well i rebuilt my mcleod adjustable master cylinder but ive been searching on bench bleeding methods. Would it be ok to just put the master back in dry and start bleeding from there. I dont have a mity vac and most of the instructions online are not that detailed on how to bench bleed for the first timer. Anyway when you bench bleed you dont have the braided line connected to the slave so what would it matter if i did it while installed on the car. Im assuming insteading of pumping it with my hands i could do it with the clutch pedal. Another thing is, i cant find any detailed instructions on how to use the mity vac. now that its put together i dont know where to go from here as far as bench bleeding goes.....


thanks

 

I just bleed it out of car w/ the line installed.
Hold the master in a vise by the flange (not the body) Use a screwdriver thru the clevis pin's whole end as something to pump with.
Depress the white plastic center at the slave end.
Then bottom the masters plunger out at a steady speed.
It wont take much to bleed it. Just make sure you let up on the valve on the slave end after you get the master bottomed out. Let the valve out before you let the master plunger start to come back up.
It will only take 4-5 strokes & it will be ready to intall.

 

I made a bench bleeding rig. I removed the rubber boot form the reservoir. Filled it w/ brake fluid. I used my finger on the Slave end of the line and a Rollpin punch to depress the valve to let the fluid out.

Hold your finger over the slave end when you release the MC. Switch to the small punch to depress the check valve AFTER you have applied pressure to the MC. THe fluid should squirt out of there pretty well after it has been bleed a couple of times. GREAT TIME FOR THE DRILL MOD. That is 1/2 the reason why I bench bled it.... to get the metal slivers and shavings out of there.

Repeat as necessary. Also give it a couple se4conds between bleeds. Don't let the fluid get too low. IT should be ROCK hard when it's fully bleed. (w/o depressing valve in Slave end)

Here's a pic of my Bench Bleeding Rig.

 

whats a roll pin punch? ill give these options a try tomorrow thanks

 

The braided line is held to the master by a roll pin. It is a small rolled steel pin. One could think of it as a retaining pin. A roll pin punch is a machined tool that is designed to fit into the opening that the roll pin is in. It makes it easy to get the pin out without marring the part that you are removing the pin from.


Master Roll pin




Roll pin


Roll Pin Punch

 

so when i push that in the fluid will come out the end that connects to the slave? Once is pressed in will it go to its norman position on its own or do i need to do something to get it back (the roll pin) to its original place.

thanks for the help

 

It SHOULD go back, it's got a spring in there to return the valve to closed.. It's a check valve. After I pushed the plunger in to bleed the fluid out, I placed my finger over the hole just in case (while holding the clynder plunger down). -To prevent air from re-entering the system. After it's bleed, give the master cylinder plunger a push....it should be ROCK HARD with no fluid escaping from the slave end.

Sorry if that got confusing... think of it this way.. clutch down, push valve in, let valve out and place finger over hole, clutch up.

 

your loosing me here!!!! what plunger are you talking about? let me get this straight i fill the resovior with fluid pump it and then place my finger over the slave end and release the fluid via a roll pin punch. so then the fluid wont come out the slave end?

sorry if im not getting this but im a newb at this.

 

When you reconnect the braided line to the slave, can air leak in,
possibly ruining the bench bleed job altogether?

 

heres how i did mine.

after i rebuilt it, i started with it completely assembled out of the car.
i had the master cyl, complete with line and reservoir...

i mounted the reservoir to a piece of wood... but anything will work.. just rig it so it wont spill.
now i had a second person to help, but if you dont, you can mount the master cyl in a vise...

fill the bottom of a glass or plastic container with a little brake fluid.
drop a bolt in it. hex head down, threads facing up


now, the quick connect on the end of the line is sealed... push the quick connect down on the bolt. this opens it.
with it held down, press and HOLD the MASTER CYL IN. (you'll see bubbles come up from the brake fluid in the cup)
RELEASE the QUICK CONNECT end FIRST...
now release the master cyl.
fluid level will drop in the reservoir.. top it off or at least watch it.

repeat this process a few times... moving the cyl so that air can work its way out... by the time you finish, you'll have the master cyl and lines full of fresh fluid with no air.

now install the master cyl... bleed the slave if needed.


thats how you can do it without a mityvac, and get all the air out.. no special tools needed.

 

the bench bleed is to remove the air that can become trapped in the master cyl with no method of escape.

now in "magic design land" the connector doesnt let air in... but if it does, it should not ruin the bench bleed... any air from the line onward into the slave can be bleed out by using the bleeder screw on the slave.

if you had air in the system when you disconnected the master, you need to bleed the slave anyway.

 

no.....

see, the connector on the end has a spring loaded plunger in it.
its designed to seal the line off when disconnected.

in order to pump the master cyl and push air/fluid out, you need to depress this plunger.

my method is to submerge the connector in brake fluid, and use a bolt to press the plunger in, but really, any method that presses the plunger in and doesnt let air back in works.



the roll pin tool hes talking about is to remove the roll pin on the master cyl connector. thats a diffrent topic then bleeding.

 

Thanks!!! ill give it a try this weekend and post results.

 

well we now have the master on the car and we've been bleeding it for about an hour or so. The resovior is full and even though we keep pumping the clutch the fluid doesnt go down... what now?

 

How are you bleeding it? Clutch down, open bleeder, wait a sec........ close bleeder, clutch up. Don't do it fast or it won't be as efficient. If the master is not completely bleed down you will not get a good slave bleed.

The only reason I used the punch w/ bleeding was something to depress the plunger on the braided line. I was going to use my finger, but I felt it wouldn't have pushed the plunger in enough.

 

thats exactly how were doing it, what happens is the clutch is pumping but the fluid isnt going down. i bought a rebuild kit from a performance shop in SA but most of those parts arent even the same size. so i may end up sending it to thunderracing to rebuild it again bleed it for me.

 

first check that the reservoir hose isnt pinched..

is the pedal coming back up on its own? if not, the freshly rebuilt master cyl might have the piston sticking... just tap lightly on the side of the cyl until it popps back on its own...
after working the pedal several times, it should "break in" and not stick anymore.