[T3] Brake Problem

[Jim Adney <jadney@vwtype3.org>]

On 3 Jun 2007 at 23:03, Phil Hof wrote:

> Brake problem!
> 
> I replaced everything but the hard lines on my '71 (with a '73 front axle
> assy including the '73 brakes) using good new or NOS German parts, and I
> now can't seen to get a proper pedal--it's almost to the floor and my
> warning light comes on near the end of the travel.
> 
> Rears are adjusted to the point of a little rubbing.  I bled them all
> (front first), first with a mitivac vacuum pump, then with the 2-man
> pump/bleeder open-and-shut routine.  I got a lot of air out, then clean
> (silicone) fluid for many consecutive pumps.
> 
> I can hear a little gurgling when I pump the pedal, telling me I still have
> some air in the area of the master.  I did not bench bleed the master on
> advice of knowledgable experts.  Will pressure bleeding solve my problem?
> I may take it to a shop for this, since they will be aligning it as well.
> Or are there other potential causes of my low pedal?

It sounds like you did everything nicely. Is there any chance that you're using 
the bottom bleeders on your calipers? If so, use the top bleeders instead.

Check the blue connecting hoses between the MC and the hard feeder line to the 
reservoir, as well as the blue connecting hoses between the reservoir and the 
hard feeder line. Make sure there are no kinks there. The gurgling should not 
be happening, so I have to wonder what's going on. A kink might keep the MC 
from refilling properly, leading it to suck in air instead.

Usually one hears this gurgling when you first put in a dry MC and then add 
fluid. The fluid then fills the MC and that's that. There should be no further 
gurgling.

I don't like the idea of the suction bleeding. It can draw air into the system 
since the seals aren't designed to accommodate vacuum. I generally just open a 
bleed valve and pump. Opening and closing isn't necessary.

It's also possible that you got a NOS MC that was rusty inside from sitting on 
someone's shelf for 30 years. It may need to be rebuilt before it will be 
usable. Is there any sign that it's leaking? Check under the pushrod boot.

As you may know, I recommend that people rebuild rather than buy new. The 
rebuilt part will usually be better than the new one. The newer is better 
philosophy is endemic in our consumer-driven society, but that attitude is 
often wrong. It just benefits the commercial interests.

Bench bleeding our brakes is unnecessary and a waste of time. You've saved 
yourself a lot of trouble and mess by avoiding that.

-- 
Jim Adney
jadney@vwtype3.org
Madison, WI USA

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