Pirate Jack - Hotrod, Restoration, & OEM Auto Parts

7" STREET ROD POWER BOOSTER (PB7001)
The 7" street rod booster requires 18" of vacuum to operate properly. With this vacuum level the booster will produce a maximum pressure output of 950 psi with a 1" bore master cylinder. This pressure level will work great for four wheel drum systems and disc/drum vehicles which are relatively light. This booster is not recommended for heavy disc brake cars like 55 Chevy's or for any four wheel disc brake system. This is the booster supplied with our under floor pedal kits.

7" DUAL DIAPHRAGM POWER BOOSTER (PB7537)
The 7" dual diaphragm street rod booster requires 18" of vacuum to operate properly. With this vacuum level the booster will produce a maximum pressure output of about 1200 psi with a 1" bore master cylinder. This pressure level will work great for four wheel disc systems and disc/drum vehicles which are heavier.

8" STREET ROD BOOSTER (PB8531)
The 8" street rod booster requires 18" of vacuum to operate properly. With this vacuum level the booster will produce a maximum pressure output of 1200 psi with a 1" bore master cylinder. This pressure level will work great for four wheel disc systems and disc/drum vehicles which are heavier. This booster is recommended for heavy disc brake cars like 55 Chevy's or for any four wheel disc brake system.

9" SLIMLINE (PB9002)
The 9" slimline booster requires 18" of vacuum to operate properly. With this vacuum level the booster will produce a maximum pressure output of 1100 psi with a 1" bore master cylinder. This pressure level will work great for disc/drum vehicles. This booster is recommended for heavy disc brake cars like 55 Chevy's or for street rods.

9" DUAL DIAPHRAGM BOOSTERS
The 9" dual diaphragm ultra booster requires 18" of vacuum to operate properly. With this vacuum level the booster will produce a maximum pressure output of 1400 psi with a 1" bore master cylinder. This pressure level will work great for four wheel disc systems on heavier cars and trucks.

MC2912H
	This 1-1/8" bore master cylinder works with any of the boosters above and is recommended for disc/disc systems.  The master Cylinder comes with a piston adapter.  Master Cylinders work for manual or power applications (see Check Booster Pushrod Adjustment Below).  Outlets: A=9/16 B=1/2
MC1321H
	This 1" bore master cylinder works with any of the boosters above and is recommended for disc/drum or drum/drum systems. Outlets on both sides. Master Cylinders work for manual or power applications (see Check Booster Pushrod Adjustment Below).   Outlets: A=9/16 B=1/2.

The pushrod that actuates the master cylinder must be properly adjusted. Ideally there should be only slight clearance between the booster pushrod and the master cylinder pushrod. Interference will preload the master cylinder. When the system is preloaded, it builds pressure each time the pedal is pressed. Since the master cylinder is not allowed to fully release the pressure from the previous stroke, the system will eventually lock the wheels. Too much clearance will cause excessive free play in the pedal.

There are basically two different master cylinders that we use for our Chevy and Ford kits, the deep bore master cylinder and the shallow bore master  ylinder. To determine which master cylinder your booster is setup to mate with, you can do the following simple check. For shallow bore master cylinders, the pushrod should be approximately flush with or below the booster face. Deep bore master cylinders will protrude past the face of the booster body by about 1” to 1-1/2”. Note that deep bore master cylinders are required for manual brakes and shallow bore master cylinders are generally used for power brake systems. We now supply a master cylinder piston adapter (pictured) to accommodate both master cylinders. You will only use this adapter when you have a deep bore master cylinder with a short booster pushrod.