Late Booster On Classic Musclecar

Retrofitting late-model four-wheel disc brakes to classic GM musclecars is gaining popularity. To achieve peak performance with such systems and a modern, high-tech look, it�s best to install a late-model dual-diaphragm power booster. However, commonly available late-model units (such as the 1982-1988 G-body, code FB, GM 18010120) typically have a different firewall mounting angle and brake-pedal attaching rod than the early unit. The G-body booster can be modified to the hybrid configuration shown in the photo, allowing it to fit the early A-body (intermediate) or F-body (Camaro/Firebird):

  1. Locate a 1967-1972 A- or F-body booster, and grind off the rivet heads that hold the firewall mounting bracket to the booster. Pry the bracket off the booster with a screwdriver.
  2. Measure and record the length of the pedal pushrod between the brake pedal clevis and the rear face of the booster.
  3. Extend the length of the G-body booster�s pedal pushrod by cutting the clevis end off the booster and either grafting on the A pedal pushrod or using a piece of Grade 8-quality 3/8-16 threaded rod stock to make the overall length of the G pushrod the same as that from the original A booster.
  4. Thread the portion of the G-body pushrod that extends out from the booster body with a 3/8-16 die.
  5. Procure a 3/8-16 coupling nut (McMaster-Carr #90264A210 or equivalent), and assemble the pushrod halves using red Loctite® on the threads. Attach the old clevis and retain with a jam nut.
  6. Place the previously removed firewall-to-booster bracket on the G booster�s existing firewall-mounting studs, and fasten with self-locking metric M10x1.5 nuts. In some instances it may be necessary to elongate the A bracket�s mounting holes slightly inboard.
  7. Attach the clevis rod to the brake pedal, then fasten the booster to the firewall using self-locking American 3/8-16 nuts.

Powermaster For Early Cars:

This one originally was installed on 1986 B-body wagons with Olds 307 engines (GM production No. 18013355, current service No. 18018236). There is a similar unit on the Grand National.

Vacuum Pumps:

There are a couple of OEM pieces used on GM vehicles to create supplemental vacuum to assist the vacuum booster to maintain sufficient amounts of vacuum.

Solution 1 - This 80's pump is still available from GM (part # 22034995). This pump application can also be found in the following vehicles (Mostly J and X cars). The note here is that these usually have bad diaphrams so use caution. They are usually on the driver's side fenderwell. And, like all other yard finds, get as much of the associated hardware as you can.

The connector from left to right are wired:

Solution 2 - Some things don't change. It turns out the 04-05 5.3 liter Chevy pickup has an updated version of a vacuum assist pump, GM #18049393. Other GM numbers are JC4 pumps 89058946 / 89040236. The problem with these is that they use a pressure sense system and the computer turns them on and off. Could be a wiring nightmare for stand alone use. A similar part is on 99-08 Ford Powerstroke diesel apps.