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Author Topic: News from the soggy pedal front  (Read 681 times)
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Michael Tryton
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« Reply #45 on: 13 July, 2019, 07:41:35 PM »

2nd photo of the reluctant piston:


* DSC_0650.JPG (3673.34 KB, 4608x3072 - viewed 5 times.)
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lancialulu
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« Reply #46 on: 13 July, 2019, 09:27:52 PM »

Not sure if this is relevant? My Flavia this year developed something similar in that the brake pedal would go down c1/3 before activating the rod (then the brake would work with a firm pedal). I deduced that the rear piston had got stuck for some reason someway down the bore. Now on the Flavia the is a rear and front priming pump in the reservoir. Out of curiosity more than any thing I gave the rear plunger a push and it went somewhat then after it had returned it would not push down anymore (ie the MC had fully primed). Now I had a firm pedal right at the top where I remember it had been normally. After several weeks of use it has stayed in the normal position. Odd....
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Its not the winning but taking part! or is it taking apart?
1955 Aurelia B12
1967 Flavia Vignale iniezione
1967 Fulvia HFR
1972 1600 HF
1972 1600 Fulvia Sport
1978 Transformer HF3000 Strato's replica
1979 2500 Gamma Coupe
1988 Delta 1.6GTi.e.
ColinMarr
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« Reply #47 on: 14 July, 2019, 08:08:24 AM »

I think you have identified the problem! As you say, the piston is not fully retracting, either because it is jammed or the return spring(s) have failed hence no pumping action. Sorry, but I guess you have to dismantle it and start again. If there are any deficiencies in the m/c body itself, I happen to have a good re-usable one.
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lancialulu
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« Reply #48 on: 14 July, 2019, 09:00:17 AM »

As Colin says this is the problem. It may be a hydraulic lock in the incorrect assembly of the one way valve at the front of plunger 2 (see attached).

BTW not all seal kits come with 4 u seals. Most come with 3 u's and an o ring. I cannot remember if the o ring replaces the rear seal or more likely the middle seal... Maybe someone can remember?

* superduplex1.pdf (77.73 KB - downloaded 18 times.)
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Its not the winning but taking part! or is it taking apart?
1955 Aurelia B12
1967 Flavia Vignale iniezione
1967 Fulvia HFR
1972 1600 HF
1972 1600 Fulvia Sport
1978 Transformer HF3000 Strato's replica
1979 2500 Gamma Coupe
1988 Delta 1.6GTi.e.
Michael Tryton
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Posts: 38


« Reply #49 on: 15 July, 2019, 03:16:11 PM »

Well, I've taken M/C off again and found that, yes, even after draining the unit, the 1st piston after the servo is absolutely stuck; so am giving up and sending it off to Past Parts, who are familiar with this type. Let's see what they make of it.

What I'm calling the 2nd piston is the one at front of the car and furthermost from the servo and that was still fine, completely free; as of course they both were initially, after my rebuild & reinstallation.

Thanks for the attached pdf - that's the same diagram from the workshop manual which I was working to when fitting the new seals to each piston, although poor print quality makes orientation of some seals passing ambiguous.... This and the choice of which seals to use from the kit has been discussed on here before - the rearmost one on the 2nd piston can either be a 'top hat' shape like all the others, or replaced with an 'o' ring, which is what I did. The 1st piston, which is stuck, was all 'top hat'.
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