heavy85 Posted January 2, 2011 Share Posted January 2, 2011 I'm noticing the right front brakes are getting hotter than the left front. This is judged by the burned paint on the spindle on the right vs the unburnt paint on the left plus the left rotor only has very fine spider cracks where the right has many more and they are larger. There is slightly more pad wear on the right but not significant. Most all tracks I run are clockwise so if anything I would think the left front would work harder but that does not seem to be the case. Since I'm in the middle of the winter teardown and detailed inspections I would like to improve this if possible for next year. Up front I'm running Outlaw calipers, vented rotors, and 15/16 master. Any ideas why the right front would be running hotter than the left? Thanks Cameron Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted January 2, 2011 Share Posted January 2, 2011 (edited) Air in one side, sticking pistons on one side, or a collapsed brake hose. Those things are pretty common and can cause left to right bias issues. Does the car pull to one side or the other when suddenly applying brakes or when steadily applying brakes? Check compartative temps with an IR meter after a drive. Edited January 2, 2011 by cygnusx1 Quote Link to comment Share on other sites More sharing options...
heavy85 Posted January 2, 2011 Author Share Posted January 2, 2011 It's nothing obvious. I bleed them after every track day so it's not air for sure. Nothing visually wrong with the lines. I actually closely inspect about everything after each track day and I've never seen anything to explain the difference but I've noticed the symptoms for quite a while. Don't think it's pistons because they were recently rebuilt and just by nature of them it's highly unlikely and they acted this way before the caliper rebuild. Only thing I can think of is the factory safety switch / tee block where the front brake lines split. I've never had that apart. What's in it? Cameron Quote Link to comment Share on other sites More sharing options...
ModernS30 Posted January 2, 2011 Share Posted January 2, 2011 Up front I'm running Outlaw calipers, vented rotors, and 15/16 master. Interested in this setup. How did you get the calipers on there? What rotors? I have a stock car outlaw caliper laying around. Quote Link to comment Share on other sites More sharing options...
Snailed Posted January 2, 2011 Share Posted January 2, 2011 Swap the calipers and see if the problem is them or the lines. Should be easy to tell with an IR thermometer. Quote Link to comment Share on other sites More sharing options...
jasper Posted January 2, 2011 Share Posted January 2, 2011 Just an FYI. I'm Toyota Tech. I do a lot of brake jobs. The wheel with the most pad wear, is almost always the right front. I've never really given it a lot of thought, it's just that way..... Quote Link to comment Share on other sites More sharing options...
heavy85 Posted January 2, 2011 Author Share Posted January 2, 2011 Due to location of bleeder screws the calipers are not the same left to right so you cant swap them. I got the hats for two piece rotors and caliper mounting bracket from I think it was JSK Innovations. I'm using 1 1/4 x 12.75 vented rotors. Interesting that the FR on a typical passenger car is usually worn more but I cant see why it would be that way other than the caliper is further from the master so the lines are slightly longer to the right front than to the left front. I dont see where this would make a difference unless one was plugged. Since I can bleed both it doesn't seem that anything is too plugged. Cameron Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted January 2, 2011 Share Posted January 2, 2011 (edited) Could it be because of the longer return path (percentage wise) that the caliper on the right drops pressure more slowly than the left one, after the brakes are released. This could cause the pads on the right to drag slightly longer on brake release. This would not be noticable to the driver, but would become apparent only when Jasper went to replace the well worn pads. If so, RHD cars should exhibit the opposite. Â Interesting. Edited January 2, 2011 by cygnusx1 Quote Link to comment Share on other sites More sharing options...
jasper Posted January 2, 2011 Share Posted January 2, 2011 (edited) Technically, the volume of fluid moved should be identical side to side. So length should not matter. Edited January 2, 2011 by jasper Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted January 3, 2011 Share Posted January 3, 2011 (edited) You have more "pipe loss" on the right side. Because the entire column of fluid is moving, creating friction multiplied by the length of the pipe. It is negligable when you have huge pressure multiplications from the MC and the brake booster, but when the pads release, the pads push back with very little pressure advantage, so these pipe losses can certainly become a factor. It's just a hypothesis that could explain what you see at the service end. Edited January 3, 2011 by cygnusx1 Quote Link to comment Share on other sites More sharing options...
johnc Posted January 3, 2011 Share Posted January 3, 2011 Uuuuuuhhh, maybe a more reliable, accurate temperature measurement is needed to determine if there really is a difference? Just a thought... Quote Link to comment Share on other sites More sharing options...
heavy85 Posted January 3, 2011 Author Share Posted January 3, 2011 Uuuuuuhhh, maybe a more reliable, accurate temperature measurement is needed to determine if there really is a difference? Just a thought... If there wasn't a difference why now on two rotors in a row have the right rotor shown much more signs of heat? The left side shows just very minor spider cracking that you have to look close to even see. At this rate I could probable get two seasons, ~20 track days, out of a single left rotor. The right rotors have very visible spider cracks all around plus several large cracks. I'm about to replace the right rotor for the second time due to the larger cracks growing beyond my comfort level. Interesting theory on pad release - I do trail brake a lot but it's hard to imagine that little extra bit of pressure would add that much more heat in the grand scheme of things since pressure and therefore torque and therefore heat generation is relatively low at that point. Cameron Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted January 3, 2011 Share Posted January 3, 2011 My theory is aimed more at what Jasper is seeing, not what you are seeing. It sounds like you have a larger differential than that. I would open up all the lines, flush and back flush them, flush the safety valve and prop valve and any other unions. Inspect or replace the flex lines at the calipers. When they fail, they can collapse internally (not visibly) and act like a check valve, allowing flow in only one direction. Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted January 3, 2011 Share Posted January 3, 2011 If this was something you had only just bought and noticed after a few runs, I would have been suspecting the PO had checked the brakes and found the pads were worn gone on one side but some left on the other. To save money he may have bought a set of pads but only changed the one side with the intention of changing the other side when they wore down more... I've bought a car like that once, worn grippy semi-metallic on one side and newish budget cheapest-junk-on-the-shelf pads on the other side. Since you're running non-stock stuff I'm betting however that your pads match... Quote Link to comment Share on other sites More sharing options...
mark Posted January 3, 2011 Share Posted January 3, 2011 (edited) If there really is a temp difference between the two sides, it may be time to replace the seals in the calipers. Old seals can cause the pistons to drag. Have they ever been apart? Edited January 3, 2011 by mark Quote Link to comment Share on other sites More sharing options...
heavy85 Posted January 4, 2011 Author Share Posted January 4, 2011 If there really is a temp difference between the two sides, it may be time to replace the seals in the calipers. Old seals can cause the pistons to drag. Have they ever been apart? The calipers are now two years old with about 20 track days on them. I put new seals in roughly halfway though. Both the brand new and now the replacement seals seems to produce the same result. I'm planning to rebuild them again just for preventative maintenance but dont expect this will change anything. I think I'll have to take apart the factory safety valve / tee to see if there is anything inside. Seeing how they bleed just fine it's hard to imagine a restriction could be causing this though. Cameron Quote Link to comment Share on other sites More sharing options...
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