Rear Disc corrosion - advice needed

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wonderloaf
Joined: Mon 02 Aug, 2010 21:55
Posts: 490

  Z3 roadster 2.2i
Location: Basingstoke

Rear Disc corrosion - advice needed

Post by wonderloaf » Sat 23 Aug, 2014 12:09

Hi all, recently put my z3 in for a service and got an advisory on the rear disc for corrosion, was advised that although not dangerous the disc should be changed ASAP ... can anybody give a independent opinion please?
Here's a picture of the disc
Image

Sorry for the large pic size, can't seem to reduce it!

I always thought a certain amount of corrosion is OK on a brake disc, but this does seem a bit excessive and doesn't disappear after I've driven a few miles , eg a 40+ mile round trip to work and back.

I've also a mind to replace the discs myself as I've done it before on previous cars and didn't find it particularly difficult, can anyone give any tips on how to do, what to watch out for etc and also recommend any reasonable priced parts?

Cheers, wonderloaf
2001 Titan Silver 2.2 Sport
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colb
Joined: Sat 05 May, 2012 23:46
Posts: 566

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Rear Disc corrosion - advice needed

Post by colb » Sat 23 Aug, 2014 13:26

Yes they certainly look well worn with the deep lips on the inner and outer edges.
If you have changed discs before you should find changing them on the Z as easy, bear in mind there are brake shoes inside the drum, maybe they will need replacing but you will not know until you strip down. Always put new pads on with the new discs.
I use Car Parts 4 less, quite a choice on makes here
http://www.carparts4less.co.uk/brake-discs
Europarts are behind Car Parts 4 less but often cheaper than the Europarts site.

Colb
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2115

  Z3 roadster 1.9

Re: Rear Disc corrosion - advice needed

Post by Del » Sat 23 Aug, 2014 14:02

The top edge/lip has spread down the face of the disc and the marks on the disc itself suggest an uneven surface due to wear/scratching/rust. All this would tend to cause less of the pad to be in contact with the disc surface. They are probably the original discs - personally, I wouldn't hesitate in changing them + new pads of course.

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lordhelpus
Joined: Sat 14 Sep, 2013 10:46
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  Z3 roadster 2.8
Location: Tax Exile

Re: Rear Disc corrosion - advice needed

Post by lordhelpus » Sat 23 Aug, 2014 15:33

There scored and pitted..........here's another advisory......... change them. :wink:
Take the opportunity to upgrade ....to a nice set of drilled and slotted discs with new pads.....plenty about on t'internet.
1997 2.8................ Montreal Blue

ironman69
Joined: Mon 18 Aug, 2014 14:58
Posts: 6

  Z3 roadster 2.2i

Re: Rear Disc corrosion - advice needed

Post by ironman69 » Sat 23 Aug, 2014 18:41

Hi Lordhelpus

Can you recommend any that are nicely priced??

Cheers in advance

IM

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wonderloaf
Joined: Mon 02 Aug, 2010 21:55
Posts: 490

  Z3 roadster 2.2i
Location: Basingstoke

Re: Rear Disc corrosion - advice needed

Post by wonderloaf » Sun 24 Aug, 2014 09:00

Hi all, thanks for the replies so far, been looking around the www for discs and pads, any recommendations? I read somewhere (don't ask where though) that drilled and slotted discs aren't really any use on the rear as they're not vented ... true?

Thanks again, wonderloaf
2001 Titan Silver 2.2 Sport
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Mike Fishwick
Joined: Fri 19 Jun, 2009 11:27
Posts: 1991

  Z3 roadster 2.8
Location: Daglan, France

Re: Rear Disc corrosion - advice needed

Post by Mike Fishwick » Sun 24 Aug, 2014 12:04

Advisories about rusted discs are very common - in the hope that the garage will getthe job of replacing them.

All you need to do is to chip away the rusty edges with a hand-held chisel or welder's chipping hammer, and use the car! My rears were once as rusty, and also quite badly scored, but after a change of pads and about 10.000 miles use they are now (at 130,000 miles) fine again.

As the diecs are onviously worn, when fitting new pads it is good practice to file a bevel on their edges to allow the pad and disc to initially seat well. As the pads wear in the rougher area of the diec will wear the edges of the pad, which will then continue to operate well. The loss of a small disc area is of no importance, as the rear only add about 15% tothe toal braking effort.

The trouble is that too many owners prefer to fit new bits rather than do any work to renovate the old ones - and garages know this well!
A Z3 is not just for Christmas - it's for life!

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lordhelpus
Joined: Sat 14 Sep, 2013 10:46
Posts: 128

  Z3 roadster 2.8
Location: Tax Exile

Re: Rear Disc corrosion - advice needed

Post by lordhelpus » Sun 24 Aug, 2014 15:19

ironman69 wrote:Hi Lordhelpus

Can you recommend any that are nicely priced??

