Removing surface rust on brake discs that have been stood

Removing surface rust on brake discs that have been stood

Author
Discussion

anarki

Original Poster:

765 posts

138 months

Tuesday 10th September 2019
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I recently purchased a big brake kit second hand which has been stood for some time off of the vehicle. As such the discs have a fair amount of surface rust/gunk.

Discs:



Test fitment: (wheels have since been refurbished and all decent tyres now!)



The discs have barely been used and have no noticeable lip on them. Fresh pads will be going in but I'm reluctant to bed them in on the discs in their current state.

Thoughts please - do I sand them with a fine grit wet and dry, wirebrush them, just put pads in and drive it? Thanks

GreenV8S

30,259 posts

286 months

Tuesday 10th September 2019
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If they are contaminated, use brake cleaner to clean them.

If they have a rough surface due to corrosion, they will clean up on their own but if it is severe and you want to address it, you could use a wire brush to take off loose corrosion and garnet paper to take off any remaining rough spots. But it's quite normal for brakes to rust and would have to be severe for it to be worth worrying about.

The main area to be concerned about is the locating collar and flange that mates against the hub. Any dirt/corrosion here would need fixing before you install them.

anarki

Original Poster:

765 posts

138 months

Tuesday 10th September 2019
quotequote all
Thanks for your reply, I'll ensure the bells are as clean as can be prior to installing on the hubs, use brake cleaner on the surface of the disc, install as usual as drive carefully for a few miles with gentle braking to get rid of the surface crap.

stevieturbo

17,306 posts

249 months

Tuesday 10th September 2019
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you could polish them with autosol or brasso.

hman

7,487 posts

196 months

Wednesday 11th September 2019
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as above - brake cleaner, wire brush both sides and in the bell - then take it out and use the brakes , should clean up ok .

Matt_E_Mulsion

1,695 posts

67 months

Wednesday 11th September 2019
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How bad is the rear face is that is the outer side?

anarki

Original Poster:

765 posts

138 months

Wednesday 11th September 2019
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Matt_E_Mulsion said:
How bad is the rear face is that is the outer side?

227bhp

10,203 posts

130 months

Wednesday 11th September 2019
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It really depends on how much effort you want to put in and how clean you want them. You could take them apart and have them blasted, soak in rust eater or simply go at them with a wire wheel and some sandpaper.

Coilspring

577 posts

65 months

Wednesday 11th September 2019
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Maybe I am missing something.

They look well past their best (not just surface rust issue) to me.

Why are you considering second hand discs? Do you know the make, and their history ?

WinstonWolf

72,857 posts

241 months

Wednesday 11th September 2019
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I'd just lightly dress them with a second cut flat file.

OldDuffer

214 posts

88 months

Thursday 12th September 2019
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Eh? Maybe I am missing something. Why the 'Big girl's blouse' approach? Why the bleat?

Make sure the mating surfaces are clean and put them on? They'll clean-up on their own in 20 miles, if they're not bad; 100 if worse. By 250 they will be fine.

And just suppose I'm wrong, and you DO have to change them, what have you lost trying to prove that I'm right. Which I almost definitely am?

I've got a £5000 bet with anyone willing to take it, by 1000 miles, there's minor pitting at worst. Dear god. There's only one way they won't come good - if your brakes don't work.


Edited by OldDuffer on Thursday 12th September 12:56

E-bmw

9,337 posts

154 months

Thursday 12th September 2019
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OldDuffer said:
They'll clean-up on their own in 20 miles, 100 if worse. By 250 they will be fine, by 1000 miles, there's minor pitting at worst.
Talk about having the courage of your convictions. wink


stevieturbo

17,306 posts

249 months

Thursday 12th September 2019
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OldDuffer said:
Eh? Maybe I am missing something. Why the 'Big girl's blouse' approach? Why the bleat?

Make sure the mating surfaces are clean and put them on? They'll clean-up on their own in 20 miles, if they're not bad; 100 if worse. By 250 they will be fine.

And just suppose I'm wrong, and you DO have to change them, what have you lost trying to prove that I'm right. Which I almost definitely am?

I've got a £5000 bet with anyone willing to take it, by 1000 miles, there's minor pitting at worst. Dear god. There's only one way they won't come good - if your brakes don't work.


Edited by OldDuffer on Thursday 12th September 12:56
Don't spoil the fun with a sensible suggestion.

anonymous-user

56 months

Thursday 12th September 2019
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They don't look that bad to me - put them on the car and go and do some proper driving.

Tony1963

4,871 posts

164 months

Thursday 12th September 2019
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Coilspring said:
Maybe I am missing something.

They look well past their best (not just surface rust issue) to me.

Why are you considering second hand discs? Do you know the make, and their history ?
I've seen worse looking discs on a car after a weekend in the rain.

InitialDave

11,990 posts

121 months

Thursday 12th September 2019
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I'd probably just fit them and see in they clean up, yes.

Though in the states you can buy what is basically a ball-type bore hone, only for use on flat surfaces rather than cylinders, they're sold specifically for lightly resurfacing discs. Be interested in seeing how well they work.

anarki

Original Poster:

765 posts

138 months

Tuesday 1st October 2019
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Update to the original post; I fitted the kit a couple of weeks ago, the discs cleaned up fairly well with a light abrasive mop prior to fitment and within 50 miles they hardly had any surface rust left on them. I have since done about 400 miles with the car having been put through its MOT last Friday so all is good.