The ads above are Google-sponsored, ......clicking on them at every visit, and looking at them helps support this website!

 

Rocker arms, rocker arm shafts and bushings/bearings;
breakage of rocker arms;  valve gear; pushrod tubes;
various parts of the cylinder heads.
 For BMW Airhead Motorcycles
Copyright, 2014, R. Fleischer

Article 60
sub-section 6
headassy.htm


Adjusting valves & rocker end play, ETC!:   will be found in article #40: SETVALVES.htm

***If you have INsufficient adjustability to set valve clearance, after milling the head, see: valves.htm


There is more top end information in article 60, section 5 and section 8.

I strongly suggest you read them!
 


BREAKAGE OF ROCKER ARMS:    This is a rare occurrence, and usually only happens under racing conditions, such as with very high rpm, and/or high lift cams, increased valve spring strength, insufficient spring clearance at maximum lift, etc.   However, it did happen, but rarely, on stock early Airheads.  This was in the /7 era.   It happened only to those early /7 era rocker arms, as far as I know.   If you look closely at a rocker arm, immediately next to where the ADJUSTOR screws into the rocker arm, the web width there on the suspect rocker arms is about 7 mm wide.  BMW made a production change, and the rockers with the change had a 11 mm width.  There was no change in the rocker part number.  It does not appear to be a formal re-call by the Factory.  I am not listing the rocker part numbers, except two, because:
1.  No new rockers are available that are 7 mm
2.  It is easy to confuse yourself over the SEVERAL part numbers used for the rockers.

The original part numbers, long gone now, were 11-33-1-262-403 and -404.

 



Rocker Arm Shafts and Needle Bearings:

This particular section does not apply to the /5 series, which used bushes, not needle bearings.  I treat the /5 series separately in this article.

In working with the valve gear, and NOT doing a bearing replacement, I recommend you do NOT disassemble the rocker arm shaft area unnecessarily.....if pulled far enough out, some tiny roller needles may fall inside...or on the floor. The needles are located at each end, as a bearing, and the proper amount of them at either end is just enough so one more will not quite fit, I will get deeper into that later here. The center area on the shaft is empty.

Rocker shafts will have either a small round aluminum insert (sort of gray in color)...used up to some 1982....or, an OFFSET punch prick, on some 1982...and all later ones. Both markings MUST face UP. The punch prick mark MUST also be outwards...that is, towards the valve cover....except that later shafts are angular drilled, and can be 180 reversed, when needed, to lengthen life.  BEST to follow my instructions, and have the markings as above, that way you do not have to worry about whether your shafts are angularly drilled.  If you are anal enough, take a look at YOUR rocker shaft(s) and notice the oil passageway drilling.... since the oil comes from the top studs, guess which way the drilling must be in order for oil to flow...?!?

Some late 1970's into at least late 1980's needle bearings were faultily made (the rolled crimp), and an end can fracture and then needles will be found in the valve cover(s).  See AIRMAIL of September 2004.  It is possible that some faulty needle bearings were installed even later.
The cage that holds the bearings was faultily-made. It is a metal sleeve that is rolled-over and inwards at the ends...forming a captive area for the needles. The rolling wasn't enough, and the cage was riding on the shaft, breaking at that rolled ends, rollers came out....note what the rocker block looks like!....there is a split, a gap, and needles can be SPIT OUT that rocker block GAP.  Needles are typically found in the valve cover, or in the oil pan.

New bearings is the fix, and you can check them with a rocker shaft to see that the shaft and bearing rolled ends no longer touch.  The bearings (you need EIGHT to do all the rockers) are 11-33-1-261-712. They fit all the rockers from the /6 onwards including the 1985+ rockers that are narrower.

Press them in so they are a tad under flush. DO NOT damage them.  They've been made with 30 (early) and 31 (now) needle rollers, both are fine....the 31 version has very slightly smaller diameter rollers. 


Hints: deburr or relieve faintly, the ends of the rockers so the new bearings install nicely. I think that in a discussion on these a long time ago, Tom Cutter recommended on the LIST that the more rounded end be inserted first....hmmmmm.   Notice that MY recommendation has been that if your brand-new rocker needle bearings have a flat end and a rolled end, the flat end is UP. This conflicts with the prior advice on installing them.

You can remove the needles and install them later; use thin grease, even Vaseline (Petroleum Jelly) to help ensure they don't fall out of place. Use of a shaped tool to install the bearing shell is best, and done in an arbor press or in a vice with soft jaws, etc. I've never tried the axle as an installing drift, as some have mentioned, I believe the lip on the axle DOES NOT have enough surface to do a proper job.  DO NOT have the bearing proud of the rocker arm end surface.  I set them a wee bit below that surface!   I have not tried this in a field repair, but see no reason it would not work:  Install the bearings using a large bolt and thick large flat washer.  Once flush, install a wee bit below flush, using a smaller washer of nearly the same OD as the bearing.   Be careful, do things carefully and squarely.

Inspect the rocker shaft for damage.


There is a pricey update kit, to convert the rockers assemblies on the 1976 and later bikes to the 1985+ style that use shims.  Restating this a bit, the retrofit kit is NOT for pre-1976, and IS for 1976-1984.    KIT Part number 11-33-9-057-699.  You will also need support bushings 11-12-1-261-405 if you use the new style rocker arm assemblies.   You could use junked heads from 1985+ to provide the parts, or swap the heads if in good condition, or rebuildable, etc.   The mentioned kit includes the fin quieting pads: QuietingPads.  The pads are available separately, as are any of the kit parts.   Don't try this kit with the early /5 heads, it won't work.   MANY folks upgrade the earlier bikes to later items in a piecemeal fashion....such as the later pushrods. This is particularly true of the /5...PERHAPS!
The 1985+ models, and fully kitted 76-84 models, adjust their end clearances by means of shims. These rocker units have a pressed-in plastic part that helps quiets noises.    NOTE that the 1985+ rocker gear uses a shortened rocker.  I think the early eighties rocker gear is better; and NO shimming needed.

