Just wanted to make a specific post for this topic for reference. One of the two front brake caliper slider pins on the RX-8 uses a rubber sleeve on its end within the bore in the caliper bracket. It is typically the lower pin. On a recent pad change, I replaced the slider pins just to be thorough. When doing so I used Permatiex brake lubricant on them that has the green label. The car sat a lot during COVID after this and some corrosion built up on the rotors, that usually is easily and thoroughly cleared. However, I could not get the rotor surfaces free of rust, and I had a lot of pulsating and vibration. I ordered new rotors thinking the old ones were too far gone. During replacement of the front rotors, I discovered one pin on each front caliper, the ones with the rubber sleeve, were not moving. Upon pulling them out of their bores, I found the rubber sleeve had swelled from the grease I used, and seized the pin, preventing it from sliding. I had old non-rubber slide pins around, so reassembled with them temporary substitutes. This setup seems fine, however, I went ahead and ordered new pins and rubber sleeves.

After some research here, I saw others that had this same problem of swelling rubber sleeves on their pins, resulting in seized slider pins, and front brakes that did not operate properly. The answer seems to be to use Sil-Glyde Silicon brake grease/lubricant (perhaps other silicon brake lubes work as well.) I have not put the new pins in yet, with the recommended Sil-Glyde lube, but this seems like what needs to be done.

I found it very surprising that such a minor detail can have such an outsized effect on the proper operation of the front brakes. It has been reported by multiple owners.

Hopefully, this dedicated post shall be useful for those searching in the future for info on this.

 

sil-glyde should always be used but as far as the rubber piece you are talking about cut them off. i did brakes on my dd last week at my brothers garage (his business) and he told me to cut that rubber off for this exact reason

 

I thought of leaving the rubber off the original pins, but rather just used the style for the upper pin bore in the lower bore, because I had spares. I think if one were to leave the rubber off, it might be better to use two upper pins, because they have full material all the way down. However, leaving the rubber sleeve off, as you suggested, is probably fine. I'd like to learn the purpose of the rubber sleeve.

 

i just cut mine off yesterday. same issues. getting stuck

 

Pretty sure the rubber sleeved pin is part of the anti rattle and/or squeal of brakes. I read this somewhere here or on the UK site possibly a while back.
I did have a stuck rubber coated slider pin in a spare set of brakes. Just threw them into the spare parts pile in case they were needed later on. Good to know they can still be used ok after a rough circumcision and application of silocone grease!