Follow up to spongy Spider barkes

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

Russ,
 
Thanks for your response.
 
The Spider is a 1977 model but the firewall mounted master cylinder has been
replaced with an underfloor dual master cylinder and floor mounted pedals
from a 1974 Australian Berlina with dual boosters . The brakes are ATE from
the original spider. Not the older Dunlop.  Car also has Euro cams and
Dellorto carbies and euro rear bumper. 
The car has been driven about 10 miles in short trips with the previous
callipers but there was no improvement in the brakes.
As the brake pedal gets nice and hard when I clamp off the flexible brake
lines as close as possible to the callipers, I can only assume that
everything before the calliper is OK with no air in it. This would include
the master cylinder and the lines to and from the boosters and rule out the
flexible hoses etc. There must be air still in the callipers, even though no
bubbles come out when you bleed it. I am planning on unbolting the callipers
and trying to bleed them as I hold them higher and wiggle them about etc,
hoping to get any air to the highest point.
The brakes will pump up to a nice firm pedal when you have the motor
running, no pedal slowly sinking to the floor or anything like that. But
once you take your foot off the brake the pedal is spongy again till you
pump it half a dozen times, and then it's nice and firm again. Got to be air
in the callipers somewhere I think.
I suppose what pisses me off is that my mate just rebuilt the callipers in
his 1974 GTV, bled them once, and the brakes are perfect. He can't believe I
am having this trouble as his went together without any problems.
Anyway thanks for your thoughts. If you have any more ideas let me know.
Regards
Marty
Newcastle
Australia
 
-----Original Message-----
From: AlfaNeely@domain.elided [mailto:AlfaNeely@domain.elided] 
Sent: Tuesday, 16 October 2001 11:22 
To: martin.wilson@domain.elided
Subject: Re: alfa-digest V8 #135
 
   You really need to tell us what spider you have.  The Duetto Dunlap
brakes with the tube from one side to the other are all most impossible to
bleed.  Best result is found by taking the caliper off and holding it up so
the cross over tube will bleed. 
      Plus if the master cylinder is under the floor boards, there could be
several places where air could be trapped.  With a firewall mounted master,
the air tends to run uphill to the master.  Raising the front or the rear of
the car can help. 
      Have you driven the car?  The motion of driving around can giggle the
air bubbles around so they move to the ends where you can bleed them out
later. 
      So again, what spider do you have? 


Ciao, 
Russ Neely 
Oklahoma City 

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