I just finished removing the stock 10-bolt rearend from my 67. Inside is an 8.2" standard differential. I wanted to upgrade to an 8.5" posi based on the info that I've been reading on this site. I don't have the tools to perform the task so I arranged for a local mechanic to do it. However, when I talked to the local Eaton rep, he tells me that the 8.5" won't fit into the stock 10-bolt housing. Is he right? Is there a different 10-bolt housing for the 8.5" differential?
bri-rock
Yes, he is right. The 8.5 is a completely different rearend. The 8.5's are found in novas. The ones that are commonly swapped into first gen camaros are 72-78 novas. I am in the process of doing the swap as I type.
BTW: A search on this forum will reveal LOTS of info on this subject. :thumbsup:
BTW: A search on this forum will reveal LOTS of info on this subject. :thumbsup:
bri-rock,
Eaton makes a posi unit for the 8.2 rear end. I'm surprized he didn't mention that to you as well.
I guess it depends on how hard you're going to be driving (or racing) the car. The 8.5 is obviously stronger.
Take a look at this: http://www.novaresource.org/axle.htm and it'll give you the info you need to help find an 8.5 rear.
Eaton makes a posi unit for the 8.2 rear end. I'm surprized he didn't mention that to you as well.
I guess it depends on how hard you're going to be driving (or racing) the car. The 8.5 is obviously stronger.
Take a look at this: http://www.novaresource.org/axle.htm and it'll give you the info you need to help find an 8.5 rear.
The Eaton rep did tell me about the 8.2. I asked him what the torque rating was on the 8.2... for example, could it take repeated loads of 600 ft-lbs. He had no information on the subject. Couldn't find any on the internet either. All I have is the experience of the people on this website. Consensus is that unless I am going try putting over 600 ft-lbs that the 8.5 will be fine. 8.2 is a bit iffy in this range over the long haul.
I'm a Nova nut, and I would definitely recommend the 8.5 for any performance car. I just rebuilt mine with used posi carrier, new gears, axles, bearings and seals for under $800.
If I'm not mistaken, the width should be the same on 72-79 Nova's, but you'll have to relocate the spring perches. You can also find them on Omega's, Skylarks, and Ventura's since they're same body and frame style as the Nova.
It uses the same size pinion gear as a 12 bolt and the ring gear is only 1/2" smaller in diameter so overall the 8.5 will provide as much stability as a 12-bolt would. The difference being whether it has 28 or 30 spline axles, the 30 spline being stronger if you're looking for high torque output. There's a couple guys running low 8's - 9's at the drag strip with the 8.5 30 spline axles, so it'll definitely hold up.
If I'm not mistaken, the width should be the same on 72-79 Nova's, but you'll have to relocate the spring perches. You can also find them on Omega's, Skylarks, and Ventura's since they're same body and frame style as the Nova.
It uses the same size pinion gear as a 12 bolt and the ring gear is only 1/2" smaller in diameter so overall the 8.5 will provide as much stability as a 12-bolt would. The difference being whether it has 28 or 30 spline axles, the 30 spline being stronger if you're looking for high torque output. There's a couple guys running low 8's - 9's at the drag strip with the 8.5 30 spline axles, so it'll definitely hold up.
The Nova rear ends from '72 to '75 will bolt in with no modifications. After that some of them have the spring perches located farther apart like the second gen Camaro rear ends. Also, some of the Novas from '76 up have the smaller 7.5 10 bolt, so be carefull what you get.
The 8.5 Nova rear ends will have 28 spline axles in them. It is easy to upgrade them to 30 spline parts with a 30 spline Eaton posi and after market axles. I have done this MANY times and it makes the rear end much stronger. Another thing that the 8.5 needs is the axle tubes welded. The 8.5 rear ends have very bad plug welds in the axle tubes and if you put a lot of torque with a lot of traction it will rotate the tubes in the center casting and you will have the drive shaft through the floor. For more information on welding the tubes look at this. http://www.nastyz28.com/forum/showthread.php?t=18890&highlight=welding+axle+tubes
The 8.5 Nova rear ends will have 28 spline axles in them. It is easy to upgrade them to 30 spline parts with a 30 spline Eaton posi and after market axles. I have done this MANY times and it makes the rear end much stronger. Another thing that the 8.5 needs is the axle tubes welded. The 8.5 rear ends have very bad plug welds in the axle tubes and if you put a lot of torque with a lot of traction it will rotate the tubes in the center casting and you will have the drive shaft through the floor. For more information on welding the tubes look at this. http://www.nastyz28.com/forum/showthread.php?t=18890&highlight=welding+axle+tubes
I know that the '75 and '76 rear end are the same width, but I have seen a few of the later rear ends that were wider and had the spring perches farther apart.
If you have the 8.5 Traction Lock it was never offered in 30 splines, so there are no 30 spline gears for it. If you have an Eaton then the case would have to be bored out to accept the 30 spline axles. If you have an Auburn then throw it away and get a 30 spline Eaton.
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