Spongy Brake Pedal - '71 Super Beetle

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vwlover77
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Spongy Brake Pedal - '71 Super Beetle

Post by vwlover77 » Mon Feb 20, 2017 5:37 pm

I've bled the brakes on my '71 Super Beetle twice now, but I just can't get rid of the spongy pedal. I'm beginning to think I've somehow done it wrong both times, but I'm not new to this!

When first beginning to brake, the pedal seems reasonably high and braking seems OK, but then I realize I need more braking force and have to depress the pedal nearly to the floor to stop.

I tried a "panic stop" today from around 45mph. I quickly (and fairly easily) pushed the pedal all the way to the floor. The car stopped straight and even, but it didn't even seem close to locking a wheel, and seemed to take a long distance to stop.

If I maintain a constant pressure on the pedal, it does not sink to the floor.

Bleed them again and hope the third time is the charm, or is there something else to check?

Thanks!
Don

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78 Westy
71 Super Beetle Convertible Autostick

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Re: Spongy Brake Pedal - '71 Super Beetle

Post by asiab3 » Tue Feb 21, 2017 12:50 am

I always make sure the adjuster stars are at their optimum point of adjustment before bleeding. Any laziness in the shoe adjustment will eat up valuable pedal travel necessary for efficient bleeding.

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Re: Spongy Brake Pedal - '71 Super Beetle

Post by vwlover77 » Tue Feb 21, 2017 6:31 am

I did the last bleed by pressurizing the fluid reservoir to a few PSI with my air compressor and opening each bleeder valve in turn. (With frequent checks to make sure the reservoir was not going dry.)

Star adjustment would make no difference using that technique.
Don

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Re: Spongy Brake Pedal - '71 Super Beetle

Post by hambone » Wed Feb 22, 2017 12:36 pm

I've had better luck with the pumping pedal method.
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Re: Spongy Brake Pedal - '71 Super Beetle

Post by cegammel » Wed Feb 22, 2017 4:18 pm

Important things I learned on my super...

If there is leaky fluid on the shoes, no good brakes.
If the drums are worn down, hard to get firm pedal.
If the rears are not equally adjusted, no firm pedal...
If the master cylinder is leaking, even the slightest, the pedal will not be firm. My only indication was a drip from the front tunnel drain, as the mc was dripping in between the pan pieces...

I have a mityvac pump...pumping the pedal is far superior.

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Re: Spongy Brake Pedal - '71 Super Beetle

Post by vwlover77 » Thu Feb 23, 2017 7:10 am

Those are good things to know.....

The rear shoes were just replaced due to fluid leaked onto them, the fronts were replaced last Fall along with two corroded/sticky wheel cylinders. The repair last Fall is when the soft pedal started.

I just bought a Mityvac pump last night at Harbor Freight. Maybe I should return it before I use it........
Don

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71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Re: Spongy Brake Pedal - '71 Super Beetle

Post by vwlover77 » Thu Feb 23, 2017 7:11 am

Does anyone know how many pumps of the pedal it takes to get fluid from the master cylinder to the furthest wheel cylinder (right rear?) ?
Don

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Re: Spongy Brake Pedal - '71 Super Beetle

Post by Amskeptic » Thu Feb 23, 2017 8:41 am

vwlover77 wrote:Those are good things to know.....

The rear shoes were just replaced due to fluid leaked onto them, the fronts were replaced last Fall along with two corroded/sticky wheel cylinders. The repair last Fall is when the soft pedal started.

I just bought a Mityvac pump last night at Harbor Freight. Maybe I should return it before I use it........
MightyVacs suck dead donkeys. You need pressure from the reservoir to the bleeders.

You do know that new shoes can add to the spongy feeling until the lining have broken in, yes?

Recheck all of your work exhaustively. Unfortunately, that means pulling each drum, checking under the boots for any signs of liquid, checking the linings for contamination, checking the springs, checking the drums for glaze (that cross-hatch sanding that I am always going on about is to let the new linings apply their own glaze recipe to the drum friction surfaces), checking the ebrake cables for drama-free release, re-assembling everything, adjusting the stars to *very difficult to turn* THEN backing off to minor scraping, adjusting the ebrake cables to factory specified point . . . . . then bleed.
Yeppers, another Saturday bites the dust.
Colin
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Chloe - 1970 bus . . . . . . . . . . .191,387 miles
Naranja - 1977 Westfalia . . . . 72,350 miles
Pluck - 1973 Squareback . . . . . 55,560 miles

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Re: Spongy Brake Pedal - '71 Super Beetle

Post by vwlover77 » Mon Feb 27, 2017 7:31 pm

I haven't done it all yet, but I did bleed the brakes again - the old fashioned way - and adjusted the shoes again (which are still breaking in on all 4 wheels now), and things are much improved.

I think the other thing that might be fooling me is that the front shoes I replaced were both contaminated with fluid from previous cylinder leaks that I tried to remove with brake cleaner. I think they were "stickier" due to the contamination and made it feel like I had more braking power than these new shoes have ???? (They also locked up far too easily under moderate braking - which is why I replaced them.)
Don

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"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Re: Spongy Brake Pedal - '71 Super Beetle

Post by asiab3 » Mon Feb 27, 2017 7:48 pm

New shoes aren't exactly matched to the arc of the drum. They should get better with time. (Old school shops used to do this in-house before releasing your vehicle to the public roads…)

Locking up under moderate braking? That's the opposite problem most people seem to have. :)

I think a main problem with the vacuum bleed approach is leakage on the threads of the bleeder screws; air can seep into the vacuum stream that way and give a "false" bleed. I realized this when I was pressure bleeding, and the fluid seeped out of the bleeder threads if I opened the blender too far.

Robbie
1969 bus, "Buddy"
"Like a good sheep dog, it is ill-suited for show competition, only becoming beautiful when it's doing its job. It is a devoted servant, delighted with its lot in life, asking only that it be treated with the respect it deserves. You can't knock that."
http://theroadtells.com

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