Bleeding Brakes

[floridawing]

Hello, I installed new brakes and discs and drained and replaced the brake fluid on my Rocket. My brake reservoirs are attached to the master cylinders. I tried to pump fluid from the bottom up. Unable to get any brake pressure. We tried to pump fluid from the top down releasing pressure at the caliper. No luck. My fluid reservoirs and not the highest point in the system. Any help would be appreciated.

[Allan Stern]

A couple of things that might give you a problem.

1. Did you pull the brake pedals as far back toward you as possible? If one of the orfices is even a tiny bit blocked, you won't get them bled.

2. If you don't open the bleed screw far enough again you won't be able to force fluid up from the brake caliper.

3. If you try from the top down by pumping the pedals and are not getting pressure there is too much air in system. You can pressure bleed from top down to bottom as vice versa.

Hope this gives you some ideas.

Allan

RV 6A sold
RV8A sold
RV 12 flying
RV 14A building
Donation paid

[swaneymj]

I had the same problem just recently on my F1. I have a Matco parking brake installed and mounted just under the center of the instrument panel. That made it the high point of the system. I was able to loosen the AN fitting on the parking brake while my helper opened the bleeder fitting on the caliper with a pressurized bleeder tank attached. I could hear the air come out - then it got messy while I tightened the AN fitting. Not a pleasant technique, but it worked for both sides.

Mark
Team Rocket F1 N76TR

[F1R]

Originally Posted by floridawing

Hello, I installed new brakes and discs and drained and replaced the brake fluid on my Rocket. My brake reservoirs are attached to the master cylinders. I tried to pump fluid from the bottom up. Unable to get any brake pressure. We tried to pump fluid from the top down releasing pressure at the caliper. No luck. My fluid reservoirs and not the highest point in the system. Any help would be appreciated.

In general, because of the large loop that rises above the gear legs before brake line drops lower at the fire wall and then a second flex loop up and back down to the master cylinders on the pedals, it takes lots of rapid flow to clear all the air out. Best results happen when you have a temporary return line out of the reservoir top/vent out of the cockpit and back down to the bottle you are pumping fluid from into the bottom bleed fitting. A see through return line lets you know when there are no more air bubbles returning.

I have owned other homebuilts where the brake line was a 100% uphill path from the bleed fitting to the reservoir top. With that you could slowly use a syringe with the exact volume of fluid needed to slowly fill from the bottom with no return line- and get rock solid brakes every time. Rockets and most RV 4's are NOT that way.

[Toobuilder]

I pull a vacuum on the top of the reservoir, the bleeder line in a can of fluid. Crack the bleeder line and it will suck a solid slug of fluid in seconds. Takes a bit to set up, but the bleed itself is done in a flash. Rock solid.

[Pat Falley]

With the RV-4, we have to unbolt one end of the master cylinder and rotate it such that the line to the brake sits lower than line to the brake fluid reservoir. This puts the "air" side up so you can pump fluid through the master cylinder without trapping a bubble. This works when you fill bottom to top using the brake bleed valve.

Other than messing with cotter pins, it's an easy one person job and there is no question all air is out of the system.

[swaneymj]

I followed the plans but always wondered why the master cylinders couldn't be mounted 180 out?