The BMW muffler repair kit is used to replace standoffs for the heat shield on the K100 muffler that have fatigued and broken due to vibration.

The kit is still available from Phil Engel of Engeland Moto, Waxhaw, NC 28173. He has an Ebay storefront as well as his own web site (www.engelandmoto.com) where he sells various componentry for BMW, Aprilla, Moto Guzzi, etc. The repair kit consists of:

• (5) cadmium plated threaded inserts
  
• (5) standoff spacers
  
• (4)M6 mounting bolts
  
• (4) rubber “O”-rings
  
• (5) wave washers
  
• (1) M6 stud
  
• (1) M6 Acorn nut
  

The threaded insert is installed in much the same fashion as a "Molly Bolt(™)" or pop-rivet, in that it is placed into a hole in the muffler up to the flange and then "pulled up" against the muffler body. This causes the crush zone of the threaded insert to expand and lock into place.

The threaded insert must be compressed using a multi-purpose riveter tool that can pull up upon the threaded insert .

These tools are multi-purpose because they can expand pop rivets using the pop rivet tip or expand threaded inserts, such as those supplied in this kit, using the threaded adapter tip.

1. Using an angle grinder, remove any remaining bits of the Original Equipment (OE)mounting hardware from the muffler. The broken pieces should be ground down to the muffler surface so that they don’t interfere with the standoffs from the kit.
   
2. Drill a 9.5mm (3/8 inch) hole in the center of the OE mount. In some cases, you will need to drill through tubes located within the muffler; don’t be alarmed.
   
3. Thread the insert onto the riveter tool.
   
4. Fully insert the body of the threaded insert into the hole up to the flange.
   
5. While holding the tool in place and exerting downwards pressure (to keep the flange of the threaded insert in contact with the muffler), carefully and repeatedly squeeze the handles together . This action will pull the body of the threaded insert up against the shell of the muffler. The crush zone of the threaded insert will swell up and lock itself into place. The tool will feedback that the insert is fully compressed by increasing force with each squeeze.
   
6. Repeat Steps 1 through 5 above for all other locations on the muffler where the OE mount have broken. At a minimum, it is only necessary to install threaded inserts in the locations where the OE mounts had cracked although it is possible to completely replace all mounts with the new threaded inserts.
   
7. As a quality assurance test, start the engine and check for puffs of air coming from around the flange of the insert. Air leaking around the flange will indicate that the threaded insert is not sufficiently compressed. Stop the engine and tighten up any loose inserts using the riveter tool.
   
8. Re-install the heat shield, using the provided O-rings, bolts, standoff spacers and wave washers. The O-rings are inserted into the recess provided on the threaded insert. The O-rings help to seal by preventing exhaust gases from escaping through the insert. A dab of LocTite(™) Blue on the bolts won't hurt, either, to keep them from vibrating loose.
   

Hi Rob

great tutorial, I'm curious if it finally fixes the annoying tinny vibration noise. Thanks

Bruce wrote:Hi Rob

great tutorial, I'm curious if it finally fixes the annoying tinny vibration noise. Thanks

Hi Bruce,

The kit does no more or less for dampening vibrations as would the original mounts. If the resonant frequency of any part of the shield matches the vibration mode of the muffler, the shield will resonate as before. What the kit does do better than the original mounts is to not break. The mounting bolts go deep into the threaded inserts and you can torque the bolts down much more than the older short screws.

If you want to dampen vibrations in the shield, add more mounting points (increases the resonant point for the shield) or add adhesive sound absorbing mat to the shield (changes the resonant mode of the shield).