I have had the usual problem with a sticky rear caliper, so I have cleaned them up, exercised the caliper pistons etc, then discovered that one of the slider pins had seized. I had to lever it out and discovered that the problem was the rubber collar which sits in a recess at the end of the pin. I guess this had swollen and even after cleaning it up and lubricating it, it would not go back into the carrier. The other slider is a plain metal pin and that was working fine.
I have serviced these things in the past but have never come across this rubber collar on the sliders before. What purpose does it serve and can it be left off?
 2011 Vogue TDV8 4.4
1992 Mazda Mx5

I am watching this post keenly because I intend to strip and clean mine soon.

Click image to enlarge

The rubber sleeve is there to reduce the liklihood of rattles while allowing relative large clearances to prevent jamming and high machining tolerances to keep costs low. Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Thanks for that. The lower slide pin is plain metal with a couple a facets, presumably to allow lubrication to circulate, but there is no rubber sleeve. I am willing to bet that many of the problems with sticking rear calipers are because of this rubber sleeve swelling up. All the more reason to only use silicon grease to lubricate these and not copper ease as some seem to do. I think that the seals referred to are the dust seals to prevent dirt getting in to the slide pins.
In the end I replaced one slide carrier and one caliper, all rear brake pads and the wear sensor. Everything is working fine now 2011 Vogue TDV8 4.4
1992 Mazda Mx5

Copper grease shouldn't be allowed anywhere near brake system parts - it's petrol based & will certainly cause those rubber sleeves to swell.
It's a shame you can't buy the grease the brake manufacturers use on the OE parts. It's much more effective - but incredibly expensive. Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

I used this silicon PTFE grease from Ebay
https://www.ebay.co.uk/itm/100ml-Silicone-...2749.l2649 2011 Vogue TDV8 4.4
1992 Mazda Mx5