Changing out master cylinder and booster, but when bench bleeding the new master cylinder I found the proportioning valve appears to be leaking, very small air bubbles showing. Looked on line for these valves but can't find one that replaces it. Did a disc/drum job a few years ago and it appears my rear drums had very little use, replaced wheel cylinders and front calipers, but not master. I suspect the valve on the master has not worked for a long time.

Thinking about eliminating it and using an adapter. Anyone else have a similar experience with this?