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fijifixit

Brake discs discoloured

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Hi guy, 

 

After some spirited driving I noticed my brakes didn’t bite as much as they do when they are cold. After I let the car cool down I checked my brake discs and the front ones were like a rainbow. Is this normal? I don’t know what make the discs are as they were already on when I purchased them. The brake pads I replaced earlier this year with EBC redstuff on front and Brembo on the rears. 
 

My rear brake pads are already low so was just wondering if the discs and pads need changing? 
 

There is a slight lip on the edges of the discs, but nothing too major.

 

Any info would be appreciated. 
 

Cheers.

Ibrahim

 

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554D35D9-9B0C-4EF5-8E42-86900D3452F2.jpeg

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Based on what you've said it looks like you've cooked the discs, possible if the brakes are not allowed to cool enough between each heavy braking cycle. They will still work, but are a lot more likely to crack and warp under heavy braking; they need replacing. Change the pads with the discs, always, then drive and brake gently for the first hundred miles. :thumbs:

Edited by Stock

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Merry Christmas! 

 

I've never seen disks that colour after any kind of driving! My rears on a previous car had a slight discolouration from dragging after the handbrake got stuck. My land rover used to not let pressure out of the system fully when the pedal was released, that would get worse and worse when driving till you had to stop for 20mins.

 

That would be my first check, how freely do the wheels spin by hand?

 

Sam

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I had this from not doing the breaking in procedure correctly   :(    one of mine is slightly warped so will need to changed it soon 

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4 hours ago, AntelopeSam said:

Merry Christmas! 

 

I've never seen disks that colour after any kind of driving! My rears on a previous car had a slight discolouration from dragging after the handbrake got stuck. My land rover used to not let pressure out of the system fully when the pedal was released, that would get worse and worse when driving till you had to stop for 20mins.

 

That would be my first check, how freely do the wheels spin by hand?

 

Sam

Hmm, I get people are saying that it happens if you incorrectly bed the pads in. But my pads have been on for atleast 7 months and Only got this multi coloured disc thing today. I do some spirited hard driving often and need had this issue. 
 

I’ll have to check how freely they spin when I get it up on a jack. There no brake pedal pulsing or vibrations so I’m convinced it’s not warped. 
 

Do you think bleeding and putting fresh dot4 brake fluid in would be a good option? 
 

Regards,

Ibrahim. 
 

P.s Merry late Christmas to you too! Happy Boxing Day :) 

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1 hour ago, PPod said:

I had this from not doing the breaking in procedure correctly   :(    one of mine is slightly warped so will need to changed it soon 

I bed mine in correctly 7 months ago.. I’ve only just got the issue today. It’s not warped though as the pedal feels completely fine so it’s just confusing. Sorry to hear about your issue :( 

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Has the bleed nipple snapped off the caliper (looking at last picture) possibly some brake fluid or oil has got onto discs and the pads have burnt it into disc under heavy braking which would poss explain the rainbow and loss of braking force. Just clutching at straws for you as i recall when i changed my fluid i thought i had tightened the nipples up enough but the force of the brakes made the fluid squirt out so had to get them mega tight. 

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At a glance I would also say it looks as though the discs are fitted the wrong way round too, thus not allowing the heat to escape effectively. 

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You can’t tell that without looking at the inner vanes. Worth checking though. 

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If it's not overheating (thought it could be because you said only both fronts showed the discolouration), it could also be an foreign fluid (could be as Glen said) that has spread on the discs. Get a clean rag and spray a little brake cleaner on it and lightly dab the disc to see if the discolouration goes away. Don't get any brake cleaner on the caliper or wheels, it will eat the paint away. Do this after the car has been sitting for an hour to cool down.

Edited by Stock

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On 26/12/2019 at 08:56, G1en@waxandshine said:

Has the bleed nipple snapped off the caliper (looking at last picture) possibly some brake fluid or oil has got onto discs and the pads have burnt it into disc under heavy braking which would poss explain the rainbow and loss of braking force. Just clutching at straws for you as i recall when i changed my fluid i thought i had tightened the nipples up enough but the force of the brakes made the fluid squirt out so had to get them mega tight. 

Good spot, looks like the outer brake nipple is broken off in that picture, so you will have fun drilling that out and fitting a new nipple.

 

Rainbow brake discs normally mean they have overheated. Odd how that has only just happened after 7 months of use though.

 

Id be tempted to fit new discs and get some which will work fine with the red stuff pads. Ive not use red stuff pads before, but id be checking if they are okay for your use etc and if not get something else. Id also check the pistons are moving freely in the caliper etc.

 

Brake fluid should be changed every couple of years anyway and it isnt (normally) an expensive job to do. The biggest problem is nipples can snap off, which incurs more labour cost for the garage to fix, but usually you can feel an improved brake pedal feel afterwards. Brake fluid wont have caused your disc to change colour though.

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4 hours ago, rabbitstew said:

Good spot, looks like the outer brake nipple is broken off in that picture, so you will have fun drilling that out and fitting a new nipple.

 

Rainbow brake discs normally mean they have overheated. Odd how that has only just happened after 7 months of use though.

 

Id be tempted to fit new discs and get some which will work fine with the red stuff pads. Ive not use red stuff pads before, but id be checking if they are okay for your use etc and if not get something else. Id also check the pistons are moving freely in the caliper etc.

 

Brake fluid should be changed every couple of years anyway and it isnt (normally) an expensive job to do. The biggest problem is nipples can snap off, which incurs more labour cost for the garage to fix, but usually you can feel an improved brake pedal feel afterwards. Brake fluid wont have caused your disc to change colour though.

Oh Man,

 

I didn't even realise. Is the brake nipple supposed to be just op top of where it says Brembo? That flat circular part?

 

Would it be possible to dremel a flat notch into it and use a flathead to unscrew it out?

 

The pads have been working perfect for me and never had an issue. I checked again about an hour ago after driving normally since the rainbow issue. The discs are back to their normal color now. 

 

I also checked the brake fluid reservoir with the cap off. The fluid is to the max line and 100% the correct color. Not murky or discolored.

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31 minutes ago, fijifixit said:

Oh Man,

 

I didn't even realise. Is the brake nipple supposed to be just op top of where it says Brembo? That flat circular part?

 

Would it be possible to dremel a flat notch into it and use a flathead to unscrew it out?

 

The pads have been working perfect for me and never had an issue. I checked again about an hour ago after driving normally since the rainbow issue. The discs are back to their normal color now. 

 

I also checked the brake fluid reservoir with the cap off. The fluid is to the max line and 100% the correct color. Not murky or discolored.

Its been a while since I looked at the zeds calipers, so look at a few pix online, but I think that small circle bit above the bit you mention is where the brake nipple is. If I remember correctly (and I may be wrong) the zed`s calipers have 2 brake nipples - one each side. You can see the other side one in the pic.

 

They are usually in very tight so you will not be able to get it out with cutting a slot & using a screw driver. May have to drill it out and re-thread it. Garages are used to that kind of thing, so it shouldnt be much work. On the plus side, if the fluid llooks fine and brake feel is okay then I wouldnt worry about it just yet.

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