Hello all, I'm wondering if anybody can answer a couple of questions about a G body master cylinder. First... I'm looking to know if there are any pressure/volume output differences between the front and rear output. I'm under the impression that the Prop. valve handles the pressure/distribution, but want to know for sure. Second... does anybody know the size of the fitting for the rear brake line at the Prop. valve... I've tried 3/8 and 5/16 and it seems to be inbetween. Thanks, Jeff
All cars have to proportion to different pressures from the rear brakes to the front due to weight transfer when braking. If you didn't when braking and the weight transfer happens and load increases to the front and it greatly lightens the rear wheels, if brake pressure was the same the rear wheels would lockup and skid every time you stop. Usually the block that distributes the brake lines to front and rear down below the master cylinder that's on the frame is what proportions the pressures I believe. As for fitmet, I find most of the G-Body's are metric, and the engine's are the last thing that have standard SAE. That is the one thing that drives me nuts about the 80's is the half and half cars. :rant:
Thanks for the info!! I actually found... after driving around to 5 parts stores, that if anybody with a G body blew the rear line from the Prop. valve... they'd be F'd. Digging on the net, I found that GM used a "oddball" size fitting there to prevent a mixup in line attachment at the factory. Since it's the only part on the car to use that fitting, and they're soo old... that equals NO replacement parts. The actual Thread size is 3/16 inverted flare NPT fitting. NONE of the auto stores had a replacement line in that size. NO Adapters, plugs, anything. I did find a "Tee" that had that size to fit in, and a 5/16 brake line size output, but it also had the same size output... so with no plug available, I can't even use that as an adapter. Years ago, I was able to block off that line with an adapter and plug from Autozone(BBB Cutlass kept popping the LR wheel cylinder).. They got nothing now. The only option I have is to see if Ace, or True Value have anything in that size. just got back from hunting... that T fits perfect... so I have something to take to Ace to see if they have an adaptor.ray: I'm still curious to know if the pressure/volume is the same at each of the Master Cylinder connections.... Just in case I have to run new lines.. one to each front caliper.ou: OR see if I can just "Tee" the fronts and block the rear at the Master Cylinder.... What a PITA. Thanks GM:af:
