I have a 72 GS with disc front and drum rear brakes. I would like to make it disc brakes all around. My wheels are 18" foose wheels so sizing of rotors shouldn't be an issue. Few questions: Can I just purchase a rear conversion kit solely? If so, is there a stock car I can reference so purchasing of parts at AutoZone can be seamless when brake work is needed? Will I need to replace the factory master cylinder or power booster to make this conversion? Any leads on this are much appreciated. The end result is slotted rotors and black calipers all around. The stock fronts can be painted if purchasing replacement black ones are not cost effective. All in all, I'd like to convert to full disc brakes and be able to go to AutoZone and say I need brakes for my 72 GS (or whatever car necessary) and buy them if able. Cheers!
A lot of the rear disc conversions consist of a late-70’s Eldorado caliper,with a late 70’s Firebird rotor,so you can get those parts at any parts store. The real piece needed is the caliper bracket,which is supplied with the kits. Yes,you will need a different master cylinder. You should have one with 1 1/8” bore,but you will need one with a 1 1/6” or 1” bore. Less volume,more pressure.
So new master cylinder-check. New proportionong valve also? Stick with the 11" power booster? My 464ci has no vacuum issues at idle, at around 15 or 16hg.
What Brian said is true. I did this conversion several years ago and it is a great improvement. Depending on your rear brake rotor size, you will probably need a proportioning valve change since disk and drums aren't really compatible and drums tend to have a residual pressure valve built in. The vavles are also commonly available and often not included with the kits though. My existing booster works just fine. If you have vacuum, you'll have no issues there. I used a Right Stuff kit on my 70 but it has a few short comings that I'm going to try to alleviate when I do my 71. First among them is you can't bleed the rears while the wheels are on the car. They have the rotor tilted so that it looks good but the bleeder is not at the top of caliper so you can't get the air out. You MUST unbolt the wheel, unbolt the caliper, wedge a block into the caliper to approximate the disc and rotate the caliper so that the bleeder is at the top. After that, it works great. I have a set of rear Trans Am rotors if you want to try to piece a setup together on your own. I'll sell them cheap. The caliper bracket or backing plate is the key to getting it done. If you can find a stock 79-80 Trans Am or Camaro with rear discs, the backing plate should be exactly what you need. Using the Eldorado caliper also gets you an e-brake. It was the first time I'd had a really nice functioning e-brake since I'd owned the car when I did the conversion. One final piece knowledge to share: The rotor is slightly tighter than the drum around the axle face perimeter so the axles have to be turned down to clear the inside of the rotor. No biggie, simple lathe operation.
Sorry,I forgot that part. You need to machine the outer diameter of the wheel flange to 6.00”,so the rotor hat will fit over it. You are not removing much material at all. Most of the time you are just removing excess material from the forging.
