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| | | | Joined: Jun 2021 Posts: 157 'Bolter | | 'Bolter Joined: Jun 2021 Posts: 157 | Hi guys, this time I'm having fun with my master cylinder.
The MC is a generic dual cylinder (often called "Corvette MC") with a booster- it sits under the floor of my 41.
Dual drums - residual valves and a proportioning valve in the rear line.
Here is the situation so far:
1 - The brakes where working great with this setup, but the car sat for 10 years, so of course the brakes needed some love. The front cylinders where shot so I replaced them.
2 - rear cylinders looked good (at least not leaking like the fronts).
3. Did a test drive, but was not happy with the brake performance (I remember that it used to be way better).
4. Took the MC out - disassembled it, no rust/crude/slush, rubber looked good - I just blew it out and cleaned everything.
6. Refilled with fresh fluid, bench bleeding - worked like a charm, everything seemed fine with the MC.
7. Put it back in the car, started bleeding the rear with a vacuum bleeder - no fluid coming.
8. I removed the proportioning valve and also the Wilwood residual valves (since I was told that they are carp) to rule those out.
9- New vacuum bleeding attempt at the rear wheels - no fluid coming no dice.
10- Tried the vacuum directly at the MC (just with a short piece of brake line) - no fluid coming.
I'm out of ideas.
Frank | | | | | Joined: Nov 2005 Posts: 6,100 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 6,100 | Hy Stovebold6, short of a hole somewhere in the system not allowing the vacuum to draw fluid when you try vacuum bleeding at the rear, I don't know what might be causing a problem. You said it won't draw fluid from a short line right from the master cylinder, will it pump fluid if you use the pedal? Have you verified your vacuum pump is working and not leaking internally? | | | | | Joined: Jan 2022 Posts: 2,441 'Bolter | | 'Bolter Joined: Jan 2022 Posts: 2,441 | 10- Tried the vacuum directly at the MC (just with a short piece of brake line) - no fluid coming.
If the pedal isn't "all the way up" you won't get any fluid you won't get any fluid.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
| | | | | Joined: Apr 2005 Posts: 7,440 Bolter | | Bolter Joined: Apr 2005 Posts: 7,440 | Brake lines collapse from the inside. Pull your rubber lines and see if they are open.
Martin
'62 Chevy C-10 Stepside Shortbed (Restomod in progress)
'47 Chevy 3100 5 Window (long term project)
‘65 Chevy Biscayne (Emily)
‘39 Dodge Business Coupe (Clarence)
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| | | | | Joined: Jun 2021 Posts: 157 'Bolter | | 'Bolter Joined: Jun 2021 Posts: 157 | If the pedal isn't "all the way up" you won't get any fluid you won't get any fluid. Good call - I will check that. The Return spring may be a bit on the weak side. thanks, Frank | | |
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