Rear brakes issue



  • I have noticed today after a long journey huge deep scoring on both sides of the discs! anyone know what causes this and how easy they are to replace?



  • Where is the scoring, is it all over the disc ??
    Has the disc got large lips on the outer edge ??
    Try and get a photo

    As for changing them dead easy, take wheel off, unbolt the caliper, the disc will slide straight off



  • thats them not so clear but you get the idea…. the pads look fine though, while i am at it i thought i would do the fronts as they are screeching under light breaking...



  • The discs are shot, they are only about £36 a pair and its worth changing the pads as those grooves will be in the pads too and may cause the problem to come back on the new discs or the pads may break up.
    If the discs are the same on the front do them as well, if they are not too bad then just take the pads out and rub some copper slip on the rear of the pads that will get rid of the squealing



  • okay so the ultimate dumb question….

    by copper grease on the back of the pad? what do you mean... sorry.

    by the way awesome response huge thanks.. :D



  • i have read your write up with rainy and you say to copper grease every moving part, now cause i am a dumbass that would lead me to go wild and grease literally every moving part, i figgure that this cannot be what you meant… :oops:



  • Mine are exactly the same and I've known about them for ages, so with MOT time around the corner I have just ordered a new set of disks from ebay.

    Here's the link for the 1.8 versions ;)

    http://cgi.ebay.co.uk/MAZDA-MX3-1-8-05-91-12-98-Brake-Discs-Rear-/250596022573?cmd=ViewItem&pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3a58afd92d



  • @e00d87a1de=jamesshack:

    okay so the ultimate dumb question….

    by copper grease on the back of the pad? what do you mean... sorry.

    by the way awesome response huge thanks.. :D

    **You want to copper grease pretty much everything except where the pad meets the disc.

    Dismantle the pad assembly. There's two metal spring clips. Clean the crap off them, then put copper grease where the pad will reseat. Get the shims, clean the crap off them, then put copper grease on the back of the pad, locate the shim on the back of the pad and locate the pad in the clip - same on the other side.

    If it's involved in moving the pad to and from the disc, it needs copper grease. If it's involved in stopping the car, it doesn't - very much doesn't.

    I bought a pair of Black Diamond rear discs very recently and haven't got around to fitting them because the two caliper mount bolts are im-cocking-possible to get at or turn. When it stops raining again, I'm out there with a blowtorch, a mallet, all the expletives in the English language and a V8-powered blender.**



  • Crackin stuff yeah I ordered some drilled rears from ebay last night along with some new pads, gonna hit it this weekend, Strangly i have a blow torch lurking about so may put rthat to use. thanks fo the advice guys :D



  • **No! Cancel cancel cancel! Never put drilled discs (particularly if they are actually drilled rather than cast with holes) on a road car.

    (actually, it might not be as much of a problem on rears, but I wouldn't touch them with a 40 foot unobtanium pole)**



  • @3f01454950=Famine:

    (but I wouldn't touch them with a 40 foot unobtanium pole)

    LOL :lol: Famine you have a way with words!!! Funnily enough I was watching Avatar the other night!

    James, go easy on the copper grease, a tiny dab on each moving part and a thin coating on the back of the pad. Don't want any of that shiz dripping on the pad face or disc once warm.

    Before you put the pads back in, clean up the pad carrier with some sand paper or a file. Make sure the pads move freely while sat in the carrier. They normally get built up with rust and brake dust which make the pads stick, they won't move away from the disc so wear quicker, reduce MPG yada yada!

    Famine, plenty of WD40 and a 3ft breaker bar, plus expletives and V8 blender lol, will get those caliper mount bolts off. Extension bar on the socket (short 4 - 5" one will do) is a god send to give you clearence.

    My Top tip of the day!
    If you're dealing with stubborn bolts, if you can, pull the ratchet/spanner/whatever towards you rather than away. Your body is alot softer than any peice of that car…. trust me I know lol!



  • ? okay so question… why not put drilled discs on a road car? is this due to the lack of heat?



  • @e76fc9e6ac=jamesshack:

    ? okay so question… why not put drilled discs on a road car? is this due to the lack of heat?

    **No. It's because they bring no benefits and some quite major downsides.

    I might go a bit "suck eggs" here, so I apologise if you know this already… The primary job of any brake disc is to conduct heat from the friction of pad on disc throughout its body, so that the pad/disc contact doesn't get excessively hot (otherwise the contact isn't as efficient - brake fade), then radiate/convect it away. The secondary job is to provide a surface for the pads to grip. So a good disc is a big slab of very conductive metal and which can get very hot without deteriorating.

    With that in mind, let's crack on to what drilled discs do/don't/are supposed to do:

    Oft-posited benefit 1 - Drilled discs dissipate heat better
    Nope. Discs are made of iron. Iron conducts heat very well, making the heat spread evenly and quickly through the disc, whereupon it can be radiated/convected away. Holes in that are made of air. Air is an insulator. Heat does not spread evenly and quickly through the disc.

    Oft-posited benefit 2 - Drilled discs effectively remove gas that builds up between disc and pad
    Bollocks. Pads haven't outgassed since the 1950s. They're made of steel and copper now. They used to be made of asbestos and glue - heating the glue generated small amounts of gas which could prevent the pad contacting the disc properly. Doesn't happen now, so… what gas?

    Oft-posited benefit 3 - Drilled discs remove brake dust more effectively
    Maybe. But why is brake dust bad?

