H1 Hummer Rear Caliper Rebuild

[drdonpalmer]

Hey all,
Got a leaky rear caliper and its leaking past the piston thru the dust boot. I've rebuilt calipers before and its a piece of cake, but I knew this was going to be a bit tougher. Bought a kit from the hummer dealer that contains two pair of piston dust boots and piston seals (enough to do both rear calipers) for about $17. BTW a remanufactured caliper is about $180 and a new is upwards of $580. $17 for two calipers sound really nice. Once the caliper was removed from the vehicle and with the 2000 Hummer service manual in hand, I proceeded to disassemble the caliper.
Now I had already started the disassembly prior to consulting the manual...I'm a typical guy...so I had the bleeder screw out, the input fitting out, and added some compressed air to push the piston out, when I noticed I couldn't get the piston free. It didn't work like other calipers. Then again, this piston is on a thrust screw so its going to be different. So I consulted the manual finally and noticed I was suppost to remove the parking brake spring and retainer, then remove the PISTON RETAINING SCREW! There it is, makes sense. I didn't bother with the parking brake, I went for the retaining screw which on the manual diagram shows it clearly in the face of the piston which contacts the brake pads...a big flat allen bolt basically. Only one problem...mine didn't have that, at least not visible. It is covered by a metal cover which looks pressed into the piston and apparently covers the piston retaining screw.
So here is my queston finally: Has anyone got any bloomin idea on how to remove the cover? Its not on the manual diagram. A saginaw pump has one of these and you remove a big metal snap ring and then spin the piston into it which presses it out from within, but I couldn't figure out how to do that with the caliper piston. UNLESS, by removing the parking brake spring and retainer, that is how it is done, but I didn't perform that step...at the time it didn't seem to me to be the answer. Has anyone done this rebuild?
Bottom line, I had to get the rig together again, so I removed the old dust boot, replace it with the new, hoping it would fix the leak only to drive it again for an hour and find it leaking again. Leak is definitely due to the piston seal.
Thanks in advance,
Dr. Don Palmer