Bleeding Master Cylinder

Started by MikeC, May 23, 2007, 01:42:27 PM

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MikeC

I am just about finished with my 39 Chevy.  I installed a 90* Brake pedal/Master cyliner under the dash. (If you ever think you want to do this contact me first!)
Because of other issues I was not able to bleed the master cylinder before installation and now I am ready but...
Bleeding the master cylinder (dual reservoir, remote fill) will I think cause an unbelivable mess inside under the dash also with very little room to move.
Is there any way to ultimately remove all the air through regular bleeding without bleeding the master cylinder?  Any possible tricks?  I have heard that if you heat Dot 5 before putting into the system it will remove a lot of air bubbles that are normal with 5.??  Since the complete system, lines, calipers, master, etc are all new; is there any reason to not re-use the fluid that is bled?
Lots of questions, I appreciate the help.
Thanks
Mike

enjenjo

To "bench bleed" the master cylinder on the car, fill the reservoir with fluid, and just move the pedal slightly with your hand to uncover and block the compensating port. You will get small bubbles in the reservoir, continue until the bubbles stop, you have it bench bled. You may need a mirror to see in there. Then proceed with normal bleeding.

I throw away any fluid that I bleed out. It's usually dirty and contaminated with metal particles. Yes, I realise how much it costs. :lol:
Welcome to hell. Here's your accordion.

MikeC

Could the Dot 5 be run through like a coffee filter,  and then re-used?

Dave

Im gonna get some static for this im sure but ive never bench bled a M/C.. I just fill em and bleed the whole system. Its never not worked for me.
Dave :wink:

wvcab

i take some brake line with fittings to match the master cyl, then bend the line to come up and go into the resivor bowl, pump the brakes and the fluid is recycled, the air gets out.....

kb426

Two other options: use a pressure bleeder. You have to have one to do this. If you know nothing about this, move on to number 2. Use a "mityvac" and suck the fluid through it just as you would bleeding but in reverse. I noticed Harbor Freight seels one for less money than the original.
TEAM SMART

Charlie Chops 1940

I used a Kugel clutch and brake system in my track roadster. I was a little concerned about bench bleeding and then opening the system again under the dash to hook up the lines, so I didn't bench bleed the master. I hooked everything up and put a small amount of fluid in the M/C and the cracked all the bleeders and checked for leaks, tightened a couple and then bled as usual. I made a wooden stick the right length to hold the pedal down after puming it up and bled one wheel at a time. Worked out fine.

Used an old pump type oil can with a flexible end to put fluid in the M/C and a mirror on a stick to check fluid level. Didn't spill a drop.

Charlie
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MikeC

Thanks for the help, I will post something after the "bleed" and let you know how it goes.
Mike

Beck

Bleeding the brakes is normally my biggest problem in rod construction. With the cars I build the MC is under the floor which is lower than the caliper and wheel cylinders. You need to push enough volume through the lines to get the bubbles traped in the lines out. Gravity is working agianst you. I always use a power bleeder. I make a plate to fit the MC being used. This isn't as hard as it sounds. Use a little 1/4" thick steel, key stock, soft gasket material,chain, bolt, 1/4 tubing, glass jar with 1/4 tube bulkhead fittings in the lid. Put the fluid in the jar and pressure it up to about 10 psi with the compressor. Go around to each wheel a few times and your set. Double check the air regulator before hooking up. Bleed the air pressure off before taking the MC cover off. Check your fluid level in the jar often. It isn't pretty but it works.