Are the axle shafts in a 6 3/4 rear end the same as an 8 inch? Diameter, splines, etc? In particular, from a 1980 sedan.
Russ
While I can't say exactly, I doubt they are interchangeable. The rearend types are distinctly different. The 6-3/4" has the gears set in the greater housing (all one piece). The 8" has a removable center section (often called the "Pumpkin").
FYI, even though both rearends have the same diameter brake drums they are not interchangeable. The center hole on the 6-3/4" is too small.
Tom
i have a set of axles for the 8" rear if interested. the 8" rear axle splines are 28 count, don't remember the 6 3/4" count, but they would not fit anyways.
I just did an 8" swap on my 78. The axle shafts are not the same. Biggest issue I noticed with interchanging the axles would be the spline count, and even more so, the diameter of the shafts. The 8" ones are at least one and a half times larger than the 6.75" shafts.
Actually Wittsend, some 6.75" drums WILL fit the 8"!
The original axle in my car was a 6.75", and I swapped it out for a 1973 station wagon axle with a lower ratio. The 73 drums have a smaller hub hole than the 78 6.75" axle, but other than that they would interchange. I was actually going to use my original 6.75" drums on my new 8" axle if the 8" drums couldn't be turned anymore.
Differences in the drums:
73' 6.75" drums - smaller center hub hole. Verified will not fit on a 78' 6.75" axle shaft. Also, the wheel stud holes are LARGER than the 78' drums. To interchange 78' drums with a 73' axle shaft, you will need to drill the stud holes larger, but MAKE SURE that the bit is CENTERED, or you will have offset holes and not a consistent braking surface which will cause a jerky motion while stopping just like a badly warped rotor.
78' 6.75" drums WILL fit on an 8" axle shaft. I have verified this myself. They have the same size center hole, and the same size stud holes!
So, 8" axle shafts will accept at least 78' brake drums and I am assuming everything up, again, just assuming. I know for a fact that 73' drums will not fit, as the center hole is to small and the stud holes are to large.
>>>Actually Wittsend, some 6.75" drums WILL fit the 8"!<<<
>>>I know for a fact that 73' drums will not fit, as the center hole is to small and the stud holes are to large.<<<
Thanks for the correction. Yes, I was basing my comment on the fact that I have a '73. When I got my 8" I got it "drum to drum". It was only $10 more and worth every penny.
Tom
Tom, I read some of your posts prior to my 8" swap. When I went to clean up the 8" axle assembly, which I got as drum to drum, I had a knot in my stomach when I saw how rusted the drums were and I know how long it takes to remove that stuff from rotors! When I did my 73 station wagon's rotors, it took about two hours to get all of the rust off them and those are flat surfaces, it's harder to do with a drum!
Just for the heck of it I put the drums from my original axle on the 8" to see for myself the differences, and lo' and behold, they fit! Lucky me, I took the rusted drums down to O'Reilly's to have them check how much more metal could be removed before they were deemed non usable. They were able to resurface both with a little room to spare!