Bob Stone pointed out how small the ports are on the common replacement PV2 Chinese brake valves sold everywhere on line compared to what came on our
coaches from Pontiac assembly. The correct part number GM 1257177 or ACD 172-1350 is getting scarce and also fits several other GM applications (1974
SD-455 Trans Am and other HD disc/drum listings). I had my friend who is an ACDelco dealer put in an order for the remaining inventory. These are
available at Highwaystars.net. Be sure to select the genuine GM part as he also stocks the cheaper PV2 in 3 different finishes. According to Bob the
smaller PV2 ports trying to satisfy 4 rear cylinders volume MAY slow full apply time. My theory is since at 70 MPH, 1 second is almost 4 coach
lengths, I prefer the correct OE part on my coach. GM does not allow licensing of any brake system parts as "GM Restoration" so there is no incentive
to do a perfect correct reproduction part. When they are gone, they are gone.
--
John Lebetski
Woodstock, IL
77 Eleganza II
coaches from Pontiac assembly. The correct part number GM 1257177 or ACD 172-1350 is getting scarce and also fits several other GM applications (1974
SD-455 Trans Am and other HD disc/drum listings). I had my friend who is an ACDelco dealer put in an order for the remaining inventory. These are
available at Highwaystars.net. Be sure to select the genuine GM part as he also stocks the cheaper PV2 in 3 different finishes. According to Bob the
smaller PV2 ports trying to satisfy 4 rear cylinders volume MAY slow full apply time. My theory is since at 70 MPH, 1 second is almost 4 coach
lengths, I prefer the correct OE part on my coach. GM does not allow licensing of any brake system parts as "GM Restoration" so there is no incentive
to do a perfect correct reproduction part. When they are gone, they are gone.
--
John Lebetski
Woodstock, IL
77 Eleganza II
