Servicing Transmission input (clutch) splines, throwout bearing and clutch arm.
cleaning, lubrication and inspection

Includes information on swing arm locknuts, adjusters, and how to adjust those items

article #43    inputsplinesthrowout.htm
© Copyright, 2012, R. Fleischer

Applicability: All BMW Airhead motorcycles, /5 and later.  Some applicability to Classic K-bikes and other BMW motorcycles with transmission input splines that work with a dry clutch.

Skill level: For input splines on Airheads...lower intermediate or better; for K-bikes, for rear drive/rear of driveshaft splines, skill level is same.  For K-bikes input splines, skill level: moderately advanced.  For the throwout bearings and clutch arm servicing of all these bikes, only low to moderate skills needed.

From this point onwards, unless specifically so stated, this is AIRHEADS information!
 

NOTE:  The swing arm bearings are the common number 30203A, although 30203 can be used.  One is sealed, one not, I prefer the UNsealed ones,
The pre-1985 wheel bearing number (all but certain R65 models) is also the 30203 series.

 

Background information:

Besides avoiding SPLINE WEAR from rusting, and helping with such as fretting corrosion; cleaning and re-lubrication of the input shaft splines will make operation of
the clutch smoother, and shifting easier.  If kept properly lubricated, the splines may last almost forever; good because replacing an input shaft is expensive.   The clutch splines
(really the transmission input shaft splines...you NEVER grease the clutch disc splines, although they work with each other)... are fine toothed, and the teeth not deep,
and dryness and rusting (or what appears to be rusting) causes problems. The normal use of the clutch causes the clutch disc splines to slide backing and forth along the
input shaft splines, wiping away the grease. I will go into this in depth a bit below.
The grease will go away after some mileage; and rusting and other serious wear begins.  You do NOT want that to happen.  MANY different  greases have been
tried, including some with very sticky, gummy or even taffy-like qualities (with and without molybdenum disulfide, usually just called MOLY). If the clutch splines wear
enough, you will hear a very uncomfortable noise, and then you are not going anyplace, as you just ripped off all the splines.  Long before this, with dry splines, it is likely
that your downshifting will be poor.

 NOTE!....whenever you clean and grease your Airhead's input splines, ALSO do the throwout bearing service. ...at least take out the parts (VERY easy to do) and inspect them, pack with a light smooth grease before reassembly.

After the mid-1980's BMW was said to nickel-plate the transmission input shaft splines and re-greasing can supposedly go to 30K miles. Sometimes, yes, sometimes NO.
No matter what type of weather you live/ride in....even wet or humid areas where regreasing is going to likely be needed sooner, for your first check on the input splines, I
suggest you check the splines at 12,000 miles since the last lubrication (and if unknown, do it NOW!!!), and if OK, go to 18,000; I doubt you will be able to go over
24,000 miles, no matter the type of shaft, plated or not. I have almost never seen any un-plated ones go much over 18K.  FEW of the plated ones go over 30,000 miles.
Those that do shorter rides, shifting a lot, in wet climates, ESPECIALLY if engine cool-down is in a high humidity area, will need re-greasing more often than those in dry
desert climates, or those who do mostly long rides.  Every time you shut the engine off after a ride, the engine cools, the internal parts, including the clutch parts, condense
some moisture on them, particularly in high humidity areas. That can promote rusting at the shaft, unless the grease is still intact. In fact, this condensed moisture can actually
promote washing-out of the grease.  For smooth operation I prefer quite a bit of moly in the grease (about 30% seems adequate) as moly tends to protect the metal from
some forms of wear, and tends to remain slippery, and even works itself into the metal somewhat.  

I have removed the discussion of various greases from this article.  For an in-depth discussion, see article #73.   That is my chemicals,etc.htm article.

The throwout bearing (this is the bearing INSIDE the more or less centrally located hole at the rear of the  transmission...
(I do not mean the clutch arm lever bearing) it is easy to get to, after the lever is removed.
***NOTE!  DO see the Clutch article which goes into this area in more depth:  CLICK!
   There have been three general types of throw-out bearings used.  In the /5, 4 speed transmission, there was a ball
bearing.  It gives little trouble.   In the 5 speed transmission up until before 09/1980, BMW used a flat radial needle bearing.  It is troublesome if not kept lubricated
and in good condition.  From 09/1980, BMW installed a ball bearing again, but it was of a new style with a plastic piston that looks like gray metal.   Much later,
BMW changed that design to a single piece design.

