04/05 Flange defect, take note

michnus

Guest
If you own a 04 1200GS, go check the flange on your bike, might be 04 and 05 models, just possibly be one of the flanges that will have cracks on the lugs securing the rear brake disc to the flange.

On my 04 1200, the flange which secures the rear wheel and rear brake disc some how got some cracks on all the lugs securing the rear brake disc. It is not a common problem and from the things of it seems to be 04 specific, not confirmed. It is suspected that it is either a design fault or metal fatigue.

This is a safety critical item and on a bike like this must never happen. You need to take of the rear wheel and inspect the flange properly. If you intent buying a 1200GS/GSA let the seller/ dealer take off the rear wheel and confirm it does not have cracks on the lugs as this item will cost you around $280 to replace.

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I recently fitted a new wavy rear disk to my '04 and didn't notice any cracks/defects with the carrier but will remove my rear wheel in the morning and inspect it more closely.

Thanks for the heads up.
 
I`ve just checked mine and it`s ok :thumb2 Mines a 54 plate with 18k. If you have alloy wheels you can check them without having to take the back wheel off :thumb2 not sure about the spoked ones :confused:
 
THANKS VERY MUCH

Michnus,
a very big THANK YOU.

Just went out to check my '04 bike. The three 'arms' I could see easily on my rear brake disk/wheel bub were fine (as I expected). Turned the wheel and to my horror, the other two arms have the cracks.:eek:

When I recently changed my rear disk due to warping with a tight spot, I did a cursory glance rather than a proper good eyeball. I'm normally a stickler for all things engineering, can't believe I didn't find this earlier (unless its only just occurred).

In hindsight, it may have been the cracked brake disk hub that allowed the disk to warp?

Either way, I'm off to Bahnstormer Motorrad this afternoon on a rideout so will ask them about possible goodwill or discount on a replacement hub. This is not good on a component which is meant to stay together for the life of the bike, and its failure could have potentially life-threatening consequences.
 
As reported on another site...the cause is from "Over Torqued" wheel bolts/lugs.
Use a Torque Wrench!!!!:blast
 
As reported on another site...the cause is from "Over Torqued" wheel bolts/lugs.
Use a Torque Wrench!!!!:blast

that doesn't seem likely. cracks come from the disc mounting holes, and are nowhere near the wheel mount bolts.

does this only affect early models or do i have to take my 06 wheel off?
 
Just been outside to check my flange.

No cracks apparent on either the brake disk mounting lugs, or as far as I can see, without removing the wheel, no cracks adjacent to the wheel mounting holes.

2005 GS 37,000 miles.
 
Michnus,
a very big THANK YOU.

Just went out to check my '04 bike. The three 'arms' I could see easily on my rear brake disk/wheel bub were fine (as I expected). Turned the wheel and to my horror, the other two arms have the cracks.:eek:

When I recently changed my rear disk due to warping with a tight spot, I did a cursory glance rather than a proper good eyeball. I'm normally a stickler for all things engineering, can't believe I didn't find this earlier (unless its only just occurred).

In hindsight, it may have been the cracked brake disk hub that allowed the disk to warp?

Either way, I'm off to Bahnstormer Motorrad this afternoon on a rideout so will ask them about possible goodwill or discount on a replacement hub. This is not good on a component which is meant to stay together for the life of the bike, and its failure could have potentially life-threatening consequences.

Maybe you cracked it when you changed the disk????????????????
 
Maybe you cracked it when you changed the disk????????????????

Perhaps, but I'm pretty sure I would have noticed it. My guess is brittle fracture but as I don't have access to a scanning electron microscope I can't prove it. The profile of the component has no obvious stress raisers and the two cracks have propagated along differing paths.

BMWRich58, I've been an Engineering Technician since 1982. I've worked on Gas Turbines and reciprocating diesels the size of a house and costing millions. I think I can be trusted to safely tighten a fastener or two on a motorbike. Of course I used a torque wrench and followed the instructions in the RepRom, I'm not stupid.

My local dealer has never seen/heard of this happening and took a look out of interest. Eyebrows were raised as the same flange is fitted to the entire R1200 range plus the K1200 model range. They asked if Michnus's bike had the stock disk and pads as mine are non-OEM.

They advised me to contact BMW customer services as a goodwill gesture is unlikely. I simply bit the bullet and ordered a replacement 'flange' under the new part number of C33.11.7.699.631 for £115.99+vat (£133.38) as the old part is no longer available ( I wonder why??).

Pity really as I am unemployed again at present so could do without the (unexpected) expense but my bike is my sole means of transport. No doubt pulling the flange from the splined rear hub will cause me some more headaches. Probably gonna need to put the FD in the freezer for a bit, then get the turbotorch out.
 
Does this only affect early models or do I have to take my 06 wheel off?

Just checked out other bikes on Bahnstormers forecourt today. They were all newer so had no cracking (yet :augie)

If you have cast alloy wheels the brake disk mounting lugs on the flange can be seen easily through the wheel without the need to remove it.

On spoked wheeled bikes, the central wheel bub is a larger diameter and hides them so you need to remove the wheel to check the flange lugs for cracking.
 
The profile of the component has no obvious stress raisers and the two cracks have propagated along differing paths.

It's got tapped holes in it, if they're not stress raiser i don't know what is?

That said if we are ruling out over / under torquing, uneven tightening patterns and everything was flat - true and clean prior to assembly then it is a disturbing failure.
 
It's got tapped holes in it, if they're not stress raiser i don't know what is?

That said if we are ruling out over / under torquing, uneven tightening patterns and everything was flat - true and clean prior to assembly then it is a disturbing failure.

Fair one, but as the tapped holes are unavoidable by design function I didn't mention them. I was referring to the shape of the component having smooth radii and a good surface finish.

It has certainly disturbed me to the tune of £133 on a component you would expect to be slightly over-engineered.:mad:
 
As reported on another site...the cause is from "Over Torqued" wheel bolts/lugs.
Use a Torque Wrench!!!!:blast

It makes sense for BWM to try and blame over torquing ove the bolts. That way its the customer's fault and they don't have to pay any goodwill. :(

Thanks for the heads up. Will have a look at mine tonight.
 
Pukmeister, the dic is still OEM and has never been removed, only the pads have been changed. BMW will not replace as a goodwill gesture, I tried in SA.

This is not the kind of thing that must fail, on a bike like this, funny thing is why is it not more common? Even my 06 1200GS flange looks exactly the same.
 
Just a thought but has anyone had a seized or semi-seized rear caliper at some point? This could induced repeated uneven side loading on the disc and hence eventually propogate cracks from the disc mounting holes. The surface cracking might not be apparent at the time but once the process has started.....
 
Just a thought but has anyone had a seized or semi-seized rear caliper at some point? This could induced repeated uneven side loading on the disc and hence eventually propogate cracks from the disc mounting holes. The surface cracking might not be apparent at the time but once the process has started.....

100% not on mine.

Pukmeister, if you heat the flange it will come of quite easy.
 
thanks Michnus, I had hoped it would, just about to load the RepRom and take a look at whats involved but should be simple and logical enough.
 


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