nova rear questions

[Ishmael]

I keep reading to use a 72 to 75 nova 8.5 rear in my 68 firebird. Why not use the 71? Does it have single leafs or is it an 8.2 or..?

How can I tell a 71 from a 72 or a 75 from a 76? The date code pattern is the same from 71 up and it doesn't seem to include a year.

I know that 72 to 76 use a 1310 yoke and 76 and later use a 3R but can someone tell me how to tell the difference?

Last question for now - are 4:11s to much gear for th350 and only 325 hp in a 68 firebird?

thanks guys
Scott

[big gear head]

The Nova didn't get the 8.5 until '72.
https://static1.pt-content.com/images/noimg.gif (http://rides.webshots.com/photo/2610816050041712107joJXQA)
The yoke on the left is a 3R and the one on the right is a 1310. Notice that the 1310 has a tab that centers the u joint and the 3R doesn't. Also notice that the 3R yoke is machined flat on the inner surfaces.

[Ishmael]

I knew you'd have an answer. Okay to reiterate for someone doing a search on the 8.5" nova posi rear to camaro or firebird swap sometime in th future: the nova rears from 68 to 79 are 60.25 from to the outside and are a bolt in for a 67-9 firebird or camaro but 68 to 71 is an 8.2" which is way weaker. From 76 to 79 it uses the 3R yoke which means you have to shorten your drive shaft. Here's the site that has the codes and dimensions: http://www.novaresource.org/axle.htm

d Some more info floating around is that a 70's trans am or camaro rear is 61.25" which is actually the same width of a pontiac rear but not the camaro. I measured both my 68 and 74. With this rear you've got to shorten your driveshaft and move the perches. The pontiac rear end can be identified by two scallops cut out of each side of the cover where they meet the tubes. They are stronger than the chev 8.2 because they have bolt in axles but they are a problem when buying brackets to mount late model brakes.

Have I got any of this wrong?

How bout that gear ratio - 4.11s on the street?

[big gear head]

Many people have had to shorten their drive shaft even with the 1310 yoke. I think you pretty well got everything else correct. The Firebird actually used the Tempest/LeMans/GTO 8.2 10 bolt rear end, which is 1 inch wider than the Camaro rear end. They have the eyes cast into the top of the housing, but have leaf spring perches welded to the tubes.

[Ishmael]

I don't have eyes on mine but its definitely pontiac. I know I can't use those axels in the 8.5 but I can use 8.2 axels from a camaro or nova and I can use the posi from any 8.5. I'm hoping not to have to shorten anything.
If I'm going to a 200r4 eventually what do you think about the 411s?

[big gear head]

The 4.11 should be fine with overdrive. It will work better with the 200 4R than it would with a 700R4.

I guess all of them didn't get the eyes on top. It was my understanding that they used the same casting as the A body cars.

[ProdigyCustoms]

No eyes on the Firebird rear.

The brakes on the bolt in axle A Body Pontiac rears can cause a brake issue if your trying to use a c clip brake kit. We have a conversion kit for Wilwood available for the bolt in axle rears.

Your doing great on your research.

Now to further confuse things, not ALL Firebird rear are 1" wider.

But yes, in summary, The 72-79 Nova 8.5 is the same width as a first gen Camaro Rear and SOME Firebird rears. And the 70-81 Camaro . Firebird rears are 1" wider then the First Gen Camaro, and the same width as MANY First gen Firebird rears