Do you think these discs are shot?

If you track the car, or just do annual brake flushes, I think it is worthwhile to alternate with different colored fluids, so that you can easily see when the old is out and the new is in.

This year, I went with ATE blue on both the 308 and the truck. Real easy to see the completion of the flush.

FWIW, I will try a match up of the 911 brake system cooling backing plate and the 308 disc to see if these off the shelf items might be easily adapted to our cars.

I am in the process of rebuilding the front suspension and brakes on my dad's old 911, including a brake cooling set up.

all for now,
chris

 

Some may find this of interest
http://www.separationofcontrols.com/posts/brake-overheating/

Sent from my ADR6350 using Tapatalk 2

 

It's a consequence of putting the drum emergency brake inside the rotor at the rear. Even though the disc portion OD at the rear is slightly larger than the disc portion OD at the front, the ID of the disc portion at the rear is much, much larger than the ID of the disc portion at the front -- so the total disc area is less at rear (and barely wide enough even with the larger OD). Have a look at the front and rear brake disc rotor illustrations in the 355 SPC.

 

ATE Blue is non DOT approved FYI. And now taken off the market by most wholesale suppliers

 

However, torque authority is also increased as a result, so overall rear braking power may be similar as with the non-ebrake drum ? One would have to know the precise dimensions to run the comparison calculations.

 

Sorry, I can't help you with specifics on your car and I understand the desire not to remove any hydraulic connections and therefore open the system to the atmosphere.

However, I can highly recommend bleeding your brakes whenever you do anything to them, especially if you have the caliper exposed, even if they feel OK. I can't recall ever saying, "gee, it feels the same" after bleeding brakes. They nearly always feel better with a higher firmer pedal. The reason most people don't bleed their brakes very often is that it's a bit of a PITA to jack the car up, remove the wheel, etc.

But if you're changing pads, for example, there is really no excuse for not bleeding the brakes. And, while you're at it, buy a larger container of fluid and flush the system. The process is just like extending bleeding. Keep at it until you see all the rust and cloudy fluid exit the system and the new clean fluid appear. You'll be doing your brake system a real favor. A mechanic signing off on a full service which includes changing all the fluids is not necessarily the same as actually changing them.

 

True, in fact, pad "area" doesn't even appear in the simple:

braking torque = pad force * friction coefficient * effective radius

equation.

but the pad needs to have an adequate volume of material (area * thickness) to give a reasonable life, and not having the width of the pad at least as large as the caliper piston diameter would be a little weird.

 

They also very likely use Loctite (threadlocker) on those bolt threads --- don't forget to re-apply when you install them --- it is important.

 

As a mid-engined car with significant weight towards the rear AND a very low certer of gravity, the larger disks on the rear are combined with the larger tire footprint on th rear to contribute rather equally with the fronts in stopping power.

There was an old Top Gear episode where one of them bought an F355 and they had track pictures of it breaking into a turn with both disks glowing cherry red. This is actually what you want, both axles contributing equally to the retardation with the break pedal applied.

 

ALL fluid is hydro-scopic, and therefore MUST be changed no longer than bi-annually, preferably, on an annual basis.

TEVES fluid(as repackaged by M/B)is a light "Pilsner" coloured liquid, as it DECAYS from water contamination/absorbtion, it becomes ever increasiningly darker...
For those technically interested-read the back label and specs on an M/B BRANDED bottle of TEVES brake oil, and compare it to thee TEVES label of the SAME listed gradeient....you will be surprised at the significant differences...hence the FNA advisory bulletin to recall all delivered -at the time-F-40s and upgrade to this fluid for brake oil...
FWIW

 

@65lbs/ft torque of the caliper bolts : I've read on other threads that a torque rate of 64nm was told to be the right value. But this sound quite low. If it is 64lbs/ft it would make a bit more sense that would equal 85nm torque. But still is not high for a M12 10.9 screw wich normaly uses 105-112nm torque. What is the right value Ferrari uses here ?

@Bigger rear discs than front : I would agree that a mid or rear engine car has more brake balance at the rear than a front engine car. But still the weight transfers to front when a deceleration occurs. Thats the reason why it still has more brake pressure in the front and a lowered break pressure at the rear. Wich could also be noticed by the small thickness of the brakediscs at the rear with only 24mm. That small disc cant take so much heat so still the front is the axle wich brakes the most. So i'm not convinced that the 10mm more diameter is used to make the rear brake more powerfull than the front. I would rather say it is there without a big reason and ferrari got that size somewhere or found this combinatino of thickness to diameter the best? But maybe someone has a better explanation for it wich makes sense?

Regards Samy