OT - Car brake disc...
 

[Closed] OT - Car brake disc skimming

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Does anywhere do this? DIY?
Seems to be a much more sensible idea than forking out £400-odd quid for the sake of what is, in effect, a few micrometres of surface rust.


 
Posted : 08/03/2011 4:51 am
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Brake discs don't cost anything like £400 do they?!


 
Posted : 08/03/2011 6:35 am
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400 quid??????????
Blimey what car is this.
The most expensive I've ever had is my 05 accord estate is 88 quid for a pair of fronts and 47 for a pair of rears, and 30 all round for pads. So 180, and its dead easy to fit them yourself. On my 406 it was about 50quid cheaper.


 
Posted : 08/03/2011 6:36 am
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What was beechdale Subaru did it in derby, sales leader openly admitted it was far cheaper for his customers to have it done, rather than paying for new discs. It's now alfa/Hyundai but they still work on all cars. Discs obviously have to be in good condition, no warping or faults in them, also there's a maximum that can be removed to flatten them, no idea what that is but if you're showing a big step from the outer edge to the braking area it may be to late??


 
Posted : 08/03/2011 6:39 am
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Try an m3 😯


 
Posted : 08/03/2011 6:40 am
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It's a Legnum VR4. I can get discs & pads for about £300 all round, but they're cheapo Ebay copies of the OEM ones. Given the standard ones are woefully underspecced for a car of the Legnum's power and weight, I was hoping to save the ones currently on it.


 
Posted : 08/03/2011 6:40 am
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I used to have a 'proper' (non-import) Legacy VR4, and I got discs of eBay for it. They weren't crappy pattern parts, they were Brembo.

Check who you are buying off; there's good stuff to be had.


 
Posted : 08/03/2011 7:00 am
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Provided theres enough "meat" on the discs any engineering firm should be able to skim them in a lathe for you relatively cheaply.

The problem is that you need to fabricate a boss / hub to mount them. That's the bit that'll cost.

Worth asking though.

Where abouts are you?


 
Posted : 08/03/2011 7:03 am
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I'm in Edinburgh. I was hoping if they only take 0.1mm off each side of the discs that there'll be no problems. It's not the bit that mounts on to the hub is being altered...

Or am I talking pish?


 
Posted : 08/03/2011 7:18 am
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I think the mount is to put your disk into the lathe properly?


 
Posted : 08/03/2011 7:24 am
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Blimey. Cars are money pits.


 
Posted : 08/03/2011 7:30 am
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Tracker1972 knows the crack. It's the part that fits in the chuck so the disc sits parallel and concentrically

What I also meant was that the disc has to have enough thickness on it after a skm. You need to know what the minimum permissible thickness is from the car manufacturer.


 
Posted : 08/03/2011 7:42 am
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Correct. Add this to the new gearbox/new exhaust system I had put in last year and the 25-ish mpg fuel economy...
As soon as this is MOTd and taxed, it is going.


 
Posted : 08/03/2011 7:43 am
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If you only need 0.1mm off each side are they really worth doing, especially if you are selling it?


 
Posted : 08/03/2011 7:57 am
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If you only need 0.1mm off each side are they really worth doing, especially if you are selling it?

Yes because it's an MOT failure if they have too much corrosion. My XC90 rear disks suffer from this as well - will need to sort something by this autumn's MOT as they were an advisory last time. Disks only about 3 years old and car does low mileage.


 
Posted : 08/03/2011 10:27 am
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Most garages have a disc lathe (my VW does). If the disc has warped through overheating, the disc will have uneven hardness, so skimming won't solve the problem - it will just warp again when it gets warm.

My Brembo GTs do this all the time - total pain at £600 for a set of discs, warped 3 sets so far...


 
Posted : 08/03/2011 10:28 am
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trying pressing the brakes? VOILA! Rust free!


 
Posted : 08/03/2011 10:29 am
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a bit of steel wool and some wet and dry should do it


 
Posted : 08/03/2011 10:33 am
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A couple of emergency stops from 70mph should get them rust free.


 
Posted : 08/03/2011 10:34 am
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I was told a lot of modern discs don't have enough material in them to be worth skimming.

My discs only last about 30,000 miles, it was a bit of a shock after never having to do anything to the discs on my little old micra


 
Posted : 08/03/2011 10:45 am
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The flying Ox, are you on Club VR4 at all? Those guys know their stuff. I used to be on there a lot, until I sold my V6 Sport 😥


 
Posted : 08/03/2011 11:06 am
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Braking with rusty discs embeds the rust in the pads and then scours the discs later, especially if it's heavy rust. I just stuck a cup brush on my angle grinder and took it all back to metal-ish, then braked as normal - fixed with no lasting damage. Only reason to skim discs is if they're "warped" which is a whole other story as they're rarely actually warped.


