Did my car brakes

[HipGnosis]

The brakes on my car ('07, 100K miles, looks like new when clean) would pulse a bit at certain amounts of pressure on the brake pedal. 
So I bought brake pads for the front from Rock Auto.  I didn't get the economy pads - because I drive faster than avg., but still just over $30. 
I got the pads and was waiting for a decent day to change them.
Then, the brakes started grinding (pretty bad). I rolled down the window and could tell it's the left rear. I got rear pads ASAP, from an auto parts store, $35, but rear pads are about half as big as front pads...
I change the left rear pads first.   The pads on the car were pretty thin, but NOT wearing even. I removed them and found that half of one of the pads is GONE. Well, that explains the grinding. To put new pads on, you have to compress the caliper piston.  I use a clamp, like I have many times before, but it didn't work. I huff, grunt, cuss... Tried a different clamp. Watch more youtube.. no help. I call the parts guy, "you gotta buy a new caliper". So I ride over there and get the caliper. I can't see how to move the parking brake cable from old caliper to new, so I wash my hands again and go back to youtube. I found out that lots of rear calipers need to be TURNED and compressed. I found another video that shows how to turn it - with channel locks instead of a special tool.  Done, easy peasy!   The next day I put the new rear pads on the right side (much quicker) and then returned the caliper.  Then I put the new brake pads on the front.
BTW, I didn't have any problems with the brake caliper bolts (the brake pads are inside the calipers) because I crack loose and re-tighten my caliper bolts twice a year - when I rotate my tires.
I called around after I was done.  The cheapest price quote to have it done I got was $300, and that was an oil and muffler place that I wouldn't trust to do brakes.

[Dr.Jeckyl]

Nice job!! I've been doing my own brakes since I was a teen. Just an FYI, for rear disc brakes you can usually borrow a kit from the local parts store or buy a small tool (looks like a square) that fits a 3/8" socket wrench for about $10. I love buying tools that pay for themselves.

[paddedhat]

You might want to see if the rear calipers have any difference is how hot they get in use. After a decent run of stop and go traffic feel both calipers. Be careful, since it's pretty easy to burn yourself if a caliper is hung up. Slowly get your fingers closer to the caliper, through a slot in the wheel and see if the left one is dramatically hotter than the right?  My guess is that the left rear caliper piston is binding up and not releasing properly, as evidenced by the pad wear. Also check for really uneven pad wear every few months. The other possibility is that the caliper is hanging on the slide bolts. The cure for that is to make sure that the bolt is shiny, clean and properly greased before reassembly. Good job so far, but there might be a bigger problem hiding here.