    Actual benefit 1 - Drilled discs run cooler
    True. They have great big holes in them, through which air can flow. This gives them a slightly higher specific heat capacity - they can hold slightly less heat because there's less metal, but their base temperature is lower. If this particular issue becomes life-or-death on your road car, please surrender your licence before you kill someone.

    Actual benefit 2 - Drilled discs are lighter
    True. Air weighs less than iron. But come on. On a race car where every gram counts, yes - and we are talking grams here.

    Problem 1 - Drilled discs have less swept area
    Yep. Where your pad contacts the disc is what stops the car. Holes don't stop your car. Again, this shouldn't be massively significant on a road car unless you're driving like an arse. On a racer, the benefits of specific heat capacity and weight outweigh the reduction in swept area.

    Problem 2 - Drilled discs can be badly made
    Ooooh yeah, big check on this one. Not such a problem with solid discs, like the MX-3's rears, but with vented ones, very much so. It's amazing how many drill patterns wholly fail to take account of vent patterns - look closely at some cheap discs (or, heaven forbid, homemade ones) and you can see they have drilled clean through a vane inside the disc.

    Problem 3 - Drilled discs are fragile
    Iron is stronger than air. A 10" disc of iron is stronger than a 10" disc of iron with holes in it. But that's not the half of it - discs that are actually drilled (rather than cast with the holes in place - like Porsche's carbon-ceramics) are a catastrophe waiting to happen. Drilling into the metal changes the structure of the crystals around the hole, not only due to cutting them, but the heat generated in the action of drilling. Every single hole drilled in a disc is an added stress point, which you're asking to withstand a tonne of car at 30 metres per second, regularly, and then, because air is an insulator, they become hot spots on the disc. This is a fantastic recipe for shattering a disc. And it happens.

    So you have a slightly lighter disc which runs a bit cooler than a solid/grooved one. This is good for a racer. You also have a load of stress points and hot spots. This isn't good for a racer, but they only need the disc to last 200 miles and for 400 stops - YOU need it for 60,000 miles and tens of thousands of stops. They don't dissipate heat better and there's no such thing as outgassing pads unless you've come through time in a Frazer-Nash. The benefits are marginal (or fictional) and the potential problems are colossal. Wouldn't touch them on a road car for any reason.

    Incidentally, similar things apply to the benefits of grooves, but grooves are all cast and none of the problems apply. I'd put grooves on my car - particularly if the prices are very close - and have. And will again.**



  • Excellent write up there Famine…

    I once used a set of drilled discs on a ford ...needless to say they cracked badly so from there on ive used groved discs since but on replacing the disc on the 3 ive stuck to std ones.....



  • FOR SALE

    brand new not even recieved yet set of crappy impulse purchase waste of money discs!

    Okay I get that they are basically gonna be binned after a few weeks of use cause i drive a damned far distance at high speed daily getting to work, suppose they'd be no issue if i used her as a shoppin trolley…..

    before i buy anythin else for my mx i am gonna be bugging u guys for whats best i think......



  • lucky you guys know this cause i was about to order the front set!!!!!!!!!!!!!



  • @43af4feca8=jamesshack:

    FOR SALE

    brand new not even recieved yet set of crappy impulse purchase waste of money discs!

    Okay I get that they are basically gonna be binned after a few weeks of use cause i drive a damned far distance at high speed daily getting to work, suppose they'd be no issue if i used her as a shoppin trolley…..

    before i buy anythin else for my mx i am gonna be bugging u guys for whats best i think......

    **On the back it probably won't be such an issue. FWD cars have heavy front brake bias and, frankly, the rear discs are just for show. Sports cars with rear drums don't sell well :lol: If you're not shovelling a lot of heat through them, then there'll probably never be an issue.

    You also won't run into the problem of drilling through vanes - it's not a vented disc, so no problem.

    And since the problems are much more diminshed, at least you have lightweight rear discs :lol:**



  • Just to provide some balance to this…

    I've had my drilled and grooved discs on my daily driven ZE car since it was on the road. Same discs for just under 2 years so far. I've had no problems, no cracking, no premature fatigue, no stress cracks. All that plus the big brakes/twin pots from the xedos 9. I've seen one of them glow with heat when my wheel bearing failed and still fine. I bought them for looks and I got a good deal. However if I were to buy again I would buy solid, grooved or grooved and dimpled, because given the choice it's not worth the risk.



  • @e558373c04=Marco:

    Just to provide some balance to this…

    I've had my drilled and grooved discs on my daily driven ZE car since it was on the road. Same discs for just under 2 years so far. I've had no problems, no cracking, no premature fatigue, no stress cracks. All that plus the big brakes/twin pots from the xedos 9. I've seen one of them glow with heat when my wheel bearing failed and still fine. I bought them for looks and I got a good deal. However if I were to buy again I would buy solid, grooved or grooved and dimpled, because given the choice it's not worth the risk.

    I think cracking with cracking brake discs is a lot about the quality of the metal and manufacturing along with driving styles !!!

    OK back to the start, you have bought some drilled discs put them on try them no point buying some others and having them sat around or losing money on them, I doubt you are going to be heavy braking into a right hander from 120mph on the way to NETTO's because they have a special on imported chicken livers.
    Because to be honest anyone who reads this is now not going to buy your discs LOL.
    I am sure they will be fine as they are rears and wont get the punishment the fronts do, bang a new set of pads in and grease it all up or even invest in a pin kit that will replace all the parts that get worn on the calipers without buying new calipers then you have pretty much a new set of brakes



  • its all good, makin these mistakes is part of me getting the hang of getting this car healthly and happy again.

    many thanks for all your input


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