Olds, Pontiac) 10 bolt.
Its still an 8.2" ring gear but no c-clips and its nodular so supposedly stronger than the Chevy 8.2.
The internal parts don't interchange.

It does bolt right in, drive shaft may be a different length and axle may be 1/2" wider.
 

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I put a 67 Pont Firebird Formula 400 in my 69 Camaro..bolted right in, used 69 staggered shocks and mounted factory traction bars (2) to plate in floor. works VERY well. I can hardy spin tires at all, mid 14's at track with very little spin, rear just drops and go's 10 boly with 3:31's j
 

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Discussion Starter #12
Something I had a hard time figuring out is whether any 8.5 posi unit will fit any 8.5 rear end. For example, will a 8.5 posi out of a 80s-90s 8.5 rear end fit a 70s Nova 8.5 rear end?
 

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Something I had a hard time figuring out is whether any 8.5 posi unit will fit any 8.5 rear end. For example, will a 8.5 posi out of a 80s-90s 8.5 rear end fit a 70s Nova 8.5 rear end?
Yes. So will the posi out of an 8.5" truck diff, front or rear. Some of those are gov-lock posis, and not very good for a hotrod. Also, at some point in the mid-late 90's they switched from 28 to 30 spline axles. The Traction Lock(big "S" shaped spring) is the better factory installed posi, but I believe they were all 28 spline. Hopefully Freddie will read this and set us straight.
 

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Yes, all 8.5 and 8.6 front and rear differentials will fit the old 8.5 housings, as long as the correct bearings are used. The old differentials won't fit the '99 and later 8.6 housings because as far as I know there are no bearings to adapt them. All 8.5 and 8.6 gears will interchange, but the Impala/Caprice had a special pinion shaft for the speed sensor reluctor. All of the traction Lock differentials were 28 spline. When the 30 spline upgrade was made in '90 the Auburn was used as the car limited slip (posi) differential.
 

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Discussion Starter #15
Thanks, Al & Freddie... The reason I was interested is because I (like lots of people here) read that article in Chevy High Performance from last year that instructs how to build a $400 8.5 10 bolt. The author only listed the posi from 70's Trans Ams as contenders for the build and that seemed like an awfully limited list.
 

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The '71 to '81 Z28 and Trans Am are the most likely place to find one. You don't want to use the truck differential. Many police cars and station wagons had them.

Just a little side note, I got news today that there are 3 companies that are looking into reproducing the clutches for the 8.5 Traction Lock. If this happens then it will be rebuildable again.
 

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Yes, all 8.5 and 8.6 front and rear differentials will fit the old 8.5 housings, as long as the correct bearings are used. The old differentials won't fit the '99 and later 8.6 housings because as far as I know there are no bearings to adapt them. All 8.5 and 8.6 gears will interchange, but the Impala/Caprice had a special pinion shaft for the speed sensor reluctor. All of the traction Lock differentials were 28 spline. When the 30 spline upgrade was made in '90 the Auburn was used as the car limited slip (posi) differential.
Timken Part Numbers

Bearing LM102949
Race LM102911

This is the Bearing and Race Set necessary to use a new 8.5 Posi in an old Nova or Camaro 8.5 Housing.
 

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Discussion Starter #18 (Edited)
It's ugly as sin until I clean it up. I couldn't wait to tell everyone I ended up grabbing 8.5 out of a 74 Nova today. It's all surface rust on it. Nothing is pitted or rough. Already got the leaf springs off. Just took a little WD40. Going junkyard diving for a posi unit and gears as soon as school's out.

Tory, I was going to call your buddy, but this guy had the multi leafs and even delivered, all for $150, so I had to jump on it. If I don't come across some gears that I can salvage after a few stops, I may hit you up for your 4.11s. I preciate the call and the advice. Very cool to talk to TCers on the other side of the country!

Yes, I know it's sitting upside down in the picture. Not anymore!
 

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Discussion Starter #20 (Edited)
Well, I've been working on getting the rear end cleaned up, and just breaking it down has been a serious effort.

Trying to stay on the cheap, I borrowed a friend's compressor and air tools. That was very cheap: free. Unfortunately, it's underpowered and I'm constantly having to wait for it to catch up. But it's free, so I can't complain.

Got leaf springs off the other day after some wrestling with a breaker bar and a bunch of WD40 on the u-bolts.

Ran an air hammer on the really tough, thick build up around the housing. When my buddy asked me if I wanted to borrow the air hammer I said I didn't think I'd need it, but why not take it. Damn glad I did.

Bought some engine degreaser: $5. Used the whole can and it didn't seem to make a bit of difference.

I spent 2 solid hours trying to get the drum covers off. I looked for the brake adjustment window that many (most?) 8.5s are supposed to have, but there's not one. I'm not keeping the brakes, so I hammered, crow barred, air hammered -- even started hacking through the cover itself with the cutting wheel. This may have worked had I stayed at it for about 4 days straight, but the compressor wasn't hacking it, and it took me an hour just to make some small cuts in it.

Here's me begging for help -- I still don't have them off, if you have ideas, I'm ALL ears!

http://www.camaros.net/forums/showthread.php?p=1517285#post1517285
 
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