brake fluid reservoir

[exasperated]

 Hello All, My work on the Appia 3 continues. I have repaired the body  but unfortunately was forced to use a fair bit of filler ,but then after a 3rd attempt to make the rear valance I accepted what I had.
My question today is , why such a strong spring holding the piston down in the brake fluid reservoir?  I imagine it is to prevent a back flow from the master cylinder ,but once the master cylinder piston moves when applying the brakes, the inlet apertures are closed, and by so doing preventing a back flow. Whilst I appreciate that Lancia had their reason  for the strong spring I am concerned about the strength of the plastic body of the reservoir to resist this force considering the age of it; approaching 60 years.
Any thoughts??
Regards, exasperated

[lancianut666]

Hi Exasperated
Jim from the Appia Consortium here...new plastic reservoirs are available from Italy as are new seals.
Jim

[lancianut666]

I think the reason the spring is a bit of a beast is Lancia cars of this era use the plunger in the reservoir as an aid to bleeding the brakes and need to maintain pressure on the fluid in the reservoir and hence further down the brake lines. This enables you to bleed the brakes single handed by pulling up the plunger and then bleeding each cylinder in turn but keeping an eye on where the plunger has got to as it will go down with the fluid level.
Clarkey

[exasperated]

Good Day, Thanks for the replies. Upon further reflection and taking into account Clarkey's comment, perhaps the idea was as he says 'to maintain a degree of pressure in the lines' so that the brakes would act a little bit quicker. Considering Lancia's racing legacy this was a consideration for their designers.
I think what I will do is replace the strong spring with a weaker one and in time see what it does.
Regards, Dennis exasperated.

[nistri]

A weaker spring can make brake bleeding by a sole person much more difficult. I use a pair of mole grips to lift the plunger and then I open each bleed nipple in turn to bleed the system, Andrea