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Conversion to 12" brakes


From: Richard Kwarciany

I have the 12" brakes on my 85 MCSS, and I'm very happy with them. The difference in stopping power is very dramatic. The pedal feel is great under hard braking. No more "hard spots" or fade, and no more need to put both feet on the brake pedal. You will need the following parts from a 78 Caprice Station Wagon. Other B bodies with 5" bolt pattern also work, but I don't know the year cut-off. All wagons had the 5" patten (12" rotors), but not all sedans did. Many had the 4-3/4" bolt pattern and 11" rotors. You'd think that 77 would be the same, but they have different bearings.


  1. Spindles & dust covers
  2. Calipers & bolts
  3. inner & outer wheel bearings, bearing washers, nuts & dust caps
  4. Wheel seals
  5. Brake pads

You need rotors from a 90 Camaro w/12" rotors (1LE).
You will also need the aftermarket upper control arms for this application, or you will end up with way too much camber.

Full size and mid size cars take the same upper and lower ball joints, and have the same taper on the tie-rod ends, so the parts bolt right on. I'm using the stock steal 15x7 SS wheels with no clearance problems. The stock lug nuts work fine. The swap does not significantly affect ride height or wheel offset requirements. The Camaro rotors are obviously just borrowed from the full size car, since they appear to be identical castings, and are even machined the same. The only difference is that the Camaro rotors are drilled for a 4-3/4" bolt pattern, and are fitted with metric studs.

These cars are canidates for the parts needed for the 12" brake swap, if you don't feel like buying all the parts new. This comes straight from the Global West catalog, so it sould be good.

Buick, Pontiac, or Chevy full size 1978-1992 Caddy Seville and Deville 1978-1992 execpt for limos Olds Delta 88 coupe and Sedan 1978-1992 Buick Riveria 1977-1979

If you go the junkyard route, then make sure to actually measure the discs as these cars also came with 11" disc. These discs are drilled for a 5x5 bolt pattern while the monte is 5x4.75. So, you can either get the camaro 1le discs which are the correct bolt pattern and metric studs, or get the discs redrilled for the smaller bolt pattern.

These are the items needed for a Hotchkis suspension mod with the 12 inch rotors: 

   Bilstein shocks 
        fronts 2ea,  pn. B360949
        rears   2ea,  pn. B460929
   Eibach Springs (call Hotchkis)
   General Motors
       front spindle, left  1ea, pn. 14012589
       front spindle, right, 1 ea, pn. 14012590
       1LE 12-inch rotors, 2 ea, pn. 18016035
       Dustshield, left, 1 ea, pn. 344023
       Dustshield, right, 1 ea, pn. 344024
       Dustcaps, 2 ea, pn. 1400344
       Washers, 2 ea, pn. 457707
       Nuts, 2 ea, pn. 378137
       Calipar bolts, 4 ea, pn. 5463495
       Caliper, left, 1 ea, pn. 18015427
       Caliper, right, 1 ea, pn. 18015427
   Wheel bearings and seals.

**Note: 70-81 camaro spindles and 11 inch rotors will also fit this car.
Hotchkis Perfomance upper trailing arms, 2ea, pn. hpta02 lower trailing arms, 2 ea, pn. hpta01 trailing arm braces, 2 ea, pn. hpbr01 tubular upper A arms, 2 ea, pn. hpaa01 Machined tie rod sleeves, 2ea, pn. hptr01 Make sure that you replace the stock master cylinder with ont that is compatible with the calipers being used. A unit from a '74 camaro fits right in. It fits the power booster and the brake line fittings on the monte. Other master cylinders will fit the booster, but be aware that later model master cylinders require metric style fittings. source: Car Craft June 93 "armed and dangerous"
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