512TR Brake problem issue

I own a 512TR, 1994, Euro specs, ABS, 10.000 miles.
Problem is following. At high speeds (+125) or at track days my car starts to shake heavily after applying brakes. Rotors are measured by the dealer and they say the rotors are o.k., pads are OEM and in good condition to, normal brake fluid just changed. What could cause this problem. On normal speed car brakes fine and never shakes. Could it still be the rotors, the pads, the fluid or maybe all 3? Why does it shake only when warm or high speed and never when cold and normal speed? Any input is appreciated.
Marcel

 

Does it shake while the brakes are being applied? Can you feel a pulsing in the steering wheel? What I am getting at is are the rotors slightly warped, and is the heat amplifying the problem. They may still be within spec thickness but warped. If so, you could have them turned for very little, assuming there is enough thickness.

Just a thought.

 

What they did not tell you is if the rotors were warped. Having the correct thickness is not this problem. It sound very much like warped rotors. Also, very old brake pads might contribute to this. Sometimes I think faulty suspension parts can be to blame, but I'd go with rotors first.

 

The 512 shakes when the brakes are applied! I can feel a pulsing in the steering wheel and also in the brake pedal. Reading your feedback i agree to think they must be warped!

 

You REALLY need to upgrade if you are doing track days bcus the stock brakes are Not up to it & parts are retardedly expensive & poor quality

At the least get new race rotors & pads from porterfield, you can use these on the road as well w no problem

If you want to get really serious get the Brembo F50 kit but you'll need new wheels bcus the front rotors wont clear stock wheels w Brembos on

 

look for the following :

1)Weight for the wheels may have come off therefore affecting the balancing of the tire.

2) Weak ball joint(s)

3) Broken or nearly broken upper control arm

4) A shock/Shocks

 

Actually Rotor thickness variation causes the biggest pulsation. I agree they need to be machined/ground or replaced depending on your preference. If you were to measure the rotor thickenss at various locations you will find it varies and this variation will force the caliper piston to follow the uneven surface.

 

Wheel balance is fine, just had them balanced (all 4) and this didn't help.
Ball joints checked and seem o.k.
Upper arm controls look o.k. to, had the left rear lower control arm replaced because of corrosion and the metal was cracking!
Shocks are o.k. to.
I came to the conclusion that the rotors must be warped.
Will change all rotors and pads, read some previous threads about porterfield brake upgrade and will try following.
4 new rotors, street/race pads front, race pads rear.
Thanks for all the help, my dealer didn't figure this out after i brought it in 3 times! He kept saying everything is o.k., pherhaps time to look for another F-dealer with good mechanics!!!

 

Pic of the track day.
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You have hot spots in your rotors.

Both my 88 Testarossa's suffered from the same problems.

For a recent track day I had the rotors machined and flattened the pads for the event. Car braked well from speeds close to 280, but after three or four hard stops I got bad brake fade.

Once the rotors were machined the shuddering went away, but the brakes are crap for even moderate track day usage.

Not wanting to spend the big bucks just yet, I will be taking the first stage upgrade path.

New original Brembo rotors have been sourced and will be sent out to be radial slotted and then cryogenically treated (spelling?)

I am going to try EPC Red Stuff Ceramic compund pads as these have worked well for me before on both street / race applications on other heavy cars.

Braided brake lines to be fitted and the system flushed and then filled with Castrol SRF fluid.

This should dramatically improve the braking under extreme conditions. Once I can outdrive this setup, then big F40/F50 Brembo's or AP's will have to go on.

 

While you are at it, if you continue w track events you will want to install an aftermarket oil cooler as the oil warms up very fast when car is pused hard, also some racing harnesses would be good

 

William H: What have you managed to get the weight of your track car down to?

 

still working on it, I have a new engine which I will rebuild normally aspirated full race, looking for 800 hp w the Penske shocks & that engine I should be able to run w Porsche 962s

Next year

 

A little bit off track here, but:

Are porterfield pads that much different than other pads? My porsche has mintex pads, and the brakes are hard to lock up at speed (no power braking). Would switching to porterfield pads be a significant upgrade in friction/stopping power, or is it more of a "fade" preventative?

Bo

 

Send 2 mails to porterfield but no reply? Guess i need to look for substitute, any suggestions?

 

I have porterfield pads on my 512 (no ABS). I have both road pads (R4S) and track pads (R4). I can lock the brakes with both, no problem. I have had the car on track once, and I put the pads on for fade resistance. I probably would have been OK with street pads, because I didn't push them very hard. But the track pads worked well, though they squeal like crazy just driving around.

I got mine from Ricambi (www.ricambiamerica.com).

I don't think they are some vast difference from any other good aftermarket pad, but they work as promised and are priced well.

 

Wheel bearings most likely.

 

Dear Ferraristi,

I had this problem on my 91 Testa. (series II discs ) At higher speeds applying the brakes lightly, they would vibrate and shake the steering wheel. If you stomped on the brakes, no reeeal vibrations.
In my case it was definately warped rotors. I had the "warped" pair machined and they came out true. But....after applying the brakes and with heating, the rotors still had the "memory" and would warp. After a new pair, the problem was completely gone.


Shamile

Freeze...Miami Vice !

 

Did you just replaced the front rotors or all?

 

Dear Ferraristi,

Didn't know if you were asking your question to me? I only replaced the front rotors as those were the only ones that were warped. The rear discs don't really do much work so don't really heat up much. After a week of driving, take a look at how much brake dust is on the front wheels compared to the rears.

Shamile

Freeze..Miami Vice !

 

again. I would check the wheel bearings for wear. Checking for wear is easy. lift it, wiggle on the wheel, and if there is play, replace them.

This often happens, but people seems to overlook. It's not always the disks. Yes, disks do cause that, but from my experience, wheel bearings seem to cause this more and people don't think about it. On a heavy car like V12 Ferraris, I would say there is a good chance.

I deal with races cars all the time, and they do have that same issue, so, I am almost sure that is the case for your car, too.

 

Will check disks and wheel bearings in about three weeks. Will inform via this thread what it was exactly. Thanks everyone for the good advice, always feels good when people know the solution for you problems.

 

I second this comment. But this type of wheel bearing wear is more common on track and race cars. However since most F-cars are not driven regularly wheel bearings also deform from carrying the weight on one spot for a long time thus further supporting this theory.

But I would still replace the rotors because the TR brakes are so inadequate for track usage so the rotor warp just has to be the most likely cause.

 

Had the rotors machined, they were warped and will try on a track day tomorrow first with normal brake pads, then after some sessions with pagid blue. I am curious to find out if this was the cause of pulsing when applying the brakes. Second i am curious to find out if i can feel and notice the differences in the brake pads. Didn´t check the bearings yet but i will tomorrow. Will inform you.

 

Did a track day, was bs! When warm and applying brakes still pulsing in the steering wheel. Changing pads no different, problem still there. Have to change rotors now, didn't check the bearing but will do next week.