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Anybody Ever Had A Brake Disc Skimmed?


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#1 neilh

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Posted 17 May 2012 - 01:52 PM

my rear brake is getting a little noisy. the pads got plenty of material left on them but they are starting to squeek.

for the sake of < 15 qwid im going to pop some new pads in.

after looing at my disc there are a couple of score marks on it so i have been thinking of getting it skimmed?

a new disc is more than i want to spend at the moment, and an engineers will only charge a tenner if that to skim it smooth and check it for flat.

just wondering is there tolerance on bike discs like the car equivalent?

anybody done the same?


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#2 chewy

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Posted 17 May 2012 - 02:53 PM

Think i've seen it etched on disc min thickness 2.4 mm. they probably start life as 3mm..so depends on what you have regards scores. As you probably know the pads often don't fully engage the disc and wear until they touch each other rather than squeeze the disc.

#3 coxy

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Posted 17 May 2012 - 05:28 PM

Neil to be able to have them skimmed you need to find a engineering company that has a surface grinder as you cant hold them in a 3 jaw or 4 jaw centre lathe chuck. Ive skimmed a couple of discs now at work and aslong as your scores aint too deep they will be fine. I personally dont think the disc works as well after its been skimmed for some reason probably something to do with the heat treatment etc and they rust up quicker. Just get them to check the width of the disc after its finished as the minimum thickness is 2.4mm

#4 neilh

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Posted 17 May 2012 - 08:42 PM

coxy, thanks for the excellent info.

the minimum thickness of the disc i have fitted is 2.7mm (etched onto disc), and to be honest, ive measured it on removal tonight and it is just above the minimum at 2.74mm at its thinnest. but im going to do it anyway as i only want the (very shallow) scores taken out, and to be checked for flat.

im going to leave the disc in the capable hands of a friend who has a Pro-Cut lathe, and keep my finger crossed his equipment is able to do it.

#5 dickielumpkin

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Posted 17 May 2012 - 08:48 PM

Had my front done on a surface grinder about a year ago. went down to 2.6 mm and its been fine so far. I think if you tried to do iton a lathe you could run in to trouble getting the faces parallel which is crucial for good operation.

#6 neilh

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Posted 17 May 2012 - 09:01 PM

you two are starting to put me off doing it now lol.

ill ask my mate tomorrow if he thinks he can do it.

it wont hurt to ask the question, and even if he buggers it up i dont mind as i need a new disc anyway

#7 billyt

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Posted 17 May 2012 - 10:16 PM

NeilH

FYI

The brake squeak is not due to the state of the disc surface but rather it is the relationship of the back part of the pad vibrating against the brake puck causing vibrations and squeaking. Pretty common and there is a product that one can get at a auto parts store for that very purpose.

Check the back of the brake and you should see a nice round wear circle that is witness to how well the round puck and brake pad are wearing together a broken circle mark tells a story.

Edited by BillyT, 17 May 2012 - 11:12 PM.


#8 axulsuv

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Posted 18 May 2012 - 01:31 AM

NeilH ;
Nissan motor Co. (cars) parts departments sell a gold colored paste(PBC grease , I think is the name ,there's a bottle on my toolbox at work.!.!.) for application to all of the metal to metal contact points on disk brake pads , Similar to the lube you got years ago when you purchased factory toyota pads . Apply just a wee bit to the contact points on the back of the pad and where the ends of the pad slide in the bracket and your noise will go away . The squeek you hear is a harmonic vibration between the pad and its mounting points and the caliper , amplified by the rotor . the lube dampens the vibration and the noise won't be heard . And it also allows for better heat transfer so your brakes last longer and work better . Scuff your rotors with a coarse scotchbrite pad and brake cleaner , then install the new pads . I personally wouldn't even think of resurfacing a rotor on any motorcycle ... They wear out fast enough on their own ... (IMHO) And be sure not to get any of the lube on the friction surfaces !!!
Glenn

Edited by axulsuv, 18 May 2012 - 11:53 AM.

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#9 nzralphy

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Posted 18 May 2012 - 05:49 AM

I did this on a really lovely big lathe. It didn't work.

I got so much chattering it just went in the bin. Buy a new one if you can't grind it!
I'm not half as good as I think I thought I was...

#10 dadof2

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Posted 18 May 2012 - 11:22 AM

Waste of time trying to do it on a lathe.

Grinding will quite possibly result in distortion.

Follow the advice others have given on getting rid of squeal - copperslip of blue hylomar btwen piston and pad work.

Cheers


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#11 pindie

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Posted 18 May 2012 - 04:26 PM

If your getting sqeaks just whip your pads out and rub all over with contact cleaner and wire wool. Clean the caliper while your at it as well.

Next you want a smear of coppa slip grease on the bach of the pad (make sure your greasy fingers do not touch the pad material).

Re fit the pads and grease the main pin/bolt lightly with coppaslip before you pop it in.

You will have no more squeaking.
Staying calm always helps. Science always wins.

#12 neilh

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Posted 18 May 2012 - 04:56 PM

hmmmm, im not sure why you think im skimming the disc cos of squeeling? i said im skimming it cos its scored.

the pads got plenty of material on them, but the rear backing plate is bubbled up with corrosion, and the scoring of the disc has worn them unevenly and grooved them.




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