mm450exc

Brand new discs/pads all around. One track day and a few hundred miles later I get this vibration on the front at around 50-70mph. Figured bad discs from the factory and had OPC change them.

Put on two track days at SPA on the new discs and a few hundred miles later get the vibration again only worse. Brakes have to warm up so clearly must be the disc.

Anybody have this problem?

orthojoe

Sounds like pad deposits to me. Certain pad and rotor combos need to be bedded properly to avoid this.
You need to remove the deposits first. If you have track compound pads, braking while cold should shave them off.

F1CrazyDriver

Joe is correct. Brake pad deposit. I have it on my car. I have to fix that issue this weekend. 80 grit should take care of it.

Spyerx

What pads? Are you bedding? Agree with above assessments.

mm450exc

Did the bedding in for a few hundred miles. Got standard GT3 pads.

So pads out and sand them down a bit?

skxf430

Check to make sure your tires aren't rotating on your wheels. This happens frequently after a track day.

F1CrazyDriver

Rotors need sanding. I'll try to take pics tomorrow when I do mine. My case I used stock pad in a race rotor..f things up .

mooty

ignore the shudder. continue to brake hard it will fix itself.

m5trol

Is this problem (and braking as solution) also related to shudder while braking?

If not, what would cause the vibration on braking?

mm450exc

Here is a picture guys. A lot of little grooves on the rotor surface....

911rox

Can you feel those grooves or are they just hot spots (darker rings)?... Do you bed in the rotors before heavy track use? I still use OEM pads and have never had an issue with shudder on OEM nor PFC rotors although they tend to leave hot spots through the centre of the friction ring surface after each trackday that takes a couple hundred kms of driving to wear away...

the_vetman

Good advice above, but also make sure that your wheel weights didn't fall off and your wheels are now out of balance. Common reason for vibration at speed.

ShakeNBake

^^^ That and tire slip on rims throwing front and rear out of balance.

mm450exc

The first front set of rotors had 600 miles of bedding in, one cold/wet track day at Silverstone on Michelin Cups. So slow and rotors got nowhere near hot. Vibration started a few hundred miles after track day.

Set #2 about 800 miles of bedding in, 2 days at SPA and vibration started about 1200 miles after. Steering wheel is about to fall out the window now when I hit the brakes. Nothing looks to be loose.

I cannot believe they are warped really unless they are made out of chocolate. I suspect the connection between the hub and the rotor. Those pins which make the connection look a bit suspect.