NOTE that all these throwout bearings are supposedly lubricated by the transmission oil.  That is true, but when
cleaning one of these throwout bearings, I strongly suggest you use a plain soft non-moly grease on them, and the associated piston.   This is
because it can take quite awhile for the transmission oil to get to and lubricate the bearing.   The radial needle bearing is a POOR design. 
When RADIAL needle bearings are rotated circularly, the needles try to rotate at the same speed at BOTH ENDS of each needle....that
is, from end to end of an individual needle.  This is NOT POSSIBLE, if you think about it, so they scrape around....moving the grease
out of themselves.   If the grease (or transmission oil) is not there, and a little moisture condenses there, or excessive clutch hold-in
times are often used ....and/or combinations of these things.....the bearing can start to deplete its lubrication, and actually freeze up.  

Expanding on the design:  There is a possible problem in the 5 speed models that have the throw-out piston separate from the bearing....in that the PISTON that drives
the bearing has a plastic outer body (doesn't look like plastic though, looks like some sort of gray metal).  Plastic expands vastly faster than
the aluminum transmission bore....and some pistons were made slightly too large in diameter, and could freeze up somewhat, when the transmission
got hot.   Makes for lousy shifting.     BMW makes a pricey replacement that replaces the earlier piston (that was too large in diameter), and the
new part also now contains the bearing as part of the assembly.
You can easily fix a sticky plastic piston however; and save lots of money.  This fix is done by cleaning it, and then chucking the small steel
nub into a drill press, and then using sandpaper squarely and evenly against the outside plastic diameter.  Information LATER in this article
gives more details.
NOTE!....it has been reported to me that BMW is now shipping an all-plastic part that has the same old problems!....so,
be sure that no matter what part you have in YOUR bike, that it is not expanding and seizing up when hot.

Again, be sure to see the CLUTCH.htm article on this website, it has a lot of information, photos of the throwout parts, etc.

Read #13 below too.

Besides that sticky piston problem, sometimes the bearing (usually the radial one, but rarely, but happens, the ball type) will start to fail.

The FIRST sign of an impending throwout bearing problem is USUALLY, but not always, a stiffening of clutch action, and/or some strange noises.  
If you keep your bearing clean and greased....say at every input spline lube job (15,000 to 20,000 miles usually), then you are far less likely
to have a problem that will strand you during a ride.

What follows is a step by step HOW-TO article, on cleaning and lubricating the throwout bearing, inspecting for any damage, and a
modification if needed; and, inspection, cleaning and lubricating the input splines.  While the procedure was developed from both a
1983 and 1984 R100RT, some generic information is included, and this procedure should be easily adaptable for YOUR bike.   There
are specific reasons the author did certain of the steps in the order shown.

Note:  This procedure does not require many special tools.  Tools from your on-bike BMW tool kit are needed.  See item #11 below for a few things you will need.
Also needed are the proper grease for the splines; a grease gun with a rubber tip that can contain almost any chassis grease (for the swing arm greasing); a modified 27 mm or modified
1-1/16th inch socket; a torque wrench; 13 mm socket; 3/8 or 1/2 inch drive as appropriate with a standard extension; 6 mm allen wrench in square
drive; 6 mm standard BMW tool kit Allen wrench, with the short side shortened...this is for the lower left transmission bolt; anti-seize compound, rags,
cleaners; two acid brushes (modified); and two pieces of almost any small rod or yardstick, etc., and a few minor items you are very likely to have. 
It is handy to have a modified Chinese bottle jack, an article on that modification is on this website...and that WAS a hyperlink, although it is listed
on the Tech Index page as item #20.   The tools above are not to be construed as an exact list of items you will need.   You may improvise for YOUR
bike as needed.   Some folks with smog parts may need a 15/16" flare nut wrench or substitute.  NOTE:  You can elect to totally remove the
transmission, which is more work, as you may have to remove the driveshaft, shock absorbers, battery tray, etc...or do it how I show it below.  Do
NOT overly grease the input shaft.  Follow directions!

***NOTE:   Removing the entire rear end makes for a longer job, but you do do an IN-DEPTH servicing of the swing arm bearings, and inspect everything better.

REFERENCE:  07-11-9-918-655 50 mm Allen head bolt with captive washer; 07-11-9-901-033 45 mm bolt or 07-11-9-901-161 40 mm bolt.  
In case you decide to replace the upper right stud.  See text.

