Fulvia 1.3 series 2, brake disc thickness

CD's with documentationElectronic distributor
Marko Mataija

Fulvia 1.3 series 2, brake disc thickness

Unread post by Marko Mataija »

Hi!

Does anyone know what is the minumum allowed thickness of the brake discs (front & rear) for Fulvia Coupe 1.3S, 2 series (from 1972)?

Thanks,
Marko
Huib Geurink

Re: Fulvia 1.3 series 2, brake disc thickness

Unread post by Huib Geurink »

I haven't found it (yet?) in the documentation. For the front discs the Data Tecnici page 09/0040 says "min. thickness for refacing 11,5mm"

I recently mounted new front disc on a S2 Fulvia. These had stamped on the side: min. thickness 10.7mm. This sort of corresponds with the 11,5mm min. thickness for refacing.

On the other hand, the nominal thickness for Fanalone discs is 9mm. I don't know if the material is the same.

Note that discs can be put under enormous strain. They may be red hot when the car goes through ice water. They are supposed not to break under these conditions. So, you are right to inquire about thickness. Unfortunately nothing in the books. I hope someone else has answers.
Paul de Raymond Leclercq

Re: Fulvia 1.3 series 2, brake disc thickness

Unread post by Paul de Raymond Leclercq »

Yes the spec was quite clear: 11mm. But this applies to the front discs; the rears are thinner, but I cannot remember the dimension.

Working on many Fulvias over the years, I have seen some very thin discs indeed, amazingly in my view, unbroken.

On my car which has S1 rear discs, I had the discs machined to 9mm. AFter nine years, I have had no trouble. The S1 discs, never seem to wear out - probably because the Dunlop brakes are usually pretty hopeless!

Paul
Huib Geurink

Re: Fulvia 1.3 series 2, brake disc thickness

Unread post by Huib Geurink »

Paul, I know your hate relation with the Dunlop brakes.
I used to have a hate relation with them too.
This turned into a love-hate relation when I took on the challenge.
Now that I have all the problems solved and know how to properly overhaul them, I have a pure love relation with them.
Overhauling them does not only mean to solve the problems of the corroded cilinder walls, but also the retraction mechanism has to be overhauled and set exactly to the proper values. I have made the tools to do so.The Dunlop system is complicated, needs regular service (as almost everything else on and old car) , corrodes easily, but, my friend, if everything is 100% in order, the pedal is super firm and braking is better than most modern cars.

The pads are important too. Regularly we have discussions on the forum about tires. Never on pads. Probably because they are not visible and do not contribute to a "masculine view". The later is probably the hidden motive for all the tire talk.
Paul de Raymond Leclercq

Re: Fulvia 1.3 series 2, brake disc thickness

Unread post by Paul de Raymond Leclercq »

Yes, well I think that Dunlop should have been a bit more "engineering" when they made the brakes.

I am sure that they were well aware that brake fluid is hygroscopic, and I think that really it was a little irresponsible of them to produce untreated cast-iron hydraulic cylinders. At least they could have been chromium plated. Even better perhaps, they could have made the cylinders from brass - like the pistons! They charged a great deal of money for the brakes in the early days, so I doubt that the cost of brass would have been significantly greater. I imagine that a suitable alloy with the necessary structural strength would have been no problem.

I do agree that when in good order, the Dunlop brakes provide good braking; it's just the "good order" bit that is so difficult to maintain. I recently drove a 3.8S Kaguar (1964); the brakes were comparable to a good S2 Fulvia's.

Your point about pads is well made; my (Dunlop) rear brakes were greatly improved by the fitting of EBC pads in place of the rather dubious ones that were installed before.

Paul
Huib Geurink

Re: Fulvia 1.3 series 2, brake disc thickness

Unread post by Huib Geurink »

Paul,

I believe the Dunlop brake to be the first generation disc brakes, already available somewhere in the mid fifties, maybe even earlier.

When an engineering team starts a new project, the first step is to specify all the required functions. Maybe corrosion protection was not one of them, but all other functions were properly specified and implemented. As with many new inventions, functions were later simplified and combined and new functions were added. Their sharp, effective and pleasurable operation is probably the result of the clear definition and separation of functions.

I don't think there was at the time any concern about corrosion whether brakes, bodywork or any other part. When I do a restoration job whether body or brakes the corrosion protection is at the top of the list. Although officially "restoration" means that the car is brought into the state it was when it left the factory, I personally have no problem with the use of epoxy primer and wax oil or whatever helps solve the problem of corrosion even if it was never used on the car originally.

Getting back to the Dunlop brakes, I think the choices that were made were the best ones available at the time for the application. Chromium plating is a galvanic process which does not work inside cilinders because of the way electric fields behave. Even if it would work, it is dangerous. It may crack and come off locally because pistons may and will hit the cilinder walls with high impact forces.

I can't really say for sure why they did not use brass for the cilinders. Instinctively I would say because the structural strength and the thermal expansion. Thermal expansion is twice as high as with cast iron. Note that the forces on the pistons try to implode the piston while the forces on the cilinders try to explode the cilinder.

At the very early stages brass was used for both the front and the rear pistons. The material of the front pistons was soon changed to steel. The story is that it was because of cost. I doubt it. I think it was certainly because of thermal expansion and possibly also strength. For the rear pistons brass was used all the time.

I am glad that we at least agree that a clear definition and seperation of functions is a good thing on the front suspension. We both like the hinges of the wishbones to be "ideal hinges" meaning no play, no distortion and very low friction even if it requires maintenance such as greasing and inspections every 50.000km or so.
Post Reply

Return to “65 Fulvia”