brakes/servo/vacuum

[Whaanga]

I wanted to add a little more information:

Per the extra pedal travel I'm experiencing, this happens when coming to a stop for example in my driveway or in a parking lot - where the speed is quite slow. If I apply the brakes once, I have normal pedal travel with the proper resistance and amount of help from the servo - but if I release the pedal and then apply it again right away, the pedal will travel further. The brakes are activated in this case but if I release the pedal and reapply, it almost always has less travel.
Not sure what this means, but this is what tends to happen.

Any thoughts/insight would be appreciated.

Thanks,

Jeff
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Late 1973 Bay w/a transplanted 914 Engine

[busdaddy]

Difficult to nail down an exact cause for that, floatie bits in the brake fluid or a slightly torn seal in the master where the dangly bit gets caught under a valve surface might be to blame. A thorough brake fluid flush is always a good idea, it likely won't make it worse.
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[Tcash]

- but if I release the pedal and then apply it again right away, the pedal will travel further.
This seams like the booster is working more. Applying more vacuum or atmospheric pressure thus further pedal travel.
Maybe you have a problem with the booster valve, or a clogged booster vent.

Link


Disconnect the booster and see if it still occurs. Be aware stopping the vehicle is going to require much more brake pedal force.
Problem goes away, brake servo is at fault.
Problem does not go away, I would be looking at the rear brake adjustment. Or for warped rotors up front.

[Whaanga]

Thanks Tcash. Pardon my newbie question but how do I unhook the servo? Do I just disconnect the vacuum line? Or something else?

Thank You
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Late 1973 Bay w/a transplanted 914 Engine

[Tcash]

Disconnect the Vacuum line and plug it.

[Whaanga]

Following up from my post last fall, I bought a used servo from the classifieds thinking that I could harvest the serviceable parts listed in the Bently.

I worked to remove the hard plastic air connection, rubber boot, filter and damping ring but could not separate the hard plastic air connection or rubber boot. Does this disassemble or is it a 'sealed' unit that cannot be transferred to another servo? OR can I test this servo and install if it still holds a vacuum?

Thanks, Jeff

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Late 1973 Bay w/a transplanted 914 Engine

[Amskeptic]

[Whaanga]

Thanks Colin -

I removed both that circlip and the small retaining ring on the bellows and could not get things to open up. The plastic air vent will rotate and the nut will turn but neither will release. When I turn the nut I hear a sound coming from the large spring in servo itself

Maybe some penetrating oil or carb cleaner sprayed might loosen things up?
Or am I missing something else?
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Late 1973 Bay w/a transplanted 914 Engine

[kreemoweet]

The metal shaft has an o-ring that holds the plastic air connection quite firmly. If you hold the shaft with a vice/tool and then rotate while pulling the plastic piece, it should
come off. A little silicone grease on the o-ring will probably make the job easier next time.

But really, are you sure these parts will work with your existing booster? You might have to remove the shaft end also (it appears to be fastened on with a roll pin according to
the diagram below). But then you'll need the proper bus connecting rod also. It never ends, eh?

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[Whaanga]

Thanks Kreemoweet -

No, I'm not totally sure the parts will transfer from one to another but per the advise here plus plenty of study and reading, I 'think' they'll swap out. I won't know until I dig into things.

Yes, it never ends but that's part of the AC journey.

Jeff
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Late 1973 Bay w/a transplanted 914 Engine