NOTE:  when entering BMW part numbers in on-line dealer fiche, delete the hyphens, use no spaces either.

For your convenience, here is the BMW bulletin, called an SI (Service Information), number 11-032-86 (2208) of May 1986....and it is clickable:  
85+rocker-kits-and-cylinder-rubber-pads.PDF
NOTE that pre-1985 heads require 11-12-1-261-405 support bushings, this statement is found on the last page, very bottom of the SI.

Here is a sketch by itself on the head quieting pads; and with a slight bit more information.   quietingpads.htm


***Note, again, that I think the early eighties valve gear (prior to the shortened rocker, plastic bush, and use of shims, of 1985+) is actually better.


Updating /5 Airhead rocker gear:
 


 First, as noted above the 1985+ rockers, kit, etc., won't fit right out of the box...although they can be made to work.  There are TWO types of these early heads.   If yours has steel tubes pressed through the fins, next to the spark plug (both sides), these tubes go into the cover area, the rockers are on them.  You will need the round spacers that fit the tubes and push against the O-rings, pushing them into the head.  Otherwise you will have oil leaks. Use the 1974-1975 needle bearing rockers.    There is a later /5 head that the tubes did not show through, and these don't use the O-rings, nor spacers.  For these you can use the later rockers and parts up to 1984.   The later ones had better heat treated tips.      See the photos and notes on the /5 here:  http://largiader.com/tech/rockers.   That page may help your understanding somewhat & has some general information that applies to ALL MODELS OF ROCKERS, ALL YEARS.
That page does not give nearly enough information.  All the information is in the article you are reading.


Additional clarity: 
A question comes up now & then, not only about how to identify those early heads, as in the previous paragraph, but whether or not an O-ring is used under the rocker block area.   Most /5 cylinder heads require O-rings at the rocker boss area, where they fit into the head.  Heads requiring these (8 per 2 heads), part 11-12-1-255-167, which became 11-11-1-460-470, size 15 x 2.5 mm, and then probably 11-11-1-460-391, can be told from the OUTside by looking for the tubes, in between the fins.
Here are photos to allow you to determine if you need O-rings:



                                           
The above head does not need the O-rings                      The above head needs the O-rings
 as the casting surrounds the tube.                                   as the tube appears with no surrounding
                                                                                      casting. Don't look at the rusting one here.


Aligning rocker gear, /5 Airhead; & information on bushings used on the /5:

/5 models with original valve gear need extra care to align the rockers/shafts/blocks assemblies.  There is no locating step machined into the rocker blocks.   These parts can all be moved about a fair amount if the rocker hold-down nuts (head nuts) are loosened.   Clymer's, Haynes, and even BMW's literature, shows an alignment tool that can be machined-up, but this tool really does NOT do what is promoted.  Alignment of the rocker gear is done every now and then during valve adjustment time....by squeezing together the rocker blocks lightly, and then positioning the pushrods in the bores, and keeping an eye on the rocker tips where they contact the valve stem (offset is proper, for valve rotation).   In any event, the /5 rockers have a pressed-in bushing, and the bushings wear, as does the shafts.  
Here is a trick to quiet those worn rockers!
   1.  Replace the worn bushings in the rockers if truly bad.
   2.  If NOT worn terribly badly, simply SWAP the rockers; ...but do NOT move
        the rocker shafts from their particular position:
        a.  move right cylinder exhaust rocker to the left cylinder intake
        b.  move right cylinder intake to the left cylinder exhaust
        c.  move left cylinder exhaust to the right cylinder intake
        d.  move the left cylinder intake to the right cylinder exhaust



NOTE!....Excellent head work (valve jobs, dual plugging, all that sort of thing) that I know of, is done by OAK.     Contact him at:  AskOak@aol.com
Oak does excellent work on transmissions, rear drives, ETC.
Oak may have retired, so be sure to send him a message first.

Below are some more recommendations:


On the WEST coast: Ted Porter.
Ted owns the Beemershop:  http://Beemershop.com

On the EAST Coast: Tom Cutter at his Rubber Chicken Racing Garage: 
        rubberchickenracing@gmail.com

Murph's, in Eugene, Oregon   www.murphsbmw.com

http://thenickwackettgarage.com/bmw/
 Bud Provin; in Vermont.

I have other recommended service places, and there are not many, in my REFERENCES page.


Pushrod tubes, seals, etc....replacement, etc:
Information will be found at:  PUSHRODSEALS, ETC
NOTE:  I have been told that Seibenrock makes a pushrod tube mandrel...some sort of mandrel is a must when installing new tubes.

 

rev:
updated through 06/26/2008
01/26/2008:  new, released
06/26/2008:  updated
10/02/2012:  Add QR code; add language button, update Google Ad-Sense code
08/21/2013:  Expand information on the rocker bushings/bearings
05/04/2014:  Review, clean up some for redundancies and clarity; add more information on the
                     rocker kits, and head photos from
                     the break-in article.  
08/03/2014:  Add more information on broken rocker arms, move to beginning of article.
09/28/2014:  Add a few links, a bit of cleanup.

Copyright, 2014, R. Fleischer

 

Return to Technical Articles LIST Page

 

Return to HomePage