Did We Hard Spot The Rotors

Sleeper_08 · 05-20-2008, 06:13 PM

I did a search on this topic because I thought there was another thread but can't find it.

On the weekend we took me car to its and my first track day. The track is a short one, max about 100 MPH with a lot of turns and my brother and I were both on the brakes pretty hard. There was no evidence of fade but by the end of the we were getting pedal vibration and the front rotors have 'smudges' on them. Not sure how many laps we put in but went through two full tanks of gas.

The car is as described below with this brake setup;
1) Front - GT500 rotors and calipers with Ferodo with DS2500 pads
2) Rear stock calipers and rotorwith Hawk HPS pads
3) SS brake lines with ATE super Blue fluid
4) Quantum motorsports brake cooilng kit but no hose

The reason there is no brake cooling hose is that with the 285/40/18s on the front we can't find enough room for the hose.

My questions are;
1) Is there any way to confirm that the rotors are hard spotted
2) If they are hard spotted are they junk?
3) Other than going easier on the brakes is there any way to prevent this from happening again?

Thanks.

Stoenr · 05-20-2008, 07:17 PM

You could try having them resurfaced.
I had the "smudges" in mine. But they were still pretty smooth when stopping.
I resurfaced them when I put my drilled/slotted ones on and they came out fine. But I have not reused them yet.
As far as preventing it, bigger brake kit maybe.

Im sure others will have some input also

jayel579 · 05-20-2008, 07:27 PM

When you parked your car did you pull the E-brake up? Or even when you came to a stop in the pits did you come to a full stop on the brakes? Anyone of those instances could have caused you to trap heat between the rotor and pad causing a hard spot. Don't stand on your brakes in the pits after a session, stop the car and turn it off in gear then chock the wheels.

Answers:

1. You can take a micrometer to them and measure the rotor out to see if it is hard spotted.

2. They aren't junk, if there is enough surfface on the rotos you can have them re-cut otherwise you'll have to live with the pulsing or just buy new rotors.

3. Loose the Ferodo pads, everyone I have ever talked to that ran them on there car says they are absolute junk. Buy a dedicated track pad and change them out at the track. Combo pads are OK to learn on but they really do not hold up well at all, hence the results you are experiencing with your rotos.

Sam Strano · 05-21-2008, 03:27 PM

I sold him the Ferodo pads, because we've had GREAT luck with them... never an issue and that includes a lot of cars ranging from Z06's, to an STi (and have pics of the rotors aglow on that car, and no issues), and even an F-body with Porsche 993TT front brakes and 421 RWHP running on VIR's full course.

I don'tbelieve this isa pad issue. I don't have the details, but no reports of fade or them falling apart. His issue is rotor related, and the only way pads can cause issues there is because they can generate a lot of heat.... and he didn't seem to have adequate cooling. Pads don't warp rotors. Rotor material, airflow (or lack thereof), and that cause uneven stresses warp rotors.

Sleeper_08 · 05-21-2008, 05:24 PM

Sam

Thanks for the response.

The main cause of the problem was probably my inexperience. My brother kept telling me I was going in too fast and out too slowly. It is also hard to stop about 4,000 lbs (car + SC + 2 less than light weight people).

There were no signs of fade but as mentioned above there now is vibration during anything other than light braking and the front rotors have these small 'smudges' on them which I think are hot spots.

Is there anyway of confirming my suspicions.

Sleeper_08 · 05-21-2008, 05:30 PM

Quote:

ORIGINAL: jayel579

When you parked your car did you pull the E-brake up? Or even when you came to a stop in the pits did you come to a full stop on the brakes? Anyone of those instances could have caused you to trap heat between the rotor and pad causing a hard spot. Don't stand on your brakes in the pits after a session, stop the car and turn it off in gear then chock the wheels.

We didn't use the E brake all day,always ran a cool down lap before coming into the pits and parked it in gear so these wereprobably not a factor.

Per my response to Sam - it was probably my over eagerness and lack of experience.

Nuke · 05-21-2008, 06:15 PM

Warped rotors... No question.

Sleeper_08 · 05-23-2008, 05:54 PM

I took a few pictures of the front and rear brake rotors last night

http://public.fotki.com/colinjohn/mustang-gt-brakes/

You can clearly see the 'smudges' on the front rotors.

Does this help any determine what we did?

F1Fan · 05-23-2008, 06:52 PM

Quote:

ORIGINAL: jayel579
When you parked your car did you pull the E-brake up? Or even when you came to a stop in the pits did you come to a full stop on the brakes? Anyone of those instances could have caused you to trap heat between the rotor and pad causing a hard spot. Don't stand on your brakes in the pits after a session, stop the car and turn it off in gear then chock the wheels.

Answers:

1. You can take a micrometer to them and measure the rotor out to see if it is hard spotted.

2. They aren't junk, if there is enough surfface on the rotos you can have them re-cut otherwise you'll have to live with the pulsing or just buy new rotors.

3. Loose the Ferodo pads, everyone I have ever talked to that ran them on there car says they are absolute junk. Buy a dedicated track pad and change them out at the track. Combo pads are OK to learn on but they really do not hold up well at all, hence the results you are experiencing with your rotos.

Hi jayel579,

You cannot measure the hard spots. All you can measure arevariations in thickness. Hard spots are hard not thicker. If the rotors have actually developed hard spots they are junk. You can have them cut and honed but if the rotors were actually hardened you cannot cut or hone your way deep enough to gat past the hard spots. I've used DS2500 for a long time and this stuff is pretty good and well proven on the track in it's own right. DS2500 is a low end track pad that happens to work well enough cold to be passable on the street. I've never had a problem withthe brakes on a car with DS2500 compound pads installed as long as the car had a few cool down laps and was chocked or left in gear when parked.

HTH!

F1Fan · 05-23-2008, 06:56 PM

Quote:

ORIGINAL: Sleeper_08

I took a few pictures of the front and rear brake rotors last night

http://public.fotki.com/colinjohn/mustang-gt-brakes/

You can clearly see the 'smudges' on the front rotors.

Does this help any determine what we did?

Hi Sleeper_08,

The front rotors are almost well done and the rears are fine based on the photos anyway. Order some new rotors and as long as the front pads are not worn have them ground flat and scuffed and put them back in with new rotors.

HTH!