Author Topic: bleeding issue  (Read 3552 times)

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Offline Jeremy

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bleeding issue
« on: December 13, 2010, 01:31:45 PM »
So I've replaced all the brakes on the '59 with discs but am having troubles getting decent pedal pressure. I rigged up a little pressure bleeder that pressurizes the fluid resivior and seem to have bled all the air out at the calipers but the pedal still depresses about half way and feels soft. If I really push it goes to the floor. The pedal doesn't seem to lose pressure when I hold it so I don't think it is leaking. I adjusted the pedal stop on the floor so the push rod just touches the master cylinder cup. I did not adjust the rod intself. It's a DCMC. Any suggetions?
'59 Beetle
'59 Single Cab

Offline Chris

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Re: bleeding issue
« Reply #1 on: December 13, 2010, 04:06:03 PM »
you need to adjust the rod as well, if its not adjusted your reducing the amount of fluid being moved

 i have the same sort of issues with my brakes and from what I have gathered it just comes down to the master cylinder not having the capacity to push enough fluid through the system to apply enough pressure to all 4 wheels, when you pump it quickly your managing to force more fluid into lines, I want to sort mine out as well but never have found a definite solution, maybe a cnc master?

Offline Bruce

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Re: bleeding issue
« Reply #2 on: December 13, 2010, 05:09:39 PM »
I adjusted the pedal stop on the floor so the push rod just touches the master cylinder cup.
Measure from the pedal to the front panel to determine the pedal travel.  It should be around 220mm.  If it isn't, Set it there then adjust the pushrod.  Normally, if the pushrod hasn't been adjusted, the pedals will be in the right place.

Offline Hansk

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Re: bleeding issue
« Reply #3 on: December 13, 2010, 08:55:02 PM »
Also, I'm sure you have ...but  , all the calipers are mounted with the bleeder to the top?
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Offline Jeremy

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Re: bleeding issue
« Reply #4 on: December 13, 2010, 09:18:23 PM »
Thanks guys. Yeah all the bleeders are mounted correctly. I'll try the push rod. I also noticed that the rear brakes seem to be dragging to the point where one is too tight to move and the other barely moves. Do you guys remove the residual valve from the master?
'59 Beetle
'59 Single Cab

Offline Hansk

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Re: bleeding issue
« Reply #5 on: December 14, 2010, 08:27:40 AM »
Rear single piston calipers with e brake?  Sticking sliders?  Mounting bracket aligning the caliper to the rotor ok ? (seen this before, needing to "tweak" the bracket a little left or right)  Shouldn't need to do anything to the master , if there is pressure in the line holding your rear brakes , opening the bleeder would release it.
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Offline Geoff

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Re: bleeding issue
« Reply #6 on: December 14, 2010, 09:07:08 AM »
If it's none of the items Hans mentioned check your brake hoses in the rear. Old hoses will swell over time and hold pressue to the brakes.

If it's one of the cheap rear disc kits with the stamped steel caliper bracket you may want to gusset it. They flex badly when you step on the brake and can bind.

Offline Jeremy

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Re: bleeding issue
« Reply #7 on: December 14, 2010, 09:47:16 AM »
Thanks again guys. I adjusted the pedal as far out as possible which was 215mm. Not quite 220mm but pretty close. Adjusted the rod accordingly. It's better. Doesn't quite go to the floor any more. Still seems to travel about half way to the floor before engaging. I was hoping they would engage right at the top of the pedal but maybe that is the way they are. I'll try one more bleed.

As for the sticky brakes. Maybe they aren't to bad. I can spin the rotor by hand with a little force. They might settle in. Wish I knew about the caliper bracket before I powder coated them and put it all together. The brake lines are all new stainless braided.
'59 Beetle
'59 Single Cab