Annual rear brake disks corrosion advisory

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Phil MGFPM
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Annual rear brake disks corrosion advisory

Post by Phil MGFPM » Wed Jul 12, 2017 6:27 pm

Hi, I seem to get an annual MOT advisory on both rear disks, and seem to be renewing the disks every two years. I suspect through low mileage, c.3000 per year, outside parking. Any tips / advice - apart from "use the car more" - about how to keep the rear disks shiny with a low usage car, even on short trips? Thanks.
Previously owned '98 F 1.8mpi bought 2008; then a '97 F Mk1 1.8 VVC in nightfire red, bought 2011; now a '01 F 1.8mpi in tahiti blue, bought Nov-19

BodgeItAndScarper
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Re: Annual rear brake disks corrosion advisory

Post by BodgeItAndScarper » Wed Jul 12, 2017 7:02 pm

Do you have any pics? My first guess for the cause would be an over-zealous MOTer.

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Phil MGFPM
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Re: Annual rear brake disks corrosion advisory

Post by Phil MGFPM » Wed Jul 12, 2017 9:06 pm

Two pics each side, sorry not great photos in this light
Attachments
photo 2.JPG
photo 1.JPG
Previously owned '98 F 1.8mpi bought 2008; then a '97 F Mk1 1.8 VVC in nightfire red, bought 2011; now a '01 F 1.8mpi in tahiti blue, bought Nov-19

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daz
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Re: Annual rear brake disks corrosion advisory

Post by daz » Wed Jul 12, 2017 10:41 pm

I always "drag" the handbrake on the way to MOT to give them a good polish :)

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RobboMC
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Re: Annual rear brake disks corrosion advisory

Post by RobboMC » Thu Jul 13, 2017 3:46 am

are the rear brakes actually working?

Do the rims get hot after rapid driving?

Perhaps the cause is 'under-zealous driving' LOL.

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ArntyR
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Re: Annual rear brake disks corrosion advisory

Post by ArntyR » Thu Jul 13, 2017 8:41 am

Just an observation...

I put new discs calipers + pads on my F prior to its MoT and had to make several refits to 'settle' a slightly binding rear brake (first one side then the other) that left my new discs looking exactly like yours. (Of course, the handbrake cable was stiff too...) I finally sussed that I wasn't quite aligning the rear piston key with the brake pad protrusion.
(You know, you wind the piston in then twist it a little for the key/indent to be at 3o'clock...) Could this be happening in your case, I wonder? The wear on one of your discs looks a little blue - perhaps it's getting hot?

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Re: Annual rear brake disks corrosion advisory

Post by beefio » Fri Jul 14, 2017 10:41 pm

daz wrote:I always "drag" the handbrake on the way to MOT to give them a good polish :)
Yeah me too, get the motorway doing 70+ and do a load of right foot braking which helps clean them up!

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daz
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Re: Annual rear brake disks corrosion advisory

Post by daz » Fri Jul 14, 2017 11:45 pm

beefio wrote:
daz wrote:I always "drag" the handbrake on the way to MOT to give them a good polish :)
Yeah me too, get the motorway doing 70+ and do a load of right foot braking which helps clean them up!
Do you see many accidents in the mirror? :lol:

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Reckless Rat
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Re: Annual rear brake disks corrosion advisory

Post by Reckless Rat » Thu Jul 20, 2017 6:08 pm

For what they cost I would change the rear discs. They look well shot. Make sure they are twinned up with a new set of pads and that all working surfaces are lubricated to prevent seizure. (not the friction surfaces!), including the handbrake mechanism. Seized rear calipers are a perennial problem but they can be replaced reasonably cheaply.

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Re: Annual rear brake disks corrosion advisory

Post by Geoff.F » Fri Jul 21, 2017 11:51 pm

I had a similar comment last year so for this time I have removed the rear discs and polished them with a Brillo pad and they came up like new with no pitting or scores. Only the contact faces had minimal rust colour with none on the painted hub or rim.
The rust damage is dependant upon the steel or cast iron used for the discs. With the demise of MGR, I was concerned that sources for aftermarket brakes may come from various "Suppliers of dubious parts". EBC are "TUV" Approved Manufacturers hence I have chosen to fit them since.
New front and rear calipers, pads and flexible pipes were also fitted as it is about time for me to give up servicing cars.
Geoff.F

beefio
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Re: Annual rear brake disks corrosion advisory

Post by beefio » Sat Jul 22, 2017 7:39 am

The next set of discs that I fit I'm going to paint the hub and outer rim with silver Hammerite to stop then rusting. Don't know why this isn't done during manufacture would be a nice feature to keep them looking good.

My disc faces rust too as I don't use my F that regularly but the rust is even across the disc face and comes off if I take it for a spirited drive to sufficiently warm up the brakes, however the rust on your discs looks uneven, so I wonder if your pads are sitting correctly in the calipers and making full contact with the discs? As all the rust on the disc face should come off after a decent drive...

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Bazzajay
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Re: Annual rear brake disks corrosion advisory

Post by Bazzajay » Sat Jul 22, 2017 9:04 am

Rather than using Hammerite, which can chip as it ages, it would be an idea to use a cold galvanising paint. There are two currently available, Zinga or Galvafroid. Of the two I prefer Zinga. You can buy the paint from Frost, www.frost.co.uk
Barrie

2000 MGF Wedgwood SE 1800i
2002 Peugeot Partner Quiksilver

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