Regarding the modified 27 mm or 1-1/16" socket:  
    Obtain a standard 12 point socket, NOT a 6 point.    3/8" or 1/2" drive, so it matches your existing torque wrench (or, get an adapter between 3/8 and 1/2 too).

   Square off the large working END of the socket until all of the small amount of INside taper is gone. You can do this BEST by chucking the socket in a lathe;
but can be done if VERY careful about flatness AND squareness, using a grinding wheel or flat sander.  The lathe does the very best job, and it REALLY is worth having this done properly
if you do not have a lathe.  This first modification of the socket is to eliminate the taper in the working INSIDE END of the socket...but the socket needs one more fix:    Remove
one of the plastic caps over one swing arm adjustment area.  Take a careful look at the inside diameter(s) of the swing arm nut/adjuster cavity.  You
will probably see TWO diameters.  Turn the outside of the socket on a lathe, or by hand on a grinder (crudeness is OK for this), so that the socket will fit
very easily through both diameters in the swing arm cavity and the newly 'made square' end of the socket fits FULLY over the 27 mm nut.  
Do not turn/grind the socket too much, nor too little.  Too much and the socket is weakened (another reason for a 12 point, not 6 point), too little
and the socket will not pass easily by BOTH of the internal swing arm cavity diameters.  SOMEtimes BMW did machine those two diameters concentric
and very nearly the same size.  It is very important that the socket fit squarely and solidly on the thin 27 mm locking nut.
 See near end of this article on how to adjust the swing arm.

1.  There are two articles, besides my clutch article on this website, that you might want to read, and use the information in those articles as an adjunct to
     THIS article.  Those articles are at:   http://www.airheads.org
     Click your mouse on the left side at Technical Tips.   Read the articles on the throwout bearing by Matt Parkhouse, dated 12/99; and mine, on Lubing the
     Transmission/Clutch Splines, dated 12/04.  Those articles are slightly out of date, but may prove useful to you.  Reading those two articles MAY give you
     somewhat different perspective on the article you are presently reading.

2.  Remove the gas tank.  Engage 5th gear on the transmission (4th on /5) and leave it engaged.

3.  Remove the clutch actuating arm at the rear of the transmission.  There were TWO basic old styles of these arms.  One earlier style is held in place by
     a steel pin that has a groove, said groove has a C-clip, and the clip is located at the lower area of the INSIDE between the transmission ears.  If you
     have a /5, you have a cotter pin to the boss. Be SURE that when you reinstall the clutch lever arm that the C clip fits TIGHTLY, and is for
     sure fully in its groove.   Be SURE!  If the clip falls out, and the pin comes partially out, actuating of the bars lever will BREAK OFF a transmission
     ear, stranding you.   The early style arm also has a grease fitting, and the throwout parts are different.  The later style arm uses a 10 mm bolt with waverly
     locking washers, and NO C-clip.  Insert the bolt so the nut is at the LOWER area.  Yes, that is a bit of insurance.  I prefer a Nyloc type of nut.   The later
     arm has no grease fitting.   The Clutch article has information on a simple modification for increased reliability.
    ...read all of #13 below.
    You can now remove the clamp, and boot, if you have those.  You will find a coil spring inside the boot if you have a boot.

4.   If the arm is the late style, push through the steel sleeve (if you can easily) and in any event do clean the arm bearing and lubricate it with OIL.  I coat
     the outer faces (where the arm rubs the transmission ears) lightly with moly grease.  It is QUITE common to see arm needle bearings as having
     NEVER been cleaned and oiled since new...and you can try a bit of heat and cooling to suck in some oil...sometimes that works on really frozen up ones.
     I usually use a bit of heat on the arm and then soak the arm needle bearing area in a light solvent, and later I clean that out, and try to get the needles
     to be movable...and grease them.  DO NOT use a moly grease.
     For the /5, grease the fitting, cleaning innards first.   Clean the bolt or pin and very lightly oil its surface.  Remove the throwout bearing, do not try to
     remove the inner central rod that is forward of the throwout bearing.    The earliest style bearing had BALL bearings,  The later not-as-good style (/6 to
    about 1984) had a flat radial needle/roller bearing, and after 1984 it supposedly is a ball bearing again.  There is some variance in the outer spring and
    black rubber cup, and the single or two part piston, ETC.    Ball bearing types have been seen on years they were not supposedly on, some 1984 for instance.   

