Spongy brakes

Jul 22, 2006 3 Replies
N

Hi,



The brakes on the wifemobile (Skoda Felicia 1.9D Estate, 1998, non-ABS), are spongy and have been so for a little while now. This was picked up on the annual service last week. In responses to some other service points, I've just replaced both rear wheel cylinders, both shoes (inc. fitting kit), drums and rear wheel bearings. I've also changed the brake fluid (pressurised bleed kit, blown all the old out first then filled with new and thoroughly bled). I've greased the sliders on the front calipers (they seemed fine anyway) and they're adjusting as they should.



The sponginess remains. :-(



The feel on the pedal is that it's a bit spongy AND if you maintain hard constant pressure the pedal slowly gives and moves downward.



I'm starting to suspect the master cylinder, or maybe something else although I can't think of a lot else!



Any comments or suggestions?



Cheers, Nick


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N

Meaning both pairs of shoes. Durrrr.

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D

Press down on the pedal relax slightly & press again, if it goes all the way down then it's time for new master cylinder seals. Also check the flexible brake lines, they go soft with time.

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T

Is there anywhere a bubble of air could conceivably remain?

Have the rubber hoses aged and are maybe expanding under pressure?

That bit sounds seriously unhealthy and sounds to me like a leak with reasonable certainty.

The only places it's likely to leak, I would have thought, are cylinders (you did the rear, what about the front?), hoses, the master cylinder or the ABS valve. If it were me I'd check the fronts for leakage, then all rubber pipes, then ease the master cylinder off and see if any fluid is evident. I suppose in theory the MC could be leaking back into the inlet from the reservoir so the leak may not be visible. I don't know anything about ABS valves so can't comment on that bit.

Unless MC technology changed while I wasn't looking, getting a seals kit and fitting should be straightforward.

Good luck.

Tim

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