Spider front brakes spongy.

[Marty Wilson <martin.wilson@domain.elided>]

Greetings,
 
My 5 year rebuild and conversion of my Ex USA Spider is down to the last
job. The bloody brakes.
The braking system has been rebuilt with resleeved and rebuilt underfloor
master cylinder and rebuilt dual booster. However the brakes were spongy and
not up to the standards of fellow 105 dual booster systems.
I checked where the fault lay by clamping off the flexible hose to the rear
brakes, no difference, still spongy so therefore fault in front brakes.
Clamped off front flexible brakes hoses one at a time, still no great
improvement.
Clamped off both front hoses near callipers, fantastic, lovely hard pedal.
Deduced front callipers the problem.
Rebuilt a spare set of calipers and put them on the car, bled the system
till the cows came home and no air coming out when bleeding. Tested brakes,
absolutely bloody hopeless, still spongy and crappy.
Clamped off both flexible hoses again next to calipers, beautiful hard
pedal.
I can only conclude there is still air in the calipers, they are up the
right way with the bleed nipples at the top.
What am I missing here? Anyone had this problem before and solved it? Can
anyone fault my logic?
Any contributions gratefully accepted.
 
Marty Wilson
Newcastle Australia

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