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Rubber Noise Silencing Pads For Cylinder Head Fins...
For your BMW Airhead Motorcycle (only)

http://bmwmotorcycletech.info/quietingpads.htm
57
Copyright, 2014, R. Fleischer

See http://bmwmotorcycletech.info/valves.htm for more information about 'noisy valves'

In 1985 BMW Airhead boxer motorcycles incorporated a new type of rocker arm assembly with adjustable end play by shims. The purpose was to quiet "valve noises".  This modification did quiet the valves, even compared to a properly set-up earlier type.   It costs $$$ to convert prior models to the 1985 style using brand-new parts.  This cannot be done on the early /5 series, although they can be updated to some of the pre-1985 modifications. I've never liked the plastic parts in the 1985+, and consider the rocker arm bearings as possibly not quite as long lasting (as the rockers are shortened in length), but they DO work OK and ARE quieter.

For those of you that feel that cost is no object for your BMW, the entire kit for the rocker conversion for your older BMW is #11-33-9-057-699. You will also need new support bushings, part is #11-12-1-261-405.  You might find a 1985 and later set of head parts in a wrecking yard though.    Do not try to add the shims to an earlier style, you need to modify or change the rocker arms. 

BMW also decided that the addition of some medium-hard silicon rubber pads/inserts into strategic places on the fins at top and bottom of the heads would also quiet things, by stopping 'metal ringing' of the fins. These help a small amount, & have no bad effect on cooling, ...maybe even help cooling, due to turbulence added. 

These pads (rubber 'pucks') are 11-12-1-337-818, no glue needed, although helpful.   You need 24 of them to do both cylinder heads.  They are included in the kit mentioned above.  If you are not spending $$$ to upgrade the rockers/etc., you may want to just order 24 of these rubber pads; but they are a bit pricey.

They are fairly easy to install ...one cleans the small head fins area for the pads a bit with a evaporating hydrocarbon solvent, and then one uses fingers and then a very blunt tool of some sort and taps/pushes them into position, trying to keep them round shaped. I put a wee dab of adhesive (glue) on them ...see below.

There are 6 of these pads used on top, 6 on bottom, of each cylinder head.   They begin, looking from the side, towards the engine, that is, facing the end of the valve cover, between the 2nd and 3rd fins from outer. 

Official spacing is measured from the center line of the spark plug (or valve cover center stud), both horizontally and vertically. The horizontal spacing is 37 mm center of rubber pad to center of spark plug/stud. The vertical spacing is 65 mm down, and up from that same stud.

Contrary to BMW information, the BEST position for these rubber pucks is actually SLIGHTLY different than what BMW states. The best position is such that the pad is at the CORNER-most of the fin, but fully touching metal all around.

The BMW bulletin on this is May 1986 11-032-86 (2208).

This bulletin also covers the 1985 R80 rocker arm assembly changes (not just the R80 ...changes were the same for all the other models).  I suggest that conversion NOT be done, due to the cost, unless you can get rocker gear from a late model wreck, cheap. I also think the earlier rocker arm bearings last a bit longer.  The later rocker gear, while it has some plastic parts, is definitely quieter.

The photo below is a scanned copy of BMW's bulletin, edited, of the reverse side.  NOTE that MY recommendation for the pads is more towards the corner of each fin, as I noted above ...where ringing is more pronounced; and, I have put somewhat hard to see lines on BMW's sketch to indicate moving the pads from BMW recommendation to closer to the spark plug. The pads are still fully on the fin, that is, no part of the pad is not touching the fin. 

There are differences in the head castings over the years, and you might not be able to place the pads exactly as shown in MY idea, nor BMW's.  Close enough is good enough. 

There have been some reported instances of pads loosening & disappearing.  Because of that, in the last batches of pads I have installed I did so with a small dab of 3M Super Weatherstrip Adhesive onto the pad as I slide it into position.

 


Revisions:
05/15/2003:  Completely updated.
05/04/2007:  Add scanned copy of pad placement side of the SI, some notes, clarified some details.
10/13/2012:  Add QR code, added language button, updated Google Ad-Sense code; minor clarifications in the text.
2013:  Remove language button, as the scripting coding conflicted with some browsers.
03/15/2016:  Update meta-code, layout, fonts, justify sketch to left side.
10/13/2016:  Cleanup metas, scripts, & obsolete HTML coding.   Improve layout.

Copyright, 2014, R. Fleischer

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Last check/edit: Thursday, October 13, 2016