NOTE:   Tolerances have varied on the diameter on some transmission throwout bores, and throwout piston tolerances were not held tight enough. 
Generally this is thought of as from 1980, when BMW changed the clutch design radically.    If the piston fits into the bore a bit too tightly...it may still
operate smooth enough when cool, but under some circumstances, as the transmission fully heats up,  may stick.   Measure the piston, and if it is over
about 1.13" (28.7 mm), you MAY want to reduce the outside diameter a bit.  I have seen these as large as about 1.142" that still worked OK.  I can't
give a hard and fast rule here, but if yours is up to 1.141 or so, I would certainly see how it fits, and if a bit too much friction when the transmission is HOT and
that piston is also hot, I would recommend sanding the OD a bit.  Remember that to REALLY test the fit, you have to HEAT the piston to around hot water hot! 
 I have done that, even with the transmission not heated......this works well-enough to determine if the fit is OK.    You can chuck the rather short shaft tip end in
a drill press and use some rather fine sandpaper for reducing the diameter.  Don't taper it.  Takes several minutes to do it right.
Inspect the bearing, and if it looks bad, replace it.  Grease it with a good thin grease (NO moly).  Transmission oil will eventually, one hopes,
dissolve the grease and lubricate the bearing with oil.

Set aside the now cleaned and lubricated arm and throwout associated parts.  It is MUCH easier to move the transmission far enough to
the rear for the input splines greasing, with the clutch lever removed.  In fact, without the lever removed, you probably can not do the
splines properly.   DO NOT injure the transmission ears in any of your work!!   KEEP FILTH AWAY FROM THE PARTS YOU JUST
CLEANED AND LUBRICATED.

5.   Remove the airbox and airfilter.  If you have the older clamshell type housing you will have to push the breather hose out of the half.  If you have the
     later rectangular housing, and depending on what is in the area (pulse air parts, breather hose setup, vacuum line setup, etc.), you may have to move the
     breather hose forward.  Replacing it can be a bit of fun, and it is easier at that time, to simply remove the starter motor cover...and you CAN do that now. 
    With the starter cover off, it is a great time to check the nuts on the electrical post of the starter. Best to have ALL the wires at the negative post of the
    battery disconnected if removing the starter cover.   If you've have had breather problems, now is a great time to fix whatever is wrong.  On late model
    airheads, you can inspect the solenoid valves and vent into the crankcase, and decide whether or not to modify them.  You may even want to change an early
     model disc breather to a later reed type, and clear the bottom of the cavity small drain hole in the breather area (not on early models prior to later
    seventies....see information elsewhere's on this site).   There is nothing wrong with using the original early disc-type breather if in good condition; you could
    even make a replacement for the disc if poor.   

6.  Remove what vacuum and smog parts, if any, that you need to on your particular bike (you may want to modify at this time or before re-assembly). 
    Remove the left lower bolt on the transmission, and the right lower bolt.  NOTE the brown grounding wire at the left lower bolt if you have that.  Pay
    attention to washers.  Remove the left upper bolt.  Remove the nut on the right upper STUD. 

SOME folks may want to fully remove the transmission:
    I suggest you add a nut to the upper right stud, lock the nuts together, and thus remove that stud.   You may want to consider changing that stud to a bolt.  The twin nut is fine,
    can be left in place that way, and you don't REALLY have to remove the stud...for the SPLINE service.  Removing the stud on some models makes
    removing the transmission and other servicing a bit easier, and then USUALLY the battery and battery box need NOT be removed. Your choice here. 
    If you decide to remove the transmission, unfasten the driveshaft U-joint  from the transmission, remove the swing arm adjusters.....this is a good time
    to inspect the 4 special bolts that hold the U-joint...they must be the correct later shorter length and NO!!! lockwashers!!! (Loctite blue is used on the
    threads).

    If you have the rectangular airbox, remove the 13 mm hex headed bolt that goes straight down through the top of the airbox, middle, of the transmission.  Removing
    that 13 mm headed bolt is NOT needed on the clamshell airboxes.  IF you removed that bolt, then when you REinstall that bolt later, coat the first few
    threads AND THE WASHER with a non-hardening thread sealant, such as Permatex Form-A-Gasket #2.    If that bolt is loose, or leaks, oil will be
    sucked out of the transmission. If you have the rectangular airbox, you should now be able to remove the base box. 