Cheers in advance

IM
Have used both these stores on ebay....but not for the zed though....but for other cars in the family. Had no probs with them.

http://stores.ebay.co.uk/PLANET-CAR-PAR ... 7675.l2563

http://stores.ebay.co.uk/MTEC-Brakes-Sh ... 7675.l2563

MTEC got a very good reputation........My mate uses them a lot he is an AA mechanic he uses MTEC for private jobs... :wink:
1997 2.8................ Montreal Blue

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TitanTim
Joined: Mon 23 Jun, 2008 19:56
Posts: 5488

  Z3 roadster 1.9i
Location: Stafford

Re: Rear Disc corrosion - advice needed

Post by TitanTim » Sun 24 Aug, 2014 15:44

Try your friendly BMW parts dept, you might be pleasantly surprised and for what they cost just get them replaced.

Mine were similar and I could have sanded/skimmed them but really isn't worth the effort.

Tim.
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2001 Z3 1.9 Roadster Sport - 2012 Z4 sDrive 2.0 M Sport

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c_w
Joined: Thu 19 Aug, 2004 17:50
Posts: 4031

  M roadster S50

Re: Rear Disc corrosion - advice needed

Post by c_w » Sun 24 Aug, 2014 22:31

It looks like the brakes are not worked enough or the pad doesn't sweep the whole of the outer disc.

Either way the rear discs are cheap, that rust is fairly established and won't wear away. It would be a good idea to put new disc and pads on taking care on cleaning the guides on the caliper carrier and sliders are nice and clean. I find the rear brakes on a BMW are used a lot more than say a FWD hatch, my Coupe doesn't do much mileage but it's discs are always clean and rust-free, though it does go on track which really uses them. That kind of rust would literal chip away if you tapped it with a hammer. Gentle driving will perhaps have some influence on this and not get the rear brakes working enough.

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wonderloaf
Joined: Mon 02 Aug, 2010 21:55
Posts: 490

  Z3 roadster 2.2i
Location: Basingstoke

Re: Rear Disc corrosion - advice needed

Post by wonderloaf » Sun 24 Aug, 2014 23:36

My car is my daily driver and I do a daily round trip of about 50 miles.... I'm also what you would call 'spirited' driver so the brakes get plenty of use! The discs and pads were also changed just before I bought the car about 4 years ago, maybe the dealer used a cheap brand disc & pads, would this cause the problem?

Anyway I've decided to replace the discs & pads as it doesn't seem a difficult job, will be following up the forum recommendations for parts. Thanks again one and all.
2001 Titan Silver 2.2 Sport
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Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2115

  Z3 roadster 1.9

Re: Rear Disc corrosion - advice needed

Post by Del » Mon 25 Aug, 2014 08:21

wonderloaf wrote:The discs and pads were also changed just before I bought the car about 4 years ago, maybe the dealer used a cheap brand disc & pads, would this cause the problem?
I would have expected 4-year OE BMW discs (or similar premium make) on their first set of pads, to still look immaculate. Like you, I would guess he used a cheap, budget brand of discs. In my view not worth mucking about with "mend and make do" when it comes to your braking system - I'd whip 'em off and get some decent ones on there. :)

HighSharpe
Joined: Sun 28 Jul, 2013 00:01
Posts: 42

  Z3 roadster 2.0

Re: Rear Disc corrosion - advice needed

Post by HighSharpe » Mon 01 Sep, 2014 22:26

Had a similar advisory on my MOT a couple weeks ago. Replaced all 4 discs with MTEC grooved and dimpled discs, and Textar brake pads. I should probably have bought the coated discs, but realised it too late. The coating on the contact surface of the plate does wear off, but the dimples, grooves and the hub(?) of the rotors does stay coated.

In any case, when i got to the indy to install these (and do the usual service), he suggested spraying some paint on.
Image

Here are the discs in place - yes the rest of the set up can use some cleaning.
Image


Next step ... a DIY caliper paint job!

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wonderloaf
Joined: Mon 02 Aug, 2010 21:55
Posts: 490

  Z3 roadster 2.2i
Location: Basingstoke

Re: Rear Disc corrosion - advice needed

Post by wonderloaf » Tue 02 Sep, 2014 18:50

Didn't go down the drilled and grooved route in the end, thought there may be hassle with the insurance so just went OEM-ish with some solid Pagid discs and pads, bargain price of approx £70 for the lot (rear only) from ECP. All was going really well until I went to take the first disc off and the internal handbrake shoes were snagging on the drum :head: :head: Took me ages to find the bl**dy little adjustment wheel to ease them off, but once I'd worked it out it was a breeze.

Re the DIY caliper repaint, yeah that's another little weekend job sometime!

Thanks again for the comments and guidance, much appreciated.
2001 Titan Silver 2.2 Sport
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