On the RX-8's front brakes, one of the slider pins for each caliper has a rubber sleeve on it:
(Photo credit: Atkins Rotary)
Until recently, I had been using an old tub of CRC Synthetic Brake and Caliper Grease for all my brake jobs. The stuff was around 10 years old -- maybe more. It had been visibly separating for a couple of years, but I kept using it anyway. No excuses; I was just lazy and never had a problem with it.
Then, when I went to replace my rotors a few months back, those rubber-sleeved pins were stuck. It took real effort to pull them out. I cleaned and re-greased them, but they still took way too much effort to push back into the holes.
After that brake job, I started to get a click/knock sound from the front brakes whenever I applied them. It got louder and more frequent over time.
Eventually I took everything apart again, cleaned it thoroughly, and re-greased with Sil Glyde. The front brakes have been quiet as a church mouse since then.
Is it possible that whatever separated out of the old grease tended to shrink elastomers, and whatever was left tended to swell elastomers, causing the rubber seals to swell? That's the only hypothesis I could come up with, but I basically don't know jack about grease. If that's likely what happened, how did it get better? Could the Sil Glyde have reduced the swelling a bit? Or maybe the small amount of brake cleaner I used directly on the rubber sleeves when cleaning them?
(Photo credit: Atkins Rotary)
Until recently, I had been using an old tub of CRC Synthetic Brake and Caliper Grease for all my brake jobs. The stuff was around 10 years old -- maybe more. It had been visibly separating for a couple of years, but I kept using it anyway. No excuses; I was just lazy and never had a problem with it.
Then, when I went to replace my rotors a few months back, those rubber-sleeved pins were stuck. It took real effort to pull them out. I cleaned and re-greased them, but they still took way too much effort to push back into the holes.
After that brake job, I started to get a click/knock sound from the front brakes whenever I applied them. It got louder and more frequent over time.
Eventually I took everything apart again, cleaned it thoroughly, and re-greased with Sil Glyde. The front brakes have been quiet as a church mouse since then.
Is it possible that whatever separated out of the old grease tended to shrink elastomers, and whatever was left tended to swell elastomers, causing the rubber seals to swell? That's the only hypothesis I could come up with, but I basically don't know jack about grease. If that's likely what happened, how did it get better? Could the Sil Glyde have reduced the swelling a bit? Or maybe the small amount of brake cleaner I used directly on the rubber sleeves when cleaning them?