Brakes are new but she still won't stop

[Mr. H]

Hi!!!

Can someone please offer some advice. I just replaced the dual chamber master cylinder, all four slave cylinders, lines, springs, and shoes on my daughter's '70 Beetle.

I've filled then bled the lines, adjusted the shoes according to directions in the Muir book, bled the system two more times, and now I am getting frustrated.

The brakes are still soft-- going halfway to the floor and needing distance to stop properly. The warning light on the dash is ON when the pedal is stationary but the light goes OFF when the pedal is depressed (I'm starting to get depressed myself ).

From what I've read, isn't the light supposed to be OFF then go on when the pedal is pressed if the system is failing?? That's what I have read anyway.

There are no leaks that I can locate. I've looked carefully. All parts I replaced are new ones including the master cylinder.

Any suggestions? Please help-- my daughter gets her license this afternoon and I would seriously like her to be able to stop the car when necessary . Thanks for the help in advance.

Mr. H

[Marc]

Did you notice that the adjuster slots are angled to match the ends of the shoes? If you got any of the adjusters in upside-down the shoes will catch and there'll be all sorts of erratic behavior. Were the drums turned? If so, how big? Did you check the radius match between the shoes and drums? If you hold a shoe against the drum and squeeze one end ito tight contact there shouldn't be more than about a millimeter of gap at the other end - if there is, the linings should be radius-ground. What's the master cylinder pushrod freeplay like? It's supposed to be 1mm, which equates to about ¼" of motion at the pedal before it contacts the M/C piston.
The two-switch warning light system will act goofy if the wires aren't connected to the correct terminals at the switches. The switches are each double-throw, so if one moves and the other doesn't power is fed back up through the idle switch to the warning light.
http://www.nls.net/mp/volks/schem/3brake.gif

[MNAirHead]

Did you notice that the adjuster slots are angled to match the ends of the shoes? If you got any of the adjusters in upside-down the shoes will catch and there'll be all sorts of erratic behavior. Were the drums turned? If so, how big? Did you check the radius match between the shoes and drums? If you hold a shoe against the drum and squeeze one end ito tight contact there shouldn't be more than about a millimeter of gap at the other end - if there is, the linings should be radius-ground. What's the master cylinder pushrod freeplay like? It's supposed to be 1mm, which equates to about ¼" of motion at the pedal before it contacts the M/C piston.
The two-switch warning light system will act goofy if the wires aren't connected to the correct terminals at the switches. The switches are each double-throw, so if one moves and the other doesn't power is fed back up through the idle switch to the warning light.
http://www.nls.net/mp/volks/schem/3brake.gif

Marc...

Learning question --- aren't the "slotted" bolts the same and just straight through at a 90? I've never heard of this before.

Piston... are they supposed to be 1mm or 1/4"

Guess I've always been lucky... just thrown them in and they work..

Looking to learn -- everything is fixable.

Thanks

Timmy

[Marc]

If you've only worked on older (or bus) brakes you'd never have come up against this, but it's the #1 rookie mistake people make on `65-up bug brakes.
All Type I/III adjuster bolts have an angled slot from 1965 up. Older brakes had a narrower slot that was the same depth all the way across. Compare `58-`64 bug front shoe frames to the `65-up ones (or `58-64 rears to `65/`67 rears) - the only difference is that the late ones have an angled tip to match the late adjusters...you can actually interchange them provided you use the correct adjuster, but the late style is better because the shoes will be less likely to get stuck in the slots and will wear more evenly.

1mm travel at the pushrod will yield approximately ¼" of freeplay at the pedal.

[kafer-cup]

Hi Marc,

I too did not know the slots were angled... Will check mine again but the brakes work great. Thanks for the tip.

Sorry for the hijack!!


Mark

[Towel Rail]

Better teach her how to pay attention and brake in advance while you're at it.

- Scott

[Mr. H]

Thanks for the tips Marc-- I'll pull the drums today and take a look. I'll let you all know how it goes.

[Haridev M]

hi, if i were u, once the driving tests are over, u ought to put on discs on the front tyres. reli it can stop the cars reli well. if i u want to keep the drums then try to put on servo assisted brakes. it is reli light and is almost as good as any new, small car. regards, dev