Rebuild K/H Calipers Versus Remanufactured???

Best I can tell no one sleeves these. I'll explain in a minute, but, essentially Dan is correct that the problem is rust. If your calipers are in decent shape, or you are set up to really clean them up, then go ahead and give it whirl.

The rust issue is mostly with the pistons. I had a new NAPA one in the box for 10 years and it pitted. Not sure why the chroming flaked and it rusted, but when I've taken the calipers apart, there is always a piston or two that's rusty. Of course I wouldnt be taking them apart if they weren't hanging up...

The other place that is rusty is the lip on the caliper where the boot sits. I've have gone years without problems with just a standard parts store (NAPA) rebuilt since flushing the system every year and using valvoline's synthetic dot 3 & 4. I was using Castrol's LMA before that.

The reason the K-4 4 pots don't normally get sleeved is because a) the groove would need to be machined into the sleeve. b) the pistons are the real problem. A few places out there do have (or claim to have) Stainless pistons.

All I can say is no matter how much you pay, check them over. I got a set this year and one of the assembly bolts was not seated! Took them out, ran a tap in, and reassembled. Actually, maybe a little overboard but I bought high strength small head bolts from McMasters that look like the original bolts used in the 60s.