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Thread: Wacky Brake Wear

  1. #1
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    Default Wacky Brake Wear

    I pulled my track pads + rotors off yesterday to fit my street set and noticed some rather uneven wear on my pads. These are Project Mu Club Racer pads that have done 4 track days.

    https://dl.dropbox.com/u/3223840/Pho...s/IMG_1304.JPG
    https://dl.dropbox.com/u/3223840/Pho...s/IMG_1307.JPG

    The left and right pads are wearing in opposing ways and in such a way that the calipers are buckling inwards at the top under the braking forces (think negative camber).

    Now this is obviously thanks to the sliding calipers that this car has moving around under the braking forces but I want to know if an effect this pronounced is likely to cause any problems, I certainly haven't noticed anything while driving but it only takes a simple geometry lesson to realize that this is leading to slightly less than optimal braking force being applied to the pads along with the uneven wear reducing the life of them.

    Is this an actual problem or typical of this kind of brake setup? Lesson to learn here is to swap brakes left & right with each change I do.

    I wonder if @gslrallysport might have an opinion on this, or someone else who knows brakes?

  2. #2

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    Brembos: get.

    Sent from my HTC One X using Tapatalk 2

  3. #3

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    Quote Originally Posted by MadAussie View Post
    Brembos: get.

    Sent from my HTC One X using Tapatalk 2
    Looks like the issue is temperature gradient. Can't see how Paris hilton calipers would do any better.

    Have you checked that the slides are adequately lubed?
    Last edited by kmh001; 19-06-2012 at 01:12 AM.

    Gone to Volvo


  4. #4
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    you might have a slightly stiff or seized piston this is the problem with single piston calipers during high temp race situations it gets hot starts to expand and starts to catch

  5. #5
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    Whatever it is it is affecting both the left and right front calipers identically and in mirror image of eachother. The pins are all lubricated and move freely and the pistons move smoothly as well. I am pretty sure its just due to the play that is present in the guide pins and the added forces involved with using racing brakes along with semi slick tyres.

    People on PF seem to think it's a fairly normal occurrence with sliding calipers and just recommend rotating the brakes left and right between track days, so I am not too worried about it, but still want to hear conclusively from someone in the know. I'll show it to the guys at Tunehouse next time I am there as well and see what their take is.

  6. #6

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    Having spent a lot of time at the track over the years my best advice is to consider that you're pushing everything beyond it's design specification and the stresses involved will reveal problems you never thought of. Once you get onto slicks you cross a line that many road cars struggle to cope with and your conversations need to be with other racers because guys with street cars wont have dealt with the challenges that racing throws up. As you further develop the car to make it faster and/or solve problems the higher stresses will reveal new problems. You'll feel like you're constantly chasing your tail because it's one thing after another. If you don't draw a line somewhere it will get hideously expensive.

    That's a long winded way of saying that if there are no faults in your brakes you have probably reached a limit. That limit may not be the brakes themselves, it may be due to flex in the caliper mount or even in the hub, in which case a brake upgrade would make things worse. Not saying you definitely have a flex issue, but it's something to consider.

    To illustrate this point, look at these contrasting pics of a Commodore hub, one from a road car and one from a race car:

    Click image for larger version. 

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Views:	180 
Size:	48.7 KB 
ID:	11312

    Click image for larger version. 

Name:	95755_HarropUprights_m.jpg 
Views:	186 
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ID:	11313

    You're probably a bit of a pioneer because there aren't many (if any) other privateers driving a 3MPS at the same level as you so there is no body of knowledge to tap into. If you can manage the pad wear issue by rotating the pads that will be the cheapest and easiest solution, or maybe the guys at GSL will chip in with a simple solution. Regardless of that, if you decide to develop the car more, have a think about all the other weaknesses you might reveal.

    Gone to Volvo


  7. #7
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    Quote Originally Posted by MadAussie View Post
    Brembos: get.

    Sent from my HTC One X using Tapatalk 2
    Wholesale High Quality Plastic Brembo Look Brake Caliper Cover Kit FrontRear /set 3D, Free shipping, $13.98~17.56/Piece | DHgate
    (ok, back on topic now...)
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    If it's good enough for the boys at Mighty Car Mods.....
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  9. #9

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    Yes, those plastic covers would look really pretty after a few laps of a track sitting over scalding hot brakes


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  10. #10
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    Quote Originally Posted by kmh001 View Post
    Having spent a lot of time at the track over the years my best advice is to consider that you're pushing everything beyond it's design specification and the stresses involved will reveal problems you never thought of. Once you get onto slicks you cross a line that many road cars struggle to cope with and your conversations need to be with other racers because guys with street cars wont have dealt with the challenges that racing throws up. As you further develop the car to make it faster and/or solve problems the higher stresses will reveal new problems. You'll feel like you're constantly chasing your tail because it's one thing after another. If you don't draw a line somewhere it will get hideously expensive.

    That's a long winded way of saying that if there are no faults in your brakes you have probably reached a limit. That limit may not be the brakes themselves, it may be due to flex in the caliper mount or even in the hub, in which case a brake upgrade would make things worse. Not saying you definitely have a flex issue, but it's something to consider.

    To illustrate this point, look at these contrasting pics of a Commodore hub, one from a road car and one from a race car:

    Click image for larger version. 

Name:	COILOVER.jpg 
Views:	180 
Size:	48.7 KB 
ID:	11312

    Click image for larger version. 

