As we all know, replacing pads on any brake caliper involves compressing the piston(s) to make room for the new pads. As pads wear, friction material thickness is reduced. As the pads get thinner, the piston(s) continue to move further out of their bores.
When the customer finally comes in for a pad change (usually because the brakes are getting noisy, since many wait until the backing plates begin to scrape against the rotors), the poor piston has nudged its way far enough from the bore that it must be shoved back fully in order to obtain enough room to install the new pads with enough clearance to slip the caliper over the rotor.
While it’s not uncommon for a tech to force the piston back home using a pair of large channel-lock pliers, that approach is clumsy and can easily damage the outer surface of the piston.
A separate challenge is faced when dealing with screw-in style caliper pistons (commonly found on many rear calipers), where the piston must be rotated (clockwise or counterclockwise depending on design) in order to move the piston back into its bore.
In order to use one tool to address either push-in or rotating pistons, Lisle Corp. recently introduced its new Combination Disc Brake Kit, P/N 29350, that makes the job easy while avoiding potential piston damage. This eliminates the need to grab another specialty tool when dealing with rotating piston designs.
The tool kit consists of a hand-lever-operated compressor tool that features a fixed plate that engages against the outer cavity section of the caliper body. As the lever is squeezed, the ram rod extends, placing pressure against the piston. A set of three adapters is included, with the appropriate adapter connecting to the end of the rod via a simple 3/8-inch square drive.
When the job calls for pushing a piston that does not require piston rotation, a flat “pinless” adapter is placed onto the ram. Insert an old pad against the piston, with the flat adapter contacting the old pad. Simply squeeze the tool’s lever grip, applying successive strokes to push the piston into its bore. The tool works easily and smoothly for a controlled piston retraction.
If you’re dealing with a piston that requires rotation, choose the appropriate adapter that features two male pins (to engage into the piston’s pin notches).
Squeeze the lever until full contact is made, then while holding the tool with one hand, use a 9/16-inch wrench socket and ratchet to rotate the piston. Two pin adapters are included, with pins featured on each side. Adapter 1A/1B features 1-1/2-inch narrow pins for applications such as most Hondas, Mazdas, Dodge Conquest, Mitsubishi Starions and GM models on the adapter’s 1A side; and 1-1/2-inch wide pins for most Fords, Toyotas and Fieros. Adapter 2A/2B features 1-5/8-inch pins, with side 2A covering most Nissan/Datsuns and Subarus; and side 2B designed for Mazda 3 and some Jaguar applications.
Once the piston has been moved to the bottom of its bore, remove your fingers from the ratcheting forward grip lever. Grab only the rear stationary grip and press the black steel retaining lever with your thumb, and pull the ram shaft rearward in order to retract the ram.
While this tool may have been specifically designed to handle single-piston calipers, Lisle also offers piston tools for multi-piston calipers as well.
We tried the tool on several calipers, with no glitches whatsoever. The piston compressor works exactly as it should, smoothly and quickly, making the job extremely easy. The sturdy plastic storage case is molded to neatly fit the tool and all three adapters. ■
PO Box 89
Clarinda, IA 51632