Do you think these discs are shot?

1mm is pretty deep for scoring. You can put new pads on and they will conform to the scored disc in fairly short order. Would I do it? No, not on a car like that. Even on a daily driver Toyota/Honda with scoring that deep I would replace the disc, and I am one to generally not get too excited about scoring on discs.

Don't know if there is machining allowance on the disc thickness; you can consider that. I don't understand how having the pads worn right out causes the brake pedal to go to the floor, but that's not your issue right now (or maybe it is as well, so make sure you replace the brake fluid at the same time since it likely overheated).

Rick

 

+1 -- without the friction material (which is a thermal insulator), heat from the disc (which was probably red-hot at the time) transfers directly into the (metal) backing plate-piston-caliper to the fluid. A little circular grooving is not a big deal (and when done by the pad material it is usually well-polished), but you are way past that (and very rough). If they haven't been turned before you should have ~1mm each side before reaching the minimum specified thickness in the WSM. I'd get them machined, and then even if they don't clean up completely at the minimum thickness -- i.e., just one or two very small grooves remaining -- I might reuse them anyway. If 10~20% of the total area doesn't clean up at the minimum thickness, then I'd replace them. JMO.

 

Do not put the new pads on, they will wear quickly and not perform as well.

If the disks are within limits, you can have them turned and they will be fine. If not, it is time for new ones. From the picture, they look solid and could be safely machined but a micrometer will tell you for sure.

" I'd get them machined, and then even if they don't clean up completely at the minimum thickness -- i.e., just one or two very small grooves remaining -- I might reuse them anyway. If 10~20% of the total area doesn't clean up at the minimum thickness, then I'd replace them."

+1

 

Nothing special about them -- any auto parts store or machine shop that does brake disc work could do them. I wouldn't even tell them that they are off a Ferrari (The minimum thickness spec is usually directly cast in small letters into the disc somewhere on a non-functional surface.)

However, what's happened here in the US is that (non-exotic) brake discs have become so cheap that it is often less expensive to just replace them rather than machine them (so fewer auto parts stores offer this service) -- but that won't be the case with an F disc.

 

FWIW, I wouldn't recommend the Brembo drilled discs..... I destroyed my oem's in pretty much the same fashion as you and the dealer recommended them, or the F40 upgrade. ( yeah, right! at the price!)

Suffice to say the Brembos didn't last long on the track until hairline cracks appeared at pretty much all the drill holes.

Went to Rifledriver who recommended Girodisc slotted ones. (Potentially only on the front). Problem solved.

Cheers,
Ian

 

Err, no sir.... I did both F&R as although the rears were OK I didn't like the idea of slotted at the front & drilled at the rear.

I could be wrong here, but IIRC they're actually the same disc. Sure someone will confirm (or set me straight of course. )

Cheers,
Ian

 

Again , FWIW, '+1' to the above.

Oops! My bad.... I was so 'focused' on giving you a heads up on the Brembos I forgot to check car type!.... 360 I believe was the same.

Cheers,
Ian

 

My guess is that they are the original Ferrari Pads.
I had a similar brake pad fade issue on the original pads at the track (with 2 day old new fluid).

Better pads are in order for any serious track use, mated to smoother disks.

 

Yes. But, also have the machine shop check them for total lateral runout --- before and after turning --- if they got excessively hot, they may also be too warped to bring back into useable condition.

Discs for these cars are expensive (compared to most any other), therefore I have no problem justifying to keep using them until they are completely trashed / used up ---- I don't mind prematurely eating up pads sets along the way, pads (standard, lower performance) are cheap.

 

There are very very few cars that come from the factory with brakes big enough to run track events without fluid / pad fade and rapid wear, in extreme cases discs or pads being used up in one day.

I noticed this in 308,355,360 and even f-40 threads.

After high performance pads and fluid, the next step is to duct lots of air to the center of the rotors, especially the front. Here are two kits for the 911 Porsche. Both kits draw air from a scoop under the front a arm. A better approach is to go to the front of the car for more high pressure air.

If you are unwilling to remove "excess" weight or slow down, the next step is more rotor diameter & mass. Going from a radially, (straight vane), to curved vane disc will also help move more air through the rotor.

Just putting larger front brakes on usually means that the rears are under-utilized, but upgrading the rear is more costly because of the e-brake issue, (if you still want to retain one).

