I have run into this issue, I wonder where the Vendors get theirs, the mark up is horrible. I was looking into getting a proportion valve and figuring it out. The large valves are all over the place.
Thank you Kodjo, I am looking at making one myself also, thanks for pictures. Nostalgic has an article in their tech articles about the installation of these.
The 630 I got is supposed to be for early Avanti's, it is too small side to side 3 1/2" vs factory 4 1/2". It looks like I would have to make a custom bezel to make it work.
How far are your parking brake handles being pulled out before engaging the brake shoes? Mine seems to be pulled pretty far and was wondering if that could be that the shoes are worn. The shop manual does not have anything on this. Thanks