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Discussion Starter #1
I have a 8.5 inch 10-bolt rear end with disc brakes out of an '81 T/A. The car I pulled it out of was wrecked and both axles are slightly bent at the axle flange. Anyone know if the disc brake axles were the same length as drum brake axles?

I would take the axles out and measure them, but the axle lengths I see in the catalogs are measured to the 1/16th of an inch and I'm afraid that the bends would affect my measurements.
 

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I'm not ure exactally the differences, but I do know for a act that the disc brake cars use different axles than the drum brake cars. I believe that the differences are the distance from the flange surface to the bearing surface is shorther and the flange diameter is smaller. I'm not 100% but I think this is the difference, but I do know that the two are not interchangeable. Your bst bet is to call Moser engineering, a set of their replacement axles are cheaper than 1 new GM axle, and they're much stronger also.
 

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That rear won't fit a 1st gen, will it? Isn't that one too wide? (I'm making an assumption this is for your 1st gen)

I'd also make sure the tubes/housing is not bent and check for bearing damage.
 

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Actually, there is no difference in the length of the 8.5 axles between a disc and drum brake car. I did the WS6 conversion on my 75 about 18 months ago. I put both axles side by side and everything measured the same. The problem you are going to have is that the 8.5 from a 2nd gen f-body will not fit a 1st gen Camaro (It's too wide). The disc brake setup from the T/A will install on the 8.5 and 8.125 ten bolts and the and 8.875 twelve bolt. using it on the shorter rear will require custom brake lines and e-brake cables.
 

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Not only overall width, but the spring perches are farther apart too. I think it's an inch wider both overall and the perches. With the right wheel offsets it could work if the perches were moved.
 

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Discussion Starter #7
Thanks for the responses. Through various other internet channels, I was also able to confirm that the disc and drum axles are the same length. However, there is some debate whether the two axles are identical.

Apparently, each axle had a separate GM part number. Additionally, I had one person tell me that the wheel centering lip machined on the face of the WS6 axle flange was smaller than the lip on the drum brake flange. The concern raised was that if the wheel was centered by the wheel studs rather than the axle flange, that too much stress would be put on the wheel studs.

Bottom line though is that you can use drum brake axles in a WS6 disc brake rear end.


P.S., the rear end is going in a friend's '72 Firebird.
 

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The only thing I don't understand is the whole the 2nd gen rear won't fit a first gen car thing. Yes you have to move the spring perches and shorten the drive shaft, but that's it. I have sitting side by side on my garage floor the original 8.2P out of my 67 Firebird and a 8.5 disc brake rear end out of a 79 Trans am. Both are completely assembled minus brakes and both are the exact same width from axle flange to axle flange. I have a 8.5 out of a 74 Camaro under my 69 and the wheels fit exactally the same as they did with the stock 8.2C axle.So my question is, which cars exactally had a wider rear end, becase it's very clear to me that it's not all the second gen cars.
 

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Discussion Starter #9
A little more clarity on the difference between disc and drum axles.

The difference is that the wheel mounting lip on the disc brake axle's flange is taller than it is on the drum brake axle. This makes sense because the mounting area of a disc brake rotor is thicker than the mounting area on a drum. As a result, there is less of the lip that sticks out to center the wheel.
 
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