NOTE:  BMW uses a metric size vacuum line crossover hose and for the gas line crossover hose that pass through the area.  Use of  SAE
(American, inch size) hose will make for more difficult fitment.  I recommend the stock BMW black hose.  If you have a classic /5, and want to keep
it original, you can get the original silver braded fuel hose from Bing Agency or VW dealerships. I don't think it is as good as the later black BMW metric fuel hose.

7.  HINT!   Some folks have a hard time removing and replacing the plastic input tubes to the carburetors.   On some models, these
     tubes are not the same, left to right, and also ARE NOT the same end for end, and only one fits the proper left or right side, and only
     one end of THAT fits the airbox and carburetor.   MARK yours and their ends before removing!  (such as: "left, to carb"; or, "right, to carb").  For the
     rectangular airboxes, and to some minor extent the clamshell type, it is FAR easier to leave these plastic tubes attached to the airbox
     half or base, and to loosen the clamp(s) at the carburetor end of them and when the the airbox is removed (especially, that rectangular
     box), the whole assembly lifts off easily, and replaces more easily.   If those plastic tubes are off and the rectangular box is already
     installed...,try re-fitting the carbs and intake hoses and plastic tubes all as one assembly at one time as you re-assemble the bike.

8.  Using the Chinese jack from my article as modified, or some other means, typically at the rear lower frame crossover tube (not as easy for a model with the
     pre-muffler under the transmission area); jack the rear tire barely off the ground.  If you have a ride-off stand you may want to find a way to put a
     3/4 inch or so piece of plywood under the ride-off stand by rocking the stand left/right, as you install a board.  Bikes vary, play with yours until you
     find out what is needed.  Remove the plastic covers over the swing arm adjusters, and loosen the two 27 mm nuts with the socket you modified, maybe only 1/4-1/2 turn loosening
     is needed, and then UNscrew the allen-center adjuster on each side, and REMOVE the adjuster with the nut still attached.  You may have to
     wiggle the tire/swing arm a bit to allow the adjusters to be removed, and that helps avoid damaging the threads.  I have seen these not lubricated
     properly and rusted badly.  I have seen the bearings rusted bad enough to crack!  If yours are bad, I recommend you remove the entire rear
     end of the bike and service the swing arm bearing area.    Various puller styles will work to remove the outer bearing race, Ed Korn (see tools.htm
     article) made a cute one, and in a kit to install the new one.  It is a simple job.   The swing arm bearing is basically the same as the pre-1985 wheel
     bearing, a common type from any bearing supply company.  I prefer to NOT use sealed versions of those bearings (or, I remove the seal), allowing
     ME to better grease from the outside, after the bike is reassembled, via the center Allen wrench hole in the threaded pin adjustor. 

9.  There is sometimes no need to undo any shift linkage for just a spline re-lubrication.   You DO have to undo the wing-nut on the rear brake rod,
      if you have a drear drum brake.

10.  Pull rearward on the transmission.  It will likely come backwards a wee bit.  The limit for the rear movement is typically not the clutch ears but the
       driveshaft housing interfering with the frame cross tube.  You will probably find you need to HOLD the transmission backwards.  While you can use
       some pieces of WOOD (NOT METAL!!) to wedge into the transmission-engine opening (and may end up doing that anyway), you MAY want to
       fashion some means to KEEP the suspension/etc moved to the rear.  I do this by hooking a STRONG bungee from a lower spring/shock unit, back to the
       turn signal tube, VERY tightly (on both sides if a twin shock model).    If you play with the transmission and rear end movement a bit, you will find that
       you can separate the transmission from the engine JUST enough so that the input shaft forward end is visible.

****NOTE!  It is not uncommon for someone to complain that the transmission will not move backwards much.  See #9, just above!!

****NOTE!   If you see an OILY spline at the transmission and see oil coming from the input end of the transmission, you MUST undo the universal
joint, remove the transmission entirely, and replace the transmission input seal.  Failure to do that will result in eventually oiling the clutch.  This is an
easy job if the transmission is out, you do NOT have to take the transmission apart.  

 Some may prefer to totally remove the transmission, and clean the area at the clutch and transmission, check for leaking oil pump seal, leaking main seal, etc.  NOT mandatory unless you see leaks.

Ideally, the transmission, when in the bike, is back far enough to see fully that input shaft end I mentioned just above of the transmission
input spline.  It is nice to be able to get the center rod to the rear enough to get to the rod tip with one droplet of lube, later.

