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7 1/4 brake components to 8 3/4
https://www.slantsix.org/forum/viewtopic.php?t=4989		 Page 1 of 1
Author:  slanted duster [ Mon Feb 10, 2003 8:24 pm ]
Post subject:  7 1/4 brake components to 8 3/4
I have a 72 duster still with th stock 7 1/4 rear end in it, Ive got a freshly rebuilt slant six in it with a cam, header, milled head with oversized valves etc. any ways I strpped the spider gears out of the rear end. I found someone who has a A-body 8 3/4 rear end out of a dart for $200. can you use th 9" drums and backing plates and bolt them to the 8 3/4 rear end. I've had people tell me yes no problem and you don't even have to bleed the brakes and others say no. I really don't know who to believe. Has anyone done this conversion?
Author:  slantzilla [ Mon Feb 10, 2003 8:51 pm ]
Post subject: 
9" brakes won't bolt on to the 8-3/4. The 7-1/4 backing plates only have 4 mounting holes and the 8-3/4 has 5 studs. I have been told that you can modify the backing plates, but I don't know for sure.

I bolted the 10" brakes off the 7-1/4 in my '76 Duster on to an 8-3/4, but my Duster had 4-1/2" bolt pattern axles to start with. (Late disc brake car) :shock:
Author:  Patrick Devlin [ Wed Feb 12, 2003 6:34 am ]
Post subject:  9" drums on 8 3/4" rear do not work
Over the summer when I did my 8 3/4" swap on my Dart, I tried re-drilling the backing plates of my 9" brake drums.

Drilling the backing plates to 5 holes is not the only problem. The diameter of the hole in the center of the backing plate (through which the axle bearing passes) is also too small...so I re-drilled that! And guess what? The dimension from the backing plate to the front of the axle flange is different on A-body 10" and 9" drum brakes.

MORAL OF THE STORY: you can't swap 9" drum brakes to an 8 3/4" rear. Found out the hard way.
Author:  Mark [ Wed Feb 12, 2003 8:05 pm ]
Post subject: 
Don't use the 9 in brakes. More than once the ones I had on a 68 Valiant caused the pucker factor to go way up. The only thing I didn't like about the car was those small brakes.
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