stingr69

Willwood calipers, not master cylinder. Sorry.

cagotzmann

Ok I have the same parts in my 1978 Corvette. My car is used for track days so BRAKES are very important to me.

So this setup has some differences to FACTORY OEM Parts. Nothing that cannot be fixed to work same as factory parts. I tried factory parts but at the track the caliper seals fail due to high heat, and that is why I now use wilwood D8-4 and D8-6 calipers.
I also have there MC. MasterCylinder No: 260-8556

So from the MC point of view. The rod between the MC & the Power Brake booster must be checked / Adjusted. Mine was to long and applied brakes / drag allways. You will need to measure the distance from mounting surfaces to see where yours sits.
This video shows the what your are measuring. The adjustment for my 1978 had a solid rod so I had to cut / file to get the length I wanted. You may need a adjustable rod or a solid longer rod as a start. Start with longer vs shorter.

1. Then Bench bleed the MC the best you can. You wont get a 100% bleed but that doesn't matter, we can bleed the MC after installed.
2. For the wilwood rear calipers DO NOT MOUNT FOR THE FIRST BLEED. The bleed ports wont let all the air out. Place them in a vertical position while connected, and place something between the brake pads similar width of the rotor.
3. Front calipers are ok to mount.
4. Fill the MC full of brake fluid.
5. then start to fill all the brake lines with fluid. Start with the longest brake lines to the shortest brake lines.
connect a plastic hose to the bleeder and collect the fluid in a jar to reuse the fluid.
6. Pressure bleed the MC to push fluid to each caliper.
Here is what I do, I use my air compresor connected to a plate I made. Set the PSI ~ 20PSI. As shown front MC Air line connected, rear MC I installed a valve to close line.



During this step you should see fluid in the hose attached to the caliper bleeder. Should flow nice and easy. Check the MC Often to make sure you dont empty the MC.
I use a 10ft long clear vinyl tube and bleed approx 40ft of fluid before I refill the MC. Add a bubble into the tube so you can see how much fluid is moving.

Once you get fluid out of each caliper bleeder then you can assume the system is full and READY TO BLEED THE AIR OUT.

So start with the Wilwood Rear Calipers. Still positioned in a vertial alignment. Push / clamp /wedge the brake pads in as far as they can go. Force the caliper piston in to push all air trapped in the caliper piston into the caliper piston fluid path. Then bleed each bleeder until you dont see any air. Then mount the calipers back on the car. You may be forced to repeat this step.

!!! important -------- The next step is the bleed the MC while installed on the car. Here is how I do this
Get the last bit of air out from the brake master cylinder. - CorvetteForum - Chevrolet Corvette Forum Discussion

Once the MC is clear of all air, then we can bleed all the calipers again.

Using pressure at the MC, clamp / wedge / push the brake pads into the calipers (push caliper pistons in) then pressure bleed the caliper. Start with the caliper with the longest brake line.
Once you are happy with the caliper bleed, relase the brake pad clamp to allow the MC pressure to push the pads to the rotor. Once the brake pads are seated on the rotor, release the MC Pressure and move onto the next caliper.

Once this has been done to each caliper, check the brake pedal firmness. If its soft then repeat.

1. Bleed the MC while on the car.
2. Place the rear wilwood caliper in the vertial position / unmount from the car.

After each step check the brake pedal firmness.

You can also test if the MC / power boosted rod is close in gap by placing your bleeder hose on 1 caliper bleeder and see how much fluid is pushed with a single push of the brake pedal.
During this test the brake pedal will move from the noraml position to the floor easily, but will push plenty of fluid.

Good luck in checking each step.

7Ronin

First, thank you very much for taking the time to write that out. Second- Holy Moly what a lot of ***-pain for something that should be easy general maintenance. I was hoping the Wilwood setup would help alleviate some of the the OE shortfalls when it comes to bleeding etc. but apparently not. As it stands now- I'm close to 3/4 the cost of the T56 conversion I did and easily way over time-wise already just to have functioning brakes. Man, just totally appalling how difficult something that is easy on every other vehicle I own (9+). Guess I'm in for a few more hours of brake bleeding nonsense.....

TOM B1

The gap is important but will not cause spongy brakes. its nearly impossible to bleed the brakes on a vette by pumping the brake pedal. you can make a simple pressure bleeder very easy. does not have to be steel, it could be a piece of heavy plastic or ceramic, and just use hose clamps to tighten it on. you only need a few pounds of air pressure, maybe 5lbs. done this plenty of times. I have a Wilwood master cylinder and made a cap for it out of a darn piece of wood with a rubber seal way back when. and its still working great. all master cylinders hold a very low amount of pressure in the piston between the seals and almost always need to be pressure blead. Start with the right rear then the left rear. then the right front then the left front. Dont make this harder than it is, keep it simple.

ctmccloskey

I am always surprised that someone doesn't suggest the Phoenix Reverse Brake Bleeder when you have a car with tough problems getting their pedal back to where it should be. I have tried several devices designed to assist you in bleeding your brakes. Many of them occupy spots on the garage shelf and are accumulating dust because I finally found the one tool that really gets the brakes bled completely. I have two Corvettes, a C3 and a C4. The C4 brakes are even harder to bleed than the C3's are. I have also had issues bleeding the Clutch hydraulics as well on a GM pickup truck.

