CSP disk brake conversion - trouble shooting.

[Peter - Belgium]

I just installed a second hand disk brake system (5 * 205 bolt patern) on my oval beetle window.

After bleeding the system I'm not able to put pressure on my brake pedal (I push it in the floor...). The bleeding seems to be fine, I'm not having any air in the bleed line, but I'm losing a bit of oil past the threaded parts of the bleeding nipple after the nipple is unscrewed a bit and I put pressure to the pedal.

Can this loss of oil be the cause of the problem? I'm not loosing any oil when the nipple is fixed so I think I should feel the prseeure in the pedal.

Can it be that the caliper is blocked? How to fix?

Any other ideas?

Thanks,

Peter

[dstefun]

How did you bleed the system, with a power bleeder, or having somebody pump the pedal while you opened the bleeder port? If it was pumping the pedal, did it ever get it pumped up tight while bleeding? If it didn't you probably have a bad master cylinder or the bleeding procedure was done wrong. Leaking around the bleeder port threads while bleeding is normal.

You can't bleed it manually by yourself without check valves on the bleeding hose, or air will be sucked back into the system as soon as you let up on the pedal.

If you used a pressure bleeder, when you step on the pedal after bleeding the brakes, it will probably go to the floor. You should be able to pump it up a couple of times and then it should tighten up. If it still doesn't tighten up you may have a bad master cylinder.

Here's a manual bleeding procedure to follow. http://www.geocities.com/aussiebug1970/bleed2.html

[Peter - Belgium]

The master cilinder should be fine since it was working OK before I installed the diskbrakes.
The procedure I used is as the link describes (and as I have used already several times).

Today I bought a vacuum based bleeder and I hope this will help with the bleeding.

Do you believe the blocked caliper could be the problem? I want to check this tomorrow if I have the time.

Thanks

[gophercat]

What master cylinder are you using? Disc brake system sometimes require a different master cylinder. I believe in most cases they require a 19mm piston in the master intead of a 17 that most bugs comes with standard. You won't build up enough pressure for the brake to engage because not enough fluid is moved to engage them. no leak or no air bubbles also can leave the hoses as a possible problem. If the hoses are old the increased pressure of a disc system may be causing one of them to balloon so the brakes won't work right either.
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1972 super
1974 Standard

[Peter - Belgium]

I'm using a standard double circuit master cilinder. I have no clue if this is a 17 or a 19 mm master?

I will check for the cracks in my hoses but they were also new a few months ago so I do not expect any problems with him.

Thanks for the help,

Peter

[Espinosa]

peter was it just front disc? or did you do all four?

if you just did the front. did you bleed the rear?

make sure you bleed all four wheels starting with the furthest wheel from the master. ie passenger rear wheel, then drivers rear, pass front, drivers front.

i usually go through and do them twice in that order.
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GFK

[Peter - Belgium]

I only changed the front drums into disk brakes.

I completely dismantled the calipers and cleaned and greased everything, but I did eventually found the problem. The threads of the adaptor of the oil line was a bit worn and think I lost the pressure there. Just mounted everything with loctite and now I have pedal pressure!

I just hope that the loctite will hold!

Thanks for all the help!

Peter