11.  Blow out any dust and dirt from the area.  Do that now, rather than later.  DO NOT breath that dust.   Under NO circumstances allow
       any prying with metal tools that will nick the transmission-engine mating surfaces, thereby causing the transmission not to re-assemble dead squarely
       to the engine.  CLEAN the splines of the INPUT shaft (NOT clutch disc!).    If the splined center of the clutch disc is very greasy,
       clean with a rag.  DO NOT SPRAY SOLVENT ON THE DISC SPLINES.

To both clean and grease the transmission shaft input splines, I make up TWO simple tools:

Take two common "acid brushes".  You can get them at most hardware stores, or Harbor Freight has quantities, cheap.
Cut the bristles down in length, by maybe nearly 1/2, so they are stiffer.  Tape or otherwise tie securely those
brushes to some sort of thin rods or any similar items, such that the brush handle length is extended.  ONE brush tool is your permanent tool for
cleaning the input splines, the other is for your permanent tool for greasing those splines.  You only need make these two tools once, so after you are done with them, put them on your
shelf of BMW tools.  I use wood dowels from the hardware store. I am guessing my dowels are maybe 3/8" in diameter.

To clean the transmission input splines, use some sort of strong petroleum-based solvent on one of the brushes, and move the brush back and forth along the INPUT
spline; that is, the TRANSMISSION spline.  Rotate the spline as need be, by rotating the rear wheel (which is off the ground and the transmission is
still in top gear).  I like to finish the INPUT spline by spraying a good cleaner on it, but remember, do NOT clean the spline of the disc!...except to wipe
with a rag if need be.   If you spray solvent into the clutch disc splines, that can easily put grease/oil/grunge, into the friction disc....so do NOT do that. 
  Common BRAKE CLEANER does NOT do a good job for cleaning; in fact it is LOUSY.  I use acetone, MEK, or similar strong and fast evaporating solvents; or,  
Berryman B12 carburetor and choke cleaner in the spray can, with a spray wand, is good!!

IF that area shows OIL leakage from the transmission, remove the transmission and replace that seal...and ask the LIST or check my transmission article on how to do that!  It is not
difficult and you do not need to disassemble the transmission.  Failure to replace a leaky seal will ruin your clutch eventually.   There are TWO ways
 transmission oil can get into your clutch.  ONE is via a bad transmission input shaft seal.  The other way is a missing round tubular FELT, that can be
somewhat of a devil to install, located, hidden, around the rod that passes from the rear throwout bearing area to the tip of the input shaft.  It is easier
to install that from the forward nose (input shaft spline end).  If you have NOT removed the transmission, you have likely not been able to remove
that rod accidentally, so, you should have no problem with that felt at this point, as the felts last darn near forever. 

Grease the INPUT SHAFT splines once the solvent is totally evaporated.  Work the grease into the splines, bit by bit, all around, using the greasing
brush tool.  It is not needed, nor desirable, for too much grease.

If the rod END that is in the center of the input shaft is not visible, make it visible.  This is usually easy with the clutch lever having been removed at the
rear.  You can either grip the rod at the rear, or use the end of a screwdriver against the forward end of that metal rod, to move it rearward to see the tip.
  Put ONE SMALL drop of moly grease on the tip, and putting a drop at the rear is a good idea too.

Clean the surfaces of the transmission shell that will contact the engine surfaces.  Take your time to do this properly.   Under NO circumstances are any nicks,
 nor filth allowable that would keep the transmission from SQUARELY and FULLY mating to the engine surface.   Clean the engine mounting surface too.
Keep in mind that a prior owner or workman could have left nicks keeping the surfaces from mating 100.000%.  Fix any such things.  Since YOU did not use
metal tools in prying the transmission-engine apart, YOU did not leave nicks.

12A.  Reassemble everything, bit by bit, slowly, and carefully.   Do NOT allow foreign matter to interfere with the transmission coming up to the engine
       cleanly, and squarely, and fully.  Be sure the transmission is fitting squarely,  and then cinch up the bolts, evenly, in a cross pattern.  Do not forget the
       vertical 13 mm bolt (you HAVE used a sealant on that bolt and washer??).    The clam shell model requires the right clam shell to be in place for this. 
       Do NOT forget the grounding wire.   You can now reinstall the throwout parts and the clutch lever at the rear....and do any cleaning and lubrication there that you did not do previously.

