Front Brake Vibration Fix
BMW's fix for vibrating/pulsing front brakes on the 1200 boxer
03 July 2008 - Updated 30 July 2012
Problems with the front brakes on the 1200 boxer machines isnt exactly unknown. Several people have reported recurring problems with vibration and pulsating of the front brake lever. If this was reported earlier as a warranty issue, new brake discs might have been fitted, but the problem could easily reoccur with the new discs.
June 2007 BMW Motorrad America issued Service Information Bulletin Ref 34 003 07 (34) Under 'Details' is the follow comment:
A combination of unfavourable tolerances of brake disc, front wheel and ABS sensor ring and/or incorrect assembly can result in an increase in runout of the front brake discs. When the motorcycle has covered a considerable distance (empirical data indicates approximately 5,000 to 12,500 miles), very shallow recesses are worn into the brake discs. The effect is perceptible to the customer as pulsating brakes, and is particularly noticeable under gentle braking.
It then advises dealers to fit new discs to the front wheel, then check them for run-out. If the new discs are found out of tolerance then a new wheel would be fitted along with the discs to correct the problem.
May 2008 BMW Motorrad USA issued Service Information Bulletin Ref 34 006 08 (028) There is now a new type of brake disc available with riveted on floating mounts. No longer is there need to measure run out or fit a replacement front wheel, just fit the new type of discs.
Even from new the front brake of my 1200RT suffered from snatch at low speed making town riding challenging and low speed U turns very interesting indeed. At around 4000 miles I started to notice mild vibration on the front brake lever during high speed braking which became steadily worse as the mileage increased. At around 8000 miles my discs were replaced by the new riveted type (Fix 2). This has transformed the front brake, gone is the vibration that had become pretty bad and gone too was the brake snatch, my front brake is now as sweet as a nut, I just hope it stays that way.
Fix 2 Detailed pictures of the new discs and mounts, the first thing you might notice is the larger fitting under the Torx screw.
Fix 2 Side view showing how the disc has been machined away to allow fitment of the floating mount
Fix 2 View from the inside showing the serrated spring washer.
The new disc mounts (shown below) are of a more complex construction than first appears, containing both rubberized and spring washers.
Fitment guide and part numbers.
New mounting screws are needed for the GS machine, check with your dealer.
Update: 30 July 2012
All is not well with the front brakes again, slowly vibration has been returning to the front brake lever, this has been coming on for a long time, but only slowly getting worse. To try and find out what the cause may be I measured the disc thickness all around both discs and plotted this in to Excel so I could view the data as a graph. it turned out to be quite interesting.
20 measurements were taken evenly around each disc with a digital micrometer. The blue line is the left disc, red for the right disc. Clearly the left disc is the culprit, showing very uneven wear from position 8 through to position 20, so what could cause such uneven wear?
Examining the left disc further, I found the culprit. Whoever had fitted the discs had installed all the screws, but hadn't tightened them all down. The mounting screw opposite position 8 was tightly glued in place with thread lock, but it wasn't holding the disc down. The disc at this point was noticeably more 'loose' if you pulled it about, the actual gap between the screw head and the disc is .9mm. Disc 'looseness' at this point was causing the left disc to wear very unevenly.
These discs have been in use around 19,000 miles and while I accept they are both worn below spec (new disc is 4.5mm, wear limit is 4.0mm) if they were working smoothly I wouldn't be looking to replace them right now. Disappointing, to say the least :-(
This information is provided as a guide only
If you think you have a problem with the front brake, I recommend you see your dealer and discuss the above with him