HELP! Brake problem...AGAIN!

[AJR8]

Hi! I'm becoming crazy about a problem that I have with the brakes. I'll describe the problem that I still have: Over 120-130 mph the brakes vibrate as if they were warped ONLY WHEN THEY ARE HOT (so after 2-3 hard-medium brakes, or after e long soft-medium braking, heated!). They dont' vibrate even if I brake at +150 mph only once (cold rotors). They vibrate ONLY at high speed and when they cold down they stop vibrating. I controlled the rotors with the instrument yesterday, the rotors aren't warped.

Since this problem have been following me for months I'm gonna tell you what I have done since now:

-I fixed the OEM warp rotors and put new Ferodo Pads = NO PROBLEM SOLVED.(P.S:STAY AWAY FROM FERODO!!!)
-I bought Stasis rotors and put on pagid RS 4-2 (blue) front & rear = Had a problem with the stasis rotors that we are still working out to fix.
- While waiting the other set of new stasis rotors I bought BRAND NEW Audi R8 rotors, installed in Audi dealer. = NO PROBLEM SOLVED.

So now I have new OEM rotors(900km), Pagid RS4-2, braided lines, motul RBF 660...and I can't drive my car fast because after 120 mph my brakes start to dance "shake shake shake...shake your booty!"

Is like the rotors warp whem hot, but then they return in shape when cold...CRAZY! I HAVE CHRISTINE'S ROTORS!!!

Tires are Pilot Super Sport and have no problem at all (checked!), the OEM rims are perfect, no bends or anything and well balance.

I'm wasting money, time and the car is not making me happy...the dealer doesn't know what could be! I'm about to surrender...

Audi dealer will never tell me that OEM rotors are rubbish, they just told me "For your kind of foot you should go with Ceramics...14k EURO"! Yeah right...with 10k I get the brembo racing line, the full system used on the R8 LMS...and we are talking about the best of the best!!! But I won't do that.

But are we sure that the problem are the rotors??? Maybe I'm wasting money on the wrong item...

Any ideas?

[Arantor]

Got the same problem, running Ferodo DS 2500 with OEM discs nearly on tracks only.
After 2 sets of brakepads the discs where done. Replaced the discs, drove a bit, replaced the the pads, brake them in (like it's recommended), and problem solved.
Got the problem that the discs where done and when they were getting hot the whole car was vibrating while braking.

EDIT: But that problem is not caused by the Ferodos, best legal brake pads available in germany!

[AJR8]

Yes but now I have new oem rotors and new pagid pads...the "bed in" procedure was done perfectly for 200km just to be really sure...but I'm still vibrating !

Did you put new oem rotors or others?

[Arantor]

OEM - strange, at my car it was working..
Did u replace both at same time? normaly it's said that u need to bed in (thanks ) new pads not together with new discs.

[harrison]

Ferodo makes several different compounds, but since yours are TUV approved ...there must be some other problem. It is often that tire problems are confused with brake issues. Cold tires are harder and could have flat spots for a while -'till things get warmed up. Some pads can be purchased allready seasoned.Doing your break-in procedure is a very good thing.

[Arantor]

yeah but tire problems are not only existing during braking so u need to feel a tire-issue also during acceleration and/or passing corners

[AJR8]

yeah but tire problems are not only existing during braking so u need to feel a tire-issue also during acceleration and/or passing corners

True...but since I tried everything...I went to a dealer 50 miles from my city to have the tires and rims controlled and balanced on the car because the dealer of my city didn't have the machine to do the job! So the tire is fine and is balance...but is not R01...just generic (not marked) michelin super sport...

The break in procedure was done with the stasis rotors...and when I mounted the new OEM rotors I "scratched" the pads and made a break-in period as the pagid techs said just to realize a good marriage between pads and rotors...

P.s: I haven't tracked the car.

[willyjp]

Many years ago (35!) I had a car (Porsche 914-6) that had front end vibration ONLY noticed with hi speed (but not nearly as high as yours....more like at 75-90 mph) braking. It was not noticeable cruising at steady speed, only on hard brake application. It turned out to be due to a very mildly bent wheel; I suspect the bend was caused by hitting something (chuckhole?) that ONLY bent the INNER rim of one front wheel. It was NOT apparent from inspection unless the wheel was removed, and then it was subtle, but visible. Your circumstance is a little different, but I raise this by way of saying that SOMETIMES (probably rarely) vibration on braking can be due to something other than a brake problem. I think that anything that rotates out of perfect balance or perfect roundness can create a vibration that is accentuated by braking...maybe because of the weight transfer magnifying the effect. Just a thought. Such a thing should have been picked up already by what you've done.

[AJR8]

Hi! I let the car at the Audi dealer this morning...they controlled all the front and rear end and made a braking test over a test dyno...all was perfect! Ok...I'm still wasting money!

[gazza1]

Have you had the roundess and trueness of the inner rims and the tyres tested.

A normal hi tech balance machine cannot detect this EVEN IF IT SHOWS IT IS FULLY BALANCED.

What balancer did you have your tyres and rims tested on

I found a very small out of alignment on one of my first R8 rims that caused a very small feel through the Steering Wheel at really high speed on the track.

Braking magnified the effect noticeably.