hydrolics

[tahoe healey]

I am getting ready to re-do the Master cylinders (brake and clutch) and it has been many, many years. I have forgotten how long I need to soak the rubber parts in brake fluid. Also, is it necessary to fill the masters with fluid to "prime" it or is gravity good enough to start the pumping? I have been waiting for Moss to get a supply of non-Classic Gold masters.
Thanks
TH

 

[Randy Forbes]

I don't soak any of the wetted parts, but I do use the red rubber grease that Girling supplies.

You definitely need to "bench bleed" the master cylinders; I use an old piece of brake tubing, long enough to reach from the m/c to below the fluid level in the reservoir.

Then I finish the job off with this...

 

[richberman]

Randy,
Won't the Bavarian auto pump bleeder clear the master cylinders?
rich

 

[Randy Forbes]

Randy,
Won't the Bavarian auto pump bleeder clear the master cylinders?
rich

You'd think it would, but the job goes far more smoothly if the masters are bled prior to the remainder of the circuits.

Note too, that when bleeding a completely dry system for the first time, it will take a few attempts before you get ALL the air out of the front calipers. I don't try to do it all at once, but wait a day or so in between bleedings.

 

[Johnny]

:thumbsup: Couldn't help notice the BIG pipe wrench laying on the motor, what's that used for?

 

[Legal Bill]

Do you guys find you need to bleed the booster too? I still have a bit of air somewhere in my system.

 

[Johnny]

TH, I bought a new MC from Moss and it came with small plastic bleeder fittings that screw into the MC. Just attach a clear hose to the fittings and "bench bleed" by hand pumping the MC. At least that's the way I remember doing it.

 

[Randy Forbes]

:thumbsup: Couldn't help notice the BIG pipe wrench laying on the motor, what's that used for?

Actually, that's a strap-wrench; the plastic bleeder cap would "lock" itself on the reservoir, and I needed its help to get the cap back off.

 

[Randy Forbes]

Do you guys find you need to bleed the booster too? I still have a bit of air somewhere in my system.

Absolutely.

Also, it takes a while to get all the air from a pair of freshly rebuilt calipers. The brake fluid manufacturers benefit the most!

 

[tahoe healey]

Wouldn't the servo bleed with the whole system if it is not tampered with? I will be removing all the brake fluid in the system and thought I could just pump new stuff in after replacing the master cylinders and flexible brake lines.(The wheel cylinders were rebuilt and/or replaced a year ago)

 

[Bob_Spidell]

The servo cylinders--there's two of them--don't have bleed screws so you can't really bleed them (without opening the lines, which defeats the purpose). In my experience it's best to pressure bleed the system--like Randy's kit does or I use a modified reservoir cap with a shroeder valve for (low) pressurization--or, do it the 'old-fashioned' way with a helper pumping the pedal. You may have to bleed more than once.

One thing I've observed: you may go through a 'typical' bleed cycle and get clear fluid (no air) then, if you keep bleeding, more air comes out. I think this may be due to the servo holding a 'bubble' of air that has to be pushed all the way through. Plan on using up to a quart of fluid to bleed both systems.

Do bench bleed the masters.

 

[Ed_K]

Don't let this happen to you !

If you have one of those HELP master cylinder rubber gaskets in place of the stock gasket, ( search for old topic on the subject), with the little vent hole covered up to keep the moisture out of the reservoir:

Do not overfill the brake reservoir when you are all done bleeding the system. Just fill it a little above the top of the inner reservoir can.
I filled mine up too full earlier this year after I replaced a lot of my brake system parts. When the fluid expanded from the heat of normal braking, there was no place for the expanded fluid to go. That made the brakes slowly apply all by themselves !
That took me a week or so of trouble shooting before I figured out what was happening.

As a result of this , I had to bleed the system so many times that week that I bought one of those bleeding tools after I saw the picture of Randy's tool on the forum. Mine is a " Motive " brand. I bought the one that comes with a cap that is made to fit in the place of the reservoir lid of our cars. That was the best money I have ever spent on a car tool. Just fill up the reservoir with fluid, screw the tool's cap onto the reservoir, and then pump it up to 4 or 5 lbs. You can bleed the entire system by yourself in no time. It worked so well that I bled the clutch system the same way. To my surprise, it spit out some real nasty looking fluid and air that I did not know I had in there. When I was done I had rock solid brakes and the clutch starts to disengage with only a small amount of pedal travel.

Get one of those tools. You will wonder why you never tried out one before.

Ed

 

[Legal Bill]

Wouldn't the servo bleed with the whole system if it is not tampered with? I will be removing all the brake fluid in the system and thought I could just pump new stuff in after replacing the master cylinders and flexible brake lines.(The wheel cylinders were rebuilt and/or replaced a year ago)

Same reason you bleed the master. Air gets trapped at each major component. You just crack the fitting line while someone stands on the brake pedal and then close it quick while you listed for air and look for bubbles and try to keep the fluid off your paint.

 

[Randy Forbes]

Wouldn't the servo bleed with the whole system if it is not tampered with? I will be removing all the brake fluid in the system and thought I could just pump new stuff in after replacing the master cylinders and flexible brake lines.(The wheel cylinders were rebuilt and/or replaced a year ago)

Same reason you bleed the master. Air gets trapped at each major component. You just crack the fitting line while someone stands on the brake pedal and then close it quick while you listed for air and look for bubbles and try to keep the fluid off your paint.

Agree. When I do a complete system, including all new pipes, I loosen every fitting to get clear fluid it out of it. Contrary to a typical bleed, I start cracking open fittings starting closest to the master cylinder and work to the farthest...

... at which point, I start the normal bleeding process, working back towards the m/c.

EdK, mine is a Motive Bleeder too, just rebranded by Bavarian :wink: