If you still have a spongy pedal after repeated bleeding, try these ideas.
1. Is your brake pedal adjusted properly? There should be almost no "flop" or
dead space. Remember, that unless your actuating rod between the pedal and
master cylinder is set correctly, ( i.e.: no flop), you can never have
comp[lete actuation of the brake system. It is amazing how many 356s have
poorly adjusted rods.
2. Perhaps a bit of air remains trapped deep within the confines of one
caliper. If you've been unable to work it out through conventional bleeding,
try removing one caliper from it's mounting, ( but keep the hose in place!),
put a wood block between the pistons, and with the caliper held upside down,
push the brake pedal about eight or ten times. Do this for each of the two
bleeder valves. Now try the system. If there was no improvement, repeat on
the remaining three calipers. Sometimes a small air pocket will resist all
other means to purge it, inverting the caliper often forces this air out.
3. Check to be sure all fittings are tight, and not sucking air, although
this is pretty unlikely.
4. Try my personal brake bleeding system. Just keep the reservoir filled and
with a l two foot length of clear plastic tubing on your first bleed valve,
open it. Now just pump the brake pedal ten strokes. Don't worry about sucking
air back into the caliper, as the two foot length of hose will contain more
than enough of a reservoir to prevent that. With the clear hose, you can also
monitor the fluid for air bubbles. This system is perfect for a one-person
It simply requires a bit of patience and about half an hour of your time.
I have to disagree with item one concerning "flop space" You need to sure
that the cylinder returns to a fully off position. This means that you
should feel some free play in the pedal before it contacts the master
cylinder. This is the only position that the cylinder will open up to let
res. fluid into it. You do not need much, any sense of a gap between the
linkage and the cylinder is ok. Too much in this area will result in a lower
pedal so just dial in a tiny amount , just enough to feel the gap. The
workshop book says "just enough to realize play between the pushrod and the
The Stable, San Francisco
Not only that, but one part of your dual system will fail eventually if you
have no free play. Don't ask...
I have not been able to get as much pedal with the dual system as with the
single although my system brakes well. Has anyone been able to get a full
pedal and how?