K1100LT [1997] Front brake disk rattle

[Anonymous]

#2263

The front brake disks (ABS) rattle crossing the driveway gutter, judder bars, etc and ‘chuckles’ constantly on anything but the smoothest tar seal.  Only a Sally Army tambourine could complete!The disk-mounting ‘bobbins’ allow the disk to move about 1mm both laterally and circumferentially, suggesting they are worn.  The bike has 72k on the clock.    I understand the disks are designed to ‘float’, so assume some movement can be expected. .  The brake operates very well but the rattle is annoying & worrying.  I’ve obtained replacement bobbins & fasteners for both disks from Motohansa Australia.  The new bobbins are hard plastic with steel washers & clips whereas the existing ones appear to be steel- is that OK?.  I have hesitated tackling the job fearing some insurmountable fitting problems arise.  Removal and installation of the circlips might be awkward?.  Strangely, Clymer is ominously silent on this subject, and the only overseas forum commentator I’ve read solved his problem by installing entirely new disks – certainly a ‘last-ditch’ solution for me!Has anyone with experience of rattling front floating disks got helpful advice or tips?

[Stuart Burns]

#8697

I had a K1 which had the same discs, had the same issues, got a local machine shop to turn me up some new 'bobbins' in stainless steel.The original ones are alloy, that's why they wear out. shouldn't be any difficulty getting the old circlips off, you might find the hardest bit is getting the discs off the wheels, the socket head screws are held in with bmw's infamous blue threadlock, small blowlamp or heat gun would probably be handy, plus a good quality 3/8 drive allen 'key' if any round off, I found you can hammer in the next size up torx head socket! Iinteresting that your new bobbins are plastic! I assume they're solid? Lots of shear forces going through them under heavy braking, plus heat……… 😕  Must have been tested though…..

[phil1]

#8698

have you replaced your brake pads with after market types that don't have the anti-rattle clips fitted??had similar on my R1100 - a smear of brake grease on the back of the pads fixed it

[dave.valma]

#8699

Hi Nigel, brake grease??? I havn't come across that before, please enlighten.Steve.

[Folker Liebenow]

#8700

Hi Bryan. The BMW Man had a go at this, & posted the results on his site. Here's the link http://www.bmwman.biz/. Good luck with it. Like the others, I'd be dubious about plastic bobbins. Are you sure that they haven't been plastic coated? Steve 

[phil1]

#8701

Hi Steve – it should rather be called Anti Squeal Paste. It holds the pads against the caliper piston. Stopped mine from rattling on my R80G/S and my R1100G/S. (still own the 80, the 1100 has gone). originally my local dealer put some on the pads, i subsequently got some more in 5 gram satchets from James Sherlocks BMW in the UK. (very good to deal with by the way)

[Anonymous]

#8702

You guys are fantastic!  I should have enough detail to get the job done, but more comments still very welcome.  Feel much more confident about doing the job too!  The BMWman site is well worth keeping for an ex-police bike owner.  Many thanks- this is the best forum I've encountered.  Bryan

[ROBIN MOSS]

#8703

Hi Bryan.I'm at work and only have a quick minute but don't worry about the "plastic". From my position as an engineer, http://www.aartpulse.co.nz I own the company, "plastic" is a blank word. Approximatly 132 types of  "plastics" exist and then there are the derivatives. Many of the "engineering Plastics" carry better resistance to mechanical forces than the likes of stainless steel and low carbon steels.Depending on the material your bobbins possible have a stainless or metal insert for added strength.I would suggest that the bobbins are of a family called "High Molecular Polyethylene" or more specifially UHMWPE-BR . This material has outstanding wear and abrasion resistance, combined with very high impact resistance, it's ductility is well beyond that of steel. (Ability to withstand plastic tensile deformation) and very low moisture absorbtion.Or they could be made from a Nylon type material, called "Nylatron MC901". I suspect my first guess as this material has higher operating temperatures, as high as 300C and does not get affected by water, many "plastics" expand when subjected to water..So what am I telling you, in short use the "PLASTIC".There are a few items associated with the actual brake system that could be at fault, that excellerates the rattle but I think the bobbin replacement will solve the problem. See my profile or introduction in the members forum.RegardsLeigh.

[ROBIN MOSS]

#8704

Hi Bryan. end of day and a chance to ask if you wish for a little more info on some brake problems. Why do I know, well my company manufactures amongst many things, much of the braking systems for the Porshe GT3's and NZ V8's, Formula Fords, and Toyota classes.If you are content with the info you have, then okay, but if you wish for some more bits to lookout for, I'm only to happy to help. Just ask.RegardsLeigh. 

[Anonymous]

#8705

I completed the installatiob of the new bobbins this afternoon.  Took about 90minutes for both disks.  Only one drama when one old disk was stubborn.  Most bobbins showed signs of wear, but not as much as expected.  Almost all play has gone.  Many thanks to all contributors, and especially to Leigh whose comments on the attributes of 'plastics' dispersed many a doubt.  The recommendation of the ' BMWman' site /.was pure gold.  Thanks everyone!

[Anonymous]

#8706

: Well done on the repair, probably saved a few dollars as well, the reluctance you showed in using the “plastic” bushes is justified because plastic will cold flow, it is only improved by adding other compounds to the mix to make it suitable for your application, and it just shows that only a little bit of wear can cause these problems, remember most bikes have very small tolerances on fitted parts, everyone should remember to keep an eye on their bikes squeaks and rattles, it usually means something is amiss and needs looking at, sooner rather than later,cheers and happy trails Bucky.

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