|The MGA With An Attitude
Tool for Removing Hydraulic Pistons -- TS-203
At 05:13 PM 1/12/04 -0500, Don Fodor wrote:
>".... drum brakes all around. .... cannot get the pistons out. They are rusted in place solid. Any ideas on getting them out?
Here is a simple to make tool for removing a hydraulic piston from a slave cylinder. If air pressure doesn't pop the piston out, then start with a bolt with the proper thread to match the thread in the port on the cylinder, and long enough to bottom out in the threaded hole. It will be 3/8-24-UNF thread for all slave cylinders on the MGA*. Drill a small hole through the length of the bolt on (or near) the central axis. Drill and tap a thread in the head end to accept a small grease fitting.
Fill the cylinder with oil to expel all air first, then install this fitting and plug any remaining port on the cylinder with another screw. Pump up pressure with a grease gun. If that doesn't push the piston out on the first try, save your special fitting and drop the cylinder into the nearest trash can (unless it's some rare or exotic part that cannot be replaced).
See Removing a siezed piston from a hydraulic cylinder for more information on finishing the job.
* Addendum October 1, 2017:
The point has been rised that not all slave cylinders on the MGA have 3/8-24-UNF thread ports. The rear slaves might be 7/16" to accommodate the banjo bolt, but on the input end of the banjo fitting the brake pipe fittings are 3/8" thread. For the 1500 with front drum brakes, all four slave cylinders have 3/8" threads. Disc brake calipers have 3/8" threads for the bleed nipples, so you just need to plug the input port. The master cylinder also has 3/8" ports. When the clutch pipe is larger, there is an adapter fitting to get from 3/8 to 7/16" to accommodate the banjo bolt. So the 3/8" fitting should work for all these applications. It might be handy to also have a 7/16" greaser bolt to avoid using the original banjo fittings.