Hi there. Will be converting my 70gs455 to front disc oem style. Can any one recommend best disc/drum proportioning valve. if you have part no. even better. Thanks, HVRAMESQ
In 1970, the factory disc brake system used a separate hold off valve, and proportioning valve. The hold off valve was up near the master cylinder. and the proportioning valve was mounted to the frame. In 1971, both valves were combined in one unit called a combination valve. If correctness isn't important, you can use a Chevelle combination valve like this one, http://www.ss396.com/chevelle/FPR-102.html
This is what I used, it is a reproduction, looks like the originals. http://www.ebay.com/itm/67-69-GM-A-...ash=item4d4c83d046:g:npcAAOSwzaJX~A7d&vxp=mtr But they come in different packages, some look original others not so much, but all work. http://www.ebay.com/itm/67-69-GM-A-...ash=item4d4c83d046:g:npcAAOSwzaJX~A7d&vxp=mtr
Those are hold off valves. The proportioning valve is separate 70 and earlier. The one I linked is a combination valve, hold off valve and proportioning valve, one piece, like in 1971 and later cars. http://www.ss396.com/chevelle/FPR-102.html
For 70 all you need is the hold off, the lower valve is just a distribution valve , it's the same on both disc and drum 70's just mount the hold off and get the line kit and all will be fine
Ethan, Are you sure that is true of the 70 factory disc/drum systems? Curiously enough, I could find no mention of a proportioning valve in the 70 Chassis manual, so you may be right. In the 71 and later chassis manuals, they describe the combination valve for disc/drum systems as having separate proportioning, hold off, and warning light sections.
Best to my knowledge that's the case, I know I've left the frame valve and just installed the hold off and it's stopped as it should with good pedal, think I read on TeamChevelle years ago that it's just a distribution valve as it has no plunger assembly like the 71+