The only 4 wheel brake improvement kit for the 308, (that I know of), is Girodisc's. Their front caliper has smaller pistons than the Brembo kit, so retains better brake balance.

Installing a big brake kit may require a master cylinder and proportioning valve change as well.

here are a few shots of my overkill upgrade, with F-50 front calipers & rotor & 360 rear, including parking brake. Absolutely un-fadeable, bullet-proof brakes. Not cheap but very confidence inspiring


chris
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If these were on my Fiat, I'd just toss in new pads. On my Ferrari, I'd first try to clean them up by going to a brake specialty shop. Although any good machine shop could do the job, the set up charge is bound to be more than what would be charged by a shop which has a disk turning machine. It's really just a specialty lathe designed to quickly mount a disk and turn it down with a minimum of fuss. The advice to not say "Ferrari" is good, but depending on the laws where you live, the shop may need to know in order to be sure they are still legal and not too thin. If the worst one won't clean up, then buy some replacement disks.

For track days, it just doesn't make sense, to me at least, not to bring some spare brake pads, a container of brake fluid, and the tools necessary to bleed the brakes. If nothing else, bring along your old used up pads which you no doubt changed last time before they got to the metal backing plate. At least they would have gotten you home.

 

One of the old road racing tricks was to back up the metal on the brake pad. Fit a thin shim of stainless steel between the pistons and pads. Stainless steel is a poor conductor of heat, and would not transfer as much brake heat to the fluid.



Ago

 

On a related note, do folk think that these can be resurfaced, or do they need to be replaced?
These Worn Brake Rotors Are Terrifying
(Sorry, couldn't resist)

 

(Worn Brake rotors are terrifying). I would think the photo in the previous post, There was a long time of metal to metal contact. Some drivers have no idea what is going on. Also changing brake fluid before and after track time helps plenty.


Ago

 

All stories of woe aside....brake rotor wear usually looks way worse for wear(no pun intended), than actual degradation in performance would otherwise suggest...{ever take a look at the brake rotors on the trains you ride on???}
That said, use is a big factor, regular street use as oppossed to extreme use on week end warrior race track forays is another story...

IN GENERAL-and for: non-drilled and or slotted discs brake rotors- lathe resurfacing within a runout of 1-2 thou is fine, as long as A MINIMUM OF 1 MM ABOVE the specified minimum thickness is observed-NO EXCEPTIONS. Furthermore, resurfacing implies 100% smooth and runout and min thick specs are observed-otherwise-REPLACE THEM.
for other non regular surfaced rotors-drilled etc-the specialized grinding equipment costs prohibt the job to the degbree that unit replacement is significantly cheaper in cost to benefit specs.

 

Smart move. While you might be able to resurface the discs and get some more use out of them, you don't want to be thinking to yourself, "Gee, I really should have bought new rotors" as you are heading into a turn going hot and need that braking to kick in for you. After all, how much is your life worth?

And good idea going with the plain, flat rotor. I learned the hard way with a couple of Corvette Z06 racecars that cross-drilled rotors do NOT hold up on the track. They crack like crazy. And slotted rotors seem like a good idea. But the slots end up acting like a cheese grater and cause the pads to wear rather fast. I found that I got the best performance and longest pad and rotor life with just plain, flat rotors.

By the way, when you are out at the track, check your brake pads and rotors after every run. Make it part of your regular check list, like checking oil levels, coolant, tire pressure, etc. I always made a point of looking at the brakes and rotors between runs. More than once, I've found that the rotors had cracked, and one time found that a pad had come off. You don't want any surprises on the track. If you are really braking hard, a lot, you may see some bluing on the rotors, and possible some heat checking on the surface of the rotor. It's the cracks that run to the edge that you want to look out for.

As for brake fluid, get some good, high temp racing fluid. I always had good success with ATE Super Blue and Amber 200. Motul 600 is also good. Bleed them before each track event and you'll never have a problem with fluid boiling.

 

I have my rotors painted with temperature sensitive paint so I can see hot hot the disks really got (with the wheels still on the car.)

And for fun: I have gotten my rotors hot enough for them to turn battleship grey and you could roast weinies on them through the holes in the wheels while sitting in the pits--all without brake fade.

 

Going to the track? Don't machine your brake rotors, it removes mass that you desperately need for thermal absorption and subsequent dissipation.

As stated, slotting = good, drilling = bad.

Best,
Rob

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