 
Posted : 08/03/2011 11:21 am
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I'm on CVR4, but to be brutally honest, they seem a bit hit-and-miss. Tried numerous times to sort out a windscreen wiper motor or an exhaust downpipe. It's always, "I've got one of them mate" and then utter silence, no PMs replied to, etc.

coffeeking - so if I attack them with a metal brush attached to my electric drill, that should do the trick enough for an MOT?


 
Posted : 08/03/2011 11:30 am
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Any surface cracking?
If you do get them skimmed and they then fail(as in crack/disintegrate) will you be prepared to accept liability?
Local machine shops used to do them until this happened to one of them 🙄

Vented discs like yours may have internal cracking.
As above there is a min thickness.

If it is just the rust around the outside edges then scrape of with a screwdriver or chisel and then file.

If they are badly worn and have brake judder and you skim below min thickness then you may be putting yourself or whoever buys the car after you in danger considering it is such a high performance car.

What price you and your families lives ❓


 
Posted : 08/03/2011 11:31 am
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coffeeking - so if I attack them with a metal brush attached to my electric drill, that should do the trick enough for an MOT?

One of these should get the bulk off:
[img] http://lh3.googleusercontent.com/public/Z4l2t09RR56VtXFBnc3SDhagAOFUFfo80UTJSmUU8Uz6Xo-9R0dW3FAN1KzTW6OvI7SRtb5Dj5Ybs4eQV6vZcw7fsG5K2JiF7LvvJK-gJN2b4Dmw0DfwZ7rs5WnM9wLabPOrrsG2IPOz [/img]
[url= http://www.google.co.uk/products/catalog?q=cup+brush&oe=utf-8&rls=org.mozilla:en-GB:official&client=firefox-a&um=1&ie=UTF-8&cid=7360527121225880559&sa=X&ei=6BN2TcqoLZCVswaG4Yn9BA&ved=0CD8Q8gIwAg# ]Linky[/url]

Then a good blast will take off the remaining visual mess for the MOT. If there's significant pitting or scoring from previous use it may still fail though, but at least it's a £2 attempt before new discs and works 90% of the time (it just worked to get my 3 year-sitting discs back to MOT passable), rather than the 50 odd quid they'll charge you for skimming discs.


 
Posted : 08/03/2011 11:35 am
 hora
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Rear or front? If rear knock on your handbrake a couple of clicks and drive a short while.


 
Posted : 08/03/2011 11:36 am
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Rear or front? If rear knock on your handbrake a couple of clicks and drive a short while.

I've written off a set of new discs doing that. MOT failed because the rust got embedded in the pads, swapped discs and the rust scored the new set too so they failed the next MOT. Not a good plan unless you plan on swapping pads soon too.


 
Posted : 08/03/2011 11:40 am
 hora
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Gently 😆


 
Posted : 08/03/2011 11:43 am
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If you only need 0.1mm off each side are they really worth doing, especially if you are selling it?

Yes because it's an MOT failure if they have too much corrosion. My XC90 rear disks suffer from this as well - will need to sort something by this autumn's MOT as they were an advisory last time. Disks only about 3 years old and car does low mileage.

I know rusty brake discs are an MOT failure, but 0.1mm would barely be perceivable by the eye. I have just replaced the pads on my car, and they did have some very slight scoring/piting, but after a few miles the discs look good.


 
Posted : 08/03/2011 11:46 am
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Hora - it was gently, it was in fact just driven off as normal, no harsh braking. If you're unlucky enough to get a bit stuck in your pads you have to strip them all down anyway and fix it, I think it's easier to just get a brush on them.


 
Posted : 08/03/2011 11:49 am
 hora
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Blimey unlucky.

A girl passed me the other day with her handbrake light on- now it might have been lightly but shirley you'd have seen that big redlight!


 
Posted : 08/03/2011 11:51 am
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If the disc has warped through overheating

See this link:
http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

The uneveness is more likely caused by a build up of brake pad material...not the disc warping.


 
Posted : 08/03/2011 12:08 pm
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[b]Trekster:[/b] Health and Safety spiel

As I say, not my problem once it's MOTd and taxed, cos then it's gone. To my neighbour probably. She's just had quadruplets and she mentioned their Corsa isn't big enough.


 
Posted : 08/03/2011 12:23 pm
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Yeah. As if.

There's no damage as such to the discs. Just surface rust. If I can get it off without skimming, then all the better. If skimming ends up compromising the discs, I'll get new discs. Just trying to spend as little as possible on a car I'll not make any money back on when it goes.


 
Posted : 08/03/2011 12:25 pm
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Dont try the handbrake thing, Galants have rear handbrake drums within the rear disc.
Sorry to hear CVR4 wasn't wany good for you, they're usually a bunch of top guys on there.
If you need any bits, give me a shout as a mate has 2 x VR4 Estates he's gonna be breaking this year.


 
Posted : 08/03/2011 9:13 pm
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Really depends on your tester and all. They have their own things they like to pick on. As long as they can see some shiny metal you should get away with an advisory.

Used to take cars to a garage I knew well back home. My car would tickover at about 3000rpm to pass its emissions test.


 
Posted : 08/03/2011 10:21 pm