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Author Topic: Soggy brake pedal  (Read 469 times)
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Michael Tryton
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« on: 17 September, 2018, 08:42:39 PM »

Pedal goes to floor on my S2 Fulvia 1300 and - unlike formerly - won't firm up with pumping, though brakes still work.
Don't think it's a brake fluid problem - suspect a lack of vacuum to servo, for whatever reason.
Does the panel think that's likely?
Have checked pipe to inlet manifold and seems OK/intact, so is it wear on the servo or some failure inside it?
(Advice much appreciated as always)
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Angle Grinder
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« Reply #1 on: 17 September, 2018, 09:13:25 PM »

If your servo isn't working then the pedal would feel stiffer. Have you checked the Master Cylinder for leaks? The leak might become apparent inside the car above the brake pedal.
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stanley sweet
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« Reply #2 on: 17 September, 2018, 10:01:23 PM »

I have an S2. I had a similar problem some years ago. You will have some braking because the duplex system will operate the small pistons on the front. It gives you something in an emergency but obviously shouldn't be driven any great distance like this. A new seal kit for the master cylinder didn't solve it because it transpired there was pitting in the wall of the cylinder. I had to have a new M/C and the problem was solved. If your cylinder lining is OK but the seals are old you might get away with a seal kit.
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Michael Tryton
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« Reply #3 on: 20 September, 2018, 07:42:26 PM »

Thanks for these thoughts, gents.
The master cylinder was overhauled not many years ago and it's been OK since, though there always used to be this tendency to need to pump the brake pedal the first time I took her out in the Spring after winter's layoff.
(After that, she was OK).
The fluid level oil the reservoir is up to the mark; there are no leaks anywhere in the system that I can see, including the pedal box, or round the callipers.
I'm still at a bit of a loss - could it just be aerated, hygroscopic, old fluid that's the cause?
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lancialulu
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« Reply #4 on: 20 September, 2018, 08:19:23 PM »

common enough problem and remedied by a new set of master cylinder seals if the bore of the master cylinder is not scored or corroded (by hydroscopic contamination).
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chriswgawne
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« Reply #5 on: 21 September, 2018, 01:31:40 PM »

If you are lucky then new master cylinder seals will do the job but it is essential that the bore of the master cylinder is highly polished with no pitting. My own view is that the home mechanic cannot hone master cylinders so if there is any doubt send iot to an expert like Past Parts or Omicron. Its just not worth the risk.
 There has been lots of correspondence on this forum about the best way to bleed the brakes so no need to repeat any of that. Lancia brakes are generally excellent if the system is in good order.
Chris
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Chris Gawne
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