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Author Topic: 1973 rear drum to disc brake conversion  (Read 5788 times)

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frbformula

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1973 rear drum to disc brake conversion
« on: October 15, 2008, 03:57:28 PM »
im trying to find anyone who has or who knows how to do a rear drum to disc brake conversion using stock GM parts so i can go to auto zone and get replacement pads/rotors and not need to order any special parts.

thanks.
« Last Edit: October 15, 2008, 11:30:34 PM by firebirdclub »

78tahitman

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Re: 1973 rear drum to disc brake conversion
« Reply #1 on: October 17, 2008, 10:44:38 AM »
They do sell rear disc brake conversion kits for about $600 to $800. Probably the easiest thing to do is find a disc brake rear end from a 1979 to 1981 Trans Am and do a swap.  It will be a direct bolt in replacing your stock rear end from the 1973. You will typically spend about $200 on the full rear end.  By doing this swap you will be using all stock parts and GM parts which you can get replacement parts from any auto store.  Now once you do this there will also be some other things to consider.  First thing you have to do is also buy a new master cylinder and proportioning valve and replace those as well, usually about $110 for both from places like The Rigth Stuff Detailing or Inline Tube.  The other thing is the rear end gears that are in there.  I don't know what set up you have, but I am guessing it might be a 2.42 or maybe a 2.56 rear end in there now.  The disc brake rear end that you will get might have a 3.08 or a 3.23 rear end gear.  So you can leave it as is, but your speedometer will be off due to the gear difference.  You can swap out the gears from your rear end into the new one, or change your speedometer and drive gears in the transmission to match the new rear end.  If you swap your existing gears into the new carrier on the disc brake rear end, I would highly suggest that be done by a professional in order to get it set right.  But if you change the speedometer and drive gears in your transmission, that can be done yourself.
Brett Campbell
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1978 Trans Am, 1989 Trans Am, 1998 Trans Am

frbformula

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Re: 1973 rear drum to disc brake conversion
« Reply #2 on: October 20, 2008, 08:15:27 PM »
Thanks. but i wanna keep the 8.5 gm rear end in it and not go to a 7.5. the only reason i need the rear disc breaks is because i got 3.73 gears and a 3000 stall converter and the drum breaks wont hold the tires past 2300 rpm. im just lookin for a little more holding power at the line.

78tahitman

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Re: 1973 rear drum to disc brake conversion
« Reply #3 on: October 23, 2008, 10:41:46 AM »
From 1979 to 1981, it is still a 10-bolt 8.5 inch rear end.  So your guts from your existing set-up will fit in there.
Brett Campbell
"Hitman"
www.78ta.com
www.89ta.com
www.taspecialties.com
www.ohiofirebirds.com
www.tanationals.com
1978 Trans Am, 1989 Trans Am, 1998 Trans Am

frbformula

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Re: 1973 rear drum to disc brake conversion
« Reply #4 on: October 25, 2008, 05:10:49 PM »
is there any way that i can just take the brakes off the later 8.5 rear end and just put the discs, calipers and brackets on the 8.5 in my firebird

National Firebird and Trans Am Club Message Board

Re: 1973 rear drum to disc brake conversion
« Reply #4 on: October 25, 2008, 05:10:49 PM »


 

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