RebekahsZ Posted September 3, 2013 Share Posted September 3, 2013 I have had trouble with my brakes since I cooked them at AMP in the spring. The front rotors are junkyard replacements that I had turned. The rears I only had turned. Pads are Hawk HPS. All four rotors have the same (skipping?) pad deposit pattern. The rotors don't seem to want to get shiny like my wife's car. This is my first time with Hawk pads. There is no pedal pulsation, and the car is stopping reasonably well. I'm just curious if I have a problem coming. I am limping this brake system along for a couple more months, then I will probably try to sell it off when I do the AZC big brake conversion over the winter. Any ideas are appreciated. Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted September 3, 2013 Share Posted September 3, 2013 Did you measure the regions with a micrometer to see if they are different? Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 3, 2013 Author Share Posted September 3, 2013 No, I haven't, but I will when I swap tires Thursday for Friday drags. Quote Link to comment Share on other sites More sharing options...
Glliw Posted September 4, 2013 Share Posted September 4, 2013 Look at it from the edge. Does the discoloration follow the cooling path pattern? It is most likely discoloration due to extreme heat cycling. You've changed the molecular structure on the rotors. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 4, 2013 Author Share Posted September 4, 2013 What's the cooling path pattern? Quote Link to comment Share on other sites More sharing options...
Glliw Posted September 5, 2013 Share Posted September 5, 2013 Nevermind, I got my daily driver's brakes and the Z's brakes confused. Either way, for reference, many rotors have cooling fins such as this: Many people also wait too long between brake jobs and get this as a result: Quote Link to comment Share on other sites More sharing options...
Domzs Posted September 5, 2013 Share Posted September 5, 2013 Nevermind, I got my daily driver's brakes and the Z's brakes confused. Either way, for reference, many rotors have cooling fins such as this: Many people also wait too long between brake jobs and get this as a result: I have seen the second photo way too many times at our shop . . And most of the customers said " it just started to make noise yesterday " . Yeah , right . Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 5, 2013 Author Share Posted September 5, 2013 No. I have solid, un-vented rotors. Quote Link to comment Share on other sites More sharing options...
beermanpete Posted September 5, 2013 Share Posted September 5, 2013 Perhaps some sort of resonance? Is there any noise while braking? Very odd pattern. I have never seen that before. Quote Link to comment Share on other sites More sharing options...
johnc Posted September 5, 2013 Share Posted September 5, 2013 Same pattern on both sides of the rotor? Quote Link to comment Share on other sites More sharing options...
Glliw Posted September 5, 2013 Share Posted September 5, 2013 Have you measured their thickness? What do the pads look like? Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 5, 2013 Author Share Posted September 5, 2013 Yes, johnc. Same on both sides. No noises at all. From the driver seat, all seems well. All four wheels are the same. Will try to mic it when I swap from streets to slicks on Saturday. I was there when the rotors were turned and I personally scuffed them a bit with sand paper on a block before installing. Car stops fine from 100mph. Weird. Quote Link to comment Share on other sites More sharing options...
johnc Posted September 5, 2013 Share Posted September 5, 2013 I would check the sliding pins on the caliper to see in they are loose, binding, or bent. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 8, 2013 Share Posted September 8, 2013 I would check the sliding pins on the caliper to see in they are loose, binding, or bent. Ditto that, something is letting your pads flutter. People think rotor thickness or "warpage" causes pulsation, when that is rarely the case. Brakes stop the car by embedding braking material into the face of the rotor, initially. If this deposition is uneven, then as the pads slide over areas with and without deposited pad material, it causes that "pulsation" .... The easiest method in the past was to turn the rotors to get a fresh surface and try re-bedding the brakes. Now there are tools that use small 3m grinding or sanding discs that clean off the existing pad material with minimum rotor metal removal, and you rebel on that. Only in the most extreme cases (grooving, scoring, actual warpage) will big brake lathes some into play. What I see is brake material deposited and building up unevenly. Brake pins, springs, etc is where I would look. Even the seals on the pistons not causing that minimal retraction can cause them to flutter. Block sand and re-bed the pads...but really, if you aren't feeling pulsation the cosmetics really don't mean much! Quote Link to comment Share on other sites More sharing options...
socorob Posted September 8, 2013 Share Posted September 8, 2013 In a pinch I bought some cheap AZ rotors about 2 years ago. I had to get them turned just slightly to work with my calipers and pads. I went straight from AZ to a place that turns brakes. I went to the back to watch the guy turn them and brand new rotors looked just like that, they were scalloped. The guy says he sees that a lot from the cheap Chinese rotors everyone sells. The lathe would cut for about an inch then not touch the rotor for about an inch alternating like that all the way around. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 8, 2013 Share Posted September 8, 2013 That would pulsate like hell. This set isn't pulsating... A 0.001" change in rotor thickness will shake your fillings out at speed when the brakes are applied! Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 8, 2013 Author Share Posted September 8, 2013 There is no detectable thickness difference between the different colored areas. Since it is stopping fine, I'm gonna blow it off. Thanks for all the insight. Quote Link to comment Share on other sites More sharing options...
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