Because your shoes might be a little tight.
A few years ago, I replaced the break shoes and rotors on the ChevOldsmobuiac, a 1990 Oldsmobile cutlass Ciera. There may even be a post here about that... I certainly took a few photos. I figured that would be like a once in a lifetime replacement. The shoes box claimed the guide pins were pre-packed and ready to go, and they certainly felt like it. I put on a coat of high temperature enamel and bolted them up.
Fast forward a few years later and the car has a funky kind of shift when the brakes are applied... like one side is engaging a bit later than the other. I took the tires off and wiggled everything, but there was no outwardly obvious signs of damage to the wheels, bearings or or breaks. I chalked it up to a dying ball joint and waited for a more obvious clunk-clunk to find the issue.
Fast forward another few years to a few weeks ago, and the Girly calls to inform me that the car is not accelerating well, not coasting for long, and smells like burning. Fairly clear signs of a seized brake (though over the phone I also expected a major fluid leak, because we've been down that road before once or twice too). I suspected the parking brake as well, given past experience, but a test drive showed no symptoms, and I would expect rear-end dragging from parking brake problems.
Taking the front wheels off, however, showed that the front drivers side calliper had seized and melted all its rubbery bits.
Perhaps most disconcerting is that the heat/pressure damaged the hydraulic line, the failure of which would have caused a worse situation to develop. I'm glad it didn't happen when I was towing the trailer the month prior!
Taking the calliper apart showed the guide pins lubrication was completely gone!
The passenger calliper was only marginally better. No lube and rusty pins, but no sign of burning.
I bought new pads and a new drivers side calliper (I had a spare hydraulic hose in the parts stash), and made sure to repack everything with grease before assembly. The new (well, rebuilt) calliper had a very thin oily substance to lubricate the guide rods. I suspect that it slowly ran out of the old calliper over time and allowed it to corrode.
This is very annoying. The old calliper worked fine for 20 odd years, yet the rebuilds barely made it 5. I'm going to add "check calliper guide rods" to my biannual checkout routine, but it's just one more thing to have to deal with.
The car stops good and straight now.
I can't help but wonder if the rebuilt callipers are designed to have a short life.
