RJFabCab

Am I missing something here?

Local Master Tech wants to fail my GT3 on the tech spec due to "bluish discoloration of the front rotors".

I didn't think that the rotors looked any different compared to other sets with track miles on them. Sorry, no pics.

The rotors are not even close to meeting replacement criteria with respect to thickness, lateral runout, or cracking. I have about 4 events on them with 3400 miles on the odo.

Is this bluish discoloration a sign of significant loss of integrity in the rotors?

DanH

Don't think so, I thought it was normal, although if you have built up a decent transfer layer from the pads it would be masked a bit.

One of the stoptech white papers even mentions blueing when bedding in new disks.

Flying Finn

I usually get some blue color when I bed my discs but the it goes away after a while.

Try do some street driving and see if the discs wear enough to get the color off.

NJ-GT

I've seen my PCCB with that blue color after a track day. The color goes away after a few days.

I've not been turned down for a track day due to my car color, brakes color, pads color, skin color...

MJSpeed

Try as others mentioned to bed them a bit and see if that works...I suspect it's not a big issue...BTW pics would really help...

JakeMate

From my experience, blued color means they are now bedded.

roberga

**** him.... go to another shop. Is this a dealer? No cracks, meets thickness standard? Is this someplace that will sell you rotors?

RJFabCab

Thanks for the feedback, fellas. I finally had a chance to get a really good look at the rotors... and they are a little more stressed than my first cursory exam revealed.

I probably have another event left in this set... perhaps even two. Without a doubt, cracking will be the limiting factor. Thickness and lateral runoff were fine.

They eventually approved my inspection. This was at the local dealer and they freely admitted that they don't "see" many GT3s.

Here's a pic of the "bluish discoloration" which I've always accepted as pad transfer and bedding as you all have mentioned.

Time to start looking for Cup parts...

bgiere

it's pad material transfer from bedding in...he's uninformed and doing you a diservice...I say write him up and hand him a Pagid Bedding Procedure manual!

RJFabCab

Roberga, there were cracks, and they looked quite small as I cruised out this morning. However, after really getting a chance to take a good look at the rotors, the cracks are a bit more prominent.

That being said, they still don't meet replacement criteria. They were initially saying that I needed to replace the rotors due to the bluish discoloration... no mention of problems with cracking, thickness, or runoff.

It was the local dealer.

RJFabCab

I took a glance at the rotors this morning and they looked "tested". Nothing unusual.

The unusual thing was receiving the phone call saying, "You need to replace the fronts due to the bluish discoloration".

So, all day I'm thinking, "Did I miss something here?" Naturally, I had to consult my Rennlist family!

Flying Finn

Based on the photos, they look ok. There are the usual cracks but it looks as if they are not connected to each other, don't go to the edge or are not longer than 5 mm.

That color is quite strong though (not that it's a factor that would mean you can't track them but just observation), more than I normally see. What pads are you using?

In any case, you should (as well as pretty much everyone who seriously track their GT3) start looking into cooling ducts.

Bob Rouleau

What kind of pads are you running?

Nordschleife

I believe that a series of extreme heat cycles can 'cook' the rotors. A strong blue hue is indicative of this. 'Cooked' rotors have undergone what might fairly be described as 'curing' or 'heat treatment'. In consequence, their behaviour under normal driving conditions is modified and their effective capacity for absorbing and releasingf heat is changed.
It is hard to tell from the photograph because of the lighting, reflections and lack of some external colour reference. However, the cracks do not seem great.
I would not dismiss your tech inspector's comments out of hand. My brake guy junks blued rotors faster than you can say 'HOW much?'
R+C

993inNC

Randy, it doesn't look like the pad is attacking the rotor evenly (which may explain the color). See the vent holes, how the top ones have pad material build up in them and it gets less as you look down the rotor? The bottom ones have nothing and are almost outside of the blue area. You may want to lightly turn the rotor, have the fronts bled real well and replace the pads......see if the problem repeats.