Disc Brake Conversion Master C and Brake Bleeding Help Needed

Mrfun2fly

Ok folks, I'm reaching out for some super powers or dynamite!

On the 63 Ghia I'm building I installed the front disk brake kit and installed all new brake lines and a new Master Cylinder.

Issue: Bleeding the brakes:

We get straight fluid out of each side after bleeding so no air in the lines and the lines and no visible leaks. I feel pressure at the peddle when pumping but the peddle still goes straight to the floor and when pumping pressure builds like there is air in the lines but bleeding there's no more air bubbles.

I'm at a loss, but there is a leak at the fluid reservoir at the top where the lines connect which I will fix but there is solid fluid and no bubbles going into the master cylinder.

Any suggestions?

Thanks!

Lee

rcooled

Mrfun2fly

Ian Godfrey

This can be a tricky process....
A few suggestions:
bleed all 4 corners, start with the corner furthest from the master cylinder, also jacking the rear of the car can help get the back brakes done. then....
give the pedal a few good hard pumps, you want to get the pistons out to where they push on the pad and the disk
Sometime tapping the caliper with a mallet can help the bubbles come to the top and get out.
sometimes letting it sit over night the bubbles come together and bleed much easier the next day.
I like to use a pressure bleeder to get the fluid flowing through the system.
good luck and let us know what worked for you

overboost

Era Vulgaris

Are you using a single circuit MC, or did you convert to dual circuit?
_________________
Currently own:
66 Karmann Ghia, L390 Gulf Blue, under construction, here: www.thesamba.com/vw/forum/viewtopic.php?t=760505&highlight=
99 Mazda MX-5 10AE, Sapphire Blue Mica, 6 speed, LSD

Previously owned:
98 Porsche Boxster, silver, 2.5L -- 67 Karmann Ghia, Black, 1500sp -- 98 BMW Z3, Atlanta Blue Metallic, 2.8L I6 -- 75 Porsche 914, Laguna Blue, 2270cc -- 72 Porsche 914, Signal Orange, 1.7 FI -- 74 Karmann Ghia, Black, 1600dp -- 74 Triumph TR6 with O.D., sapphire blue

Mrfun2fly

Mrfun2fly

LVGhia72

If there is a leak, like you said at the reservoir. Then, the system is sucking air from the leak. Fix the leak, then bleed the entire system starting from the right rear, left rear, right front and lastly left front.

If the problem still exists, then check the hose the goes from the reservoir to the master cylinder. The hose can become porous overtime and suck air into the system. Even if the hose appears to look good.

I normally do what is called a reverse bleed. Meaning I push the fluid from the caliper or wheel cylinder into master cylinder then reservoir using a bleeder tool. Then, using the same tool, pull the fluid out of the caliper/wheel cylinder. Of course you can use the old school pump the brake pedal method.

Steve

I forgot to mention, normally when switching from drum brakes to disc you need a bigger master cylinder (ie dual circuit) to provide enough pressure to apply the brakes.