Hello all,
So I have been trouble shooting front end shudder. While taking apart the calipers for a rebuild, I noted that the pistons on one side are black, the other side chrome. I suspect perhaps the previous owner did a rebuild of one side. The one black one I pulled looks good, no pitting nor corrosion. I am confident that this is not the cause of the problem. Now I am contemplating the replacement of the pistons during the rebuild vs. just replacing the seals.
Does anyone have any experience with these black, seemingly lightweight pistons?
Any advise on spending an extra 60 bucks or so that may not be necessary? Thanks in advance

About the shudder...

I don't have any sure fire answer. I'm using EBC HH sintered and notice a shudder sometimes especially at lower speed braking. I do not recall this occuring with the OE pads. These fronts are at 50%, and inspecting the pads they were wearing evenly on both sides for both rotors.

I replaced the OE pads at 12.8k miles. I know EBCs have a great reputation, but I actually prefer the OE pads. The EBCs have a vague feel to them, and I feel like braking feel was more clear with the OE pads. And as I say, I don't seem to recall any shuddering at all.

I have a set of SBS (whatever the high perf street ones are, RS and LS I think) pads on the way, and I'm going to replace the EBC's hoping perhaps they will give me more of the feel and perhaps (although only a minor annoyance) the occasional low speed shudder.

A couple other things, if you haven't considered already. Suspension control issues, tire wear (cupping), balance. A couple things to consider to is does this happen in the same roads or times of day or year?

My thought would be;
1. Were they leaking? No. I'd reuse them but swap two for two so OE is in one hole, aftermarket in the other hole, not all aftmk in the one caliper and all OE in the other caliper.
2. Are the blacks lighter than what looks stock OE? Yes. Even if they didn't solve the shudder, at least they are all OEM for another 60 bucks.
3. With wheel in the air, calipers off, a toothpick taped to the fork; and the end of the pick about a hair off the disc and now is there more air-gap or is now the rubbing of the toothpick? And there you go, warp discs.
4. No leaks, no warp, and is this high speed, grab the lever and feel the shudder? Yes. Normal. I have video of coming down from high speed and you can see the camera pickup the shudder.

I have experienced shudder and stopped it by cleaning the spools that the disk mounts on to the carrier. There is thread somewhere on here about it but I could not find it. Liberal amounts of brake cleaner until there is some movement in the spools