I have struggled for years on getting a good brake feel in my cars. If you have every driven a new Camaro or Corvette the brake feel is fantastic! I looked into how GM does it from the assembly plant.
We use an evacuation and fill process.
• If the system will not hold pressure you have a leak. I used my set up to pressurize the system (Dry) to 50 psi. At 50 psi you can hear any major leaks. I forgot to tighten on flare nut. Once I tightened that up system would still not hold 50 psi for 30 minutes. I used soap and water on all the fitting until I found the one slightly leaking. Once the system held 50 psi rock solid I knew it would not leak..
• Connect a vacuum source to a 100% dry system and pull a vacuum down to around 28 to 30 inches of mercury. Hold the vacuum for approx. 30 minutes. This does 2 things: shows the system is air tight and boils any water vapor out of the complete system. So the system is air tight, the bleeders are closed and the entire system is under vacuum.
• My set up has two ports on it. One to pull a vacuum via an A/C evacuation pump and the 2nd hold brake fluid pressurized to 50 psi via pressure regulator.
• Once the complete brake system is pulled down to full vacuum, I close the valve to the vacuum pump. The upper tank has 1.5 quarts of brake fluid in it pressurized to 50 psi.
• When I opened the valve it allows the brake fluid to be forced into the system. It fill everything: brake master cylinder, brake ABS module and all 4 calipers.
• After the fill the brake master cylinder reservoir is also over filled. I applied a vacuum to my set up and pulled a little brake fluid out to set it at the “full” line on the reservoir.
I know this will work on new GM brake parts because GM validated the parts to be used this way in the assembly plant. The parts will withstand full vacuum and 50 psi. I am not sure if aftermarket parts will hold up to this!
After I did the first evacuation and fill I had fluid in all the calibers and ABS module. I did a quick ABS bleed on the system by pressurizing the brake reservoir to 50 PSI and cycling the ABS module.
After that I have not touched my brake system again and my brake pedal feel is like a stock ZR1 Corvette.
Having spent almost 6 hours on Sat bleeding mine using a vacuum approach and old school manual bleeding (my daughter earned 10 bucks for sitting in the drivers seat laying on her ipad and pumping the brake pedal) your idea presents an interesting idea.
I like the simplicity of the idea, but you mention an empty system. For most of us, that's rarely the case. We might be changing an existing part in an existing system. But this could still work. Firstly, take an existing system with fluid in the lines. Connect your system, open all the bleeders (connect some plastic hose and "pots" to each one). Power it up, open the valve and flush all fluid from all lines, emptying the system.
Then repeat the process as you've described in your video to refill and bleed the system.
Thoughts ?
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Having spent almost 6 hours on Sat bleeding mine using a vacuum approach and old school manual bleeding (my daughter earned 10 bucks for sitting in the drivers seat laying on her ipad and pumping the brake pedal) your idea presents an interesting idea.
I like the simplicity of the idea, but you mention an empty system. For most of us, that's rarely the case. We might be changing an existing part in an existing system. But this could still work. Firstly, take an existing system with fluid in the lines. Connect your system, open all the bleeders (connect some plastic hose and "pots" to each one). Power it up, open the valve and flush all fluid from all lines, emptying the system.
Then repeat the process as you've described in your video to refill and bleed the system.
Thoughts ?
You'd blow the line right off the bleeders..... and then blow fluid everywhere.
Mark doesn't go into enough detail about where he took the vacuum from --- and put the pressure to. Is the vacuum at ONE caliper - farthest away from the Master cylinder or where?? If so - how do the other calipers get fluid?
I like the idea but was left totally not understanding the detail of the process.....
Mark doesn't go into enough detail about where he took the vacuum from --- and put the pressure to. Is the vacuum at ONE caliper - farthest away from the Master cylinder or where?? If so - how do the other calipers get fluid?
I like the idea but was left totally not understanding the detail of the process.....
It looks like the lower gauge on the manifold is where the vacuum is pulled from and the pressure is applied from the top of his reservoir, which would work just fine....if all the ports in the system are wide open. Obviously not the bleeders.
Brian Hobaugh SCCA National Tour June 2014
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