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MG MGF Technical - Rusty Brake Discs

I've just had my 3 year 34,000 mile service before the warranty expired.

The garage tells me I need new discs and pads all round. I declined when they quoted 78.92 each for front discs and 61.80 for each rear disc. Pads were 55 per axle. I didn't ask if this included labour - I don't think so. Not covered by warranty of course.

Basically the contact surfaces look OK to me - shiney with no grooves in them. The garage claimed that they were rusty. There is certainly light surface rust on the hub part, and the outer edges now have a lip were the rust has expanded, and the vent slots are a bit the same - I doubt that the discs have worn down below spec - I am still on my first set of pads.

Does any one think a change all round is justified? I've changed discs on other cars, is it straight forward on the 'F'? Any body tried the gold plated discs that B & G sell - doesn't the gold wear off? Who does the
best deal on these parts?

Any advice gratefully received.

Andy R272NDG VVC

Andy from the limited information this does sound a bit "iffy". You could ask the garage to explain where this rust is on the disks and why this means they need changing. I think you will find the lip on the edge of the disk is not rust expanding but the part of the disk that has not been rubbed away by the pad - a good indicattion as to how warn the disk is.

I have recently changed my pads for green stuff bought through B&G and once Ted Newman had faxed me the page from the manual, was dead easy to change.

I do not believe changing the disks would be very difficult as this part of the F is largely Metro based I understand.

There was a thread on the topic of disk wear some weeks ago. From memory the conclusion was that modern disks to wear faster due to pad change - but they should expect 60k+ miles. Roger Parker also give the minimum width for disks (ie the maximum wear allowed).

Hope this helps



mild rusting of the contact surfaces of the discs is not unusual for a car that may not have been used for a few days. It wears off very rapidly with use, as I am sure you know. It certainly is not an indication in itself for brake disc replacement.

I cannot believe that a service department would recommend disc replacement on this observation alone? Perhaps this is a classic case of 'Chinnese wispers' where the last thing that the service engineer said to the receptionist (or who ever) was 'Oh and there is some surface rust on the discs' which was eventually relayed to you as the primary reason for disc replacement!!! Best get the information direct from the 'horses mouth'.

If the is a detectable ridge around the circumference of the disc, then there is a very real chance that the dscs may well be due for replacement. Expanding ferrous oxide deposits is rather unlikely to be the explanation for this ridge.

Therefore, a disc change may be warranted, but without having seen them... can't be 100% sure.

>>I've changed discs on other cars, is it straight forward on the 'F'? <<

I haven't tried this myself -I have on other cars like you though. I can't see that the MGF should be at all tricky in this regard. Have you got the workshop manual? I don't know the torque settings hand.

>>Any body tried the gold plated discs that B & G sell - doesn't the gold wear off?<<

I doubt that the discs are really gold plated, but if they are, they're a bargain! ;o) (Sorry, I do apologise, couldn't resist it!!!)

The gold coloured finish certainly does wear off, but it isn't a problem.

Their grooved discs are a good idea- it stops pad glazing and therefore maintains braking performance.

How much are the B&G discs? Halfords sell the same discs as Rover (front only, according to my local branch) for 30 quid each. Not too bad really.

Pads wise, I'd go for EBC Roadsport 'Green stuff' pads- they're cheap (around forty quid a pair) and perform far better than the OE Rover pads, with the additional advantage of less brake dust (although you'd be forgiven for not believing me if you could see the state of my wheels after last Friday's track day... :o)

Try B&G, Trevor Taylor or JRT Motorsport for the pads.

Hope that helps!

Rob Bell

Thanks for the comments so far.
The B&G discs are 99 pair.
My discs have always suffered from rusting as the car is left outside, and the 5 spoke alloys provide no protection from the rain - the rust has always gone after being driven.
I accept that the discs are more likely to wear on the outer edge - from experience - but the inner edge has no such ridge. I can put a micrometer on them to be sure - anybody know what the limits are?


P.S. Has the archive disappeared?

At my last MOT (40k, the cars 3rd) the mechanic let me underneath to see the pitting that had occured on the visible inside surface of my NS rear disc.

It was patchy and fairly bad.

But on the brake tester you could only detect a slight drop in efficiency on that wheel.
As I believe the rear brakes are mostly along for the ride - and the hand brake - I shall plan a replacement at my leisure..

Unless your 'rusting' has caused surface pitting I would leave it alone Andy.

Looks a very easy job - replace pairs only of course

Remove 2 bolts securing brake caliper to hub.
Release caliper from disc. Tie caliper clear of brake disc, ensuring the weight of the caliper is supported.
Remove 2 screws securing brake disc to drive flange.
Remove brake disc.

a10jst '95 N
John Thomas

Andy - By my elementary maths your total is about 392 plus probably another 150 or so for labour. Total around 550 for the status quo. Do yourself a favour and get the EBC Disc's, green pads, and stainless steel flexibles. Total price, including fitting at B&G in Baldock for me was 355. The difference this makes to the brakes is amazing. If you bought the parts and fitted them all yourself the money spent would be well short of 200. Even with my elementary calculations thats a pretty fair saving over having the same again.

As for the "gold" discs the discs are grooved and pitted, then given a zinc coat and then "gold" anodised on top. It has taken me about 400 miles to bed them all in. The reduction in brake dust is an added bonus on top of brakes that work well and feel marvellous. Something I was never comfortable with on the original discs and pads.

Treat yourself. It will be one of the best things you can do for the car.

I recently had front brake pads (AP Lockheed) and discs (Lucas) fitted. Cost was 110 (parts&labour) including VAT. I went to local Lucas brake fitting compnay (also a tyre fitter)

These parts are for standard road use - not for racing.

I reckon if you shop around you get the whole job done for a little over 200.


if the time has come, buy uprated discs & pads. The bigger, drilled & vented discs are cheaper than the wimpy F/Metro ones. The kevlar pads make things even more exciting, reducing brake distance dramatically, improving looks aswell.

And remember, it's all cheaper than the official kwatsch from Rover.

Need I say more? ;-)

This thread was discussed between 14/08/2000 and 16/08/2000

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