Fulvia S1 Sport 1.3S brake master cylinder

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Bryan
Posts: 41
Joined: 14 May 2010, 19:19

Fulvia S1 Sport 1.3S brake master cylinder

Unread post by Bryan »

I had a thread on the problem with spongy brakes, which disappeared from the forum so I will follow on with this post. Having taken everything apart and replaced all seals, cups, flexible pipes I still have a soft pedal and begin to suspect the master cylinder even though it's only 5 years old. It's a19 mm modern replacement purchased from a well known Lancia dealer and has also had new cups fitted, but with no effect. I still have my old 18mm original cylinder and acquired another to try to build up a good one. I soon came to the conclusion that one of them is for an 818 100 car and not the 818 300 which should be in my car. Unfortunately I got some parts mixed up. Can anyone tell me which is the correct front piston and spring for my car from the 2 shown in the photo?. I ordered a revision kit for the 18mm which came with 2 cups and 2 rubber washers. A post from Huib in 2010 very clearly shows 4 cups and no washers. The picture from part 2 of the parts catalogue on page 40B (items 6 and 7) itemizes 2 cups and 2 washers. Now I am very confused. Do I have the wrong page in the parts catalogue ? Do I have the wrong revision set? Was there a change since the parts catalogue was issued ? Can anybody put me out of my misery !!!!
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Bryan
Huib
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Posts: 1778
Joined: 17 Dec 2008, 10:12

Re: Fulvia S1 Sport 1.3S brake master cylinder

Unread post by Huib »

Bryan. I am not in favour of replacing the original master brake cilinders with an alternative for various reasons among which the fluid displacement of each of the chambers and the length of the pin on the pedal. Remember that those Dunlop brakes were invented in the 40's. The idea was to insulate the heath from the fluid by using small but thick pads. This worked very well with the asbestos pads. Mintex supplied them with varying degrees of hardness. On a Fuvia with 18mm master cilinder you want hard pads as the 18 mm plungers do not displace much fluid. The 25 or so mm of the master brake cilinders of Flavia and Flaminia displace twice as much fluid for every mm of movement. Remember that in hydraulics you have to calculate in surface areas. So for Flavia and Flaminia one could use softer pads. At the same time that asbestos was banned the filosofy also changed to providing more cooling for the pads. The pads changed from thick small pads to large pads with a thick steel back plate. The new asbestos free friction materials were ok for the new callipers but not well suited for the Dunlop brakes. Since end of the 90'sMintex makes a friction material which comes close to the old asbestos material. You have to be carefull about the selection of the friction material. Not just buy any pads from any supplier. Mintex M68FF or Mintex M69FF friction material is still the best. Also your discs may no longer be flat enough. Your discs may be wobbling. We reduce the wobbling to less than 30 micron measured on the outer diameter for rally cars and 100 micron for street cars. Quite a challange sometimes. The average brake shop does not have the equipment to do that. About the master brake cilinder. Why not come to our shop near Breda. I can look at the inner parts and probably have enough good used ones to give you the right parts. I usually have new original master brake cilinders in stock as well.
Bryan
Posts: 41
Joined: 14 May 2010, 19:19

Re: Fulvia S1 Sport 1.3S brake master cylinder

Unread post by Bryan »

Thanks Huib and yes, I would be very happy to bring it to you to get a working cylinder. I will be out of NL for a week so I will phone you when I get back to fix an appointment. regards
Bryan
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