Rear caliper

[andy york]

Ok, so I pulled the rear brake caliper off today do give it some serious cleaning.

Completely disassembled and split in 2.

I guess I'm curious as to why the pistons are of a composite material ie.non-metallic? If this was the latest greatest road racer I could understand a few less grams of weight. I also understand that it maybe bypasses any corrosion issues.

Guess I'm just sorta old fashoned when it comes to my brake pistons

I usually don't use a lot of rear brake but this is the 2nd set of pads for the back and they are almost gone at 31,000m. I can see the discoloration in the rotor so I know it has been hot.

I think it is important to keep this caliper clean. I know that this has been discussed before. Before cleaning it seemed like the pads could not move freely. After cleaning the pads rattled a little when I carried the caliper back to the bike and I think this is a good thing. Upon reassembly I wil check and make sure that the rear brake lever is adjusted to make absolutely sure that it is not "on " unless my foot is pushing on the lever.

I don' think a few shots of brake clean in there will do the trick. From now on I will pull the pads and use simple green and a toothbrush to get em really clean....hey, don't have to worry about the pistons rusting....I know...They did that for our fellow riders across the pond

 

andy

[Guest ratchethack]

Andy, there seems to be some mystery surounding the tendency of the rear brake to drag, even despite pretty aggressive cleaning (I use Oral-B toothbrushes and Brakleen ). Despite this, my rear pads seem to wear out prematurely, and there've been a number of posts that refer to this. Rich Maund offered a suggestion awhile back that made sense to me. Since the caliper bleeder points downward , there's probably no real chance of getting all the trapped air out when bleeding it. When heated up from normal braking, any trapped air would expand, causing the pads to drag on the disk, causing more heat, causing more drag and wear, etc.

 

Your post gave me a reminder to take Rich's advice and turn the caliper upside down to bleed it. Gotta get a round tuit.

 

Thanks for the reminder and thanks for the idea, Rich!

 

Ratchethack

[andy york]

Yeah, I agree with the upside down bleeder point. It's one of those things that I see and myself says" whose the dipshit that did this" and me responds by saying "Just take the damn thing off and bleed it with the bleed valve pointing up" and then I get through with it and don't realize that not everyone sees things like me,myself,and I .later

 

andy

[Guest Nogbad]

If you fully retract the pistons of any caliper and wedge them back before bleeding it is a lot easier to get all the air out as there is virtually no free volume in there.