I worked on the brakes of the Fulvia, because they occasionally stuck. After replacing the seals in the master brake cylinder, I took the front callipers apart. The pads showed very uneven wear. The bottom end was almost gone, while the top end was still reasonable. On hindsight the stucking might have come from the uneven pads. When I started to assemble the front brakes again, I noticed that the front hoses had been switched (both on the left hand and on the right hand side) connecting the small pistons to the front circuit and the large pistons to the combined circuit. This explains perhaps the uneven wear. When I switched the hoses, I noticed that the longer one was almost worn through by the tyre. Put in a new one with a twist and a stainless coil spring around it.
I replaced seals and pads about a year ago. There was and is no corrosion. My theory now is, that the very uneven wear of the pads resulting from the switched front hoses put the pads in a tilted position thereby restricting free movement. There is no trace of sticking now. The car brakes straight from any speed at any decelaration.
A new experience with the Fulvia is now, that I can't get the brakes to lock on good condition high friction asphalt. I have new Goodyear Grand Prix S 165x14 tyres. Also, the brake pedal travel is more than it used to be. This might be caused by the fact that one chamber of the master cylinder now has to move the larger pistons and the other chamber now moves the smaller pisstons at the front plus rear pistons (As it should). Until now the small front pistons, which had a complete circuit of their own, must have done the lions share of the braking. The long pedal travel is all the more obvious because the Flavia (and Flaminia), which I have driven for the last weeks, has almost no pedal travel at all. At this moment I am not fully convinced, that the long pedal travel is allright. If it is fully depressed, I can still get my left foot under the pedal. So it is still some way off from the floor. On the other hand the pedal goes so far down, that one has to be carefull not to step on the throttle when braking.
The brake pedal does not come up when pumping, indicating there is no air in the system.
- Huib -
The story of sticking brake calipers is not new. Often it is due to inadequate rubber ring seals inside the cylinders of the calipers. The problem is made worse by the variable degree of corrosion affecting cylinders and their housings. Lack of pedal pressure in the absence of any split somewhere in the brake lines indicates a problem with the master cylinder (not rarely a corroded bore).
On a Fulvia the long travel of the brake pedal is definetely not right. On a standard car it would be probably due to worn rear brake shoes but of course they are not fitted to Fulvias! I notice you have done work to the master cylinder and the problem could originate here, including the need to reset the length of the rod pushed by the brake pedal. Any non-standard component of the brake master cylinder can give this problem. Another possibility is that one (or more) flexible rubber hoses is getting deformed (because of old age) under heavy breaking. Moreover, the brake limiter valve might be leaking just a bit. I would continue to investigate the cause of the problem, bearing in mind the safety aspect. Try to isolate the rubber hoses to each wheel in turn (using appropriate hose clamps to avoid damage) and, with the engine running (servo thus operative) and the car stationary, feel if the length of brake travel changes. If it does not, it points to the master cylinder.
- Andrea -
We are now almost one year and over 10.000 km further without any further work on the brakes. The pads wear evenly, there is no trace of sticking and the car still brakes straight. Andrea has in the meantime driven the car and judged the pedal travel to be ok.
Make sure that the cylinders of the front callipers, which differ in size, are connected to the proper circuits. See the page on the Superduplex brake system.
- Huib -