Need advice please. Disc brake set up on the GS is from a 1971 GS, which means the combination/ proportioning valve is on the frame. The master is new, the vacuum booster is the original. The valve is the old 0411 Bendix (see below). The problem I am having is that the fronts have bled perfectly, with high pressure. However, there is not a DROP coming out of the rear wheel cylinders. There's fluid spraying out of the Bendix 0411 with the rear line removed. The rear intermediate line flows fine, the rubber diff line is new, both lines going to the wheel cylinders are new, and the wheel cylinders are new. So... 1. Do I need to get the little tool that keeps the switch located in the proportioning valve in the middle? 2. Is it possible that the master cylinder rod is too short? This is driving me mad. I have replaced the 0411 Bendix valve with 3 different ones and now am using an aftermarket one....
Do you have pressure going into the rear flex line? Can you try bleeding it from there to see if you have fluid?
The rear flex line that splits off to the 2 sides can collapse internally making it act like a check valve. Nothing shows on the outside of it. I found out the hard way , spent an entire long weekend messing with my brake system to come down to that conclusion. I could get fluid by bleeding but problem was it wouldn't return to release pressure on shoes.
George I took one of those apart years ago. It was gummed up and had some rust. Cleaned it and worked fine afterwords.
Something like this, Larry. It's got a good cross section shot of the part. You stick like an awl in and center it, then the tool holds it. https://www.ebay.com/itm/152216419694?hash=item2370ce3d6e:g:GjsAAOSwnAJeK0OL
That has to be a real pita with the combo valve mounted on the frame. Guess that's why I opted for the under master style mount.
With the under master mount, you can unscrew the brake light switch and see right in there to see if piston is centered neutrally...very easily.
This is gonna sound crazy but a few years ago I was replacing wheel cylinders on the rear of my wildcat. I always take the bleeder screws out to antisieze the bleeders and noticed that they did not have a hole drilled from beneath the bleeder screw into the fluid chamber between the pistons. I was lucky to catch this otherwise I don’t know how long I’d have been banging my head trying to bleed the rears.
Well... even though I bench bled the master, I had air in it.... ughhhh. Once we blew out the line and drove the air out, amazingly, I have perfect brakes! This has been a PITA... On the brighter side, this car will be ready to cruise in the next week or so... More to follow! Thank you all!
