I understand we can swap a 8.5" 10 bolt from novas into our cars. perch spacing and pinion angles are the same; however the rear is 1" narrower and requires the driveshaft to be shortened.
Alternately we can use 2nd gen rear ends however perches need to be moved and the rear is 1" wider and driveshaft mods needed.
I am looking for our cars rear axle dimensions to double check!
Also the main reason I am leaning this way is to avoid getting too deep into the 8.2 to change from 4.10's to 3.55 w/ posi as the way I see it that will be 1K provided there is nothing wrong with bearings, axles, etc.....
My car is a non original mild 400, w/ 5 speed basically for the street.
Thoughts from those who have been there, done that?????
I think you'll be spending a grand no matter which option you choose...unless you get a rediculously good deal on a Nova rearend...
New Posi unti = $400ish Gears = $150ish install kit = $100ish If you're gonna change the gears, you really oughta change the bearings while you're in there, too...and maybe the wheel bearings and oil seals.
it never ends.
I'm a hobbyist. Not a professional. Don't be hatin'!
The 1st gen Nova 1962-65 and the 2nd gen Nova 1966-67 are the ones that have the rear housing narrower, and are 8.2" The 1968-1974 Nova is a direct bolt in rear-end. 68-71 were 8.2", 72 and up should be 8.5" The Ventura's are also the same. I have heard but don't know for sure that the 8.5" has a longer pinion so it will require the drive-shaft to be shortened. The 8.2" 10 bolt and the 12 bolt are the same as the Firebird so no drive-shaft mod is needed other than maybe the U-joint. When I put the 12 bolt in my 69 it was a bolt in swap with a u-joint change only. I just picked up an 8.5" 10 bolt, 3:43 gears, posi on Craig's for $600. Had it checked out by my rear-end guy and said it was in great shape. So they are out there if you look. I will know about the drive-shaft shorting in a few weeks when I install my 8.5" http://www.novaresource.org/axle.htm
i've got a line on a 78' that has a open 3.08 for $200.00, no idea what it looks like inside..... but assuming it is a core and basically start with new ring and pinion, posi, bearings, etc...
I did the swap about 2 years ago with an 8.5 corporate rear end. I ended up determining it was from a 73 Nova, but why were the perches wider? Seals fit the application for a 73 Nova, but I am not 100% positive.
The rear end width was exactly within 1/4" of my 8.2 original. I just had a welder move the perches in about 1 inch. My gears are 3.42
I had a brand new driveshaft built as my old one was too long. I opted for a new one because it was cheaper to build a new one that to try to shorten and rebalance the old one.
When the welder moved the perches, he actually bolted the rear end to a table and made a jig that put the new ones exactly where they needed to be.
When I put the new rear in the car, it bolted up perfectly.
Even with the stock 400 the car really rips compared to the old 2.73 open rear. Also I run with an M22 4 speed.
I picked up a 8.5" out of a 72 Nova that was fully beefed up by DTS, housing welded for reinforcement, and rebuilt disc brakes for $1k off a guy that was swapping in a 4-link with a 9".
The 1967-1969 10 bolt 8.2 firebirds are the same width as the 10 bolt 8.5 1970 -1981 firebirds the only difference are the perch center line.
The Nova 1972-1976 8.5 10 bolt rears are 1" NARROWER than the fire bird 10 bolt 8.2 and also have a smaller 1310 yoke for the u-joint. they do have the same spring perch center line and will bolt into the firebirds 67-69.
BOTH camaro 1970-1981 and the nova 1972-1976 8.5 10 bolt rears will require the drive shaft shortening to fit your firebirds from 1967-1969.
We do this spring perch relocation all the time and have used chevelle 68-72 12 bolts with leaf spring perch as a firebird rear also.
Hope some of the info clears the air on the diff swaps...if you need more help or info just ask. Jim
I can pick up a 2nd gen rear end rebuilt with new posi gears and aluminum drums for $250.00 it has 3.70 which I would swap for 3.42/3.55's as the keisler 5 speed and 4.10's feels like I should be towing something currently!
