650 Rear Disc Wear

[antvtr1000]

Hi,
Took my 650GS twin (09) for it's 2nd annual service recently @ 9000mls.
Rear tyre (original) had to be replaced.
Rear Brake pads (originals) had to be replaced, no probs.
Told that the rear disc was below minimum thickness!!! (what, at 9000mls???).
Many weeks of discussions with Main Dealer / BMW Technical (no)helpline have resulted in nothing but insulting reasons for this wear (as long as the product is not at fault!).
Can you believe these to include:-
1) excessive use of the rear brake
2) riding in bad weather (i.e. salt/grit on discs).
I pointed out that if both the above conditions had been encountered, then surely the pads would have been 'sacrificial' and i would have been thro' several sets of rear pads by this time?
As it was we are talking here of having to renew a disc at the same rate as a set of pads!!?? (ouch!!)................not something i would expect on any brand of m'cycle, let alone a BMW with their so-called touring credentials.

Has anyone had a similar problem?
Can anyone recommend a course of action?
(BMW are seemingly not prepared to consider there may be a product issue here..............on this basis this is my 1st and definately last Beemer (back to the good old Japs then!)

 

[v8legend]

Have you actually checked the disc thickness? I'm struggling to understand how a disc wears out at the same time as the pads?

 

[bob buck]

Rear disc

I also had a service and mot on my 2008 F650 @ 8k on the mot i was given an advisory as the rear disc is very slightly warped, now I can count on one hand the amount of times I have used the rear brake, and this is what I had said to the service advisor to which he replyed, that may have caused it, how dumb do they get !!!

 

[Sooty09]

A problem not too unknown on enduro bikes. If you are riding with motocross style boots you may be pressing the rear pedal without noticing. This is easier to do on the BM because the height of the pedal is not adjustable. I don't know why this dose not effect the pad wear as severely.
As to a faulty component, they are part of a very large production run so a one off material problem is very unlikely, our 2008 and 2009 bikes have both covered 27000m+ , both now towards the wear limit of their second set of pads. The disks look new with only a few grooves and ridges.
On the + side the rear disk is readily available as a pattern part for about £80.

 

[antvtr1000]

650GS Disc Wear

Thanks for the replies......
Regarding the actual thickness, initially BMW Technical no-help line stated there was NO specification for minimum thickness?!....so i went back to the Dealer to challenge them, and to be fair they quickly produced the spec sheets (straight off the BMW service database!) and actual thickness measurement reports to confirm disc was 0.1mm below minimum.
The disc itself is in good condition, no warping, cracks or crazing and no grooves, so i have no intention of changing it out of my own pocket.
If i was to get 27000 out of a disc i would have no cause for complaint....what sucks here is i have only got 9000mls, BMW want me to part with the thick end of £200, and there 'technical' reasoning (excuses) are downright insulting........i just want them to recognise that on this occasion there must be a problem with the product.
(sorry, but i do not buy the 'dragging the rear brake' as a cause..............this would surely lead to premature wear of the original pads well before the brake disc?

 

[Gert]

For what it's worth. Am at 73000kms with my F650GS and still stock discs on the bike, front disk thickness at 4,18mm and back disk at 4,23mm.

take care
Gert

 

[v8legend]

front disk thickness at 4,18mm Gert

Aren't they marked minimum thickness 4.5mm?

 

[antvtr1000]

gs650 brake disc

Probably are marked 4.5 ('new' width is 5.0mm).
Gert should be happy in the knowledge that he's drained mega-Kms out of his, and i don't blame him for sticking with it for a little longer if it's generally in good nick and performing OK.
As for mine, it was measured 4.4 at the service after 9000mls............come on boys and girls...........does anyone out there agree that BMW have sold me a duffer rear disc!? (and should acknowledge this FACT).

 

[old-man-andy]

F650GS rear disc

Hi

For comparision, my 3 yr-old 650GS now has 21,300 miles on the clock. Just measured my rear disc at 4.72mm. The original pads lasted 9k miles and the replacement EBC (non sintered) pads are down to <2mm and need replacing pretty soon! The front disc measured at 4.41mm. Original pads lasted 10.5k miles, whilst the 2nd set of pads have a couple of thou miles left in them.

The disc & pad wear is (obviously) going to depend on your riding style and where you ride - 9k town riding is likely to wear pads/discs much faster than 9k on the motorway.

Your disc wear is a bit of an odd one..........

What is/was the compound of the rear pads? The Owner's Manual spec is for organic, if my memory serves me - if the pads were sintered (HH) then that may explain excessive wear.

Is it possible the disc was "swapped" (for whatever reason) when it was previously serviced?

Presumably you occasionally checked the rear wheel rotated freely, with no brake drag......

If it's still in warranty it's probably worth still hounding BMW customer service. If not, personally I'd live with a 4.4mm thick disc and keep an eye on how it wore every 500 miles or so (but I am a tight-fisted..........)

Cheers
Andy

 

[Gert]

Aren't they marked minimum thickness 4.5mm?

quite possible, but I do not find any requirement in the manual. Anyway; the other day, I was forced to execute an emergency stop during which the front tyre was screaching. So I think all's still well with the discs.

Is disc thickness that critical then? Is the minimum of 4,5mm for the purpose of heat dissipation? Can't really imagine it's a strength requirement, as the F650GS is not 'that' powerful or heavy a bike.

I probably squeeze out an extra 6000km out of them and have them replaced on the next service interval.

Gert

 

[Tim Cullis]

Why is disc thickness important: http://www.justpartsbiz.co.uk/acatalog/What_is_Brake_Disc_Minimum_Thickness_.html

Seems to be primarily to do with poor heat dissipation and consequential brake fade. Highly important if you are touring in the Alps, but I would have thought it won't occur during normal riding unless you are constantly using the brakes.

 

[antvtr1000]

f650 BRAKE DISC

Gents Ladies,
Thanks for the various responses!!!
Bu my question remains...........what do i now do about a Manufacturer who will not acknowledge premature disc wear? Why should this 'fault' be potentially at my expense? (BMW Customer Services are not interested!)

 

[v8legend]

Why should this 'fault' be potentially at my expense? (BMW Customer Services are not interested!)

Have you had this bike from new? Do you know that this is it's first set of pads? I can't imagine a situation where the disc wears out quicker than the pads, unless they've had a prolonged spell of being really dirty with something abrasive like sand.

Having said that, most manufacturers back away from brake warranty claims, because they can be so adversly affected by the user.

 

[rce]

A lot is down to the new pad materials they are fitting, my car gets through a set of rear discs every 30,000

While yours sounds a short life, and I would be upset, it is a consumable.