12B.  Centralizing and adjusting the rear swing arm:

    After the adjusters and locknuts are replaced into the frame cavities and engaging the swing arm, these adjusters (pivot bolts) need to be adjusted.  
If you did not move the locknuts originally except perhaps 1/2 turn, or 1 turn, as needed to just loosen them, it will be a bit quicker.  In any case, what
you must do is screw both adjusters inward with an Allen wrench, a bit and as evenly as you can on each side.  DO NOT try to really tighten them much.  
Try to keep the swing arm roughly centered in the frame.  You can use a small allen wrench from the BMW on-bike tool kit, or a selected diameter of
drill shank, using them as a thickness gauge, placed between the FRAME and the SWING ARM, to get the swing arm centered in the frame.  This may
take a few attempts until the swing arm is centered; that is, the selected size of drill shank or allen wrench inserted between frame and swing arm shows
the same spacing, side to side.  Loosen one pivot bolt, tighten a wee bit the other, until things are close.  DO NOT USE MUCH FORCE.
  What you will then do is torque one of these pivot adjusters to 15 ftlbs, back off a bit, re-torque to 7-1/2 foot pounds,
stopping at 7-1/2 whilst going in the clockwise tightening direction.  If the spacing is now fairly equal, fine, if not, back off one adjuster, tighten the other,
in the same manner, and repeat until near perfect, then tighten the 27 mm thin steel nuts with your modified socket and torque wrench to 70 to 75 foot pounds.  
Some folks paint mark the end of adjusters to be sure that they have not moved while the 27 mm nut is being tightened, usually they do not move.

There is nothing super-critical about the equality of the spacing.  If you are within maybe .020", that is good enough.  

NOTE!!....just to be sure there is NO confusion here.....there will be NO feelable side to side freeplay in the swing arm to frame mounting, when you
have adjusted the pivot adjusters properly.   You are taking up all free play, equally spacing the swing arm in the frame (side to side), and then leaving
the adjustors with some torque on them, specified at 7-1/2 footpounds, AFTER first torquing to 15 footpounds, backing off, and resetting to 7-1/2. 
Obviously, setting one side presses the swing arm against the other side, so you can't do both at the same time together.  You do the centering
adjustment, bring the pivot adjusters close to correctness, and then adjust ONE side for proper torque, and see if the other side and the first side
 match in DISTANCE.   After you have done this once, you will find it very easy.  Use your torque wrench with the Allen of 6 mm size, the other end
 the square drive to match your torque wrench.

NOTE!!   I grease my swing arm pivot/bearings roughly twice a year, depending on my traveling conditions.  I grease both sides with my pointy-tipped grease
gun with the tapered rubber tip (common item, NAPA stores).    Every few years I pull the entire rear structure backwards enough to hand-clean and
eyeball inspect, and finger-feel, the condition of the bearings.  You can also use a chain saw grease gun with pointy tip.  At one time there was a
BMW grease gun.    I use quite a goodly amount of grease, and then I use my fingertip to wipe the excess grease, all-around, down to smooth coverage.
Making this clear, the grease is in the area between the frame inside surface and the swing arm inside surface. 
That way, any water getting in the area will see a layer of grease in that 'cavity' for which you set the equality distance.  I prefer the NON-sealed
bearings, so all this greasing works properly.  If I have a sealed bearing I am installing, I may destroy the seal first ON PURPOSE.  Late models may have sealed
swing arm bearings....I have seen earlier models with this type and with an intact seal you have to go about greasing things differently....like with a
sharp grease needle from the side;....through the seal.....etc.   I prefer UNsealed bearings, with a lot of grease, smoothly done, in the mentioned space.

Every few years it is not a bad idea to remove the swing arm...or move it backwards...enough to do a thorough bearing service.  As noted, I like to
leave enough grease in the measured space area that rain, washing, etc. does not get in there.  As mentioned, a sealed bearing is not needed.  In fact,
the R45/R65 models came without one spacer and grease containment item.  Again, as mentioned,  if I find the bearing sealed, I usually prick or otherwise actually on
purpose damage the seal, so greasing goes to the proper areas.   The bearing is the same type and size as used on the PRE-1985 wheel bearings....
type 30203, a very common part.

