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Hey guys,
so last week I started the vette and when I pushed the pedal, further travel than normal and the brake light came on. Turns out one of the seals on my right rear caliper had torn and all the fluid had leaked out. Rear MC was dry.
so I replaced the caliper, recentered the proportioning valve by stomping on the brake(light went out on dash)
but I cannot get any fluid to the caliper. When I use my vacuum pump it just holds a vacuum. I had tried letting it sit for 24 hours with the bleeders open to gravity fill it but the level in the MC doesn’t change at all.
I think the proportioning valve still has fluid cut off to it, but I thought I had centered it and the light is off on the dash.
i can bleed the left rear caliper no problem. And if I crack the bleeder and push on the brake fluid squirts out of the left rear. Fronts are the same way.
Any thoughts or ideas to try?
Last edited by randallsteel; Oct 23, 2021 at 07:57 AM.
Hey guys,
so last week I started the vette and when I pushed the pedal, further travel than normal and the brake light came on. Turns out one of the seals on my right rear caliper had torn and all the fluid had leaked out. Rear MC was dry.
so I replaced the caliper, recentered the proportioning valve by stomping on the brake(light went out on dash)
but I cannot get any fluid to the caliper. When I use my vacuum pump it just holds a vacuum. I had tried letting it sit for 24 hours with the bleeders open to gravity fill it but the level in the MC doesn’t change at all.
I think the proportioning valve still has fluid cut off to it, but I thought I had centered it and the light is off on the dash.
i can bleed the left rear caliper no problem. And if I crack the bleeder and push on the brake fluid squirts out of the left rear. Fronts are the same way.
Any thoughts or ideas to try?
Debris in the line? Maybe take the line off at the front and blow it out with air pressure from the back to the front? Especially the line from MC to prop valve. When a MC gets run dry, whatever junk is in the bottom of the MC might go into the lines. The ports are pretty small on MC, but who knows? Other possibles: deteriorated flex line (just replace them, not worth the hassle), junk in caliper behind the bleeder screws.
Last edited by wwiiavfan; Oct 23, 2021 at 08:20 AM.
How old are the hose's? My last brake bleed before I replaced all of the hose's, with the master cylinder pressurized to 25 PSI one of the calipers was slow to bleed. CSSBinc.com has a hose kit made with Goodyear rubber.
The fact that you have fluid & pressure at the left rear means that the line going to the rears is fine right? So the prop valve is not the issue here.
I think I would back track at the right rear. If both bleeders have zero fluid, then back track to the steel line. Just barely crack that open. Push on pedal.
Still no fluid? Back track to rubber hose and so on.
The fact that you have fluid & pressure at the left rear means that the line going to the rears is fine right? So the prop valve is not the issue here.
I think I would back track at the right rear. If both bleeders have zero fluid, then back track to the steel line. Just barely crack that open. Push on pedal.
Still no fluid? Back track to rubber hose and so on.
that was my understanding of the system, thanks for confirming. If I can bleed the left rear then I should be getting fluid to both rear lines.
I think you all might be right with the hose, if I crack the steel line to the caliper I still get no fluid. I’ll check the hose next, it looks to be very old and has a slight bulge/bubble on one side.
I suspect the rubber lines. They can look great, but the inside could be filled with old hard brake fluid. If the line look bad on the outside, no doubt they are clogged on the inside. I would replace all four lines. Should be $40 to $50. If not concerned about originality, consider braided stainless steel with a Teflon liner. You will also get a firmer pedal. Jerry
There is a brass “T” that is tucked under the left rear frame support with a steel line traversing the aft main frame crossmember over to the right side. That steel line tucks under the differential bracket along that traverse, forming a low point. Years ago, I had a car with a similar problem and found out that line was pinched. I’d recommend removing the rubber hose on the right side and confirming you are getting fluid to the brass connector (where the hose attaches)
Well I replaced the hose, and no change. I ended up using the tubing from my vacuum pump and filled the caliper myself. After I filled it I was able to bleed it with the two person method just fine.
I have no idea the root cause, I am assuming I just had an air lock case, maybe it’s from the specific caliper design. The replacement is duralast brand. Or maybe the hose did have something to do with it and it just wasn’t immediately obvious.
thanks everyone for the ideas and tips.
It was probably the hose; and a good thing that you replaced it as they age-out; often without tattletale. Replace the others as well; no asinine accounting here.
That will be $119.
How do you wish to make your payment?
lol this forum has been a huge help to many people.
I know I’ve learned a lot from reading old forum posts. Probably the single most important thing I learned from this forum was an ingenious way to tell if old material in an oil pan is gasket or babbitt. Hold a flame to it. Babbitt melts and makes a shiny silver puddle, old gasket material doesn’t.
I would have never thought of that, and it let me eventually find out my cam bearings would going bad.
Brake caliper replacement
