Brake Bleeding - The When and The How

[cv2065]

I've tried a couple different ways to bleed brakes in the past. The two person pump and hold method, as well as the gravity bleed. The wife hates the former. I once tried a pressure bleeder from HF but could never get it to work right. The last build had OK brakes, but I never felt that I had gotten it 100% despite a few times trying. Maybe it was just because I was manual. I'm not quite there yet but wanted to see what most people were using.

First is the when. Do you all bleed the brakes once the lines are completed, and the engine is in or prior to installation? Seems like there would be an advantage to bleeding before an engine install in the event a line or union needed to be swapped out.

Second is the how. A few options:

1. 2 person Pump and Hold
2. Gravity Bleed
3. MityVac
4. Motive Power Bleeder
5. Speed Bleeders
6. Phoenix Bleeder Kit (Reverse Bleeding System)

Is bench bleeding the MCs absolutely necessary and is it a good idea to pressurize the system with air prior to filling with fluid to check for leaks?

Anyone have any dos/don'ts on these methods, or others, as well as tips on keeping a clean shop, as that stuff eats through anything it touches, including new Wilwood caliper paint.

[nuhale]

I built a pressure bleeder using a garden sprayer and some random parts. This coupled with bench bleeding the MC works best IMO. Very easy and I think was under $15.

[JohnK]

My preference is pressure bleeding. CNC used to make a cap for their reservoirs specifically for pressure bleeding but you could do the same thing with a spare cap and a schrader valve. If you have a compressor, set the outlet pressure really low (5-10 psi) and then just crack the bleeder at each caliper and let fluid flow until there are no more bubbles. Repeat a few times as necessary. I bench bled the MC, and then went around and bled each caliper this way 3 times, and was good to go. Make sure and top off the reservoir after you bleed each caliper to avoid running out of brake fluid and sucking air back into the system.

[cv2065]

My preference is pressure bleeding. CNC used to make a cap for their reservoirs specifically for pressure bleeding but you could do the same thing with a spare cap and a schrader valve. If you have a compressor, set the outlet pressure really low (5-10 psi) and then just crack the bleeder at each caliper and let fluid flow until there are no more bubbles. Repeat a few times as necessary. I bench bled the MC, and then went around and bled each caliper this way 3 times, and was good to go. Make sure and top off the reservoir after you bleed each caliper to avoid running out of brake fluid and sucking air back into the system.

John - Did you fill the system with air before adding fluid to confirm no leaks or did you just start with fluid first? I see that the Motive instructions have you fill the system with air and leave for 10 minutes or so prior to bleeding.

[JohnK]

No, I went straight to fluid.

[gbranham]

I've bled a lot of brake systems over the years, and hated every second of it. Gravity, vacuum, etc...it all stinks. On my MkIV, I bought a $65 pressure pump on Amazon, and it was the easiest thing ever...it took 15 minutes to bleed my brakes, and I went 'round the horn' twice. Rock solid brakes. And I didn't fill the pressure bleeder reservoir with any fluid, so there was no mess. I will never, ever bleed brakes any other way. The pressure bleeder looks like one of those weed killer pressure pump/sprayers. It has a cap that fits the Complete Kit-supplied brake fluid reservoir; screw it on, attach the air line, pump it up, and start bleeding brakes.

Greg

[cv2065]

I've bled a lot of brake systems over the years, and hated every second of it. Gravity, vacuum, etc...it all stinks. On my MkIV, I bought a $65 pressure pump on Amazon, and it was the easiest thing ever...it took 15 minutes to bleed my brakes, and I went 'round the horn' twice. Rock solid brakes. And I didn't fill the pressure bleeder reservoir with any fluid, so there was no mess. I will never, ever bleed brakes any other way. The pressure bleeder looks like one of those weed killer pressure pump/sprayers. It has a cap that fits the Complete Kit-supplied brake fluid reservoir; screw it on, attach the air line, pump it up, and start bleeding brakes.

Greg

Hey Greg. Do you have the link? I think I saw Frank on ie427 do the same thing with the Motive system. He didn’t fill the canister with fluid to avoid the mess and said it worked great.

[gbranham]

Hey Greg. Do you have the link? I think I saw Frank on ie427 do the same thing with the Motive system. He didn’t fill the canister with fluid to avoid the mess and said it worked great.

Yes, sir! Here you go! It makes the task so much easier! Apologies for the sidey-ways picture...I don't know how to rotate them.

Brake Bleeder.jpg

Amazon.com: SMOTIVEPRO 2L Manual Brake Bleeder Fluid Pump, One Man Professional Brake Bleeder Kit Suitable for Most Brake Mast Cylinder Reservoirs : Automotive

Also, I 'bench bled' my Wilwood MCs in the car. I connected a fitting to their 'output' (where you hook up a hard line), and connected a short piece of hose to that fitting, and routed it to a mason jar full of brake fluid. I pumped the brakes a million times, ensuring the brake fluid reservoir didn't run dry, and kept pumping the brake pedal until I didn't see air bubbles in the line that dumped into the mason jar. In short, it was a closed system, and I just kept cycling brake fluid until I felt there was no air in the master cylinders.

[JJK]

I had a helper and followed Wilwood's advice for bleeding the two on the passenger side simultaneously, followed by the two on the driver's side simultaneously. Firm pedal with no issues
https://www.youtube.com/watch?v=jELllXdtjdc

[OB6]

Hands down, I always get the best pedal feel with gravity bleeding. However it helps to start with pressure if you're dealing with an empty system. I use a garden sprayer for that.