Name:	95755_HarropUprights_m.jpg 
Views:	186 
Size:	100.8 KB 
ID:	11313

    You're probably a bit of a pioneer because there aren't many (if any) other privateers driving a 3MPS at the same level as you so there is no body of knowledge to tap into. If you can manage the pad wear issue by rotating the pads that will be the cheapest and easiest solution, or maybe the guys at GSL will chip in with a simple solution. Regardless of that, if you decide to develop the car more, have a think about all the other weaknesses you might reveal.

    You nailed it right there, I am asking more than just here for that very reason, looking where I am now I will probably take a step back from the semi slicks once they wear out and stick to the Neova's for track days for that reason, but the addiction to speed is still growing in me so I can't really say exactly which way I will end up going heh.

  11. #11

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    It sounds like you will have to stick to neovas, or fork out a decent brake set up, quaife, clutch, suspension. 6k min i rekon
    To gain a few seconds.

    Definatly looks like some flexing in caliper bolts or hub. With decent semi slicks not budging or sliding much on road something has to give.

    ---------- Post added at 12:32 PM ---------- Previous post was at 12:29 PM ----------

    Those bolts are under a lot of stress there reedy, would definatly not want one to snap after the straight of wakefield.
    I would look into decent brake set up!

  12. #12

    Default

    Lol @ Paris Hilton brakes.
    MPs brakes are bollocks. Upgrade.

    And yeah, 10.8 shearing strength bolts, at the very minimum. I run FPV spec falcon bolts on mine.

    Sent from my HTC One X using Tapatalk 2

  13. #13
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    Alloy floating caliper. This is normal when you bash the crap out of them on the track. Swaping each side is normal practice after each track day.

    Suggest going to a solid caliper with 2 or more pistons if you want to keep pad wear even.

  14. Default

    From the second image you post its clear you have the wrong pads in there. your just running a pad that is the same shape but is not held in the caliper correctly.
    We change two or three a week for this same reason (Brake noise, uneven pad wear).

  15. #15
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    If rotating them is all thats needed to deal with the uneven pad wear then that's no drama. With this pad and rotor combo the stock brakes work brilliantly, I can trigger ABS using semi slicks without much effort, so bigger brakes really aren't required.

    ---------- Post added at 06:18 PM ---------- Previous post was at 06:13 PM ----------

    Quote Originally Posted by mpsgarage View Post
    From the second image you post its clear you have the wrong pads in there. your just running a pad that is the same shape but is not held in the caliper correctly.
    We change two or three a week for this same reason (Brake noise, uneven pad wear).
    I queried the lack of a retaining clip with GSL when they first arrived, they do squeal like a bastard but I am only swapping them in for track days so the noise isn't a problem. The retaining clip doesn't do much anyway apart from make the pads harder to change. It isn't a load bearing component so doesn't have anything to do with the uneven wear I am seeing here, from what I can tell this is thanks to the entire caliper moving relative to the disc, not due to movement of the pads within it.
    Last edited by Reedy; 19-06-2012 at 06:53 PM.

  16. Default

    Quote Originally Posted by Reedy View Post
    If rotating them is all thats needed to deal with the uneven pad wear then that's no drama. With this pad and rotor combo the stock brakes work brilliantly, I can trigger ABS using semi slicks without much effort, so bigger brakes really aren't required.

    ---------- Post added at 06:18 PM ---------- Previous post was at 06:13 PM ----------



    I queried the lack of a retaining clip with GSL when they first arrived, they do squeal like a bastard but I am only swapping them in for track days so the noise isn't a problem. The retaining clip doesn't do much anyway apart from make the pads harder to change. It isn't a load bearing component so doesn't have anything to do with the uneven wear I am seeing here, from what I can tell this is thanks to the entire caliper moving relative to the disc, not due to movement of the pads within it.
    Not really, the clip fastens the outter pad to the caliper & stops it turning in it, If it wasn't needed why was it fitted. As that pad design has been around for years. This is the same problem with the Volvo & Focus pads. When we buy pads for these cars from the suppliers their even state this.
    The clip holds the pad firm on it housing therefore giving the caliper a coincident feel & no noise.quoted from Mazda tech support.
    The caliper is supported at each end & if your is twisting that much on the slides, you would have some serius issues with them.

  17. #17
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    That's exactly the concern, if the caliper is twisting on the slides then is it/isn't it a problem.
    There is no way the pads will be able to move this far off centre within the caliper when they are being compressed by the piston, that naturally forces them to lie flat against their backing plate.

    The general opinion of people with more track experience than I have is that this is something that just happens with single piston floating calipers when you use them as hard as I do, and that it's not ideal but not necessarily a problem as long as the brakes get rotated between track days.

    I'll have the Tunehouse guys take a look at this when I take the car in for a service next and will let the GSL guys know as well, that's where I bought them from and when I first queried them about the missing clip

  18. Default

    Your pads has moved in the cailper & under force its jammed, that simple. That is why Mazda/ford/Volvo moved to having a clip on it.
    Its not rocket science, it just the friction on the pad under force when its jumping round.

  19. #19
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    If the pads can move that much within the caliper then they would be popping those retaining clips off all the time, I accidentally did that once myself with my bare hands. Under braking type forces they wouldn't have a chance. I just find it very hard to believe that the piston and caliper arm are anything other than flush with the backing plate of the pads when they have a couple of tonnes of clamping force applied to them. The caliper forces the pads into their own correct position, not out of it.

  20. #20
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    Would it pay for someone to measure the caliper braket/mounting points to see if you have bent yours?

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