Trying to push or force air to go down is not an easy thing to do. When a system has been completely drained even more air likes to stay in the brass blocks and other spots inside the calipers themselves. Using the Phoenix system you actually PUSH the fluid up back to the master cylinder and this is the best way to get air out of the system. You can gravity drain for weeks and it will not remove all the air, putting 20-40 psi of air pressure pushing the fluid down from the master cylinder can squirt a lot of fluid out but not the air that is trapped in the system.

I tried switching to a Silicone brake fluid and this required flushing the system several times to get it prepared for the silicone brake fluid. The Phoenix Bleeder made the job fast and easy and I was able to get a solid brake pedal very easily. I have used my Phoenix bleeder on Aircraft, boats, motorcycles and cars and it has worked perfectly every time I use it. You don't need to buy the most expensive Phoenix pump to do the job but the one I have came with a kit full of fittings and adapters. I like that fact that it is re-buildable so after a few years of use I can restore the unit to new condition and keep on using it. It is a quality tool and it will make brake bleeding a lot easier and this makes it easier to do every five years like manufacturers recommend. I am tired of replacing rusted out lines so I have a tool which makes flushing the brakes a whole lot easier.

This is a tool that really makes the job of bleeding the brakes easier. Pushing the brake fluid and air UP makes more sense. It is different and can be messy if you are not careful but once you master the tool you will not go back to the older gadgets.

HeadsU.P.

Some year C3 s have bleeder screws on the Master. Then, a reverse flush makes sense. With the MC lid clamped on and two hoses on the MC bleeders into a plastic bottle, I can see the idea.

But, a MC without the bleeders? Reverse flush would make a horrible mess. How would you collect the overflow at the MC?

I am real skeptical about that reverse system. The Dot 3 would remove paint all around the MC.

riverracer au

how do you go about doing the rear calipers with 2 bleeders per caliper?

cagotzmann

Well after many years of track days, and bleeding brakes to make sure they can be trusted, its all about knowing where the air gets trapped.

For my 78 with wilwood caliper / wilwood MC I have found 2 main places.

1. behind the pistons in the caliper
2. in the MC it self.
3. exception for wilwood rear (first time bleed) bleeder screws poor angle.

#1 best to pressure bleed, shortest path for air bing pushed.

#2 best to bleed the MC while on the car.

Its not the path of pushing fluid that helps, its knowing where its trapped. and the shortest path to remove the air.

#1 requires pushing / clamping the pistons in as far as they can go and using ~ 20 PSI at the MC to flush
#2 requires positioning the MC at the proper angle while on the car to bleed as designed. This can be done lifting the rear of the car, or parking on a road with ~ 11+ degree of slope.
#3 bleeding without mounting.

ctmccloskey

With the multiple bleeders on a Caliper I have found it helpful to push fluid up to the master cylinder from each of them. On occasion I have found that "tapping" on the caliper with a Rubber Mallet can sometimes help the bubbles get out of the caliper while pushing the fluid up and out. On cars with a new master cylinder I bleed each wheel up to the lines that connect to the master cylinder and after getting all the wheels done I then make the connections and then push just a little bit of fluid up afterwards.

Reverse bleeding can make a big mess and damage the paint if the fluid is not contained. I use a turkey baster and drain the master cylinder reservoir's to a low level and then push the fluid up. I also have a container below the master cylinder to catch any excess fluid. When flushing or bleeding I like to remove the lines at the master cylinder and connect a rubber hose over them to catch the fluid and put into a container. This is not a big problem as long as you are prepared for the fluid coming UP to the master cylinder. I keep pumping fluid up until it runs clear like the new brake fluid is.

On the C4 I have the rear brake circuit is one line that goes to left side and then tee's off to the get fluid into the right rear caliper. There is a nice air gap built into the system and it really makes it easier using the Phoenix pump. The same goes for the very crude and basic ABS system they used in the 1988 C4's, there are several places that have air locks built into the system. I have been activating the power to the system while pushing fluid through to get the ABS filled up and all the air out of it as well. Every time I work on the C4's brake system I sure appreciate the C3 brake system's simplicity. I am still looking for the cartridge made for the Snap on MT2500 that makes bleeding the brakes even easier with the Bosch ABS as it cycles the solenoids to allow easy bleeding of the system.

I have not had to raise the front of the car to get my brakes working properly on either the C3 or the C4. The only time I raise the front of the Corvette is to ensure that I have a full cooling system and that seems to be more effective on the later C4 and it's strange cooling quirks.

I hear what you are all saying about the tricks you have learned and shared with us here online at the Corvette Forum. Obviously there are many ways to get the air out and the pedal hard as we have been driving these cars. I just wanted to mention the Phoenix as it turned out to be my primary "go-to" tool when working on brakes. I still have my other brake bleeding tools available but have found that the Phoenix makes flushing or bleeding the brakes the easiest for me on my Corvettes. Just as heat wants to rise naturally so does the air so why try and force it down and out? Using the Phoenix bleeder I can flush the brakes on my RV in less than an hour which means it gets done on schedule since it is easier to do. The Phoenix also makes the Corvette easier to flush so I try to stick to every five years as my service interval. Without the Phoenix reverse bleeder I would be paying someone to do it for me as it can be a real PIA at times.

Best regards,
Chris