front brake mystery

[adam.h]

hi guys i have a GS 1150 and when i got it there was a rattle from one of the front brake disks and it turned out to be missing the wavy washers so i got some and fitted them. but now the rattle is back so i had a look and the washers have gone can anyone think why

thanks
adam

 

[Packer]

Corrosion of the pads where the disc attaches to the wheel might cause the disk to run out of true. When you use the brakes there would be high loading side to side on the disk which could feasibly fatigue he washers and cause them to break and fall out.

You need someone with a dial test indicator to check the run-out on the discs when bolted up with new spring washers but with the calipers dismounted from the fork legs.

 

[columbus]

I had the same problem with my left disc.

The cause was traced to the inner caliper pistons. One was sticking and one had seized. I tried going down the repair route but it appear that something had damaged the machined face the piston slides in so I ended up replacing the caliper.

 

[Timolgra]

First the wavey washers break, then the disc bobbins wear flats on them so can be turned 90deg for a temporary fix.

Then the disc holes wear oval.

Finally, look where the bobbins seat on the wheel hub threaded bosses. Through time the bosses wear which prevent the disc being held tight enough for the wavey washers to do their job.

The fix is to carefully file or get machined the bosses all perfectly flat and square again.

 

[DrFarkoff]

The fix is to carefully file or get machined the bosses all perfectly flat and square again.

Sorry Tim Disagree The fix is to fit the washers from the inside of the discs on a R1150R / Roxter

Called stop disc 34117670217 about 86p each they are a thin stainless shim that goes between the brake mount post and the disc The corrosion normally works outside the bobbin mount so these are a cheap and safe method of repair to keep the disc square to the wheel