Brake bleed question

[bugedd]

I am replacing my master in the bugeye, and will have to bleed the system. With this, I would think that all I would need to bleed would be the shortest line to get all the air out, the passenger side front. Would that be accurate, or will I have to bleed all four corners?

 

[Pythias]

This isn't the place to take shortcuts. Do them all, starting with the longest.

 

[LarryK]

Here, Here! Always start the farthest from M/C from rear then front. There are no shortcuts here. Usually , you should bench bleed M/C before assembly, taking care not to spill brake fluid on paint in mounting in car.

 

[Jim_Gruber]

So I had a buggered up thread on one of the lines and did not bench bleed in advance. Other than Pump, pump, pump and then use the MityVac any thoughts / tips.

 

[bugedd]

Huh, I thought you started at the line closest to the MC. And what is the procedure for a bench bleed?

 

[Biff]

Do yourself a big favor and make one of these. It reduces bleeding to a one person job. https://www.bmw-m.net/TechProc/bleeder.htm One modification I made to this system was on the inside of the master cylinder cap was to add a 3/4" piece of tubing. This will create a air gap at the top of the fluid chamber so no turkey baster needed.

You bench bleed a master cylinder to get all the air out before attempting to bleed the entire system. Sometimes a new unbleed master cylinder will become air locked and no amount of pumping will cure that. The easiest way is to install the master cylinder, hook up the brake pedal rod. and make one or two short brake lines from the output connection and run the line(s) back into the brake resivior. Fill the master cylinder and pump the pedal until no air is seen coming out of the return line(s). Remove the temporery lie(s) and connect the real brake line. Then you can bleed thge system without introducing a ton of air into it.

 

[Bayless]

Like apparently most of you, I was always taught to start bleeding from the farthest wheel. Most everything I have read recently though says start with the closest. SWMBO's Saab manual definately says start with the closest. I recently help son-in-law with his Chevy truck and its manual says the same. I know I also read it from some respected source but I can't remember who. So now I am confused.

 

[Jim_Gruber]

LBC Manual says start with furthest wheel.

 

[dklawson]

Regardless of the direction (furthest to closest or closest to furthest) I advise the flush bleed method. I have never used the "pump, pump, pump" method that Jim mentioned.

In the flush method you still need 2 people, plastic tubing, the right box end wrench for the nipple, a catch jar, and lots of new brake fluid. The method is...
Fill the reservoir, then connect the tubing to the bleed nipple and place the other end of the tubing in the catch jar.

1. Open the bleed nipple 1/2 turn and call "down" to your assistant.
2. Your assistant SLOWLY pushes the pedal down, stopping and holding at the bottom.
3. With the pedal at the bottom your assistant calls "down" back to you and you close the bleed nipple.
4. With the nipple closed you call "up" to your assistant who releases the pedal.
5. When the pedal is up, your assistant calls "up" to you and once again you open the bleed nipple again.
6. Repeat steps 1 through 5 until no air bubbles are seen in the fluid moving down the clear tubing.

Every few pumps, slide out from under the car and top of the reservoir.

This has always worked for me and your helper doesn't have to be a strong adult, even a young child can be your helper.

 

[Jim_Gruber]

Hey I just did this last night. Tried with LR at first and could not get any fluid back there. Since this was a new rebuilt MC I thought a big Uh Oh! Tried with LF got fluid there, moved over to RF fluid there, RR good pressure , and back to LR - nothing. Pulled bleeder, cleaned with drill bit, used drill bit in bleeder hole to root around, reassembled bleeder and tried again. Seemed to be an issue getting fluid through wheel cylinder when all of a sudden what appeared to be a lot of really dark, heavy fluid popped out in the hose and then great pressure. Just had to be patient. Wheels went back on and Bugsy went for a test drive in snow flurries last night. He was a little cranky after not being out of the garage since August but started up and all worked well, all systems functioning. Both Clutch and brakes bled with fresh new fluid and new MC on brakes.

A little sad this AM seeing Bugsy in the driveway this morning out of the garage. Needed to rearrange garage and make access room as new kitchen appliances are scheduled for delivery tomorrow so he needs to sit outside for a night or two. But next weekend Bugsy is scheduled to go to a new owner in RI. After 12 years I will be without a Sprite in the garage. But it will not be long before my new '59 Sprite in a Box gets brought home from Toronto later this month. Then the fun starts.