13.  If not already done, I add a wee dab of moly grease to the working end of the clutch arm where it fits against the rod in the transmission and
     re-install the clutch arm and associated parts. Note that I, as mentioned previously, have also put a small amount on the tip of the rod at the front before the transmission is pushed forward. 
     AGAIN, I caution that if you have the early style lever that uses the pin with the C-clip, it MUST be installed properly...better yet, change it,
     so read onwards (and also refer back to #3): 

The /5 uses a cotter pin; totally reliable.  The later models use a bolt, put the bolt in from the top. Watch how the arm is installed, even on the later
models.  The arm thickness with its sleeve, whatever, is such that you should not be able to break the ears off the transmission as tightening progresses.
The spacing between transmission ears is a fixed spacing. Be sure what you are doing is not going to try to bend the ears inwards.

From the 1980 model, BMW changed the pin through the clutch lever at the rear of the transmission.  The new style is easily fitted to earlier 5 speed transmissions. 
This is a mushroom headed pin part 23-13-1-241-484 with clip 51-23-1-864-963.   Many (/6 onwards) early models had the clutch actuating lever at the rear
of the transmission held to the two bosses of the transmission cover by a PIN, that used a single C clip.  That C-clip fit on the pin at the INside of the
lower boss.  If the clip came loose, or was not fitted fully, the pin could come upwards, and come out of the lower boss, and the next clutch application
could, and often did, break off a transmission boss ear...necessitating a transmission overhaul....or some inert gas welding at a minimum.   A cure is to
remove the old pin and clip and install the above two parts.    VERY highly recommended!!

WATCH what you are doing!    Refer back to #3.   Adjust the clutch per the book if need be.  You normally will not have to if it was OK before
you started all this.  It is a darn good idea to lubricate the two barrels of the clutch cable, one at the bars, one at the lever at the transmission.   At the
lever at the handlebars, inspect to be sure that the cable is NOT being fouled by the lever movement, and all strands are INTACT!  

 

14.   The adjustment of the early style (up to 1980) and the 1981+ style clutch/levers is different.    They end up being about the same though.  About
        3/32" of free play at the inner opening point of the bar lever is about right, and the lever at the transmission will be parallel with the transmission rear
        with the bar lever pulled half way.  For the 1981+ bikes, the tip of the transmission mounted lever should be 5.0 inches from the cable boss with the
        lever NOT being actuated at the bars.   Set the free-play for the lever at the bars via the adjustment in the clutch arm; and set the transmission lever
        via the bars knurled nut; all of which is exactly opposite of what common sense would seem to tell you.  For the 1981+ bikes, the transmission mounted
        lever will actually face rearward about 4° at rest.

  Revisions:
01-15-2003:  Clarify and add to tools list; add applicability and skill level; add reference note on 50,45, 40 mm bolts.
01-22-2003:  Add section on adjusting the swing arm, and modify here and there to incorporate clarity for that, add hyperlink within the page for that adjustment.  Add #13.
04-16-2003:  add .htm title; clarify many details.
05/06/2003:  add note on ball type throwout bearing seen on 1984; note to coat the 13 mm bolt's WASHER in top of transmission; typos; input seal note in #10; clarifications
05/11/2003:  rework #12, to eliminate one reported incident of someone managing to jam something or other.  How???
05/15/2003:  correct typo, 1-1/6" should be 1-1/16".
07/26/2003:  expand #13, add ref to #3, and add #14
08/28/2003:  add #15.
11/21/2004:  remove #15, back into #13, and references to #3 added as necessary.
06/01/2005:  bearing number added
07/10/2005:  updated to eliminate some confusion in procedure
07/11/2005:  additional small changes on adjusting swing arm, and about the seals there
07/23/2007:  Some editing for clarity
11/04/2008:  In item 13, change part number of pin from 23-21-1-241-484 to proper 23-13-1-241-484
12/05/2008:  Update item 12 for clarity.
08/31/2009:  minor clarifications
10/27/2009:  Clarify a lot more details
10/28/2009:  Add wing-nut information, #9, #10.
06/24/2010:  Add information on why fine and not coarse splines at the input shaft, clean up article a bit (not a thorough job)
07/02/2010:  Corrected minor typos, clean up article, add notations to clarify about K bikes, other minor stuff.
05/16/2011:  fix typo in #12
10/13/2011:  minor for clarity
10/19/2011:  Do a bit more re-arranging, etc., for clarity
11/16/2011:  Removed discussion on specific greases, and refer to my extensive article #73.
04/08/2012:  Clarify details on throw-out bearings, and a few more minor points elsewhere's.

© Copyright, 2012, R. Fleischer

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